treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

[mirror_ubuntu-hirsute-kernel.git] / arch / powerpc / kvm / book3s_64_mmu_radix.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *
 * Copyright 2016 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
 */

#include <linux/types.h>
#include <linux/string.h>
#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include <linux/anon_inodes.h>
#include <linux/file.h>
#include <linux/debugfs.h>

#include <asm/kvm_ppc.h>
#include <asm/kvm_book3s.h>
#include <asm/page.h>
#include <asm/mmu.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/pte-walk.h>

/*
 * Supported radix tree geometry.
 * Like p9, we support either 5 or 9 bits at the first (lowest) level,
 * for a page size of 64k or 4k.
 */
static int p9_supported_radix_bits[4] = { 5, 9, 9, 13 };

unsigned long __kvmhv_copy_tofrom_guest_radix(int lpid, int pid,
                                              gva_t eaddr, void *to, void *from,
                                              unsigned long n)
{
        int uninitialized_var(old_pid), old_lpid;
        unsigned long quadrant, ret = n;
        bool is_load = !!to;

        /* Can't access quadrants 1 or 2 in non-HV mode, call the HV to do it */
        if (kvmhv_on_pseries())
                return plpar_hcall_norets(H_COPY_TOFROM_GUEST, lpid, pid, eaddr,
                                          __pa(to), __pa(from), n);

        quadrant = 1;
        if (!pid)
                quadrant = 2;
        if (is_load)
                from = (void *) (eaddr | (quadrant << 62));
        else
                to = (void *) (eaddr | (quadrant << 62));

        preempt_disable();

        /* switch the lpid first to avoid running host with unallocated pid */
        old_lpid = mfspr(SPRN_LPID);
        if (old_lpid != lpid)
                mtspr(SPRN_LPID, lpid);
        if (quadrant == 1) {
                old_pid = mfspr(SPRN_PID);
                if (old_pid != pid)
                        mtspr(SPRN_PID, pid);
        }
        isync();

        pagefault_disable();
        if (is_load)
                ret = raw_copy_from_user(to, from, n);
        else
                ret = raw_copy_to_user(to, from, n);
        pagefault_enable();

        /* switch the pid first to avoid running host with unallocated pid */
        if (quadrant == 1 && pid != old_pid)
                mtspr(SPRN_PID, old_pid);
        if (lpid != old_lpid)
                mtspr(SPRN_LPID, old_lpid);
        isync();

        preempt_enable();

        return ret;
}
EXPORT_SYMBOL_GPL(__kvmhv_copy_tofrom_guest_radix);

static long kvmhv_copy_tofrom_guest_radix(struct kvm_vcpu *vcpu, gva_t eaddr,
                                          void *to, void *from, unsigned long n)
{
        int lpid = vcpu->kvm->arch.lpid;
        int pid = vcpu->arch.pid;

        /* This would cause a data segment intr so don't allow the access */
        if (eaddr & (0x3FFUL << 52))
                return -EINVAL;

        /* Should we be using the nested lpid */
        if (vcpu->arch.nested)
                lpid = vcpu->arch.nested->shadow_lpid;

        /* If accessing quadrant 3 then pid is expected to be 0 */
        if (((eaddr >> 62) & 0x3) == 0x3)
                pid = 0;

        eaddr &= ~(0xFFFUL << 52);

        return __kvmhv_copy_tofrom_guest_radix(lpid, pid, eaddr, to, from, n);
}

long kvmhv_copy_from_guest_radix(struct kvm_vcpu *vcpu, gva_t eaddr, void *to,
                                 unsigned long n)
{
        long ret;

        ret = kvmhv_copy_tofrom_guest_radix(vcpu, eaddr, to, NULL, n);
        if (ret > 0)
                memset(to + (n - ret), 0, ret);

        return ret;
}
EXPORT_SYMBOL_GPL(kvmhv_copy_from_guest_radix);

long kvmhv_copy_to_guest_radix(struct kvm_vcpu *vcpu, gva_t eaddr, void *from,
                               unsigned long n)
{
        return kvmhv_copy_tofrom_guest_radix(vcpu, eaddr, NULL, from, n);
}
EXPORT_SYMBOL_GPL(kvmhv_copy_to_guest_radix);

int kvmppc_mmu_walk_radix_tree(struct kvm_vcpu *vcpu, gva_t eaddr,
                               struct kvmppc_pte *gpte, u64 root,
                               u64 *pte_ret_p)
{
        struct kvm *kvm = vcpu->kvm;
        int ret, level, ps;
        unsigned long rts, bits, offset, index;
        u64 pte, base, gpa;
        __be64 rpte;

        rts = ((root & RTS1_MASK) >> (RTS1_SHIFT - 3)) |
                ((root & RTS2_MASK) >> RTS2_SHIFT);
        bits = root & RPDS_MASK;
        base = root & RPDB_MASK;

        offset = rts + 31;

        /* Current implementations only support 52-bit space */
        if (offset != 52)
                return -EINVAL;

        /* Walk each level of the radix tree */
        for (level = 3; level >= 0; --level) {
                u64 addr;
                /* Check a valid size */
                if (level && bits != p9_supported_radix_bits[level])
                        return -EINVAL;
                if (level == 0 && !(bits == 5 || bits == 9))
                        return -EINVAL;
                offset -= bits;
                index = (eaddr >> offset) & ((1UL << bits) - 1);
                /* Check that low bits of page table base are zero */
                if (base & ((1UL << (bits + 3)) - 1))
                        return -EINVAL;
                /* Read the entry from guest memory */
                addr = base + (index * sizeof(rpte));
                ret = kvm_read_guest(kvm, addr, &rpte, sizeof(rpte));
                if (ret) {
                        if (pte_ret_p)
                                *pte_ret_p = addr;
                        return ret;
                }
                pte = __be64_to_cpu(rpte);
                if (!(pte & _PAGE_PRESENT))
                        return -ENOENT;
                /* Check if a leaf entry */
                if (pte & _PAGE_PTE)
                        break;
                /* Get ready to walk the next level */
                base = pte & RPDB_MASK;
                bits = pte & RPDS_MASK;
        }

        /* Need a leaf at lowest level; 512GB pages not supported */
        if (level < 0 || level == 3)
                return -EINVAL;

        /* We found a valid leaf PTE */
        /* Offset is now log base 2 of the page size */
        gpa = pte & 0x01fffffffffff000ul;
        if (gpa & ((1ul << offset) - 1))
                return -EINVAL;
        gpa |= eaddr & ((1ul << offset) - 1);
        for (ps = MMU_PAGE_4K; ps < MMU_PAGE_COUNT; ++ps)
                if (offset == mmu_psize_defs[ps].shift)
                        break;
        gpte->page_size = ps;
        gpte->page_shift = offset;

        gpte->eaddr = eaddr;
        gpte->raddr = gpa;

        /* Work out permissions */
        gpte->may_read = !!(pte & _PAGE_READ);
        gpte->may_write = !!(pte & _PAGE_WRITE);
        gpte->may_execute = !!(pte & _PAGE_EXEC);

        gpte->rc = pte & (_PAGE_ACCESSED | _PAGE_DIRTY);

        if (pte_ret_p)
                *pte_ret_p = pte;

        return 0;
}

/*
 * Used to walk a partition or process table radix tree in guest memory
 * Note: We exploit the fact that a partition table and a process
 * table have the same layout, a partition-scoped page table and a
 * process-scoped page table have the same layout, and the 2nd
 * doubleword of a partition table entry has the same layout as
 * the PTCR register.
 */
int kvmppc_mmu_radix_translate_table(struct kvm_vcpu *vcpu, gva_t eaddr,
                                     struct kvmppc_pte *gpte, u64 table,
                                     int table_index, u64 *pte_ret_p)
{
        struct kvm *kvm = vcpu->kvm;
        int ret;
        unsigned long size, ptbl, root;
        struct prtb_entry entry;

        if ((table & PRTS_MASK) > 24)
                return -EINVAL;
        size = 1ul << ((table & PRTS_MASK) + 12);

        /* Is the table big enough to contain this entry? */
        if ((table_index * sizeof(entry)) >= size)
                return -EINVAL;

        /* Read the table to find the root of the radix tree */
        ptbl = (table & PRTB_MASK) + (table_index * sizeof(entry));
        ret = kvm_read_guest(kvm, ptbl, &entry, sizeof(entry));
        if (ret)
                return ret;

        /* Root is stored in the first double word */
        root = be64_to_cpu(entry.prtb0);

        return kvmppc_mmu_walk_radix_tree(vcpu, eaddr, gpte, root, pte_ret_p);
}

int kvmppc_mmu_radix_xlate(struct kvm_vcpu *vcpu, gva_t eaddr,
                           struct kvmppc_pte *gpte, bool data, bool iswrite)
{
        u32 pid;
        u64 pte;
        int ret;

        /* Work out effective PID */
        switch (eaddr >> 62) {
        case 0:
                pid = vcpu->arch.pid;
                break;
        case 3:
                pid = 0;
                break;
        default:
                return -EINVAL;
        }

        ret = kvmppc_mmu_radix_translate_table(vcpu, eaddr, gpte,
                                vcpu->kvm->arch.process_table, pid, &pte);
        if (ret)
                return ret;

        /* Check privilege (applies only to process scoped translations) */
        if (kvmppc_get_msr(vcpu) & MSR_PR) {
                if (pte & _PAGE_PRIVILEGED) {
                        gpte->may_read = 0;
                        gpte->may_write = 0;
                        gpte->may_execute = 0;
                }
        } else {
                if (!(pte & _PAGE_PRIVILEGED)) {
                        /* Check AMR/IAMR to see if strict mode is in force */
                        if (vcpu->arch.amr & (1ul << 62))
                                gpte->may_read = 0;
                        if (vcpu->arch.amr & (1ul << 63))
                                gpte->may_write = 0;
                        if (vcpu->arch.iamr & (1ul << 62))
                                gpte->may_execute = 0;
                }
        }

        return 0;
}

void kvmppc_radix_tlbie_page(struct kvm *kvm, unsigned long addr,
                             unsigned int pshift, unsigned int lpid)
{
        unsigned long psize = PAGE_SIZE;
        int psi;
        long rc;
        unsigned long rb;

        if (pshift)
                psize = 1UL << pshift;
        else
                pshift = PAGE_SHIFT;

        addr &= ~(psize - 1);

        if (!kvmhv_on_pseries()) {
                radix__flush_tlb_lpid_page(lpid, addr, psize);
                return;
        }

        psi = shift_to_mmu_psize(pshift);
        rb = addr | (mmu_get_ap(psi) << PPC_BITLSHIFT(58));
        rc = plpar_hcall_norets(H_TLB_INVALIDATE, H_TLBIE_P1_ENC(0, 0, 1),
                                lpid, rb);
        if (rc)
                pr_err("KVM: TLB page invalidation hcall failed, rc=%ld\n", rc);
}

static void kvmppc_radix_flush_pwc(struct kvm *kvm, unsigned int lpid)
{
        long rc;

        if (!kvmhv_on_pseries()) {
                radix__flush_pwc_lpid(lpid);
                return;
        }

        rc = plpar_hcall_norets(H_TLB_INVALIDATE, H_TLBIE_P1_ENC(1, 0, 1),
                                lpid, TLBIEL_INVAL_SET_LPID);
        if (rc)
                pr_err("KVM: TLB PWC invalidation hcall failed, rc=%ld\n", rc);
}

static unsigned long kvmppc_radix_update_pte(struct kvm *kvm, pte_t *ptep,
                                      unsigned long clr, unsigned long set,
                                      unsigned long addr, unsigned int shift)
{
        return __radix_pte_update(ptep, clr, set);
}

void kvmppc_radix_set_pte_at(struct kvm *kvm, unsigned long addr,
                             pte_t *ptep, pte_t pte)
{
        radix__set_pte_at(kvm->mm, addr, ptep, pte, 0);
}

static struct kmem_cache *kvm_pte_cache;
static struct kmem_cache *kvm_pmd_cache;

static pte_t *kvmppc_pte_alloc(void)
{
        return kmem_cache_alloc(kvm_pte_cache, GFP_KERNEL);
}

static void kvmppc_pte_free(pte_t *ptep)
{
        kmem_cache_free(kvm_pte_cache, ptep);
}

/* Like pmd_huge() and pmd_large(), but works regardless of config options */
static inline int pmd_is_leaf(pmd_t pmd)
{
        return !!(pmd_val(pmd) & _PAGE_PTE);
}

static pmd_t *kvmppc_pmd_alloc(void)
{
        return kmem_cache_alloc(kvm_pmd_cache, GFP_KERNEL);
}

static void kvmppc_pmd_free(pmd_t *pmdp)
{
        kmem_cache_free(kvm_pmd_cache, pmdp);
}

/* Called with kvm->mmu_lock held */
void kvmppc_unmap_pte(struct kvm *kvm, pte_t *pte, unsigned long gpa,
                      unsigned int shift,
                      const struct kvm_memory_slot *memslot,
                      unsigned int lpid)

{
        unsigned long old;
        unsigned long gfn = gpa >> PAGE_SHIFT;
        unsigned long page_size = PAGE_SIZE;
        unsigned long hpa;

        old = kvmppc_radix_update_pte(kvm, pte, ~0UL, 0, gpa, shift);
        kvmppc_radix_tlbie_page(kvm, gpa, shift, lpid);

        /* The following only applies to L1 entries */
        if (lpid != kvm->arch.lpid)
                return;

        if (!memslot) {
                memslot = gfn_to_memslot(kvm, gfn);
                if (!memslot)
                        return;
        }
        if (shift) { /* 1GB or 2MB page */
                page_size = 1ul << shift;
                if (shift == PMD_SHIFT)
                        kvm->stat.num_2M_pages--;
                else if (shift == PUD_SHIFT)
                        kvm->stat.num_1G_pages--;
        }

        gpa &= ~(page_size - 1);
        hpa = old & PTE_RPN_MASK;
        kvmhv_remove_nest_rmap_range(kvm, memslot, gpa, hpa, page_size);

        if ((old & _PAGE_DIRTY) && memslot->dirty_bitmap)
                kvmppc_update_dirty_map(memslot, gfn, page_size);
}

/*
 * kvmppc_free_p?d are used to free existing page tables, and recursively
 * descend and clear and free children.
 * Callers are responsible for flushing the PWC.
 *
 * When page tables are being unmapped/freed as part of page fault path
 * (full == false), ptes are not expected. There is code to unmap them
 * and emit a warning if encountered, but there may already be data
 * corruption due to the unexpected mappings.
 */
static void kvmppc_unmap_free_pte(struct kvm *kvm, pte_t *pte, bool full,
                                  unsigned int lpid)
{
        if (full) {
                memset(pte, 0, sizeof(long) << PTE_INDEX_SIZE);
        } else {
                pte_t *p = pte;
                unsigned long it;

                for (it = 0; it < PTRS_PER_PTE; ++it, ++p) {
                        if (pte_val(*p) == 0)
                                continue;
                        WARN_ON_ONCE(1);
                        kvmppc_unmap_pte(kvm, p,
                                         pte_pfn(*p) << PAGE_SHIFT,
                                         PAGE_SHIFT, NULL, lpid);
                }
        }

        kvmppc_pte_free(pte);
}

static void kvmppc_unmap_free_pmd(struct kvm *kvm, pmd_t *pmd, bool full,
                                  unsigned int lpid)
{
        unsigned long im;
        pmd_t *p = pmd;

        for (im = 0; im < PTRS_PER_PMD; ++im, ++p) {
                if (!pmd_present(*p))
                        continue;
                if (pmd_is_leaf(*p)) {
                        if (full) {
                                pmd_clear(p);
                        } else {
                                WARN_ON_ONCE(1);
                                kvmppc_unmap_pte(kvm, (pte_t *)p,
                                         pte_pfn(*(pte_t *)p) << PAGE_SHIFT,
                                         PMD_SHIFT, NULL, lpid);
                        }
                } else {
                        pte_t *pte;

                        pte = pte_offset_map(p, 0);
                        kvmppc_unmap_free_pte(kvm, pte, full, lpid);
                        pmd_clear(p);
                }
        }
        kvmppc_pmd_free(pmd);
}

static void kvmppc_unmap_free_pud(struct kvm *kvm, pud_t *pud,
                                  unsigned int lpid)
{
        unsigned long iu;
        pud_t *p = pud;

        for (iu = 0; iu < PTRS_PER_PUD; ++iu, ++p) {
                if (!pud_present(*p))
                        continue;
                if (pud_huge(*p)) {
                        pud_clear(p);
                } else {
                        pmd_t *pmd;

                        pmd = pmd_offset(p, 0);
                        kvmppc_unmap_free_pmd(kvm, pmd, true, lpid);
                        pud_clear(p);
                }
        }
        pud_free(kvm->mm, pud);
}

void kvmppc_free_pgtable_radix(struct kvm *kvm, pgd_t *pgd, unsigned int lpid)
{
        unsigned long ig;

        for (ig = 0; ig < PTRS_PER_PGD; ++ig, ++pgd) {
                pud_t *pud;

                if (!pgd_present(*pgd))
                        continue;
                pud = pud_offset(pgd, 0);
                kvmppc_unmap_free_pud(kvm, pud, lpid);
                pgd_clear(pgd);
        }
}

void kvmppc_free_radix(struct kvm *kvm)
{
        if (kvm->arch.pgtable) {
                kvmppc_free_pgtable_radix(kvm, kvm->arch.pgtable,
                                          kvm->arch.lpid);
                pgd_free(kvm->mm, kvm->arch.pgtable);
                kvm->arch.pgtable = NULL;
        }
}

static void kvmppc_unmap_free_pmd_entry_table(struct kvm *kvm, pmd_t *pmd,
                                        unsigned long gpa, unsigned int lpid)
{
        pte_t *pte = pte_offset_kernel(pmd, 0);

        /*
         * Clearing the pmd entry then flushing the PWC ensures that the pte
         * page no longer be cached by the MMU, so can be freed without
         * flushing the PWC again.
         */
        pmd_clear(pmd);
        kvmppc_radix_flush_pwc(kvm, lpid);

        kvmppc_unmap_free_pte(kvm, pte, false, lpid);
}

static void kvmppc_unmap_free_pud_entry_table(struct kvm *kvm, pud_t *pud,
                                        unsigned long gpa, unsigned int lpid)
{
        pmd_t *pmd = pmd_offset(pud, 0);

        /*
         * Clearing the pud entry then flushing the PWC ensures that the pmd
         * page and any children pte pages will no longer be cached by the MMU,
         * so can be freed without flushing the PWC again.
         */
        pud_clear(pud);
        kvmppc_radix_flush_pwc(kvm, lpid);

        kvmppc_unmap_free_pmd(kvm, pmd, false, lpid);
}

/*
 * There are a number of bits which may differ between different faults to
 * the same partition scope entry. RC bits, in the course of cleaning and
 * aging. And the write bit can change, either the access could have been
 * upgraded, or a read fault could happen concurrently with a write fault
 * that sets those bits first.
 */
#define PTE_BITS_MUST_MATCH (~(_PAGE_WRITE | _PAGE_DIRTY | _PAGE_ACCESSED))

int kvmppc_create_pte(struct kvm *kvm, pgd_t *pgtable, pte_t pte,
                      unsigned long gpa, unsigned int level,
                      unsigned long mmu_seq, unsigned int lpid,
                      unsigned long *rmapp, struct rmap_nested **n_rmap)
{
        pgd_t *pgd;
        pud_t *pud, *new_pud = NULL;
        pmd_t *pmd, *new_pmd = NULL;
        pte_t *ptep, *new_ptep = NULL;
        int ret;

        /* Traverse the guest's 2nd-level tree, allocate new levels needed */
        pgd = pgtable + pgd_index(gpa);
        pud = NULL;
        if (pgd_present(*pgd))
                pud = pud_offset(pgd, gpa);
        else
                new_pud = pud_alloc_one(kvm->mm, gpa);

        pmd = NULL;
        if (pud && pud_present(*pud) && !pud_huge(*pud))
                pmd = pmd_offset(pud, gpa);
        else if (level <= 1)
                new_pmd = kvmppc_pmd_alloc();

        if (level == 0 && !(pmd && pmd_present(*pmd) && !pmd_is_leaf(*pmd)))
                new_ptep = kvmppc_pte_alloc();

        /* Check if we might have been invalidated; let the guest retry if so */
        spin_lock(&kvm->mmu_lock);
        ret = -EAGAIN;
        if (mmu_notifier_retry(kvm, mmu_seq))
                goto out_unlock;

        /* Now traverse again under the lock and change the tree */
        ret = -ENOMEM;
        if (pgd_none(*pgd)) {
                if (!new_pud)
                        goto out_unlock;
                pgd_populate(kvm->mm, pgd, new_pud);
                new_pud = NULL;
        }
        pud = pud_offset(pgd, gpa);
        if (pud_huge(*pud)) {
                unsigned long hgpa = gpa & PUD_MASK;

                /* Check if we raced and someone else has set the same thing */
                if (level == 2) {
                        if (pud_raw(*pud) == pte_raw(pte)) {
                                ret = 0;
                                goto out_unlock;
                        }
                        /* Valid 1GB page here already, add our extra bits */
                        WARN_ON_ONCE((pud_val(*pud) ^ pte_val(pte)) &
                                                        PTE_BITS_MUST_MATCH);
                        kvmppc_radix_update_pte(kvm, (pte_t *)pud,
                                              0, pte_val(pte), hgpa, PUD_SHIFT);
                        ret = 0;
                        goto out_unlock;
                }
                /*
                 * If we raced with another CPU which has just put
                 * a 1GB pte in after we saw a pmd page, try again.
                 */
                if (!new_pmd) {
                        ret = -EAGAIN;
                        goto out_unlock;
                }
                /* Valid 1GB page here already, remove it */
                kvmppc_unmap_pte(kvm, (pte_t *)pud, hgpa, PUD_SHIFT, NULL,
                                 lpid);
        }
        if (level == 2) {
                if (!pud_none(*pud)) {
                        /*
                         * There's a page table page here, but we wanted to
                         * install a large page, so remove and free the page
                         * table page.
                         */
                        kvmppc_unmap_free_pud_entry_table(kvm, pud, gpa, lpid);
                }
                kvmppc_radix_set_pte_at(kvm, gpa, (pte_t *)pud, pte);
                if (rmapp && n_rmap)
                        kvmhv_insert_nest_rmap(kvm, rmapp, n_rmap);
                ret = 0;
                goto out_unlock;
        }
        if (pud_none(*pud)) {
                if (!new_pmd)
                        goto out_unlock;
                pud_populate(kvm->mm, pud, new_pmd);
                new_pmd = NULL;
        }
        pmd = pmd_offset(pud, gpa);
        if (pmd_is_leaf(*pmd)) {
                unsigned long lgpa = gpa & PMD_MASK;

                /* Check if we raced and someone else has set the same thing */
                if (level == 1) {
                        if (pmd_raw(*pmd) == pte_raw(pte)) {
                                ret = 0;
                                goto out_unlock;
                        }
                        /* Valid 2MB page here already, add our extra bits */
                        WARN_ON_ONCE((pmd_val(*pmd) ^ pte_val(pte)) &
                                                        PTE_BITS_MUST_MATCH);
                        kvmppc_radix_update_pte(kvm, pmdp_ptep(pmd),
                                        0, pte_val(pte), lgpa, PMD_SHIFT);
                        ret = 0;
                        goto out_unlock;
                }

                /*
                 * If we raced with another CPU which has just put
                 * a 2MB pte in after we saw a pte page, try again.
                 */
                if (!new_ptep) {
                        ret = -EAGAIN;
                        goto out_unlock;
                }
                /* Valid 2MB page here already, remove it */
                kvmppc_unmap_pte(kvm, pmdp_ptep(pmd), lgpa, PMD_SHIFT, NULL,
                                 lpid);
        }
        if (level == 1) {
                if (!pmd_none(*pmd)) {
                        /*
                         * There's a page table page here, but we wanted to
                         * install a large page, so remove and free the page
                         * table page.
                         */
                        kvmppc_unmap_free_pmd_entry_table(kvm, pmd, gpa, lpid);
                }
                kvmppc_radix_set_pte_at(kvm, gpa, pmdp_ptep(pmd), pte);
                if (rmapp && n_rmap)
                        kvmhv_insert_nest_rmap(kvm, rmapp, n_rmap);
                ret = 0;
                goto out_unlock;
        }
        if (pmd_none(*pmd)) {
                if (!new_ptep)
                        goto out_unlock;
                pmd_populate(kvm->mm, pmd, new_ptep);
                new_ptep = NULL;
        }
        ptep = pte_offset_kernel(pmd, gpa);
        if (pte_present(*ptep)) {
                /* Check if someone else set the same thing */
                if (pte_raw(*ptep) == pte_raw(pte)) {
                        ret = 0;
                        goto out_unlock;
                }
                /* Valid page here already, add our extra bits */
                WARN_ON_ONCE((pte_val(*ptep) ^ pte_val(pte)) &
                                                        PTE_BITS_MUST_MATCH);
                kvmppc_radix_update_pte(kvm, ptep, 0, pte_val(pte), gpa, 0);
                ret = 0;
                goto out_unlock;
        }
        kvmppc_radix_set_pte_at(kvm, gpa, ptep, pte);
        if (rmapp && n_rmap)
                kvmhv_insert_nest_rmap(kvm, rmapp, n_rmap);
        ret = 0;

 out_unlock:
        spin_unlock(&kvm->mmu_lock);
        if (new_pud)
                pud_free(kvm->mm, new_pud);
        if (new_pmd)
                kvmppc_pmd_free(new_pmd);
        if (new_ptep)
                kvmppc_pte_free(new_ptep);
        return ret;
}

bool kvmppc_hv_handle_set_rc(struct kvm *kvm, pgd_t *pgtable, bool writing,
                             unsigned long gpa, unsigned int lpid)
{
        unsigned long pgflags;
        unsigned int shift;
        pte_t *ptep;

        /*
         * Need to set an R or C bit in the 2nd-level tables;
         * since we are just helping out the hardware here,
         * it is sufficient to do what the hardware does.
         */
        pgflags = _PAGE_ACCESSED;
        if (writing)
                pgflags |= _PAGE_DIRTY;
        /*
         * We are walking the secondary (partition-scoped) page table here.
         * We can do this without disabling irq because the Linux MM
         * subsystem doesn't do THP splits and collapses on this tree.
         */
        ptep = __find_linux_pte(pgtable, gpa, NULL, &shift);
        if (ptep && pte_present(*ptep) && (!writing || pte_write(*ptep))) {
                kvmppc_radix_update_pte(kvm, ptep, 0, pgflags, gpa, shift);
                return true;
        }
        return false;
}

int kvmppc_book3s_instantiate_page(struct kvm_vcpu *vcpu,
                                   unsigned long gpa,
                                   struct kvm_memory_slot *memslot,
                                   bool writing, bool kvm_ro,
                                   pte_t *inserted_pte, unsigned int *levelp)
{
        struct kvm *kvm = vcpu->kvm;
        struct page *page = NULL;
        unsigned long mmu_seq;
        unsigned long hva, gfn = gpa >> PAGE_SHIFT;
        bool upgrade_write = false;
        bool *upgrade_p = &upgrade_write;
        pte_t pte, *ptep;
        unsigned int shift, level;
        int ret;
        bool large_enable;

        /* used to check for invalidations in progress */
        mmu_seq = kvm->mmu_notifier_seq;
        smp_rmb();

        /*
         * Do a fast check first, since __gfn_to_pfn_memslot doesn't
         * do it with !atomic && !async, which is how we call it.
         * We always ask for write permission since the common case
         * is that the page is writable.
         */
        hva = gfn_to_hva_memslot(memslot, gfn);
        if (!kvm_ro && __get_user_pages_fast(hva, 1, 1, &page) == 1) {
                upgrade_write = true;
        } else {
                unsigned long pfn;

                /* Call KVM generic code to do the slow-path check */
                pfn = __gfn_to_pfn_memslot(memslot, gfn, false, NULL,
                                           writing, upgrade_p);
                if (is_error_noslot_pfn(pfn))
                        return -EFAULT;
                page = NULL;
                if (pfn_valid(pfn)) {
                        page = pfn_to_page(pfn);
                        if (PageReserved(page))
                                page = NULL;
                }
        }

        /*
         * Read the PTE from the process' radix tree and use that
         * so we get the shift and attribute bits.
         */
        local_irq_disable();
        ptep = __find_linux_pte(vcpu->arch.pgdir, hva, NULL, &shift);
        /*
         * If the PTE disappeared temporarily due to a THP
         * collapse, just return and let the guest try again.
         */
        if (!ptep) {
                local_irq_enable();
                if (page)
                        put_page(page);
                return RESUME_GUEST;
        }
        pte = *ptep;
        local_irq_enable();

        /* If we're logging dirty pages, always map single pages */
        large_enable = !(memslot->flags & KVM_MEM_LOG_DIRTY_PAGES);

        /* Get pte level from shift/size */
        if (large_enable && shift == PUD_SHIFT &&
            (gpa & (PUD_SIZE - PAGE_SIZE)) ==
            (hva & (PUD_SIZE - PAGE_SIZE))) {
                level = 2;
        } else if (large_enable && shift == PMD_SHIFT &&
                   (gpa & (PMD_SIZE - PAGE_SIZE)) ==
                   (hva & (PMD_SIZE - PAGE_SIZE))) {
                level = 1;
        } else {
                level = 0;
                if (shift > PAGE_SHIFT) {
                        /*
                         * If the pte maps more than one page, bring over
                         * bits from the virtual address to get the real
                         * address of the specific single page we want.
                         */
                        unsigned long rpnmask = (1ul << shift) - PAGE_SIZE;
                        pte = __pte(pte_val(pte) | (hva & rpnmask));
                }
        }

        pte = __pte(pte_val(pte) | _PAGE_EXEC | _PAGE_ACCESSED);
        if (writing || upgrade_write) {
                if (pte_val(pte) & _PAGE_WRITE)
                        pte = __pte(pte_val(pte) | _PAGE_DIRTY);
        } else {
                pte = __pte(pte_val(pte) & ~(_PAGE_WRITE | _PAGE_DIRTY));
        }

        /* Allocate space in the tree and write the PTE */
        ret = kvmppc_create_pte(kvm, kvm->arch.pgtable, pte, gpa, level,
                                mmu_seq, kvm->arch.lpid, NULL, NULL);
        if (inserted_pte)
                *inserted_pte = pte;
        if (levelp)
                *levelp = level;

        if (page) {
                if (!ret && (pte_val(pte) & _PAGE_WRITE))
                        set_page_dirty_lock(page);
                put_page(page);
        }

        /* Increment number of large pages if we (successfully) inserted one */
        if (!ret) {
                if (level == 1)
                        kvm->stat.num_2M_pages++;
                else if (level == 2)
                        kvm->stat.num_1G_pages++;
        }

        return ret;
}

int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
                                   unsigned long ea, unsigned long dsisr)
{
        struct kvm *kvm = vcpu->kvm;
        unsigned long gpa, gfn;
        struct kvm_memory_slot *memslot;
        long ret;
        bool writing = !!(dsisr & DSISR_ISSTORE);
        bool kvm_ro = false;

        /* Check for unusual errors */
        if (dsisr & DSISR_UNSUPP_MMU) {
                pr_err("KVM: Got unsupported MMU fault\n");
                return -EFAULT;
        }
        if (dsisr & DSISR_BADACCESS) {
                /* Reflect to the guest as DSI */
                pr_err("KVM: Got radix HV page fault with DSISR=%lx\n", dsisr);
                kvmppc_core_queue_data_storage(vcpu, ea, dsisr);
                return RESUME_GUEST;
        }

        /* Translate the logical address */
        gpa = vcpu->arch.fault_gpa & ~0xfffUL;
        gpa &= ~0xF000000000000000ul;
        gfn = gpa >> PAGE_SHIFT;
        if (!(dsisr & DSISR_PRTABLE_FAULT))
                gpa |= ea & 0xfff;

        /* Get the corresponding memslot */
        memslot = gfn_to_memslot(kvm, gfn);

        /* No memslot means it's an emulated MMIO region */
        if (!memslot || (memslot->flags & KVM_MEMSLOT_INVALID)) {
                if (dsisr & (DSISR_PRTABLE_FAULT | DSISR_BADACCESS |
                             DSISR_SET_RC)) {
                        /*
                         * Bad address in guest page table tree, or other
                         * unusual error - reflect it to the guest as DSI.
                         */
                        kvmppc_core_queue_data_storage(vcpu, ea, dsisr);
                        return RESUME_GUEST;
                }
                return kvmppc_hv_emulate_mmio(run, vcpu, gpa, ea, writing);
        }

        if (memslot->flags & KVM_MEM_READONLY) {
                if (writing) {
                        /* give the guest a DSI */
                        kvmppc_core_queue_data_storage(vcpu, ea, DSISR_ISSTORE |
                                                       DSISR_PROTFAULT);
                        return RESUME_GUEST;
                }
                kvm_ro = true;
        }

        /* Failed to set the reference/change bits */
        if (dsisr & DSISR_SET_RC) {
                spin_lock(&kvm->mmu_lock);
                if (kvmppc_hv_handle_set_rc(kvm, kvm->arch.pgtable,
                                            writing, gpa, kvm->arch.lpid))
                        dsisr &= ~DSISR_SET_RC;
                spin_unlock(&kvm->mmu_lock);

                if (!(dsisr & (DSISR_BAD_FAULT_64S | DSISR_NOHPTE |
                               DSISR_PROTFAULT | DSISR_SET_RC)))
                        return RESUME_GUEST;
        }

        /* Try to insert a pte */
        ret = kvmppc_book3s_instantiate_page(vcpu, gpa, memslot, writing,
                                             kvm_ro, NULL, NULL);

        if (ret == 0 || ret == -EAGAIN)
                ret = RESUME_GUEST;
        return ret;
}

/* Called with kvm->mmu_lock held */
int kvm_unmap_radix(struct kvm *kvm, struct kvm_memory_slot *memslot,
                    unsigned long gfn)
{
        pte_t *ptep;
        unsigned long gpa = gfn << PAGE_SHIFT;
        unsigned int shift;

        ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
        if (ptep && pte_present(*ptep))
                kvmppc_unmap_pte(kvm, ptep, gpa, shift, memslot,
                                 kvm->arch.lpid);
        return 0;                               
}

/* Called with kvm->mmu_lock held */
int kvm_age_radix(struct kvm *kvm, struct kvm_memory_slot *memslot,
                  unsigned long gfn)
{
        pte_t *ptep;
        unsigned long gpa = gfn << PAGE_SHIFT;
        unsigned int shift;
        int ref = 0;
        unsigned long old, *rmapp;

        ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
        if (ptep && pte_present(*ptep) && pte_young(*ptep)) {
                old = kvmppc_radix_update_pte(kvm, ptep, _PAGE_ACCESSED, 0,
                                              gpa, shift);
                /* XXX need to flush tlb here? */
                /* Also clear bit in ptes in shadow pgtable for nested guests */
                rmapp = &memslot->arch.rmap[gfn - memslot->base_gfn];
                kvmhv_update_nest_rmap_rc_list(kvm, rmapp, _PAGE_ACCESSED, 0,
                                               old & PTE_RPN_MASK,
                                               1UL << shift);
                ref = 1;
        }
        return ref;
}

/* Called with kvm->mmu_lock held */
int kvm_test_age_radix(struct kvm *kvm, struct kvm_memory_slot *memslot,
                       unsigned long gfn)
{
        pte_t *ptep;
        unsigned long gpa = gfn << PAGE_SHIFT;
        unsigned int shift;
        int ref = 0;

        ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
        if (ptep && pte_present(*ptep) && pte_young(*ptep))
                ref = 1;
        return ref;
}

/* Returns the number of PAGE_SIZE pages that are dirty */
static int kvm_radix_test_clear_dirty(struct kvm *kvm,
                                struct kvm_memory_slot *memslot, int pagenum)
{
        unsigned long gfn = memslot->base_gfn + pagenum;
        unsigned long gpa = gfn << PAGE_SHIFT;
        pte_t *ptep;
        unsigned int shift;
        int ret = 0;
        unsigned long old, *rmapp;

        ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
        if (ptep && pte_present(*ptep) && pte_dirty(*ptep)) {
                ret = 1;
                if (shift)
                        ret = 1 << (shift - PAGE_SHIFT);
                spin_lock(&kvm->mmu_lock);
                old = kvmppc_radix_update_pte(kvm, ptep, _PAGE_DIRTY, 0,
                                              gpa, shift);
                kvmppc_radix_tlbie_page(kvm, gpa, shift, kvm->arch.lpid);
                /* Also clear bit in ptes in shadow pgtable for nested guests */
                rmapp = &memslot->arch.rmap[gfn - memslot->base_gfn];
                kvmhv_update_nest_rmap_rc_list(kvm, rmapp, _PAGE_DIRTY, 0,
                                               old & PTE_RPN_MASK,
                                               1UL << shift);
                spin_unlock(&kvm->mmu_lock);
        }
        return ret;
}

long kvmppc_hv_get_dirty_log_radix(struct kvm *kvm,
                        struct kvm_memory_slot *memslot, unsigned long *map)
{
        unsigned long i, j;
        int npages;

        for (i = 0; i < memslot->npages; i = j) {
                npages = kvm_radix_test_clear_dirty(kvm, memslot, i);

                /*
                 * Note that if npages > 0 then i must be a multiple of npages,
                 * since huge pages are only used to back the guest at guest
                 * real addresses that are a multiple of their size.
                 * Since we have at most one PTE covering any given guest
                 * real address, if npages > 1 we can skip to i + npages.
                 */
                j = i + 1;
                if (npages) {
                        set_dirty_bits(map, i, npages);
                        j = i + npages;
                }
        }
        return 0;
}

void kvmppc_radix_flush_memslot(struct kvm *kvm,
                                const struct kvm_memory_slot *memslot)
{
        unsigned long n;
        pte_t *ptep;
        unsigned long gpa;
        unsigned int shift;

        gpa = memslot->base_gfn << PAGE_SHIFT;
        spin_lock(&kvm->mmu_lock);
        for (n = memslot->npages; n; --n) {
                ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
                if (ptep && pte_present(*ptep))
                        kvmppc_unmap_pte(kvm, ptep, gpa, shift, memslot,
                                         kvm->arch.lpid);
                gpa += PAGE_SIZE;
        }
        spin_unlock(&kvm->mmu_lock);
}

static void add_rmmu_ap_encoding(struct kvm_ppc_rmmu_info *info,
                                 int psize, int *indexp)
{
        if (!mmu_psize_defs[psize].shift)
                return;
        info->ap_encodings[*indexp] = mmu_psize_defs[psize].shift |
                (mmu_psize_defs[psize].ap << 29);
        ++(*indexp);
}

int kvmhv_get_rmmu_info(struct kvm *kvm, struct kvm_ppc_rmmu_info *info)
{
        int i;

        if (!radix_enabled())
                return -EINVAL;
        memset(info, 0, sizeof(*info));

        /* 4k page size */
        info->geometries[0].page_shift = 12;
        info->geometries[0].level_bits[0] = 9;
        for (i = 1; i < 4; ++i)
                info->geometries[0].level_bits[i] = p9_supported_radix_bits[i];
        /* 64k page size */
        info->geometries[1].page_shift = 16;
        for (i = 0; i < 4; ++i)
                info->geometries[1].level_bits[i] = p9_supported_radix_bits[i];

        i = 0;
        add_rmmu_ap_encoding(info, MMU_PAGE_4K, &i);
        add_rmmu_ap_encoding(info, MMU_PAGE_64K, &i);
        add_rmmu_ap_encoding(info, MMU_PAGE_2M, &i);
        add_rmmu_ap_encoding(info, MMU_PAGE_1G, &i);

        return 0;
}

int kvmppc_init_vm_radix(struct kvm *kvm)
{
        kvm->arch.pgtable = pgd_alloc(kvm->mm);
        if (!kvm->arch.pgtable)
                return -ENOMEM;
        return 0;
}

static void pte_ctor(void *addr)
{
        memset(addr, 0, RADIX_PTE_TABLE_SIZE);
}

static void pmd_ctor(void *addr)
{
        memset(addr, 0, RADIX_PMD_TABLE_SIZE);
}

struct debugfs_radix_state {
        struct kvm      *kvm;
        struct mutex    mutex;
        unsigned long   gpa;
        int             lpid;
        int             chars_left;
        int             buf_index;
        char            buf[128];
        u8              hdr;
};

static int debugfs_radix_open(struct inode *inode, struct file *file)
{
        struct kvm *kvm = inode->i_private;
        struct debugfs_radix_state *p;

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

        kvm_get_kvm(kvm);
        p->kvm = kvm;
        mutex_init(&p->mutex);
        file->private_data = p;

        return nonseekable_open(inode, file);
}

static int debugfs_radix_release(struct inode *inode, struct file *file)
{
        struct debugfs_radix_state *p = file->private_data;

        kvm_put_kvm(p->kvm);
        kfree(p);
        return 0;
}

static ssize_t debugfs_radix_read(struct file *file, char __user *buf,
                                 size_t len, loff_t *ppos)
{
        struct debugfs_radix_state *p = file->private_data;
        ssize_t ret, r;
        unsigned long n;
        struct kvm *kvm;
        unsigned long gpa;
        pgd_t *pgt;
        struct kvm_nested_guest *nested;
        pgd_t pgd, *pgdp;
        pud_t pud, *pudp;
        pmd_t pmd, *pmdp;
        pte_t *ptep;
        int shift;
        unsigned long pte;

        kvm = p->kvm;
        if (!kvm_is_radix(kvm))
                return 0;

        ret = mutex_lock_interruptible(&p->mutex);
        if (ret)
                return ret;

        if (p->chars_left) {
                n = p->chars_left;
                if (n > len)
                        n = len;
                r = copy_to_user(buf, p->buf + p->buf_index, n);
                n -= r;
                p->chars_left -= n;
                p->buf_index += n;
                buf += n;
                len -= n;
                ret = n;
                if (r) {
                        if (!n)
                                ret = -EFAULT;
                        goto out;
                }
        }

        gpa = p->gpa;
        nested = NULL;
        pgt = NULL;
        while (len != 0 && p->lpid >= 0) {
                if (gpa >= RADIX_PGTABLE_RANGE) {
                        gpa = 0;
                        pgt = NULL;
                        if (nested) {
                                kvmhv_put_nested(nested);
                                nested = NULL;
                        }
                        p->lpid = kvmhv_nested_next_lpid(kvm, p->lpid);
                        p->hdr = 0;
                        if (p->lpid < 0)
                                break;
                }
                if (!pgt) {
                        if (p->lpid == 0) {
                                pgt = kvm->arch.pgtable;
                        } else {
                                nested = kvmhv_get_nested(kvm, p->lpid, false);
                                if (!nested) {
                                        gpa = RADIX_PGTABLE_RANGE;
                                        continue;
                                }
                                pgt = nested->shadow_pgtable;
                        }
                }
                n = 0;
                if (!p->hdr) {
                        if (p->lpid > 0)
                                n = scnprintf(p->buf, sizeof(p->buf),
                                              "\nNested LPID %d: ", p->lpid);
                        n += scnprintf(p->buf + n, sizeof(p->buf) - n,
                                      "pgdir: %lx\n", (unsigned long)pgt);
                        p->hdr = 1;
                        goto copy;
                }

                pgdp = pgt + pgd_index(gpa);
                pgd = READ_ONCE(*pgdp);
                if (!(pgd_val(pgd) & _PAGE_PRESENT)) {
                        gpa = (gpa & PGDIR_MASK) + PGDIR_SIZE;
                        continue;
                }

                pudp = pud_offset(&pgd, gpa);
                pud = READ_ONCE(*pudp);
                if (!(pud_val(pud) & _PAGE_PRESENT)) {
                        gpa = (gpa & PUD_MASK) + PUD_SIZE;
                        continue;
                }
                if (pud_val(pud) & _PAGE_PTE) {
                        pte = pud_val(pud);
                        shift = PUD_SHIFT;
                        goto leaf;
                }

                pmdp = pmd_offset(&pud, gpa);
                pmd = READ_ONCE(*pmdp);
                if (!(pmd_val(pmd) & _PAGE_PRESENT)) {
                        gpa = (gpa & PMD_MASK) + PMD_SIZE;
                        continue;
                }
                if (pmd_val(pmd) & _PAGE_PTE) {
                        pte = pmd_val(pmd);
                        shift = PMD_SHIFT;
                        goto leaf;
                }

                ptep = pte_offset_kernel(&pmd, gpa);
                pte = pte_val(READ_ONCE(*ptep));
                if (!(pte & _PAGE_PRESENT)) {
                        gpa += PAGE_SIZE;
                        continue;
                }
                shift = PAGE_SHIFT;
        leaf:
                n = scnprintf(p->buf, sizeof(p->buf),
                              " %lx: %lx %d\n", gpa, pte, shift);
                gpa += 1ul << shift;
        copy:
                p->chars_left = n;
                if (n > len)
                        n = len;
                r = copy_to_user(buf, p->buf, n);
                n -= r;
                p->chars_left -= n;
                p->buf_index = n;
                buf += n;
                len -= n;
                ret += n;
                if (r) {
                        if (!ret)
                                ret = -EFAULT;
                        break;
                }
        }
        p->gpa = gpa;
        if (nested)
                kvmhv_put_nested(nested);

 out:
        mutex_unlock(&p->mutex);
        return ret;
}

static ssize_t debugfs_radix_write(struct file *file, const char __user *buf,
                           size_t len, loff_t *ppos)
{
        return -EACCES;
}

static const struct file_operations debugfs_radix_fops = {
        .owner   = THIS_MODULE,
        .open    = debugfs_radix_open,
        .release = debugfs_radix_release,
        .read    = debugfs_radix_read,
        .write   = debugfs_radix_write,
        .llseek  = generic_file_llseek,
};

void kvmhv_radix_debugfs_init(struct kvm *kvm)
{
        kvm->arch.radix_dentry = debugfs_create_file("radix", 0400,
                                                     kvm->arch.debugfs_dir, kvm,
                                                     &debugfs_radix_fops);
}

int kvmppc_radix_init(void)
{
        unsigned long size = sizeof(void *) << RADIX_PTE_INDEX_SIZE;

        kvm_pte_cache = kmem_cache_create("kvm-pte", size, size, 0, pte_ctor);
        if (!kvm_pte_cache)
                return -ENOMEM;

        size = sizeof(void *) << RADIX_PMD_INDEX_SIZE;

        kvm_pmd_cache = kmem_cache_create("kvm-pmd", size, size, 0, pmd_ctor);
        if (!kvm_pmd_cache) {
                kmem_cache_destroy(kvm_pte_cache);
                return -ENOMEM;
        }

        return 0;
}

void kvmppc_radix_exit(void)
{
        kmem_cache_destroy(kvm_pte_cache);
        kmem_cache_destroy(kvm_pmd_cache);
}