drm/i915: s/gen8_setup_page_directory/gen8_setup_pdpe/

[mirror_ubuntu-bionic-kernel.git] / drivers / gpu / drm / i915 / i915_gem_gtt.c

/*
 * Copyright © 2010 Daniel Vetter
 * Copyright © 2011-2014 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 */

#include <linux/seq_file.h>
#include <linux/stop_machine.h>
#include <drm/drmP.h>
#include <drm/i915_drm.h>
#include "i915_drv.h"
#include "i915_vgpu.h"
#include "i915_trace.h"
#include "intel_drv.h"
#include "intel_frontbuffer.h"

#define I915_GFP_DMA (GFP_KERNEL | __GFP_HIGHMEM)

/**
 * DOC: Global GTT views
 *
 * Background and previous state
 *
 * Historically objects could exists (be bound) in global GTT space only as
 * singular instances with a view representing all of the object's backing pages
 * in a linear fashion. This view will be called a normal view.
 *
 * To support multiple views of the same object, where the number of mapped
 * pages is not equal to the backing store, or where the layout of the pages
 * is not linear, concept of a GGTT view was added.
 *
 * One example of an alternative view is a stereo display driven by a single
 * image. In this case we would have a framebuffer looking like this
 * (2x2 pages):
 *
 *    12
 *    34
 *
 * Above would represent a normal GGTT view as normally mapped for GPU or CPU
 * rendering. In contrast, fed to the display engine would be an alternative
 * view which could look something like this:
 *
 *   1212
 *   3434
 *
 * In this example both the size and layout of pages in the alternative view is
 * different from the normal view.
 *
 * Implementation and usage
 *
 * GGTT views are implemented using VMAs and are distinguished via enum
 * i915_ggtt_view_type and struct i915_ggtt_view.
 *
 * A new flavour of core GEM functions which work with GGTT bound objects were
 * added with the _ggtt_ infix, and sometimes with _view postfix to avoid
 * renaming  in large amounts of code. They take the struct i915_ggtt_view
 * parameter encapsulating all metadata required to implement a view.
 *
 * As a helper for callers which are only interested in the normal view,
 * globally const i915_ggtt_view_normal singleton instance exists. All old core
 * GEM API functions, the ones not taking the view parameter, are operating on,
 * or with the normal GGTT view.
 *
 * Code wanting to add or use a new GGTT view needs to:
 *
 * 1. Add a new enum with a suitable name.
 * 2. Extend the metadata in the i915_ggtt_view structure if required.
 * 3. Add support to i915_get_vma_pages().
 *
 * New views are required to build a scatter-gather table from within the
 * i915_get_vma_pages function. This table is stored in the vma.ggtt_view and
 * exists for the lifetime of an VMA.
 *
 * Core API is designed to have copy semantics which means that passed in
 * struct i915_ggtt_view does not need to be persistent (left around after
 * calling the core API functions).
 *
 */

static int
i915_get_ggtt_vma_pages(struct i915_vma *vma);

const struct i915_ggtt_view i915_ggtt_view_normal = {
        .type = I915_GGTT_VIEW_NORMAL,
};
const struct i915_ggtt_view i915_ggtt_view_rotated = {
        .type = I915_GGTT_VIEW_ROTATED,
};

int intel_sanitize_enable_ppgtt(struct drm_i915_private *dev_priv,
                                int enable_ppgtt)
{
        bool has_aliasing_ppgtt;
        bool has_full_ppgtt;
        bool has_full_48bit_ppgtt;

        has_aliasing_ppgtt = dev_priv->info.has_aliasing_ppgtt;
        has_full_ppgtt = dev_priv->info.has_full_ppgtt;
        has_full_48bit_ppgtt = dev_priv->info.has_full_48bit_ppgtt;

        if (intel_vgpu_active(dev_priv)) {
                /* emulation is too hard */
                has_full_ppgtt = false;
                has_full_48bit_ppgtt = false;
        }

        if (!has_aliasing_ppgtt)
                return 0;

        /*
         * We don't allow disabling PPGTT for gen9+ as it's a requirement for
         * execlists, the sole mechanism available to submit work.
         */
        if (enable_ppgtt == 0 && INTEL_GEN(dev_priv) < 9)
                return 0;

        if (enable_ppgtt == 1)
                return 1;

        if (enable_ppgtt == 2 && has_full_ppgtt)
                return 2;

        if (enable_ppgtt == 3 && has_full_48bit_ppgtt)
                return 3;

#ifdef CONFIG_INTEL_IOMMU
        /* Disable ppgtt on SNB if VT-d is on. */
        if (IS_GEN6(dev_priv) && intel_iommu_gfx_mapped) {
                DRM_INFO("Disabling PPGTT because VT-d is on\n");
                return 0;
        }
#endif

        /* Early VLV doesn't have this */
        if (IS_VALLEYVIEW(dev_priv) && dev_priv->drm.pdev->revision < 0xb) {
                DRM_DEBUG_DRIVER("disabling PPGTT on pre-B3 step VLV\n");
                return 0;
        }

        if (INTEL_GEN(dev_priv) >= 8 && i915.enable_execlists && has_full_ppgtt)
                return has_full_48bit_ppgtt ? 3 : 2;
        else
                return has_aliasing_ppgtt ? 1 : 0;
}

static int ppgtt_bind_vma(struct i915_vma *vma,
                          enum i915_cache_level cache_level,
                          u32 unused)
{
        u32 pte_flags = 0;

        vma->pages = vma->obj->mm.pages;

        /* Currently applicable only to VLV */
        if (vma->obj->gt_ro)
                pte_flags |= PTE_READ_ONLY;

        vma->vm->insert_entries(vma->vm, vma->pages, vma->node.start,
                                cache_level, pte_flags);

        return 0;
}

static void ppgtt_unbind_vma(struct i915_vma *vma)
{
        vma->vm->clear_range(vma->vm,
                             vma->node.start,
                             vma->size);
}

static gen8_pte_t gen8_pte_encode(dma_addr_t addr,
                                  enum i915_cache_level level)
{
        gen8_pte_t pte = _PAGE_PRESENT | _PAGE_RW;
        pte |= addr;

        switch (level) {
        case I915_CACHE_NONE:
                pte |= PPAT_UNCACHED_INDEX;
                break;
        case I915_CACHE_WT:
                pte |= PPAT_DISPLAY_ELLC_INDEX;
                break;
        default:
                pte |= PPAT_CACHED_INDEX;
                break;
        }

        return pte;
}

static gen8_pde_t gen8_pde_encode(const dma_addr_t addr,
                                  const enum i915_cache_level level)
{
        gen8_pde_t pde = _PAGE_PRESENT | _PAGE_RW;
        pde |= addr;
        if (level != I915_CACHE_NONE)
                pde |= PPAT_CACHED_PDE_INDEX;
        else
                pde |= PPAT_UNCACHED_INDEX;
        return pde;
}

#define gen8_pdpe_encode gen8_pde_encode
#define gen8_pml4e_encode gen8_pde_encode

static gen6_pte_t snb_pte_encode(dma_addr_t addr,
                                 enum i915_cache_level level,
                                 u32 unused)
{
        gen6_pte_t pte = GEN6_PTE_VALID;
        pte |= GEN6_PTE_ADDR_ENCODE(addr);

        switch (level) {
        case I915_CACHE_L3_LLC:
        case I915_CACHE_LLC:
                pte |= GEN6_PTE_CACHE_LLC;
                break;
        case I915_CACHE_NONE:
                pte |= GEN6_PTE_UNCACHED;
                break;
        default:
                MISSING_CASE(level);
        }

        return pte;
}

static gen6_pte_t ivb_pte_encode(dma_addr_t addr,
                                 enum i915_cache_level level,
                                 u32 unused)
{
        gen6_pte_t pte = GEN6_PTE_VALID;
        pte |= GEN6_PTE_ADDR_ENCODE(addr);

        switch (level) {
        case I915_CACHE_L3_LLC:
                pte |= GEN7_PTE_CACHE_L3_LLC;
                break;
        case I915_CACHE_LLC:
                pte |= GEN6_PTE_CACHE_LLC;
                break;
        case I915_CACHE_NONE:
                pte |= GEN6_PTE_UNCACHED;
                break;
        default:
                MISSING_CASE(level);
        }

        return pte;
}

static gen6_pte_t byt_pte_encode(dma_addr_t addr,
                                 enum i915_cache_level level,
                                 u32 flags)
{
        gen6_pte_t pte = GEN6_PTE_VALID;
        pte |= GEN6_PTE_ADDR_ENCODE(addr);

        if (!(flags & PTE_READ_ONLY))
                pte |= BYT_PTE_WRITEABLE;

        if (level != I915_CACHE_NONE)
                pte |= BYT_PTE_SNOOPED_BY_CPU_CACHES;

        return pte;
}

static gen6_pte_t hsw_pte_encode(dma_addr_t addr,
                                 enum i915_cache_level level,
                                 u32 unused)
{
        gen6_pte_t pte = GEN6_PTE_VALID;
        pte |= HSW_PTE_ADDR_ENCODE(addr);

        if (level != I915_CACHE_NONE)
                pte |= HSW_WB_LLC_AGE3;

        return pte;
}

static gen6_pte_t iris_pte_encode(dma_addr_t addr,
                                  enum i915_cache_level level,
                                  u32 unused)
{
        gen6_pte_t pte = GEN6_PTE_VALID;
        pte |= HSW_PTE_ADDR_ENCODE(addr);

        switch (level) {
        case I915_CACHE_NONE:
                break;
        case I915_CACHE_WT:
                pte |= HSW_WT_ELLC_LLC_AGE3;
                break;
        default:
                pte |= HSW_WB_ELLC_LLC_AGE3;
                break;
        }

        return pte;
}

static int __setup_page_dma(struct drm_i915_private *dev_priv,
                            struct i915_page_dma *p, gfp_t flags)
{
        struct device *kdev = &dev_priv->drm.pdev->dev;

        p->page = alloc_page(flags);
        if (!p->page)
                return -ENOMEM;

        p->daddr = dma_map_page(kdev,
                                p->page, 0, 4096, PCI_DMA_BIDIRECTIONAL);

        if (dma_mapping_error(kdev, p->daddr)) {
                __free_page(p->page);
                return -EINVAL;
        }

        return 0;
}

static int setup_page_dma(struct drm_i915_private *dev_priv,
                          struct i915_page_dma *p)
{
        return __setup_page_dma(dev_priv, p, I915_GFP_DMA);
}

static void cleanup_page_dma(struct drm_i915_private *dev_priv,
                             struct i915_page_dma *p)
{
        struct pci_dev *pdev = dev_priv->drm.pdev;

        if (WARN_ON(!p->page))
                return;

        dma_unmap_page(&pdev->dev, p->daddr, 4096, PCI_DMA_BIDIRECTIONAL);
        __free_page(p->page);
        memset(p, 0, sizeof(*p));
}

static void *kmap_page_dma(struct i915_page_dma *p)
{
        return kmap_atomic(p->page);
}

/* We use the flushing unmap only with ppgtt structures:
 * page directories, page tables and scratch pages.
 */
static void kunmap_page_dma(struct drm_i915_private *dev_priv, void *vaddr)
{
        /* There are only few exceptions for gen >=6. chv and bxt.
         * And we are not sure about the latter so play safe for now.
         */
        if (IS_CHERRYVIEW(dev_priv) || IS_GEN9_LP(dev_priv))
                drm_clflush_virt_range(vaddr, PAGE_SIZE);

        kunmap_atomic(vaddr);
}

#define kmap_px(px) kmap_page_dma(px_base(px))
#define kunmap_px(ppgtt, vaddr) \
                kunmap_page_dma((ppgtt)->base.i915, (vaddr))

#define setup_px(dev_priv, px) setup_page_dma((dev_priv), px_base(px))
#define cleanup_px(dev_priv, px) cleanup_page_dma((dev_priv), px_base(px))
#define fill_px(dev_priv, px, v) fill_page_dma((dev_priv), px_base(px), (v))
#define fill32_px(dev_priv, px, v) \
                fill_page_dma_32((dev_priv), px_base(px), (v))

static void fill_page_dma(struct drm_i915_private *dev_priv,
                          struct i915_page_dma *p, const uint64_t val)
{
        int i;
        uint64_t * const vaddr = kmap_page_dma(p);

        for (i = 0; i < 512; i++)
                vaddr[i] = val;

        kunmap_page_dma(dev_priv, vaddr);
}

static void fill_page_dma_32(struct drm_i915_private *dev_priv,
                             struct i915_page_dma *p, const uint32_t val32)
{
        uint64_t v = val32;

        v = v << 32 | val32;

        fill_page_dma(dev_priv, p, v);
}

static int
setup_scratch_page(struct drm_i915_private *dev_priv,
                   struct i915_page_dma *scratch,
                   gfp_t gfp)
{
        return __setup_page_dma(dev_priv, scratch, gfp | __GFP_ZERO);
}

static void cleanup_scratch_page(struct drm_i915_private *dev_priv,
                                 struct i915_page_dma *scratch)
{
        cleanup_page_dma(dev_priv, scratch);
}

static struct i915_page_table *alloc_pt(struct drm_i915_private *dev_priv)
{
        struct i915_page_table *pt;
        const size_t count = INTEL_GEN(dev_priv) >= 8 ? GEN8_PTES : GEN6_PTES;
        int ret = -ENOMEM;

        pt = kzalloc(sizeof(*pt), GFP_KERNEL);
        if (!pt)
                return ERR_PTR(-ENOMEM);

        pt->used_ptes = kcalloc(BITS_TO_LONGS(count), sizeof(*pt->used_ptes),
                                GFP_KERNEL);

        if (!pt->used_ptes)
                goto fail_bitmap;

        ret = setup_px(dev_priv, pt);
        if (ret)
                goto fail_page_m;

        return pt;

fail_page_m:
        kfree(pt->used_ptes);
fail_bitmap:
        kfree(pt);

        return ERR_PTR(ret);
}

static void free_pt(struct drm_i915_private *dev_priv,
                    struct i915_page_table *pt)
{
        cleanup_px(dev_priv, pt);
        kfree(pt->used_ptes);
        kfree(pt);
}

static void gen8_initialize_pt(struct i915_address_space *vm,
                               struct i915_page_table *pt)
{
        gen8_pte_t scratch_pte;

        scratch_pte = gen8_pte_encode(vm->scratch_page.daddr,
                                      I915_CACHE_LLC);

        fill_px(vm->i915, pt, scratch_pte);
}

static void gen6_initialize_pt(struct i915_address_space *vm,
                               struct i915_page_table *pt)
{
        gen6_pte_t scratch_pte;

        WARN_ON(vm->scratch_page.daddr == 0);

        scratch_pte = vm->pte_encode(vm->scratch_page.daddr,
                                     I915_CACHE_LLC, 0);

        fill32_px(vm->i915, pt, scratch_pte);
}

static struct i915_page_directory *alloc_pd(struct drm_i915_private *dev_priv)
{
        struct i915_page_directory *pd;
        int ret = -ENOMEM;

        pd = kzalloc(sizeof(*pd), GFP_KERNEL);
        if (!pd)
                return ERR_PTR(-ENOMEM);

        pd->used_pdes = kcalloc(BITS_TO_LONGS(I915_PDES),
                                sizeof(*pd->used_pdes), GFP_KERNEL);
        if (!pd->used_pdes)
                goto fail_bitmap;

        ret = setup_px(dev_priv, pd);
        if (ret)
                goto fail_page_m;

        return pd;

fail_page_m:
        kfree(pd->used_pdes);
fail_bitmap:
        kfree(pd);

        return ERR_PTR(ret);
}

static void free_pd(struct drm_i915_private *dev_priv,
                    struct i915_page_directory *pd)
{
        if (px_page(pd)) {
                cleanup_px(dev_priv, pd);
                kfree(pd->used_pdes);
                kfree(pd);
        }
}

static void gen8_initialize_pd(struct i915_address_space *vm,
                               struct i915_page_directory *pd)
{
        gen8_pde_t scratch_pde;

        scratch_pde = gen8_pde_encode(px_dma(vm->scratch_pt), I915_CACHE_LLC);

        fill_px(vm->i915, pd, scratch_pde);
}

static int __pdp_init(struct drm_i915_private *dev_priv,
                      struct i915_page_directory_pointer *pdp)
{
        size_t pdpes = I915_PDPES_PER_PDP(dev_priv);

        pdp->used_pdpes = kcalloc(BITS_TO_LONGS(pdpes),
                                  sizeof(unsigned long),
                                  GFP_KERNEL);
        if (!pdp->used_pdpes)
                return -ENOMEM;

        pdp->page_directory = kcalloc(pdpes, sizeof(*pdp->page_directory),
                                      GFP_KERNEL);
        if (!pdp->page_directory) {
                kfree(pdp->used_pdpes);
                /* the PDP might be the statically allocated top level. Keep it
                 * as clean as possible */
                pdp->used_pdpes = NULL;
                return -ENOMEM;
        }

        return 0;
}

static void __pdp_fini(struct i915_page_directory_pointer *pdp)
{
        kfree(pdp->used_pdpes);
        kfree(pdp->page_directory);
        pdp->page_directory = NULL;
}

static struct
i915_page_directory_pointer *alloc_pdp(struct drm_i915_private *dev_priv)
{
        struct i915_page_directory_pointer *pdp;
        int ret = -ENOMEM;

        WARN_ON(!USES_FULL_48BIT_PPGTT(dev_priv));

        pdp = kzalloc(sizeof(*pdp), GFP_KERNEL);
        if (!pdp)
                return ERR_PTR(-ENOMEM);

        ret = __pdp_init(dev_priv, pdp);
        if (ret)
                goto fail_bitmap;

        ret = setup_px(dev_priv, pdp);
        if (ret)
                goto fail_page_m;

        return pdp;

fail_page_m:
        __pdp_fini(pdp);
fail_bitmap:
        kfree(pdp);

        return ERR_PTR(ret);
}

static void free_pdp(struct drm_i915_private *dev_priv,
                     struct i915_page_directory_pointer *pdp)
{
        __pdp_fini(pdp);
        if (USES_FULL_48BIT_PPGTT(dev_priv)) {
                cleanup_px(dev_priv, pdp);
                kfree(pdp);
        }
}

static void gen8_initialize_pdp(struct i915_address_space *vm,
                                struct i915_page_directory_pointer *pdp)
{
        gen8_ppgtt_pdpe_t scratch_pdpe;

        scratch_pdpe = gen8_pdpe_encode(px_dma(vm->scratch_pd), I915_CACHE_LLC);

        fill_px(vm->i915, pdp, scratch_pdpe);
}

static void gen8_initialize_pml4(struct i915_address_space *vm,
                                 struct i915_pml4 *pml4)
{
        gen8_ppgtt_pml4e_t scratch_pml4e;

        scratch_pml4e = gen8_pml4e_encode(px_dma(vm->scratch_pdp),
                                          I915_CACHE_LLC);

        fill_px(vm->i915, pml4, scratch_pml4e);
}

static void
gen8_setup_pdpe(struct i915_hw_ppgtt *ppgtt,
                struct i915_page_directory_pointer *pdp,
                struct i915_page_directory *pd,
                int index)
{
        gen8_ppgtt_pdpe_t *page_directorypo;

        if (!USES_FULL_48BIT_PPGTT(to_i915(ppgtt->base.dev)))
                return;

        page_directorypo = kmap_px(pdp);
        page_directorypo[index] = gen8_pdpe_encode(px_dma(pd), I915_CACHE_LLC);
        kunmap_px(ppgtt, page_directorypo);
}

static void
gen8_setup_page_directory_pointer(struct i915_hw_ppgtt *ppgtt,
                                  struct i915_pml4 *pml4,
                                  struct i915_page_directory_pointer *pdp,
                                  int index)
{
        gen8_ppgtt_pml4e_t *pagemap = kmap_px(pml4);

        WARN_ON(!USES_FULL_48BIT_PPGTT(to_i915(ppgtt->base.dev)));
        pagemap[index] = gen8_pml4e_encode(px_dma(pdp), I915_CACHE_LLC);
        kunmap_px(ppgtt, pagemap);
}

/* Broadwell Page Directory Pointer Descriptors */
static int gen8_write_pdp(struct drm_i915_gem_request *req,
                          unsigned entry,
                          dma_addr_t addr)
{
        struct intel_ring *ring = req->ring;
        struct intel_engine_cs *engine = req->engine;
        int ret;

        BUG_ON(entry >= 4);

        ret = intel_ring_begin(req, 6);
        if (ret)
                return ret;

        intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(1));
        intel_ring_emit_reg(ring, GEN8_RING_PDP_UDW(engine, entry));
        intel_ring_emit(ring, upper_32_bits(addr));
        intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(1));
        intel_ring_emit_reg(ring, GEN8_RING_PDP_LDW(engine, entry));
        intel_ring_emit(ring, lower_32_bits(addr));
        intel_ring_advance(ring);

        return 0;
}

static int gen8_legacy_mm_switch(struct i915_hw_ppgtt *ppgtt,
                                 struct drm_i915_gem_request *req)
{
        int i, ret;

        for (i = GEN8_LEGACY_PDPES - 1; i >= 0; i--) {
                const dma_addr_t pd_daddr = i915_page_dir_dma_addr(ppgtt, i);

                ret = gen8_write_pdp(req, i, pd_daddr);
                if (ret)
                        return ret;
        }

        return 0;
}

static int gen8_48b_mm_switch(struct i915_hw_ppgtt *ppgtt,
                              struct drm_i915_gem_request *req)
{
        return gen8_write_pdp(req, 0, px_dma(&ppgtt->pml4));
}

/* PDE TLBs are a pain to invalidate on GEN8+. When we modify
 * the page table structures, we mark them dirty so that
 * context switching/execlist queuing code takes extra steps
 * to ensure that tlbs are flushed.
 */
static void mark_tlbs_dirty(struct i915_hw_ppgtt *ppgtt)
{
        ppgtt->pd_dirty_rings = INTEL_INFO(ppgtt->base.i915)->ring_mask;
}

/* Removes entries from a single page table, releasing it if it's empty.
 * Caller can use the return value to update higher-level entries.
 */
static bool gen8_ppgtt_clear_pt(struct i915_address_space *vm,
                                struct i915_page_table *pt,
                                uint64_t start,
                                uint64_t length)
{
        struct i915_hw_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
        unsigned int num_entries = gen8_pte_count(start, length);
        unsigned int pte = gen8_pte_index(start);
        unsigned int pte_end = pte + num_entries;
        gen8_pte_t *pt_vaddr;
        gen8_pte_t scratch_pte = gen8_pte_encode(vm->scratch_page.daddr,
                                                 I915_CACHE_LLC);

        if (WARN_ON(!px_page(pt)))
                return false;

        GEM_BUG_ON(pte_end > GEN8_PTES);

        bitmap_clear(pt->used_ptes, pte, num_entries);

        if (bitmap_empty(pt->used_ptes, GEN8_PTES))
                return true;

        pt_vaddr = kmap_px(pt);

        while (pte < pte_end)
                pt_vaddr[pte++] = scratch_pte;

        kunmap_px(ppgtt, pt_vaddr);

        return false;
}

/* Removes entries from a single page dir, releasing it if it's empty.
 * Caller can use the return value to update higher-level entries
 */
static bool gen8_ppgtt_clear_pd(struct i915_address_space *vm,
                                struct i915_page_directory *pd,
                                uint64_t start,
                                uint64_t length)
{
        struct i915_hw_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
        struct i915_page_table *pt;
        uint64_t pde;
        gen8_pde_t *pde_vaddr;
        gen8_pde_t scratch_pde = gen8_pde_encode(px_dma(vm->scratch_pt),
                                                 I915_CACHE_LLC);

        gen8_for_each_pde(pt, pd, start, length, pde) {
                if (WARN_ON(!pd->page_table[pde]))
                        break;

                if (gen8_ppgtt_clear_pt(vm, pt, start, length)) {
                        __clear_bit(pde, pd->used_pdes);
                        pde_vaddr = kmap_px(pd);
                        pde_vaddr[pde] = scratch_pde;
                        kunmap_px(ppgtt, pde_vaddr);
                        free_pt(vm->i915, pt);
                }
        }

        if (bitmap_empty(pd->used_pdes, I915_PDES))
                return true;

        return false;
}

/* Removes entries from a single page dir pointer, releasing it if it's empty.
 * Caller can use the return value to update higher-level entries
 */
static bool gen8_ppgtt_clear_pdp(struct i915_address_space *vm,
                                 struct i915_page_directory_pointer *pdp,
                                 uint64_t start,
                                 uint64_t length)
{
        struct i915_hw_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
        struct i915_page_directory *pd;
        uint64_t pdpe;
        gen8_ppgtt_pdpe_t *pdpe_vaddr;
        gen8_ppgtt_pdpe_t scratch_pdpe =
                gen8_pdpe_encode(px_dma(vm->scratch_pd), I915_CACHE_LLC);

        gen8_for_each_pdpe(pd, pdp, start, length, pdpe) {
                if (WARN_ON(!pdp->page_directory[pdpe]))
                        break;

                if (gen8_ppgtt_clear_pd(vm, pd, start, length)) {
                        __clear_bit(pdpe, pdp->used_pdpes);
                        if (USES_FULL_48BIT_PPGTT(dev_priv)) {
                                pdpe_vaddr = kmap_px(pdp);
                                pdpe_vaddr[pdpe] = scratch_pdpe;
                                kunmap_px(ppgtt, pdpe_vaddr);
                        }
                        free_pd(vm->i915, pd);
                }
        }

        mark_tlbs_dirty(ppgtt);

        if (bitmap_empty(pdp->used_pdpes, I915_PDPES_PER_PDP(dev_priv)))
                return true;

        return false;
}

/* Removes entries from a single pml4.
 * This is the top-level structure in 4-level page tables used on gen8+.
 * Empty entries are always scratch pml4e.
 */
static void gen8_ppgtt_clear_pml4(struct i915_address_space *vm,
                                  struct i915_pml4 *pml4,
                                  uint64_t start,
                                  uint64_t length)
{
        struct i915_hw_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
        struct i915_page_directory_pointer *pdp;
        uint64_t pml4e;
        gen8_ppgtt_pml4e_t *pml4e_vaddr;
        gen8_ppgtt_pml4e_t scratch_pml4e =
                gen8_pml4e_encode(px_dma(vm->scratch_pdp), I915_CACHE_LLC);

        GEM_BUG_ON(!USES_FULL_48BIT_PPGTT(vm->i915));

        gen8_for_each_pml4e(pdp, pml4, start, length, pml4e) {
                if (WARN_ON(!pml4->pdps[pml4e]))
                        break;

                if (gen8_ppgtt_clear_pdp(vm, pdp, start, length)) {
                        __clear_bit(pml4e, pml4->used_pml4es);
                        pml4e_vaddr = kmap_px(pml4);
                        pml4e_vaddr[pml4e] = scratch_pml4e;
                        kunmap_px(ppgtt, pml4e_vaddr);
                        free_pdp(vm->i915, pdp);
                }
        }
}

static void gen8_ppgtt_clear_range(struct i915_address_space *vm,
                                   uint64_t start, uint64_t length)
{
        struct i915_hw_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);

        if (USES_FULL_48BIT_PPGTT(vm->i915))
                gen8_ppgtt_clear_pml4(vm, &ppgtt->pml4, start, length);
        else
                gen8_ppgtt_clear_pdp(vm, &ppgtt->pdp, start, length);
}

static void
gen8_ppgtt_insert_pte_entries(struct i915_address_space *vm,
                              struct i915_page_directory_pointer *pdp,
                              struct sg_page_iter *sg_iter,
                              uint64_t start,
                              enum i915_cache_level cache_level)
{
        struct i915_hw_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
        gen8_pte_t *pt_vaddr;
        unsigned pdpe = gen8_pdpe_index(start);
        unsigned pde = gen8_pde_index(start);
        unsigned pte = gen8_pte_index(start);

        pt_vaddr = NULL;

        while (__sg_page_iter_next(sg_iter)) {
                if (pt_vaddr == NULL) {
                        struct i915_page_directory *pd = pdp->page_directory[pdpe];
                        struct i915_page_table *pt = pd->page_table[pde];
                        pt_vaddr = kmap_px(pt);
                }

                pt_vaddr[pte] =
                        gen8_pte_encode(sg_page_iter_dma_address(sg_iter),
                                        cache_level);
                if (++pte == GEN8_PTES) {
                        kunmap_px(ppgtt, pt_vaddr);
                        pt_vaddr = NULL;
                        if (++pde == I915_PDES) {
                                if (++pdpe == I915_PDPES_PER_PDP(vm->i915))
                                        break;
                                pde = 0;
                        }
                        pte = 0;
                }
        }

        if (pt_vaddr)
                kunmap_px(ppgtt, pt_vaddr);
}

static void gen8_ppgtt_insert_entries(struct i915_address_space *vm,
                                      struct sg_table *pages,
                                      uint64_t start,
                                      enum i915_cache_level cache_level,
                                      u32 unused)
{
        struct i915_hw_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
        struct sg_page_iter sg_iter;

        __sg_page_iter_start(&sg_iter, pages->sgl, sg_nents(pages->sgl), 0);

        if (!USES_FULL_48BIT_PPGTT(vm->i915)) {
                gen8_ppgtt_insert_pte_entries(vm, &ppgtt->pdp, &sg_iter, start,
                                              cache_level);
        } else {
                struct i915_page_directory_pointer *pdp;
                uint64_t pml4e;
                uint64_t length = (uint64_t)pages->orig_nents << PAGE_SHIFT;

                gen8_for_each_pml4e(pdp, &ppgtt->pml4, start, length, pml4e) {
                        gen8_ppgtt_insert_pte_entries(vm, pdp, &sg_iter,
                                                      start, cache_level);
                }
        }
}

static void gen8_free_page_tables(struct drm_i915_private *dev_priv,
                                  struct i915_page_directory *pd)
{
        int i;

        if (!px_page(pd))
                return;

        for_each_set_bit(i, pd->used_pdes, I915_PDES) {
                if (WARN_ON(!pd->page_table[i]))
                        continue;

                free_pt(dev_priv, pd->page_table[i]);
                pd->page_table[i] = NULL;
        }
}

static int gen8_init_scratch(struct i915_address_space *vm)
{
        struct drm_i915_private *dev_priv = vm->i915;
        int ret;

        ret = setup_scratch_page(dev_priv, &vm->scratch_page, I915_GFP_DMA);
        if (ret)
                return ret;

        vm->scratch_pt = alloc_pt(dev_priv);
        if (IS_ERR(vm->scratch_pt)) {
                ret = PTR_ERR(vm->scratch_pt);
                goto free_scratch_page;
        }

        vm->scratch_pd = alloc_pd(dev_priv);
        if (IS_ERR(vm->scratch_pd)) {
                ret = PTR_ERR(vm->scratch_pd);
                goto free_pt;
        }

        if (USES_FULL_48BIT_PPGTT(dev_priv)) {
                vm->scratch_pdp = alloc_pdp(dev_priv);
                if (IS_ERR(vm->scratch_pdp)) {
                        ret = PTR_ERR(vm->scratch_pdp);
                        goto free_pd;
                }
        }

        gen8_initialize_pt(vm, vm->scratch_pt);
        gen8_initialize_pd(vm, vm->scratch_pd);
        if (USES_FULL_48BIT_PPGTT(dev_priv))
                gen8_initialize_pdp(vm, vm->scratch_pdp);

        return 0;

free_pd:
        free_pd(dev_priv, vm->scratch_pd);
free_pt:
        free_pt(dev_priv, vm->scratch_pt);
free_scratch_page:
        cleanup_scratch_page(dev_priv, &vm->scratch_page);

        return ret;
}

static int gen8_ppgtt_notify_vgt(struct i915_hw_ppgtt *ppgtt, bool create)
{
        enum vgt_g2v_type msg;
        struct drm_i915_private *dev_priv = ppgtt->base.i915;
        int i;

        if (USES_FULL_48BIT_PPGTT(dev_priv)) {
                u64 daddr = px_dma(&ppgtt->pml4);

                I915_WRITE(vgtif_reg(pdp[0].lo), lower_32_bits(daddr));
                I915_WRITE(vgtif_reg(pdp[0].hi), upper_32_bits(daddr));

                msg = (create ? VGT_G2V_PPGTT_L4_PAGE_TABLE_CREATE :
                                VGT_G2V_PPGTT_L4_PAGE_TABLE_DESTROY);
        } else {
                for (i = 0; i < GEN8_LEGACY_PDPES; i++) {
                        u64 daddr = i915_page_dir_dma_addr(ppgtt, i);

                        I915_WRITE(vgtif_reg(pdp[i].lo), lower_32_bits(daddr));
                        I915_WRITE(vgtif_reg(pdp[i].hi), upper_32_bits(daddr));
                }

                msg = (create ? VGT_G2V_PPGTT_L3_PAGE_TABLE_CREATE :
                                VGT_G2V_PPGTT_L3_PAGE_TABLE_DESTROY);
        }

        I915_WRITE(vgtif_reg(g2v_notify), msg);

        return 0;
}

static void gen8_free_scratch(struct i915_address_space *vm)
{
        struct drm_i915_private *dev_priv = vm->i915;

        if (USES_FULL_48BIT_PPGTT(dev_priv))
                free_pdp(dev_priv, vm->scratch_pdp);
        free_pd(dev_priv, vm->scratch_pd);
        free_pt(dev_priv, vm->scratch_pt);
        cleanup_scratch_page(dev_priv, &vm->scratch_page);
}

static void gen8_ppgtt_cleanup_3lvl(struct drm_i915_private *dev_priv,
                                    struct i915_page_directory_pointer *pdp)
{
        int i;

        for_each_set_bit(i, pdp->used_pdpes, I915_PDPES_PER_PDP(dev_priv)) {
                if (WARN_ON(!pdp->page_directory[i]))
                        continue;

                gen8_free_page_tables(dev_priv, pdp->page_directory[i]);
                free_pd(dev_priv, pdp->page_directory[i]);
        }

        free_pdp(dev_priv, pdp);
}

static void gen8_ppgtt_cleanup_4lvl(struct i915_hw_ppgtt *ppgtt)
{
        struct drm_i915_private *dev_priv = ppgtt->base.i915;
        int i;

        for_each_set_bit(i, ppgtt->pml4.used_pml4es, GEN8_PML4ES_PER_PML4) {
                if (WARN_ON(!ppgtt->pml4.pdps[i]))
                        continue;

                gen8_ppgtt_cleanup_3lvl(dev_priv, ppgtt->pml4.pdps[i]);
        }

        cleanup_px(dev_priv, &ppgtt->pml4);
}

static void gen8_ppgtt_cleanup(struct i915_address_space *vm)
{
        struct drm_i915_private *dev_priv = vm->i915;
        struct i915_hw_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);

        if (intel_vgpu_active(dev_priv))
                gen8_ppgtt_notify_vgt(ppgtt, false);

        if (!USES_FULL_48BIT_PPGTT(dev_priv))
                gen8_ppgtt_cleanup_3lvl(dev_priv, &ppgtt->pdp);
        else
                gen8_ppgtt_cleanup_4lvl(ppgtt);

        gen8_free_scratch(vm);
}

/**
 * gen8_ppgtt_alloc_pagetabs() - Allocate page tables for VA range.
 * @vm: Master vm structure.
 * @pd: Page directory for this address range.
 * @start:      Starting virtual address to begin allocations.
 * @length:     Size of the allocations.
 * @new_pts:    Bitmap set by function with new allocations. Likely used by the
 *              caller to free on error.
 *
 * Allocate the required number of page tables. Extremely similar to
 * gen8_ppgtt_alloc_page_directories(). The main difference is here we are limited by
 * the page directory boundary (instead of the page directory pointer). That
 * boundary is 1GB virtual. Therefore, unlike gen8_ppgtt_alloc_page_directories(), it is
 * possible, and likely that the caller will need to use multiple calls of this
 * function to achieve the appropriate allocation.
 *
 * Return: 0 if success; negative error code otherwise.
 */
static int gen8_ppgtt_alloc_pagetabs(struct i915_address_space *vm,
                                     struct i915_page_directory *pd,
                                     uint64_t start,
                                     uint64_t length,
                                     unsigned long *new_pts)
{
        struct drm_i915_private *dev_priv = vm->i915;
        struct i915_page_table *pt;
        uint32_t pde;

        gen8_for_each_pde(pt, pd, start, length, pde) {
                /* Don't reallocate page tables */
                if (test_bit(pde, pd->used_pdes)) {
                        /* Scratch is never allocated this way */
                        WARN_ON(pt == vm->scratch_pt);
                        continue;
                }

                pt = alloc_pt(dev_priv);
                if (IS_ERR(pt))
                        goto unwind_out;

                gen8_initialize_pt(vm, pt);
                pd->page_table[pde] = pt;
                __set_bit(pde, new_pts);
                trace_i915_page_table_entry_alloc(vm, pde, start, GEN8_PDE_SHIFT);
        }

        return 0;

unwind_out:
        for_each_set_bit(pde, new_pts, I915_PDES)
                free_pt(dev_priv, pd->page_table[pde]);

        return -ENOMEM;
}

/**
 * gen8_ppgtt_alloc_page_directories() - Allocate page directories for VA range.
 * @vm: Master vm structure.
 * @pdp:        Page directory pointer for this address range.
 * @start:      Starting virtual address to begin allocations.
 * @length:     Size of the allocations.
 * @new_pds:    Bitmap set by function with new allocations. Likely used by the
 *              caller to free on error.
 *
 * Allocate the required number of page directories starting at the pde index of
 * @start, and ending at the pde index @start + @length. This function will skip
 * over already allocated page directories within the range, and only allocate
 * new ones, setting the appropriate pointer within the pdp as well as the
 * correct position in the bitmap @new_pds.
 *
 * The function will only allocate the pages within the range for a give page
 * directory pointer. In other words, if @start + @length straddles a virtually
 * addressed PDP boundary (512GB for 4k pages), there will be more allocations
 * required by the caller, This is not currently possible, and the BUG in the
 * code will prevent it.
 *
 * Return: 0 if success; negative error code otherwise.
 */
static int
gen8_ppgtt_alloc_page_directories(struct i915_address_space *vm,
                                  struct i915_page_directory_pointer *pdp,
                                  uint64_t start,
                                  uint64_t length,
                                  unsigned long *new_pds)
{
        struct drm_i915_private *dev_priv = vm->i915;
        struct i915_page_directory *pd;
        uint32_t pdpe;
        uint32_t pdpes = I915_PDPES_PER_PDP(dev_priv);

        WARN_ON(!bitmap_empty(new_pds, pdpes));

        gen8_for_each_pdpe(pd, pdp, start, length, pdpe) {
                if (test_bit(pdpe, pdp->used_pdpes))
                        continue;

                pd = alloc_pd(dev_priv);
                if (IS_ERR(pd))
                        goto unwind_out;

                gen8_initialize_pd(vm, pd);
                pdp->page_directory[pdpe] = pd;
                __set_bit(pdpe, new_pds);
                trace_i915_page_directory_entry_alloc(vm, pdpe, start, GEN8_PDPE_SHIFT);
        }

        return 0;

unwind_out:
        for_each_set_bit(pdpe, new_pds, pdpes)
                free_pd(dev_priv, pdp->page_directory[pdpe]);

        return -ENOMEM;
}

/**
 * gen8_ppgtt_alloc_page_dirpointers() - Allocate pdps for VA range.
 * @vm: Master vm structure.
 * @pml4:       Page map level 4 for this address range.
 * @start:      Starting virtual address to begin allocations.
 * @length:     Size of the allocations.
 * @new_pdps:   Bitmap set by function with new allocations. Likely used by the
 *              caller to free on error.
 *
 * Allocate the required number of page directory pointers. Extremely similar to
 * gen8_ppgtt_alloc_page_directories() and gen8_ppgtt_alloc_pagetabs().
 * The main difference is here we are limited by the pml4 boundary (instead of
 * the page directory pointer).
 *
 * Return: 0 if success; negative error code otherwise.
 */
static int
gen8_ppgtt_alloc_page_dirpointers(struct i915_address_space *vm,
                                  struct i915_pml4 *pml4,
                                  uint64_t start,
                                  uint64_t length,
                                  unsigned long *new_pdps)
{
        struct drm_i915_private *dev_priv = vm->i915;
        struct i915_page_directory_pointer *pdp;
        uint32_t pml4e;

        WARN_ON(!bitmap_empty(new_pdps, GEN8_PML4ES_PER_PML4));

        gen8_for_each_pml4e(pdp, pml4, start, length, pml4e) {
                if (!test_bit(pml4e, pml4->used_pml4es)) {
                        pdp = alloc_pdp(dev_priv);
                        if (IS_ERR(pdp))
                                goto unwind_out;

                        gen8_initialize_pdp(vm, pdp);
                        pml4->pdps[pml4e] = pdp;
                        __set_bit(pml4e, new_pdps);
                        trace_i915_page_directory_pointer_entry_alloc(vm,
                                                                      pml4e,
                                                                      start,
                                                                      GEN8_PML4E_SHIFT);
                }
        }

        return 0;

unwind_out:
        for_each_set_bit(pml4e, new_pdps, GEN8_PML4ES_PER_PML4)
                free_pdp(dev_priv, pml4->pdps[pml4e]);

        return -ENOMEM;
}

static void
free_gen8_temp_bitmaps(unsigned long *new_pds, unsigned long *new_pts)
{
        kfree(new_pts);
        kfree(new_pds);
}

/* Fills in the page directory bitmap, and the array of page tables bitmap. Both
 * of these are based on the number of PDPEs in the system.
 */
static
int __must_check alloc_gen8_temp_bitmaps(unsigned long **new_pds,
                                         unsigned long **new_pts,
                                         uint32_t pdpes)
{
        unsigned long *pds;
        unsigned long *pts;

        pds = kcalloc(BITS_TO_LONGS(pdpes), sizeof(unsigned long), GFP_TEMPORARY);
        if (!pds)
                return -ENOMEM;

        pts = kcalloc(pdpes, BITS_TO_LONGS(I915_PDES) * sizeof(unsigned long),
                      GFP_TEMPORARY);
        if (!pts)
                goto err_out;

        *new_pds = pds;
        *new_pts = pts;

        return 0;

err_out:
        free_gen8_temp_bitmaps(pds, pts);
        return -ENOMEM;
}

static int gen8_alloc_va_range_3lvl(struct i915_address_space *vm,
                                    struct i915_page_directory_pointer *pdp,
                                    uint64_t start,
                                    uint64_t length)
{
        struct i915_hw_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
        unsigned long *new_page_dirs, *new_page_tables;
        struct drm_i915_private *dev_priv = vm->i915;
        struct i915_page_directory *pd;
        const uint64_t orig_start = start;
        const uint64_t orig_length = length;
        uint32_t pdpe;
        uint32_t pdpes = I915_PDPES_PER_PDP(dev_priv);
        int ret;

        ret = alloc_gen8_temp_bitmaps(&new_page_dirs, &new_page_tables, pdpes);
        if (ret)
                return ret;

        /* Do the allocations first so we can easily bail out */
        ret = gen8_ppgtt_alloc_page_directories(vm, pdp, start, length,
                                                new_page_dirs);
        if (ret) {
                free_gen8_temp_bitmaps(new_page_dirs, new_page_tables);
                return ret;
        }

        /* For every page directory referenced, allocate page tables */
        gen8_for_each_pdpe(pd, pdp, start, length, pdpe) {
                ret = gen8_ppgtt_alloc_pagetabs(vm, pd, start, length,
                                                new_page_tables + pdpe * BITS_TO_LONGS(I915_PDES));
                if (ret)
                        goto err_out;
        }

        start = orig_start;
        length = orig_length;

        /* Allocations have completed successfully, so set the bitmaps, and do
         * the mappings. */
        gen8_for_each_pdpe(pd, pdp, start, length, pdpe) {
                gen8_pde_t *const page_directory = kmap_px(pd);
                struct i915_page_table *pt;
                uint64_t pd_len = length;
                uint64_t pd_start = start;
                uint32_t pde;

                /* Every pd should be allocated, we just did that above. */
                WARN_ON(!pd);

                gen8_for_each_pde(pt, pd, pd_start, pd_len, pde) {
                        /* Same reasoning as pd */
                        WARN_ON(!pt);
                        WARN_ON(!pd_len);
                        WARN_ON(!gen8_pte_count(pd_start, pd_len));

                        /* Set our used ptes within the page table */
                        bitmap_set(pt->used_ptes,
                                   gen8_pte_index(pd_start),
                                   gen8_pte_count(pd_start, pd_len));

                        /* Our pde is now pointing to the pagetable, pt */
                        __set_bit(pde, pd->used_pdes);

                        /* Map the PDE to the page table */
                        page_directory[pde] = gen8_pde_encode(px_dma(pt),
                                                              I915_CACHE_LLC);
                        trace_i915_page_table_entry_map(&ppgtt->base, pde, pt,
                                                        gen8_pte_index(start),
                                                        gen8_pte_count(start, length),
                                                        GEN8_PTES);

                        /* NB: We haven't yet mapped ptes to pages. At this
                         * point we're still relying on insert_entries() */
                }

                kunmap_px(ppgtt, page_directory);
                __set_bit(pdpe, pdp->used_pdpes);
                gen8_setup_pdpe(ppgtt, pdp, pd, pdpe);
        }

        free_gen8_temp_bitmaps(new_page_dirs, new_page_tables);
        mark_tlbs_dirty(ppgtt);
        return 0;

err_out:
        while (pdpe--) {
                unsigned long temp;

                for_each_set_bit(temp, new_page_tables + pdpe *
                                BITS_TO_LONGS(I915_PDES), I915_PDES)
                        free_pt(dev_priv,
                                pdp->page_directory[pdpe]->page_table[temp]);
        }

        for_each_set_bit(pdpe, new_page_dirs, pdpes)
                free_pd(dev_priv, pdp->page_directory[pdpe]);

        free_gen8_temp_bitmaps(new_page_dirs, new_page_tables);
        mark_tlbs_dirty(ppgtt);
        return ret;
}

static int gen8_alloc_va_range_4lvl(struct i915_address_space *vm,
                                    struct i915_pml4 *pml4,
                                    uint64_t start,
                                    uint64_t length)
{
        DECLARE_BITMAP(new_pdps, GEN8_PML4ES_PER_PML4);
        struct i915_hw_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
        struct i915_page_directory_pointer *pdp;
        uint64_t pml4e;
        int ret = 0;

        /* Do the pml4 allocations first, so we don't need to track the newly
         * allocated tables below the pdp */
        bitmap_zero(new_pdps, GEN8_PML4ES_PER_PML4);

        /* The pagedirectory and pagetable allocations are done in the shared 3
         * and 4 level code. Just allocate the pdps.
         */
        ret = gen8_ppgtt_alloc_page_dirpointers(vm, pml4, start, length,
                                                new_pdps);
        if (ret)
                return ret;

        WARN(bitmap_weight(new_pdps, GEN8_PML4ES_PER_PML4) > 2,
             "The allocation has spanned more than 512GB. "
             "It is highly likely this is incorrect.");

        gen8_for_each_pml4e(pdp, pml4, start, length, pml4e) {
                WARN_ON(!pdp);

                ret = gen8_alloc_va_range_3lvl(vm, pdp, start, length);
                if (ret)
                        goto err_out;

                gen8_setup_page_directory_pointer(ppgtt, pml4, pdp, pml4e);
        }

        bitmap_or(pml4->used_pml4es, new_pdps, pml4->used_pml4es,
                  GEN8_PML4ES_PER_PML4);

        return 0;

err_out:
        for_each_set_bit(pml4e, new_pdps, GEN8_PML4ES_PER_PML4)
                gen8_ppgtt_cleanup_3lvl(vm->i915, pml4->pdps[pml4e]);

        return ret;
}

static int gen8_alloc_va_range(struct i915_address_space *vm,
                               uint64_t start, uint64_t length)
{
        struct i915_hw_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);

        if (USES_FULL_48BIT_PPGTT(vm->i915))
                return gen8_alloc_va_range_4lvl(vm, &ppgtt->pml4, start, length);
        else
                return gen8_alloc_va_range_3lvl(vm, &ppgtt->pdp, start, length);
}

static void gen8_dump_pdp(struct i915_page_directory_pointer *pdp,
                          uint64_t start, uint64_t length,
                          gen8_pte_t scratch_pte,
                          struct seq_file *m)
{
        struct i915_page_directory *pd;
        uint32_t pdpe;

        gen8_for_each_pdpe(pd, pdp, start, length, pdpe) {
                struct i915_page_table *pt;
                uint64_t pd_len = length;
                uint64_t pd_start = start;
                uint32_t pde;

                if (!test_bit(pdpe, pdp->used_pdpes))
                        continue;

                seq_printf(m, "\tPDPE #%d\n", pdpe);
                gen8_for_each_pde(pt, pd, pd_start, pd_len, pde) {
                        uint32_t  pte;
                        gen8_pte_t *pt_vaddr;

                        if (!test_bit(pde, pd->used_pdes))
                                continue;

                        pt_vaddr = kmap_px(pt);
                        for (pte = 0; pte < GEN8_PTES; pte += 4) {
                                uint64_t va =
                                        (pdpe << GEN8_PDPE_SHIFT) |
                                        (pde << GEN8_PDE_SHIFT) |
                                        (pte << GEN8_PTE_SHIFT);
                                int i;
                                bool found = false;

                                for (i = 0; i < 4; i++)
                                        if (pt_vaddr[pte + i] != scratch_pte)
                                                found = true;
                                if (!found)
                                        continue;

                                seq_printf(m, "\t\t0x%llx [%03d,%03d,%04d]: =", va, pdpe, pde, pte);
                                for (i = 0; i < 4; i++) {
                                        if (pt_vaddr[pte + i] != scratch_pte)
                                                seq_printf(m, " %llx", pt_vaddr[pte + i]);
                                        else
                                                seq_puts(m, "  SCRATCH ");
                                }
                                seq_puts(m, "\n");
                        }
                        /* don't use kunmap_px, it could trigger
                         * an unnecessary flush.
                         */
                        kunmap_atomic(pt_vaddr);
                }
        }
}

static void gen8_dump_ppgtt(struct i915_hw_ppgtt *ppgtt, struct seq_file *m)
{
        struct i915_address_space *vm = &ppgtt->base;
        uint64_t start = ppgtt->base.start;
        uint64_t length = ppgtt->base.total;
        gen8_pte_t scratch_pte = gen8_pte_encode(vm->scratch_page.daddr,
                                                 I915_CACHE_LLC);

        if (!USES_FULL_48BIT_PPGTT(vm->i915)) {
                gen8_dump_pdp(&ppgtt->pdp, start, length, scratch_pte, m);
        } else {
                uint64_t pml4e;
                struct i915_pml4 *pml4 = &ppgtt->pml4;
                struct i915_page_directory_pointer *pdp;

                gen8_for_each_pml4e(pdp, pml4, start, length, pml4e) {
                        if (!test_bit(pml4e, pml4->used_pml4es))
                                continue;

                        seq_printf(m, "    PML4E #%llu\n", pml4e);
                        gen8_dump_pdp(pdp, start, length, scratch_pte, m);
                }
        }
}

static int gen8_preallocate_top_level_pdps(struct i915_hw_ppgtt *ppgtt)
{
        unsigned long *new_page_dirs, *new_page_tables;
        uint32_t pdpes = I915_PDPES_PER_PDP(to_i915(ppgtt->base.dev));
        int ret;

        /* We allocate temp bitmap for page tables for no gain
         * but as this is for init only, lets keep the things simple
         */
        ret = alloc_gen8_temp_bitmaps(&new_page_dirs, &new_page_tables, pdpes);
        if (ret)
                return ret;

        /* Allocate for all pdps regardless of how the ppgtt
         * was defined.
         */
        ret = gen8_ppgtt_alloc_page_directories(&ppgtt->base, &ppgtt->pdp,
                                                0, 1ULL << 32,
                                                new_page_dirs);
        if (!ret)
                *ppgtt->pdp.used_pdpes = *new_page_dirs;

        free_gen8_temp_bitmaps(new_page_dirs, new_page_tables);

        return ret;
}

/*
 * GEN8 legacy ppgtt programming is accomplished through a max 4 PDP registers
 * with a net effect resembling a 2-level page table in normal x86 terms. Each
 * PDP represents 1GB of memory 4 * 512 * 512 * 4096 = 4GB legacy 32b address
 * space.
 *
 */
static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
{
        struct drm_i915_private *dev_priv = ppgtt->base.i915;
        int ret;

        ret = gen8_init_scratch(&ppgtt->base);
        if (ret)
                return ret;

        ppgtt->base.start = 0;
        ppgtt->base.cleanup = gen8_ppgtt_cleanup;
        ppgtt->base.allocate_va_range = gen8_alloc_va_range;
        ppgtt->base.insert_entries = gen8_ppgtt_insert_entries;
        ppgtt->base.clear_range = gen8_ppgtt_clear_range;
        ppgtt->base.unbind_vma = ppgtt_unbind_vma;
        ppgtt->base.bind_vma = ppgtt_bind_vma;
        ppgtt->debug_dump = gen8_dump_ppgtt;

        if (USES_FULL_48BIT_PPGTT(dev_priv)) {
                ret = setup_px(dev_priv, &ppgtt->pml4);
                if (ret)
                        goto free_scratch;

                gen8_initialize_pml4(&ppgtt->base, &ppgtt->pml4);

                ppgtt->base.total = 1ULL << 48;
                ppgtt->switch_mm = gen8_48b_mm_switch;
        } else {
                ret = __pdp_init(dev_priv, &ppgtt->pdp);
                if (ret)
                        goto free_scratch;

                ppgtt->base.total = 1ULL << 32;
                ppgtt->switch_mm = gen8_legacy_mm_switch;
                trace_i915_page_directory_pointer_entry_alloc(&ppgtt->base,
                                                              0, 0,
                                                              GEN8_PML4E_SHIFT);

                if (intel_vgpu_active(dev_priv)) {
                        ret = gen8_preallocate_top_level_pdps(ppgtt);
                        if (ret)
                                goto free_scratch;
                }
        }

        if (intel_vgpu_active(dev_priv))
                gen8_ppgtt_notify_vgt(ppgtt, true);

        return 0;

free_scratch:
        gen8_free_scratch(&ppgtt->base);
        return ret;
}

static void gen6_dump_ppgtt(struct i915_hw_ppgtt *ppgtt, struct seq_file *m)
{
        struct i915_address_space *vm = &ppgtt->base;
        struct i915_page_table *unused;
        gen6_pte_t scratch_pte;
        uint32_t pd_entry;
        uint32_t  pte, pde;
        uint32_t start = ppgtt->base.start, length = ppgtt->base.total;

        scratch_pte = vm->pte_encode(vm->scratch_page.daddr,
                                     I915_CACHE_LLC, 0);

        gen6_for_each_pde(unused, &ppgtt->pd, start, length, pde) {
                u32 expected;
                gen6_pte_t *pt_vaddr;
                const dma_addr_t pt_addr = px_dma(ppgtt->pd.page_table[pde]);
                pd_entry = readl(ppgtt->pd_addr + pde);
                expected = (GEN6_PDE_ADDR_ENCODE(pt_addr) | GEN6_PDE_VALID);

                if (pd_entry != expected)
                        seq_printf(m, "\tPDE #%d mismatch: Actual PDE: %x Expected PDE: %x\n",
                                   pde,
                                   pd_entry,
                                   expected);
                seq_printf(m, "\tPDE: %x\n", pd_entry);

                pt_vaddr = kmap_px(ppgtt->pd.page_table[pde]);

                for (pte = 0; pte < GEN6_PTES; pte+=4) {
                        unsigned long va =
                                (pde * PAGE_SIZE * GEN6_PTES) +
                                (pte * PAGE_SIZE);
                        int i;
                        bool found = false;
                        for (i = 0; i < 4; i++)
                                if (pt_vaddr[pte + i] != scratch_pte)
                                        found = true;
                        if (!found)
                                continue;

                        seq_printf(m, "\t\t0x%lx [%03d,%04d]: =", va, pde, pte);
                        for (i = 0; i < 4; i++) {
                                if (pt_vaddr[pte + i] != scratch_pte)
                                        seq_printf(m, " %08x", pt_vaddr[pte + i]);
                                else
                                        seq_puts(m, "  SCRATCH ");
                        }
                        seq_puts(m, "\n");
                }
                kunmap_px(ppgtt, pt_vaddr);
        }
}

/* Write pde (index) from the page directory @pd to the page table @pt */
static void gen6_write_pde(struct i915_page_directory *pd,
                            const int pde, struct i915_page_table *pt)
{
        /* Caller needs to make sure the write completes if necessary */
        struct i915_hw_ppgtt *ppgtt =
                container_of(pd, struct i915_hw_ppgtt, pd);
        u32 pd_entry;

        pd_entry = GEN6_PDE_ADDR_ENCODE(px_dma(pt));
        pd_entry |= GEN6_PDE_VALID;

        writel(pd_entry, ppgtt->pd_addr + pde);
}

/* Write all the page tables found in the ppgtt structure to incrementing page
 * directories. */
static void gen6_write_page_range(struct drm_i915_private *dev_priv,
                                  struct i915_page_directory *pd,
                                  uint32_t start, uint32_t length)
{
        struct i915_ggtt *ggtt = &dev_priv->ggtt;
        struct i915_page_table *pt;
        uint32_t pde;

        gen6_for_each_pde(pt, pd, start, length, pde)
                gen6_write_pde(pd, pde, pt);

        /* Make sure write is complete before other code can use this page
         * table. Also require for WC mapped PTEs */
        readl(ggtt->gsm);
}

static uint32_t get_pd_offset(struct i915_hw_ppgtt *ppgtt)
{
        BUG_ON(ppgtt->pd.base.ggtt_offset & 0x3f);

        return (ppgtt->pd.base.ggtt_offset / 64) << 16;
}

static int hsw_mm_switch(struct i915_hw_ppgtt *ppgtt,
                         struct drm_i915_gem_request *req)
{
        struct intel_ring *ring = req->ring;
        struct intel_engine_cs *engine = req->engine;
        int ret;

        /* NB: TLBs must be flushed and invalidated before a switch */
        ret = engine->emit_flush(req, EMIT_INVALIDATE | EMIT_FLUSH);
        if (ret)
                return ret;

        ret = intel_ring_begin(req, 6);
        if (ret)
                return ret;

        intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(2));
        intel_ring_emit_reg(ring, RING_PP_DIR_DCLV(engine));
        intel_ring_emit(ring, PP_DIR_DCLV_2G);
        intel_ring_emit_reg(ring, RING_PP_DIR_BASE(engine));
        intel_ring_emit(ring, get_pd_offset(ppgtt));
        intel_ring_emit(ring, MI_NOOP);
        intel_ring_advance(ring);

        return 0;
}

static int gen7_mm_switch(struct i915_hw_ppgtt *ppgtt,
                          struct drm_i915_gem_request *req)
{
        struct intel_ring *ring = req->ring;
        struct intel_engine_cs *engine = req->engine;
        int ret;

        /* NB: TLBs must be flushed and invalidated before a switch */
        ret = engine->emit_flush(req, EMIT_INVALIDATE | EMIT_FLUSH);
        if (ret)
                return ret;

        ret = intel_ring_begin(req, 6);
        if (ret)
                return ret;

        intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(2));
        intel_ring_emit_reg(ring, RING_PP_DIR_DCLV(engine));
        intel_ring_emit(ring, PP_DIR_DCLV_2G);
        intel_ring_emit_reg(ring, RING_PP_DIR_BASE(engine));
        intel_ring_emit(ring, get_pd_offset(ppgtt));
        intel_ring_emit(ring, MI_NOOP);
        intel_ring_advance(ring);

        /* XXX: RCS is the only one to auto invalidate the TLBs? */
        if (engine->id != RCS) {
                ret = engine->emit_flush(req, EMIT_INVALIDATE | EMIT_FLUSH);
                if (ret)
                        return ret;
        }

        return 0;
}

static int gen6_mm_switch(struct i915_hw_ppgtt *ppgtt,
                          struct drm_i915_gem_request *req)
{
        struct intel_engine_cs *engine = req->engine;
        struct drm_i915_private *dev_priv = req->i915;

        I915_WRITE(RING_PP_DIR_DCLV(engine), PP_DIR_DCLV_2G);
        I915_WRITE(RING_PP_DIR_BASE(engine), get_pd_offset(ppgtt));
        return 0;
}

static void gen8_ppgtt_enable(struct drm_i915_private *dev_priv)
{
        struct intel_engine_cs *engine;
        enum intel_engine_id id;

        for_each_engine(engine, dev_priv, id) {
                u32 four_level = USES_FULL_48BIT_PPGTT(dev_priv) ?
                                 GEN8_GFX_PPGTT_48B : 0;
                I915_WRITE(RING_MODE_GEN7(engine),
                           _MASKED_BIT_ENABLE(GFX_PPGTT_ENABLE | four_level));
        }
}

static void gen7_ppgtt_enable(struct drm_i915_private *dev_priv)
{
        struct intel_engine_cs *engine;
        uint32_t ecochk, ecobits;
        enum intel_engine_id id;

        ecobits = I915_READ(GAC_ECO_BITS);
        I915_WRITE(GAC_ECO_BITS, ecobits | ECOBITS_PPGTT_CACHE64B);

        ecochk = I915_READ(GAM_ECOCHK);
        if (IS_HASWELL(dev_priv)) {
                ecochk |= ECOCHK_PPGTT_WB_HSW;
        } else {
                ecochk |= ECOCHK_PPGTT_LLC_IVB;
                ecochk &= ~ECOCHK_PPGTT_GFDT_IVB;
        }
        I915_WRITE(GAM_ECOCHK, ecochk);

        for_each_engine(engine, dev_priv, id) {
                /* GFX_MODE is per-ring on gen7+ */
                I915_WRITE(RING_MODE_GEN7(engine),
                           _MASKED_BIT_ENABLE(GFX_PPGTT_ENABLE));
        }
}

static void gen6_ppgtt_enable(struct drm_i915_private *dev_priv)
{
        uint32_t ecochk, gab_ctl, ecobits;

        ecobits = I915_READ(GAC_ECO_BITS);
        I915_WRITE(GAC_ECO_BITS, ecobits | ECOBITS_SNB_BIT |
                   ECOBITS_PPGTT_CACHE64B);

        gab_ctl = I915_READ(GAB_CTL);
        I915_WRITE(GAB_CTL, gab_ctl | GAB_CTL_CONT_AFTER_PAGEFAULT);

        ecochk = I915_READ(GAM_ECOCHK);
        I915_WRITE(GAM_ECOCHK, ecochk | ECOCHK_SNB_BIT | ECOCHK_PPGTT_CACHE64B);

        I915_WRITE(GFX_MODE, _MASKED_BIT_ENABLE(GFX_PPGTT_ENABLE));
}

/* PPGTT support for Sandybdrige/Gen6 and later */
static void gen6_ppgtt_clear_range(struct i915_address_space *vm,
                                   uint64_t start,
                                   uint64_t length)
{
        struct i915_hw_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
        gen6_pte_t *pt_vaddr, scratch_pte;
        unsigned first_entry = start >> PAGE_SHIFT;
        unsigned num_entries = length >> PAGE_SHIFT;
        unsigned act_pt = first_entry / GEN6_PTES;
        unsigned first_pte = first_entry % GEN6_PTES;
        unsigned last_pte, i;

        scratch_pte = vm->pte_encode(vm->scratch_page.daddr,
                                     I915_CACHE_LLC, 0);

        while (num_entries) {
                last_pte = first_pte + num_entries;
                if (last_pte > GEN6_PTES)
                        last_pte = GEN6_PTES;

                pt_vaddr = kmap_px(ppgtt->pd.page_table[act_pt]);

                for (i = first_pte; i < last_pte; i++)
                        pt_vaddr[i] = scratch_pte;

                kunmap_px(ppgtt, pt_vaddr);

                num_entries -= last_pte - first_pte;
                first_pte = 0;
                act_pt++;
        }
}

static void gen6_ppgtt_insert_entries(struct i915_address_space *vm,
                                      struct sg_table *pages,
                                      uint64_t start,
                                      enum i915_cache_level cache_level, u32 flags)
{
        struct i915_hw_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
        unsigned first_entry = start >> PAGE_SHIFT;
        unsigned act_pt = first_entry / GEN6_PTES;
        unsigned act_pte = first_entry % GEN6_PTES;
        gen6_pte_t *pt_vaddr = NULL;
        struct sgt_iter sgt_iter;
        dma_addr_t addr;

        for_each_sgt_dma(addr, sgt_iter, pages) {
                if (pt_vaddr == NULL)
                        pt_vaddr = kmap_px(ppgtt->pd.page_table[act_pt]);

                pt_vaddr[act_pte] =
                        vm->pte_encode(addr, cache_level, flags);

                if (++act_pte == GEN6_PTES) {
                        kunmap_px(ppgtt, pt_vaddr);
                        pt_vaddr = NULL;
                        act_pt++;
                        act_pte = 0;
                }
        }

        if (pt_vaddr)
                kunmap_px(ppgtt, pt_vaddr);
}

static int gen6_alloc_va_range(struct i915_address_space *vm,
                               uint64_t start_in, uint64_t length_in)
{
        DECLARE_BITMAP(new_page_tables, I915_PDES);
        struct drm_i915_private *dev_priv = vm->i915;
        struct i915_ggtt *ggtt = &dev_priv->ggtt;
        struct i915_hw_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
        struct i915_page_table *pt;
        uint32_t start, length, start_save, length_save;
        uint32_t pde;
        int ret;

        start = start_save = start_in;
        length = length_save = length_in;

        bitmap_zero(new_page_tables, I915_PDES);

        /* The allocation is done in two stages so that we can bail out with
         * minimal amount of pain. The first stage finds new page tables that
         * need allocation. The second stage marks use ptes within the page
         * tables.
         */
        gen6_for_each_pde(pt, &ppgtt->pd, start, length, pde) {
                if (pt != vm->scratch_pt) {
                        WARN_ON(bitmap_empty(pt->used_ptes, GEN6_PTES));
                        continue;
                }

                /* We've already allocated a page table */
                WARN_ON(!bitmap_empty(pt->used_ptes, GEN6_PTES));

                pt = alloc_pt(dev_priv);
                if (IS_ERR(pt)) {
                        ret = PTR_ERR(pt);
                        goto unwind_out;
                }

                gen6_initialize_pt(vm, pt);

                ppgtt->pd.page_table[pde] = pt;
                __set_bit(pde, new_page_tables);
                trace_i915_page_table_entry_alloc(vm, pde, start, GEN6_PDE_SHIFT);
        }

        start = start_save;
        length = length_save;

        gen6_for_each_pde(pt, &ppgtt->pd, start, length, pde) {
                DECLARE_BITMAP(tmp_bitmap, GEN6_PTES);

                bitmap_zero(tmp_bitmap, GEN6_PTES);
                bitmap_set(tmp_bitmap, gen6_pte_index(start),
                           gen6_pte_count(start, length));

                if (__test_and_clear_bit(pde, new_page_tables))
                        gen6_write_pde(&ppgtt->pd, pde, pt);

                trace_i915_page_table_entry_map(vm, pde, pt,
                                         gen6_pte_index(start),
                                         gen6_pte_count(start, length),
                                         GEN6_PTES);
                bitmap_or(pt->used_ptes, tmp_bitmap, pt->used_ptes,
                                GEN6_PTES);
        }

        WARN_ON(!bitmap_empty(new_page_tables, I915_PDES));

        /* Make sure write is complete before other code can use this page
         * table. Also require for WC mapped PTEs */
        readl(ggtt->gsm);

        mark_tlbs_dirty(ppgtt);
        return 0;

unwind_out:
        for_each_set_bit(pde, new_page_tables, I915_PDES) {
                struct i915_page_table *pt = ppgtt->pd.page_table[pde];

                ppgtt->pd.page_table[pde] = vm->scratch_pt;
                free_pt(dev_priv, pt);
        }

        mark_tlbs_dirty(ppgtt);
        return ret;
}

static int gen6_init_scratch(struct i915_address_space *vm)
{
        struct drm_i915_private *dev_priv = vm->i915;
        int ret;

        ret = setup_scratch_page(dev_priv, &vm->scratch_page, I915_GFP_DMA);
        if (ret)
                return ret;

        vm->scratch_pt = alloc_pt(dev_priv);
        if (IS_ERR(vm->scratch_pt)) {
                cleanup_scratch_page(dev_priv, &vm->scratch_page);
                return PTR_ERR(vm->scratch_pt);
        }

        gen6_initialize_pt(vm, vm->scratch_pt);

        return 0;
}

static void gen6_free_scratch(struct i915_address_space *vm)
{
        struct drm_i915_private *dev_priv = vm->i915;

        free_pt(dev_priv, vm->scratch_pt);
        cleanup_scratch_page(dev_priv, &vm->scratch_page);
}

static void gen6_ppgtt_cleanup(struct i915_address_space *vm)
{
        struct i915_hw_ppgtt *ppgtt = i915_vm_to_ppgtt(vm);
        struct i915_page_directory *pd = &ppgtt->pd;
        struct drm_i915_private *dev_priv = vm->i915;
        struct i915_page_table *pt;
        uint32_t pde;

        drm_mm_remove_node(&ppgtt->node);

        gen6_for_all_pdes(pt, pd, pde)
                if (pt != vm->scratch_pt)
                        free_pt(dev_priv, pt);

        gen6_free_scratch(vm);
}

static int gen6_ppgtt_allocate_page_directories(struct i915_hw_ppgtt *ppgtt)
{
        struct i915_address_space *vm = &ppgtt->base;
        struct drm_i915_private *dev_priv = ppgtt->base.i915;
        struct i915_ggtt *ggtt = &dev_priv->ggtt;
        bool retried = false;
        int ret;

        /* PPGTT PDEs reside in the GGTT and consists of 512 entries. The
         * allocator works in address space sizes, so it's multiplied by page
         * size. We allocate at the top of the GTT to avoid fragmentation.
         */
        BUG_ON(!drm_mm_initialized(&ggtt->base.mm));

        ret = gen6_init_scratch(vm);
        if (ret)
                return ret;

alloc:
        ret = drm_mm_insert_node_in_range_generic(&ggtt->base.mm, &ppgtt->node,
                                                  GEN6_PD_SIZE, GEN6_PD_ALIGN,
                                                  I915_COLOR_UNEVICTABLE,
                                                  0, ggtt->base.total,
                                                  DRM_MM_TOPDOWN);
        if (ret == -ENOSPC && !retried) {
                ret = i915_gem_evict_something(&ggtt->base,
                                               GEN6_PD_SIZE, GEN6_PD_ALIGN,
                                               I915_COLOR_UNEVICTABLE,
                                               0, ggtt->base.total,
                                               0);
                if (ret)
                        goto err_out;

                retried = true;
                goto alloc;
        }

        if (ret)
                goto err_out;


        if (ppgtt->node.start < ggtt->mappable_end)
                DRM_DEBUG("Forced to use aperture for PDEs\n");

        return 0;

err_out:
        gen6_free_scratch(vm);
        return ret;
}

static int gen6_ppgtt_alloc(struct i915_hw_ppgtt *ppgtt)
{
        return gen6_ppgtt_allocate_page_directories(ppgtt);
}

static void gen6_scratch_va_range(struct i915_hw_ppgtt *ppgtt,
                                  uint64_t start, uint64_t length)
{
        struct i915_page_table *unused;
        uint32_t pde;

        gen6_for_each_pde(unused, &ppgtt->pd, start, length, pde)
                ppgtt->pd.page_table[pde] = ppgtt->base.scratch_pt;
}

static int gen6_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
{
        struct drm_i915_private *dev_priv = ppgtt->base.i915;
        struct i915_ggtt *ggtt = &dev_priv->ggtt;
        int ret;

        ppgtt->base.pte_encode = ggtt->base.pte_encode;
        if (intel_vgpu_active(dev_priv) || IS_GEN6(dev_priv))
                ppgtt->switch_mm = gen6_mm_switch;
        else if (IS_HASWELL(dev_priv))
                ppgtt->switch_mm = hsw_mm_switch;
        else if (IS_GEN7(dev_priv))
                ppgtt->switch_mm = gen7_mm_switch;
        else
                BUG();

        ret = gen6_ppgtt_alloc(ppgtt);
        if (ret)
                return ret;

        ppgtt->base.allocate_va_range = gen6_alloc_va_range;
        ppgtt->base.clear_range = gen6_ppgtt_clear_range;
        ppgtt->base.insert_entries = gen6_ppgtt_insert_entries;
        ppgtt->base.unbind_vma = ppgtt_unbind_vma;
        ppgtt->base.bind_vma = ppgtt_bind_vma;
        ppgtt->base.cleanup = gen6_ppgtt_cleanup;
        ppgtt->base.start = 0;
        ppgtt->base.total = I915_PDES * GEN6_PTES * PAGE_SIZE;
        ppgtt->debug_dump = gen6_dump_ppgtt;

        ppgtt->pd.base.ggtt_offset =
                ppgtt->node.start / PAGE_SIZE * sizeof(gen6_pte_t);

        ppgtt->pd_addr = (gen6_pte_t __iomem *)ggtt->gsm +
                ppgtt->pd.base.ggtt_offset / sizeof(gen6_pte_t);

        gen6_scratch_va_range(ppgtt, 0, ppgtt->base.total);

        gen6_write_page_range(dev_priv, &ppgtt->pd, 0, ppgtt->base.total);

        DRM_DEBUG_DRIVER("Allocated pde space (%lldM) at GTT entry: %llx\n",
                         ppgtt->node.size >> 20,
                         ppgtt->node.start / PAGE_SIZE);

        DRM_DEBUG("Adding PPGTT at offset %x\n",
                  ppgtt->pd.base.ggtt_offset << 10);

        return 0;
}

static int __hw_ppgtt_init(struct i915_hw_ppgtt *ppgtt,
                           struct drm_i915_private *dev_priv)
{
        ppgtt->base.i915 = dev_priv;

        if (INTEL_INFO(dev_priv)->gen < 8)
                return gen6_ppgtt_init(ppgtt);
        else
                return gen8_ppgtt_init(ppgtt);
}

static void i915_address_space_init(struct i915_address_space *vm,
                                    struct drm_i915_private *dev_priv,
                                    const char *name)
{
        i915_gem_timeline_init(dev_priv, &vm->timeline, name);
        drm_mm_init(&vm->mm, vm->start, vm->total);
        INIT_LIST_HEAD(&vm->active_list);
        INIT_LIST_HEAD(&vm->inactive_list);
        INIT_LIST_HEAD(&vm->unbound_list);
        list_add_tail(&vm->global_link, &dev_priv->vm_list);
}

static void i915_address_space_fini(struct i915_address_space *vm)
{
        i915_gem_timeline_fini(&vm->timeline);
        drm_mm_takedown(&vm->mm);
        list_del(&vm->global_link);
}

static void gtt_write_workarounds(struct drm_i915_private *dev_priv)
{
        /* This function is for gtt related workarounds. This function is
         * called on driver load and after a GPU reset, so you can place
         * workarounds here even if they get overwritten by GPU reset.
         */
        /* WaIncreaseDefaultTLBEntries:chv,bdw,skl,bxt */
        if (IS_BROADWELL(dev_priv))
                I915_WRITE(GEN8_L3_LRA_1_GPGPU, GEN8_L3_LRA_1_GPGPU_DEFAULT_VALUE_BDW);
        else if (IS_CHERRYVIEW(dev_priv))
                I915_WRITE(GEN8_L3_LRA_1_GPGPU, GEN8_L3_LRA_1_GPGPU_DEFAULT_VALUE_CHV);
        else if (IS_SKYLAKE(dev_priv))
                I915_WRITE(GEN8_L3_LRA_1_GPGPU, GEN9_L3_LRA_1_GPGPU_DEFAULT_VALUE_SKL);
        else if (IS_BROXTON(dev_priv))
                I915_WRITE(GEN8_L3_LRA_1_GPGPU, GEN9_L3_LRA_1_GPGPU_DEFAULT_VALUE_BXT);
}

static int i915_ppgtt_init(struct i915_hw_ppgtt *ppgtt,
                           struct drm_i915_private *dev_priv,
                           struct drm_i915_file_private *file_priv,
                           const char *name)
{
        int ret;

        ret = __hw_ppgtt_init(ppgtt, dev_priv);
        if (ret == 0) {
                kref_init(&ppgtt->ref);
                i915_address_space_init(&ppgtt->base, dev_priv, name);
                ppgtt->base.file = file_priv;
        }

        return ret;
}

int i915_ppgtt_init_hw(struct drm_i915_private *dev_priv)
{
        gtt_write_workarounds(dev_priv);

        /* In the case of execlists, PPGTT is enabled by the context descriptor
         * and the PDPs are contained within the context itself.  We don't
         * need to do anything here. */
        if (i915.enable_execlists)
                return 0;

        if (!USES_PPGTT(dev_priv))
                return 0;

        if (IS_GEN6(dev_priv))
                gen6_ppgtt_enable(dev_priv);
        else if (IS_GEN7(dev_priv))
                gen7_ppgtt_enable(dev_priv);
        else if (INTEL_GEN(dev_priv) >= 8)
                gen8_ppgtt_enable(dev_priv);
        else
                MISSING_CASE(INTEL_GEN(dev_priv));

        return 0;
}

struct i915_hw_ppgtt *
i915_ppgtt_create(struct drm_i915_private *dev_priv,
                  struct drm_i915_file_private *fpriv,
                  const char *name)
{
        struct i915_hw_ppgtt *ppgtt;
        int ret;

        ppgtt = kzalloc(sizeof(*ppgtt), GFP_KERNEL);
        if (!ppgtt)
                return ERR_PTR(-ENOMEM);

        ret = i915_ppgtt_init(ppgtt, dev_priv, fpriv, name);
        if (ret) {
                kfree(ppgtt);
                return ERR_PTR(ret);
        }

        trace_i915_ppgtt_create(&ppgtt->base);

        return ppgtt;
}

void i915_ppgtt_release(struct kref *kref)
{
        struct i915_hw_ppgtt *ppgtt =
                container_of(kref, struct i915_hw_ppgtt, ref);

        trace_i915_ppgtt_release(&ppgtt->base);

        /* vmas should already be unbound and destroyed */
        WARN_ON(!list_empty(&ppgtt->base.active_list));
        WARN_ON(!list_empty(&ppgtt->base.inactive_list));
        WARN_ON(!list_empty(&ppgtt->base.unbound_list));

        i915_address_space_fini(&ppgtt->base);

        ppgtt->base.cleanup(&ppgtt->base);
        kfree(ppgtt);
}

/* Certain Gen5 chipsets require require idling the GPU before
 * unmapping anything from the GTT when VT-d is enabled.
 */
static bool needs_idle_maps(struct drm_i915_private *dev_priv)
{
#ifdef CONFIG_INTEL_IOMMU
        /* Query intel_iommu to see if we need the workaround. Presumably that
         * was loaded first.
         */
        if (IS_GEN5(dev_priv) && IS_MOBILE(dev_priv) && intel_iommu_gfx_mapped)
                return true;
#endif
        return false;
}

void i915_check_and_clear_faults(struct drm_i915_private *dev_priv)
{
        struct intel_engine_cs *engine;
        enum intel_engine_id id;

        if (INTEL_INFO(dev_priv)->gen < 6)
                return;

        for_each_engine(engine, dev_priv, id) {
                u32 fault_reg;
                fault_reg = I915_READ(RING_FAULT_REG(engine));
                if (fault_reg & RING_FAULT_VALID) {
                        DRM_DEBUG_DRIVER("Unexpected fault\n"
                                         "\tAddr: 0x%08lx\n"
                                         "\tAddress space: %s\n"
                                         "\tSource ID: %d\n"
                                         "\tType: %d\n",
                                         fault_reg & PAGE_MASK,
                                         fault_reg & RING_FAULT_GTTSEL_MASK ? "GGTT" : "PPGTT",
                                         RING_FAULT_SRCID(fault_reg),
                                         RING_FAULT_FAULT_TYPE(fault_reg));
                        I915_WRITE(RING_FAULT_REG(engine),
                                   fault_reg & ~RING_FAULT_VALID);
                }
        }

        /* Engine specific init may not have been done till this point. */
        if (dev_priv->engine[RCS])
                POSTING_READ(RING_FAULT_REG(dev_priv->engine[RCS]));
}

static void i915_ggtt_flush(struct drm_i915_private *dev_priv)
{
        if (INTEL_INFO(dev_priv)->gen < 6) {
                intel_gtt_chipset_flush();
        } else {
                I915_WRITE(GFX_FLSH_CNTL_GEN6, GFX_FLSH_CNTL_EN);
                POSTING_READ(GFX_FLSH_CNTL_GEN6);
        }
}

void i915_gem_suspend_gtt_mappings(struct drm_i915_private *dev_priv)
{
        struct i915_ggtt *ggtt = &dev_priv->ggtt;

        /* Don't bother messing with faults pre GEN6 as we have little
         * documentation supporting that it's a good idea.
         */
        if (INTEL_GEN(dev_priv) < 6)
                return;

        i915_check_and_clear_faults(dev_priv);

        ggtt->base.clear_range(&ggtt->base, ggtt->base.start, ggtt->base.total);

        i915_ggtt_flush(dev_priv);
}

int i915_gem_gtt_prepare_pages(struct drm_i915_gem_object *obj,
                               struct sg_table *pages)
{
        do {
                if (dma_map_sg(&obj->base.dev->pdev->dev,
                               pages->sgl, pages->nents,
                               PCI_DMA_BIDIRECTIONAL))
                        return 0;

                /* If the DMA remap fails, one cause can be that we have
                 * too many objects pinned in a small remapping table,
                 * such as swiotlb. Incrementally purge all other objects and
                 * try again - if there are no more pages to remove from
                 * the DMA remapper, i915_gem_shrink will return 0.
                 */
                GEM_BUG_ON(obj->mm.pages == pages);
        } while (i915_gem_shrink(to_i915(obj->base.dev),
                                 obj->base.size >> PAGE_SHIFT,
                                 I915_SHRINK_BOUND |
                                 I915_SHRINK_UNBOUND |
                                 I915_SHRINK_ACTIVE));

        return -ENOSPC;
}

static void gen8_set_pte(void __iomem *addr, gen8_pte_t pte)
{
        writeq(pte, addr);
}

static void gen8_ggtt_insert_page(struct i915_address_space *vm,
                                  dma_addr_t addr,
                                  uint64_t offset,
                                  enum i915_cache_level level,
                                  u32 unused)
{
        struct drm_i915_private *dev_priv = vm->i915;
        gen8_pte_t __iomem *pte =
                (gen8_pte_t __iomem *)dev_priv->ggtt.gsm +
                (offset >> PAGE_SHIFT);

        gen8_set_pte(pte, gen8_pte_encode(addr, level));

        I915_WRITE(GFX_FLSH_CNTL_GEN6, GFX_FLSH_CNTL_EN);
        POSTING_READ(GFX_FLSH_CNTL_GEN6);
}

static void gen8_ggtt_insert_entries(struct i915_address_space *vm,
                                     struct sg_table *st,
                                     uint64_t start,
                                     enum i915_cache_level level, u32 unused)
{
        struct drm_i915_private *dev_priv = vm->i915;
        struct i915_ggtt *ggtt = i915_vm_to_ggtt(vm);
        struct sgt_iter sgt_iter;
        gen8_pte_t __iomem *gtt_entries;
        gen8_pte_t gtt_entry;
        dma_addr_t addr;
        int i = 0;

        gtt_entries = (gen8_pte_t __iomem *)ggtt->gsm + (start >> PAGE_SHIFT);

        for_each_sgt_dma(addr, sgt_iter, st) {
                gtt_entry = gen8_pte_encode(addr, level);
                gen8_set_pte(&gtt_entries[i++], gtt_entry);
        }

        /*
         * XXX: This serves as a posting read to make sure that the PTE has
         * actually been updated. There is some concern that even though
         * registers and PTEs are within the same BAR that they are potentially
         * of NUMA access patterns. Therefore, even with the way we assume
         * hardware should work, we must keep this posting read for paranoia.
         */
        if (i != 0)
                WARN_ON(readq(&gtt_entries[i-1]) != gtt_entry);

        /* This next bit makes the above posting read even more important. We
         * want to flush the TLBs only after we're certain all the PTE updates
         * have finished.
         */
        I915_WRITE(GFX_FLSH_CNTL_GEN6, GFX_FLSH_CNTL_EN);
        POSTING_READ(GFX_FLSH_CNTL_GEN6);
}

struct insert_entries {
        struct i915_address_space *vm;
        struct sg_table *st;
        uint64_t start;
        enum i915_cache_level level;
        u32 flags;
};

static int gen8_ggtt_insert_entries__cb(void *_arg)
{
        struct insert_entries *arg = _arg;
        gen8_ggtt_insert_entries(arg->vm, arg->st,
                                 arg->start, arg->level, arg->flags);
        return 0;
}

static void gen8_ggtt_insert_entries__BKL(struct i915_address_space *vm,
                                          struct sg_table *st,
                                          uint64_t start,
                                          enum i915_cache_level level,
                                          u32 flags)
{
        struct insert_entries arg = { vm, st, start, level, flags };
        stop_machine(gen8_ggtt_insert_entries__cb, &arg, NULL);
}

static void gen6_ggtt_insert_page(struct i915_address_space *vm,
                                  dma_addr_t addr,
                                  uint64_t offset,
                                  enum i915_cache_level level,
                                  u32 flags)
{
        struct drm_i915_private *dev_priv = vm->i915;
        gen6_pte_t __iomem *pte =
                (gen6_pte_t __iomem *)dev_priv->ggtt.gsm +
                (offset >> PAGE_SHIFT);

        iowrite32(vm->pte_encode(addr, level, flags), pte);

        I915_WRITE(GFX_FLSH_CNTL_GEN6, GFX_FLSH_CNTL_EN);
        POSTING_READ(GFX_FLSH_CNTL_GEN6);
}

/*
 * Binds an object into the global gtt with the specified cache level. The object
 * will be accessible to the GPU via commands whose operands reference offsets
 * within the global GTT as well as accessible by the GPU through the GMADR
 * mapped BAR (dev_priv->mm.gtt->gtt).
 */
static void gen6_ggtt_insert_entries(struct i915_address_space *vm,
                                     struct sg_table *st,
                                     uint64_t start,
                                     enum i915_cache_level level, u32 flags)
{
        struct drm_i915_private *dev_priv = vm->i915;
        struct i915_ggtt *ggtt = i915_vm_to_ggtt(vm);
        struct sgt_iter sgt_iter;
        gen6_pte_t __iomem *gtt_entries;
        gen6_pte_t gtt_entry;
        dma_addr_t addr;
        int i = 0;

        gtt_entries = (gen6_pte_t __iomem *)ggtt->gsm + (start >> PAGE_SHIFT);

        for_each_sgt_dma(addr, sgt_iter, st) {
                gtt_entry = vm->pte_encode(addr, level, flags);
                iowrite32(gtt_entry, &gtt_entries[i++]);
        }

        /* XXX: This serves as a posting read to make sure that the PTE has
         * actually been updated. There is some concern that even though
         * registers and PTEs are within the same BAR that they are potentially
         * of NUMA access patterns. Therefore, even with the way we assume
         * hardware should work, we must keep this posting read for paranoia.
         */
        if (i != 0)
                WARN_ON(readl(&gtt_entries[i-1]) != gtt_entry);

        /* This next bit makes the above posting read even more important. We
         * want to flush the TLBs only after we're certain all the PTE updates
         * have finished.
         */
        I915_WRITE(GFX_FLSH_CNTL_GEN6, GFX_FLSH_CNTL_EN);
        POSTING_READ(GFX_FLSH_CNTL_GEN6);
}

static void nop_clear_range(struct i915_address_space *vm,
                            uint64_t start, uint64_t length)
{
}

static void gen8_ggtt_clear_range(struct i915_address_space *vm,
                                  uint64_t start, uint64_t length)
{
        struct i915_ggtt *ggtt = i915_vm_to_ggtt(vm);
        unsigned first_entry = start >> PAGE_SHIFT;
        unsigned num_entries = length >> PAGE_SHIFT;
        gen8_pte_t scratch_pte, __iomem *gtt_base =
                (gen8_pte_t __iomem *)ggtt->gsm + first_entry;
        const int max_entries = ggtt_total_entries(ggtt) - first_entry;
        int i;

        if (WARN(num_entries > max_entries,
                 "First entry = %d; Num entries = %d (max=%d)\n",
                 first_entry, num_entries, max_entries))
                num_entries = max_entries;

        scratch_pte = gen8_pte_encode(vm->scratch_page.daddr,
                                      I915_CACHE_LLC);
        for (i = 0; i < num_entries; i++)
                gen8_set_pte(&gtt_base[i], scratch_pte);
        readl(gtt_base);
}

static void gen6_ggtt_clear_range(struct i915_address_space *vm,
                                  uint64_t start,
                                  uint64_t length)
{
        struct i915_ggtt *ggtt = i915_vm_to_ggtt(vm);
        unsigned first_entry = start >> PAGE_SHIFT;
        unsigned num_entries = length >> PAGE_SHIFT;
        gen6_pte_t scratch_pte, __iomem *gtt_base =
                (gen6_pte_t __iomem *)ggtt->gsm + first_entry;
        const int max_entries = ggtt_total_entries(ggtt) - first_entry;
        int i;

        if (WARN(num_entries > max_entries,
                 "First entry = %d; Num entries = %d (max=%d)\n",
                 first_entry, num_entries, max_entries))
                num_entries = max_entries;

        scratch_pte = vm->pte_encode(vm->scratch_page.daddr,
                                     I915_CACHE_LLC, 0);

        for (i = 0; i < num_entries; i++)
                iowrite32(scratch_pte, &gtt_base[i]);
        readl(gtt_base);
}

static void i915_ggtt_insert_page(struct i915_address_space *vm,
                                  dma_addr_t addr,
                                  uint64_t offset,
                                  enum i915_cache_level cache_level,
                                  u32 unused)
{
        unsigned int flags = (cache_level == I915_CACHE_NONE) ?
                AGP_USER_MEMORY : AGP_USER_CACHED_MEMORY;

        intel_gtt_insert_page(addr, offset >> PAGE_SHIFT, flags);
}

static void i915_ggtt_insert_entries(struct i915_address_space *vm,
                                     struct sg_table *pages,
                                     uint64_t start,
                                     enum i915_cache_level cache_level, u32 unused)
{
        unsigned int flags = (cache_level == I915_CACHE_NONE) ?
                AGP_USER_MEMORY : AGP_USER_CACHED_MEMORY;

        intel_gtt_insert_sg_entries(pages, start >> PAGE_SHIFT, flags);

}

static void i915_ggtt_clear_range(struct i915_address_space *vm,
                                  uint64_t start,
                                  uint64_t length)
{
        intel_gtt_clear_range(start >> PAGE_SHIFT, length >> PAGE_SHIFT);
}

static int ggtt_bind_vma(struct i915_vma *vma,
                         enum i915_cache_level cache_level,
                         u32 flags)
{
        struct drm_i915_private *i915 = vma->vm->i915;
        struct drm_i915_gem_object *obj = vma->obj;
        u32 pte_flags = 0;
        int ret;

        ret = i915_get_ggtt_vma_pages(vma);
        if (ret)
                return ret;

        /* Currently applicable only to VLV */
        if (obj->gt_ro)
                pte_flags |= PTE_READ_ONLY;

        intel_runtime_pm_get(i915);
        vma->vm->insert_entries(vma->vm, vma->pages, vma->node.start,
                                cache_level, pte_flags);
        intel_runtime_pm_put(i915);

        /*
         * Without aliasing PPGTT there's no difference between
         * GLOBAL/LOCAL_BIND, it's all the same ptes. Hence unconditionally
         * upgrade to both bound if we bind either to avoid double-binding.
         */
        vma->flags |= I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND;

        return 0;
}

static int aliasing_gtt_bind_vma(struct i915_vma *vma,
                                 enum i915_cache_level cache_level,
                                 u32 flags)
{
        struct drm_i915_private *i915 = vma->vm->i915;
        u32 pte_flags;
        int ret;

        ret = i915_get_ggtt_vma_pages(vma);
        if (ret)
                return ret;

        /* Currently applicable only to VLV */
        pte_flags = 0;
        if (vma->obj->gt_ro)
                pte_flags |= PTE_READ_ONLY;


        if (flags & I915_VMA_GLOBAL_BIND) {
                intel_runtime_pm_get(i915);
                vma->vm->insert_entries(vma->vm,
                                        vma->pages, vma->node.start,
                                        cache_level, pte_flags);
                intel_runtime_pm_put(i915);
        }

        if (flags & I915_VMA_LOCAL_BIND) {
                struct i915_hw_ppgtt *appgtt = i915->mm.aliasing_ppgtt;
                appgtt->base.insert_entries(&appgtt->base,
                                            vma->pages, vma->node.start,
                                            cache_level, pte_flags);
        }

        return 0;
}

static void ggtt_unbind_vma(struct i915_vma *vma)
{
        struct drm_i915_private *i915 = vma->vm->i915;
        struct i915_hw_ppgtt *appgtt = i915->mm.aliasing_ppgtt;
        const u64 size = min(vma->size, vma->node.size);

        if (vma->flags & I915_VMA_GLOBAL_BIND) {
                intel_runtime_pm_get(i915);
                vma->vm->clear_range(vma->vm,
                                     vma->node.start, size);
                intel_runtime_pm_put(i915);
        }

        if (vma->flags & I915_VMA_LOCAL_BIND && appgtt)
                appgtt->base.clear_range(&appgtt->base,
                                         vma->node.start, size);
}

void i915_gem_gtt_finish_pages(struct drm_i915_gem_object *obj,
                               struct sg_table *pages)
{
        struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
        struct device *kdev = &dev_priv->drm.pdev->dev;
        struct i915_ggtt *ggtt = &dev_priv->ggtt;

        if (unlikely(ggtt->do_idle_maps)) {
                if (i915_gem_wait_for_idle(dev_priv, I915_WAIT_LOCKED)) {
                        DRM_ERROR("Failed to wait for idle; VT'd may hang.\n");
                        /* Wait a bit, in hopes it avoids the hang */
                        udelay(10);
                }
        }

        dma_unmap_sg(kdev, pages->sgl, pages->nents, PCI_DMA_BIDIRECTIONAL);
}

static void i915_gtt_color_adjust(const struct drm_mm_node *node,
                                  unsigned long color,
                                  u64 *start,
                                  u64 *end)
{
        if (node->color != color)
                *start += 4096;

        node = list_next_entry(node, node_list);
        if (node->allocated && node->color != color)
                *end -= 4096;
}

int i915_gem_init_ggtt(struct drm_i915_private *dev_priv)
{
        /* Let GEM Manage all of the aperture.
         *
         * However, leave one page at the end still bound to the scratch page.
         * There are a number of places where the hardware apparently prefetches
         * past the end of the object, and we've seen multiple hangs with the
         * GPU head pointer stuck in a batchbuffer bound at the last page of the
         * aperture.  One page should be enough to keep any prefetching inside
         * of the aperture.
         */
        struct i915_ggtt *ggtt = &dev_priv->ggtt;
        unsigned long hole_start, hole_end;
        struct i915_hw_ppgtt *ppgtt;
        struct drm_mm_node *entry;
        int ret;

        ret = intel_vgt_balloon(dev_priv);
        if (ret)
                return ret;

        /* Reserve a mappable slot for our lockless error capture */
        ret = drm_mm_insert_node_in_range_generic(&ggtt->base.mm,
                                                  &ggtt->error_capture,
                                                  4096, 0,
                                                  I915_COLOR_UNEVICTABLE,
                                                  0, ggtt->mappable_end,
                                                  0, 0);
        if (ret)
                return ret;

        /* Clear any non-preallocated blocks */
        drm_mm_for_each_hole(entry, &ggtt->base.mm, hole_start, hole_end) {
                DRM_DEBUG_KMS("clearing unused GTT space: [%lx, %lx]\n",
                              hole_start, hole_end);
                ggtt->base.clear_range(&ggtt->base, hole_start,
                                       hole_end - hole_start);
        }

        /* And finally clear the reserved guard page */
        ggtt->base.clear_range(&ggtt->base,
                               ggtt->base.total - PAGE_SIZE, PAGE_SIZE);

        if (USES_PPGTT(dev_priv) && !USES_FULL_PPGTT(dev_priv)) {
                ppgtt = kzalloc(sizeof(*ppgtt), GFP_KERNEL);
                if (!ppgtt) {
                        ret = -ENOMEM;
                        goto err;
                }

                ret = __hw_ppgtt_init(ppgtt, dev_priv);
                if (ret)
                        goto err_ppgtt;

                if (ppgtt->base.allocate_va_range) {
                        ret = ppgtt->base.allocate_va_range(&ppgtt->base, 0,
                                                            ppgtt->base.total);
                        if (ret)
                                goto err_ppgtt_cleanup;
                }

                ppgtt->base.clear_range(&ppgtt->base,
                                        ppgtt->base.start,
                                        ppgtt->base.total);

                dev_priv->mm.aliasing_ppgtt = ppgtt;
                WARN_ON(ggtt->base.bind_vma != ggtt_bind_vma);
                ggtt->base.bind_vma = aliasing_gtt_bind_vma;
        }

        return 0;

err_ppgtt_cleanup:
        ppgtt->base.cleanup(&ppgtt->base);
err_ppgtt:
        kfree(ppgtt);
err:
        drm_mm_remove_node(&ggtt->error_capture);
        return ret;
}

/**
 * i915_ggtt_cleanup_hw - Clean up GGTT hardware initialization
 * @dev_priv: i915 device
 */
void i915_ggtt_cleanup_hw(struct drm_i915_private *dev_priv)
{
        struct i915_ggtt *ggtt = &dev_priv->ggtt;

        if (dev_priv->mm.aliasing_ppgtt) {
                struct i915_hw_ppgtt *ppgtt = dev_priv->mm.aliasing_ppgtt;
                ppgtt->base.cleanup(&ppgtt->base);
                kfree(ppgtt);
        }

        i915_gem_cleanup_stolen(&dev_priv->drm);

        if (drm_mm_node_allocated(&ggtt->error_capture))
                drm_mm_remove_node(&ggtt->error_capture);

        if (drm_mm_initialized(&ggtt->base.mm)) {
                intel_vgt_deballoon(dev_priv);

                mutex_lock(&dev_priv->drm.struct_mutex);
                i915_address_space_fini(&ggtt->base);
                mutex_unlock(&dev_priv->drm.struct_mutex);
        }

        ggtt->base.cleanup(&ggtt->base);

        arch_phys_wc_del(ggtt->mtrr);
        io_mapping_fini(&ggtt->mappable);
}

static unsigned int gen6_get_total_gtt_size(u16 snb_gmch_ctl)
{
        snb_gmch_ctl >>= SNB_GMCH_GGMS_SHIFT;
        snb_gmch_ctl &= SNB_GMCH_GGMS_MASK;
        return snb_gmch_ctl << 20;
}

static unsigned int gen8_get_total_gtt_size(u16 bdw_gmch_ctl)
{
        bdw_gmch_ctl >>= BDW_GMCH_GGMS_SHIFT;
        bdw_gmch_ctl &= BDW_GMCH_GGMS_MASK;
        if (bdw_gmch_ctl)
                bdw_gmch_ctl = 1 << bdw_gmch_ctl;

#ifdef CONFIG_X86_32
        /* Limit 32b platforms to a 2GB GGTT: 4 << 20 / pte size * PAGE_SIZE */
        if (bdw_gmch_ctl > 4)
                bdw_gmch_ctl = 4;
#endif

        return bdw_gmch_ctl << 20;
}

static unsigned int chv_get_total_gtt_size(u16 gmch_ctrl)
{
        gmch_ctrl >>= SNB_GMCH_GGMS_SHIFT;
        gmch_ctrl &= SNB_GMCH_GGMS_MASK;

        if (gmch_ctrl)
                return 1 << (20 + gmch_ctrl);

        return 0;
}

static size_t gen6_get_stolen_size(u16 snb_gmch_ctl)
{
        snb_gmch_ctl >>= SNB_GMCH_GMS_SHIFT;
        snb_gmch_ctl &= SNB_GMCH_GMS_MASK;
        return snb_gmch_ctl << 25; /* 32 MB units */
}

static size_t gen8_get_stolen_size(u16 bdw_gmch_ctl)
{
        bdw_gmch_ctl >>= BDW_GMCH_GMS_SHIFT;
        bdw_gmch_ctl &= BDW_GMCH_GMS_MASK;
        return bdw_gmch_ctl << 25; /* 32 MB units */
}

static size_t chv_get_stolen_size(u16 gmch_ctrl)
{
        gmch_ctrl >>= SNB_GMCH_GMS_SHIFT;
        gmch_ctrl &= SNB_GMCH_GMS_MASK;

        /*
         * 0x0  to 0x10: 32MB increments starting at 0MB
         * 0x11 to 0x16: 4MB increments starting at 8MB
         * 0x17 to 0x1d: 4MB increments start at 36MB
         */
        if (gmch_ctrl < 0x11)
                return gmch_ctrl << 25;
        else if (gmch_ctrl < 0x17)
                return (gmch_ctrl - 0x11 + 2) << 22;
        else
                return (gmch_ctrl - 0x17 + 9) << 22;
}

static size_t gen9_get_stolen_size(u16 gen9_gmch_ctl)
{
        gen9_gmch_ctl >>= BDW_GMCH_GMS_SHIFT;
        gen9_gmch_ctl &= BDW_GMCH_GMS_MASK;

        if (gen9_gmch_ctl < 0xf0)
                return gen9_gmch_ctl << 25; /* 32 MB units */
        else
                /* 4MB increments starting at 0xf0 for 4MB */
                return (gen9_gmch_ctl - 0xf0 + 1) << 22;
}

static int ggtt_probe_common(struct i915_ggtt *ggtt, u64 size)
{
        struct drm_i915_private *dev_priv = ggtt->base.i915;
        struct pci_dev *pdev = dev_priv->drm.pdev;
        phys_addr_t phys_addr;
        int ret;

        /* For Modern GENs the PTEs and register space are split in the BAR */
        phys_addr = pci_resource_start(pdev, 0) + pci_resource_len(pdev, 0) / 2;

        /*
         * On BXT writes larger than 64 bit to the GTT pagetable range will be
         * dropped. For WC mappings in general we have 64 byte burst writes
         * when the WC buffer is flushed, so we can't use it, but have to
         * resort to an uncached mapping. The WC issue is easily caught by the
         * readback check when writing GTT PTE entries.
         */
        if (IS_GEN9_LP(dev_priv))
                ggtt->gsm = ioremap_nocache(phys_addr, size);
        else
                ggtt->gsm = ioremap_wc(phys_addr, size);
        if (!ggtt->gsm) {
                DRM_ERROR("Failed to map the ggtt page table\n");
                return -ENOMEM;
        }

        ret = setup_scratch_page(dev_priv, &ggtt->base.scratch_page, GFP_DMA32);
        if (ret) {
                DRM_ERROR("Scratch setup failed\n");
                /* iounmap will also get called at remove, but meh */
                iounmap(ggtt->gsm);
                return ret;
        }

        return 0;
}

/* The GGTT and PPGTT need a private PPAT setup in order to handle cacheability
 * bits. When using advanced contexts each context stores its own PAT, but
 * writing this data shouldn't be harmful even in those cases. */
static void bdw_setup_private_ppat(struct drm_i915_private *dev_priv)
{
        uint64_t pat;

        pat = GEN8_PPAT(0, GEN8_PPAT_WB | GEN8_PPAT_LLC)     | /* for normal objects, no eLLC */
              GEN8_PPAT(1, GEN8_PPAT_WC | GEN8_PPAT_LLCELLC) | /* for something pointing to ptes? */
              GEN8_PPAT(2, GEN8_PPAT_WT | GEN8_PPAT_LLCELLC) | /* for scanout with eLLC */
              GEN8_PPAT(3, GEN8_PPAT_UC)                     | /* Uncached objects, mostly for scanout */
              GEN8_PPAT(4, GEN8_PPAT_WB | GEN8_PPAT_LLCELLC | GEN8_PPAT_AGE(0)) |
              GEN8_PPAT(5, GEN8_PPAT_WB | GEN8_PPAT_LLCELLC | GEN8_PPAT_AGE(1)) |
              GEN8_PPAT(6, GEN8_PPAT_WB | GEN8_PPAT_LLCELLC | GEN8_PPAT_AGE(2)) |
              GEN8_PPAT(7, GEN8_PPAT_WB | GEN8_PPAT_LLCELLC | GEN8_PPAT_AGE(3));

        if (!USES_PPGTT(dev_priv))
                /* Spec: "For GGTT, there is NO pat_sel[2:0] from the entry,
                 * so RTL will always use the value corresponding to
                 * pat_sel = 000".
                 * So let's disable cache for GGTT to avoid screen corruptions.
                 * MOCS still can be used though.
                 * - System agent ggtt writes (i.e. cpu gtt mmaps) already work
                 * before this patch, i.e. the same uncached + snooping access
                 * like on gen6/7 seems to be in effect.
                 * - So this just fixes blitter/render access. Again it looks
                 * like it's not just uncached access, but uncached + snooping.
                 * So we can still hold onto all our assumptions wrt cpu
                 * clflushing on LLC machines.
                 */
                pat = GEN8_PPAT(0, GEN8_PPAT_UC);

        /* XXX: spec defines this as 2 distinct registers. It's unclear if a 64b
         * write would work. */
        I915_WRITE(GEN8_PRIVATE_PAT_LO, pat);
        I915_WRITE(GEN8_PRIVATE_PAT_HI, pat >> 32);
}

static void chv_setup_private_ppat(struct drm_i915_private *dev_priv)
{
        uint64_t pat;

        /*
         * Map WB on BDW to snooped on CHV.
         *
         * Only the snoop bit has meaning for CHV, the rest is
         * ignored.
         *
         * The hardware will never snoop for certain types of accesses:
         * - CPU GTT (GMADR->GGTT->no snoop->memory)
         * - PPGTT page tables
         * - some other special cycles
         *
         * As with BDW, we also need to consider the following for GT accesses:
         * "For GGTT, there is NO pat_sel[2:0] from the entry,
         * so RTL will always use the value corresponding to
         * pat_sel = 000".
         * Which means we must set the snoop bit in PAT entry 0
         * in order to keep the global status page working.
         */
        pat = GEN8_PPAT(0, CHV_PPAT_SNOOP) |
              GEN8_PPAT(1, 0) |
              GEN8_PPAT(2, 0) |
              GEN8_PPAT(3, 0) |
              GEN8_PPAT(4, CHV_PPAT_SNOOP) |
              GEN8_PPAT(5, CHV_PPAT_SNOOP) |
              GEN8_PPAT(6, CHV_PPAT_SNOOP) |
              GEN8_PPAT(7, CHV_PPAT_SNOOP);

        I915_WRITE(GEN8_PRIVATE_PAT_LO, pat);
        I915_WRITE(GEN8_PRIVATE_PAT_HI, pat >> 32);
}

static void gen6_gmch_remove(struct i915_address_space *vm)
{
        struct i915_ggtt *ggtt = i915_vm_to_ggtt(vm);

        iounmap(ggtt->gsm);
        cleanup_scratch_page(vm->i915, &vm->scratch_page);
}

static int gen8_gmch_probe(struct i915_ggtt *ggtt)
{
        struct drm_i915_private *dev_priv = ggtt->base.i915;
        struct pci_dev *pdev = dev_priv->drm.pdev;
        unsigned int size;
        u16 snb_gmch_ctl;

        /* TODO: We're not aware of mappable constraints on gen8 yet */
        ggtt->mappable_base = pci_resource_start(pdev, 2);
        ggtt->mappable_end = pci_resource_len(pdev, 2);

        if (!pci_set_dma_mask(pdev, DMA_BIT_MASK(39)))
                pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(39));

        pci_read_config_word(pdev, SNB_GMCH_CTRL, &snb_gmch_ctl);

        if (INTEL_GEN(dev_priv) >= 9) {
                ggtt->stolen_size = gen9_get_stolen_size(snb_gmch_ctl);
                size = gen8_get_total_gtt_size(snb_gmch_ctl);
        } else if (IS_CHERRYVIEW(dev_priv)) {
                ggtt->stolen_size = chv_get_stolen_size(snb_gmch_ctl);
                size = chv_get_total_gtt_size(snb_gmch_ctl);
        } else {
                ggtt->stolen_size = gen8_get_stolen_size(snb_gmch_ctl);
                size = gen8_get_total_gtt_size(snb_gmch_ctl);
        }

        ggtt->base.total = (size / sizeof(gen8_pte_t)) << PAGE_SHIFT;

        if (IS_CHERRYVIEW(dev_priv) || IS_GEN9_LP(dev_priv))
                chv_setup_private_ppat(dev_priv);
        else
                bdw_setup_private_ppat(dev_priv);

        ggtt->base.cleanup = gen6_gmch_remove;
        ggtt->base.bind_vma = ggtt_bind_vma;
        ggtt->base.unbind_vma = ggtt_unbind_vma;
        ggtt->base.insert_page = gen8_ggtt_insert_page;
        ggtt->base.clear_range = nop_clear_range;
        if (!USES_FULL_PPGTT(dev_priv) || intel_scanout_needs_vtd_wa(dev_priv))
                ggtt->base.clear_range = gen8_ggtt_clear_range;

        ggtt->base.insert_entries = gen8_ggtt_insert_entries;
        if (IS_CHERRYVIEW(dev_priv))
                ggtt->base.insert_entries = gen8_ggtt_insert_entries__BKL;

        return ggtt_probe_common(ggtt, size);
}

static int gen6_gmch_probe(struct i915_ggtt *ggtt)
{
        struct drm_i915_private *dev_priv = ggtt->base.i915;
        struct pci_dev *pdev = dev_priv->drm.pdev;
        unsigned int size;
        u16 snb_gmch_ctl;

        ggtt->mappable_base = pci_resource_start(pdev, 2);
        ggtt->mappable_end = pci_resource_len(pdev, 2);

        /* 64/512MB is the current min/max we actually know of, but this is just
         * a coarse sanity check.
         */
        if (ggtt->mappable_end < (64<<20) || ggtt->mappable_end > (512<<20)) {
                DRM_ERROR("Unknown GMADR size (%llx)\n", ggtt->mappable_end);
                return -ENXIO;
        }

        if (!pci_set_dma_mask(pdev, DMA_BIT_MASK(40)))
                pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(40));
        pci_read_config_word(pdev, SNB_GMCH_CTRL, &snb_gmch_ctl);

        ggtt->stolen_size = gen6_get_stolen_size(snb_gmch_ctl);

        size = gen6_get_total_gtt_size(snb_gmch_ctl);
        ggtt->base.total = (size / sizeof(gen6_pte_t)) << PAGE_SHIFT;

        ggtt->base.clear_range = gen6_ggtt_clear_range;
        ggtt->base.insert_page = gen6_ggtt_insert_page;
        ggtt->base.insert_entries = gen6_ggtt_insert_entries;
        ggtt->base.bind_vma = ggtt_bind_vma;
        ggtt->base.unbind_vma = ggtt_unbind_vma;
        ggtt->base.cleanup = gen6_gmch_remove;

        if (HAS_EDRAM(dev_priv))
                ggtt->base.pte_encode = iris_pte_encode;
        else if (IS_HASWELL(dev_priv))
                ggtt->base.pte_encode = hsw_pte_encode;
        else if (IS_VALLEYVIEW(dev_priv))
                ggtt->base.pte_encode = byt_pte_encode;
        else if (INTEL_GEN(dev_priv) >= 7)
                ggtt->base.pte_encode = ivb_pte_encode;
        else
                ggtt->base.pte_encode = snb_pte_encode;

        return ggtt_probe_common(ggtt, size);
}

static void i915_gmch_remove(struct i915_address_space *vm)
{
        intel_gmch_remove();
}

static int i915_gmch_probe(struct i915_ggtt *ggtt)
{
        struct drm_i915_private *dev_priv = ggtt->base.i915;
        int ret;

        ret = intel_gmch_probe(dev_priv->bridge_dev, dev_priv->drm.pdev, NULL);
        if (!ret) {
                DRM_ERROR("failed to set up gmch\n");
                return -EIO;
        }

        intel_gtt_get(&ggtt->base.total,
                      &ggtt->stolen_size,
                      &ggtt->mappable_base,
                      &ggtt->mappable_end);

        ggtt->do_idle_maps = needs_idle_maps(dev_priv);
        ggtt->base.insert_page = i915_ggtt_insert_page;
        ggtt->base.insert_entries = i915_ggtt_insert_entries;
        ggtt->base.clear_range = i915_ggtt_clear_range;
        ggtt->base.bind_vma = ggtt_bind_vma;
        ggtt->base.unbind_vma = ggtt_unbind_vma;
        ggtt->base.cleanup = i915_gmch_remove;

        if (unlikely(ggtt->do_idle_maps))
                DRM_INFO("applying Ironlake quirks for intel_iommu\n");

        return 0;
}

/**
 * i915_ggtt_probe_hw - Probe GGTT hardware location
 * @dev_priv: i915 device
 */
int i915_ggtt_probe_hw(struct drm_i915_private *dev_priv)
{
        struct i915_ggtt *ggtt = &dev_priv->ggtt;
        int ret;

        ggtt->base.i915 = dev_priv;

        if (INTEL_GEN(dev_priv) <= 5)
                ret = i915_gmch_probe(ggtt);
        else if (INTEL_GEN(dev_priv) < 8)
                ret = gen6_gmch_probe(ggtt);
        else
                ret = gen8_gmch_probe(ggtt);
        if (ret)
                return ret;

        /* Trim the GGTT to fit the GuC mappable upper range (when enabled).
         * This is easier than doing range restriction on the fly, as we
         * currently don't have any bits spare to pass in this upper
         * restriction!
         */
        if (HAS_GUC(dev_priv) && i915.enable_guc_loading) {
                ggtt->base.total = min_t(u64, ggtt->base.total, GUC_GGTT_TOP);
                ggtt->mappable_end = min(ggtt->mappable_end, ggtt->base.total);
        }

        if ((ggtt->base.total - 1) >> 32) {
                DRM_ERROR("We never expected a Global GTT with more than 32bits"
                          " of address space! Found %lldM!\n",
                          ggtt->base.total >> 20);
                ggtt->base.total = 1ULL << 32;
                ggtt->mappable_end = min(ggtt->mappable_end, ggtt->base.total);
        }

        if (ggtt->mappable_end > ggtt->base.total) {
                DRM_ERROR("mappable aperture extends past end of GGTT,"
                          " aperture=%llx, total=%llx\n",
                          ggtt->mappable_end, ggtt->base.total);
                ggtt->mappable_end = ggtt->base.total;
        }

        /* GMADR is the PCI mmio aperture into the global GTT. */
        DRM_INFO("Memory usable by graphics device = %lluM\n",
                 ggtt->base.total >> 20);
        DRM_DEBUG_DRIVER("GMADR size = %lldM\n", ggtt->mappable_end >> 20);
        DRM_DEBUG_DRIVER("GTT stolen size = %uM\n", ggtt->stolen_size >> 20);
#ifdef CONFIG_INTEL_IOMMU
        if (intel_iommu_gfx_mapped)
                DRM_INFO("VT-d active for gfx access\n");
#endif

        return 0;
}

/**
 * i915_ggtt_init_hw - Initialize GGTT hardware
 * @dev_priv: i915 device
 */
int i915_ggtt_init_hw(struct drm_i915_private *dev_priv)
{
        struct i915_ggtt *ggtt = &dev_priv->ggtt;
        int ret;

        INIT_LIST_HEAD(&dev_priv->vm_list);

        /* Subtract the guard page before address space initialization to
         * shrink the range used by drm_mm.
         */
        mutex_lock(&dev_priv->drm.struct_mutex);
        ggtt->base.total -= PAGE_SIZE;
        i915_address_space_init(&ggtt->base, dev_priv, "[global]");
        ggtt->base.total += PAGE_SIZE;
        if (!HAS_LLC(dev_priv))
                ggtt->base.mm.color_adjust = i915_gtt_color_adjust;
        mutex_unlock(&dev_priv->drm.struct_mutex);

        if (!io_mapping_init_wc(&dev_priv->ggtt.mappable,
                                dev_priv->ggtt.mappable_base,
                                dev_priv->ggtt.mappable_end)) {
                ret = -EIO;
                goto out_gtt_cleanup;
        }

        ggtt->mtrr = arch_phys_wc_add(ggtt->mappable_base, ggtt->mappable_end);

        /*
         * Initialise stolen early so that we may reserve preallocated
         * objects for the BIOS to KMS transition.
         */
        ret = i915_gem_init_stolen(dev_priv);
        if (ret)
                goto out_gtt_cleanup;

        return 0;

out_gtt_cleanup:
        ggtt->base.cleanup(&ggtt->base);
        return ret;
}

int i915_ggtt_enable_hw(struct drm_i915_private *dev_priv)
{
        if (INTEL_GEN(dev_priv) < 6 && !intel_enable_gtt())
                return -EIO;

        return 0;
}

void i915_gem_restore_gtt_mappings(struct drm_i915_private *dev_priv)
{
        struct i915_ggtt *ggtt = &dev_priv->ggtt;
        struct drm_i915_gem_object *obj, *on;

        i915_check_and_clear_faults(dev_priv);

        /* First fill our portion of the GTT with scratch pages */
        ggtt->base.clear_range(&ggtt->base, ggtt->base.start, ggtt->base.total);

        ggtt->base.closed = true; /* skip rewriting PTE on VMA unbind */

        /* clflush objects bound into the GGTT and rebind them. */
        list_for_each_entry_safe(obj, on,
                                 &dev_priv->mm.bound_list, global_link) {
                bool ggtt_bound = false;
                struct i915_vma *vma;

                list_for_each_entry(vma, &obj->vma_list, obj_link) {
                        if (vma->vm != &ggtt->base)
                                continue;

                        if (!i915_vma_unbind(vma))
                                continue;

                        WARN_ON(i915_vma_bind(vma, obj->cache_level,
                                              PIN_UPDATE));
                        ggtt_bound = true;
                }

                if (ggtt_bound)
                        WARN_ON(i915_gem_object_set_to_gtt_domain(obj, false));
        }

        ggtt->base.closed = false;

        if (INTEL_GEN(dev_priv) >= 8) {
                if (IS_CHERRYVIEW(dev_priv) || IS_GEN9_LP(dev_priv))
                        chv_setup_private_ppat(dev_priv);
                else
                        bdw_setup_private_ppat(dev_priv);

                return;
        }

        if (USES_PPGTT(dev_priv)) {
                struct i915_address_space *vm;

                list_for_each_entry(vm, &dev_priv->vm_list, global_link) {
                        /* TODO: Perhaps it shouldn't be gen6 specific */

                        struct i915_hw_ppgtt *ppgtt;

                        if (i915_is_ggtt(vm))
                                ppgtt = dev_priv->mm.aliasing_ppgtt;
                        else
                                ppgtt = i915_vm_to_ppgtt(vm);

                        gen6_write_page_range(dev_priv, &ppgtt->pd,
                                              0, ppgtt->base.total);
                }
        }

        i915_ggtt_flush(dev_priv);
}

struct i915_vma *
i915_gem_obj_to_vma(struct drm_i915_gem_object *obj,
                    struct i915_address_space *vm,
                    const struct i915_ggtt_view *view)
{
        struct rb_node *rb;

        rb = obj->vma_tree.rb_node;
        while (rb) {
                struct i915_vma *vma = rb_entry(rb, struct i915_vma, obj_node);
                long cmp;

                cmp = i915_vma_compare(vma, vm, view);
                if (cmp == 0)
                        return vma;

                if (cmp < 0)
                        rb = rb->rb_right;
                else
                        rb = rb->rb_left;
        }

        return NULL;
}

struct i915_vma *
i915_gem_obj_lookup_or_create_vma(struct drm_i915_gem_object *obj,
                                  struct i915_address_space *vm,
                                  const struct i915_ggtt_view *view)
{
        struct i915_vma *vma;

        lockdep_assert_held(&obj->base.dev->struct_mutex);
        GEM_BUG_ON(view && !i915_is_ggtt(vm));

        vma = i915_gem_obj_to_vma(obj, vm, view);
        if (!vma) {
                vma = i915_vma_create(obj, vm, view);
                GEM_BUG_ON(vma != i915_gem_obj_to_vma(obj, vm, view));
        }

        GEM_BUG_ON(i915_vma_is_closed(vma));
        return vma;
}

static struct scatterlist *
rotate_pages(const dma_addr_t *in, unsigned int offset,
             unsigned int width, unsigned int height,
             unsigned int stride,
             struct sg_table *st, struct scatterlist *sg)
{
        unsigned int column, row;
        unsigned int src_idx;

        for (column = 0; column < width; column++) {
                src_idx = stride * (height - 1) + column;
                for (row = 0; row < height; row++) {
                        st->nents++;
                        /* We don't need the pages, but need to initialize
                         * the entries so the sg list can be happily traversed.
                         * The only thing we need are DMA addresses.
                         */
                        sg_set_page(sg, NULL, PAGE_SIZE, 0);
                        sg_dma_address(sg) = in[offset + src_idx];
                        sg_dma_len(sg) = PAGE_SIZE;
                        sg = sg_next(sg);
                        src_idx -= stride;
                }
        }

        return sg;
}

static struct sg_table *
intel_rotate_fb_obj_pages(const struct intel_rotation_info *rot_info,
                          struct drm_i915_gem_object *obj)
{
        const size_t n_pages = obj->base.size / PAGE_SIZE;
        unsigned int size = intel_rotation_info_size(rot_info);
        struct sgt_iter sgt_iter;
        dma_addr_t dma_addr;
        unsigned long i;
        dma_addr_t *page_addr_list;
        struct sg_table *st;
        struct scatterlist *sg;
        int ret = -ENOMEM;

        /* Allocate a temporary list of source pages for random access. */
        page_addr_list = drm_malloc_gfp(n_pages,
                                        sizeof(dma_addr_t),
                                        GFP_TEMPORARY);
        if (!page_addr_list)
                return ERR_PTR(ret);

        /* Allocate target SG list. */
        st = kmalloc(sizeof(*st), GFP_KERNEL);
        if (!st)
                goto err_st_alloc;

        ret = sg_alloc_table(st, size, GFP_KERNEL);
        if (ret)
                goto err_sg_alloc;

        /* Populate source page list from the object. */
        i = 0;
        for_each_sgt_dma(dma_addr, sgt_iter, obj->mm.pages)
                page_addr_list[i++] = dma_addr;

        GEM_BUG_ON(i != n_pages);
        st->nents = 0;
        sg = st->sgl;

        for (i = 0 ; i < ARRAY_SIZE(rot_info->plane); i++) {
                sg = rotate_pages(page_addr_list, rot_info->plane[i].offset,
                                  rot_info->plane[i].width, rot_info->plane[i].height,
                                  rot_info->plane[i].stride, st, sg);
        }

        DRM_DEBUG_KMS("Created rotated page mapping for object size %zu (%ux%u tiles, %u pages)\n",
                      obj->base.size, rot_info->plane[0].width, rot_info->plane[0].height, size);

        drm_free_large(page_addr_list);

        return st;

err_sg_alloc:
        kfree(st);
err_st_alloc:
        drm_free_large(page_addr_list);

        DRM_DEBUG_KMS("Failed to create rotated mapping for object size %zu! (%ux%u tiles, %u pages)\n",
                      obj->base.size, rot_info->plane[0].width, rot_info->plane[0].height, size);

        return ERR_PTR(ret);
}

static struct sg_table *
intel_partial_pages(const struct i915_ggtt_view *view,
                    struct drm_i915_gem_object *obj)
{
        struct sg_table *st;
        struct scatterlist *sg, *iter;
        unsigned int count = view->params.partial.size;
        unsigned int offset;
        int ret = -ENOMEM;

        st = kmalloc(sizeof(*st), GFP_KERNEL);
        if (!st)
                goto err_st_alloc;

        ret = sg_alloc_table(st, count, GFP_KERNEL);
        if (ret)
                goto err_sg_alloc;

        iter = i915_gem_object_get_sg(obj,
                                      view->params.partial.offset,
                                      &offset);
        GEM_BUG_ON(!iter);

        sg = st->sgl;
        st->nents = 0;
        do {
                unsigned int len;

                len = min(iter->length - (offset << PAGE_SHIFT),
                          count << PAGE_SHIFT);
                sg_set_page(sg, NULL, len, 0);
                sg_dma_address(sg) =
                        sg_dma_address(iter) + (offset << PAGE_SHIFT);
                sg_dma_len(sg) = len;

                st->nents++;
                count -= len >> PAGE_SHIFT;
                if (count == 0) {
                        sg_mark_end(sg);
                        return st;
                }

                sg = __sg_next(sg);
                iter = __sg_next(iter);
                offset = 0;
        } while (1);

err_sg_alloc:
        kfree(st);
err_st_alloc:
        return ERR_PTR(ret);
}

static int
i915_get_ggtt_vma_pages(struct i915_vma *vma)
{
        int ret = 0;

        /* The vma->pages are only valid within the lifespan of the borrowed
         * obj->mm.pages. When the obj->mm.pages sg_table is regenerated, so
         * must be the vma->pages. A simple rule is that vma->pages must only
         * be accessed when the obj->mm.pages are pinned.
         */
        GEM_BUG_ON(!i915_gem_object_has_pinned_pages(vma->obj));

        if (vma->pages)
                return 0;

        if (vma->ggtt_view.type == I915_GGTT_VIEW_NORMAL)
                vma->pages = vma->obj->mm.pages;
        else if (vma->ggtt_view.type == I915_GGTT_VIEW_ROTATED)
                vma->pages =
                        intel_rotate_fb_obj_pages(&vma->ggtt_view.params.rotated, vma->obj);
        else if (vma->ggtt_view.type == I915_GGTT_VIEW_PARTIAL)
                vma->pages = intel_partial_pages(&vma->ggtt_view, vma->obj);
        else
                WARN_ONCE(1, "GGTT view %u not implemented!\n",
                          vma->ggtt_view.type);

        if (!vma->pages) {
                DRM_ERROR("Failed to get pages for GGTT view type %u!\n",
                          vma->ggtt_view.type);
                ret = -EINVAL;
        } else if (IS_ERR(vma->pages)) {
                ret = PTR_ERR(vma->pages);
                vma->pages = NULL;
                DRM_ERROR("Failed to get pages for VMA view type %u (%d)!\n",
                          vma->ggtt_view.type, ret);
        }

        return ret;
}