drivers/gpu/drm/i915/i915_vgpu.c

   1 /*
   2  * Copyright(c) 2011-2015 Intel Corporation. All rights reserved.
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  20  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  21  * SOFTWARE.
  22  */
  23
  24 #include "intel_drv.h"
  25 #include "i915_vgpu.h"
  26
  27 /**
  28  * DOC: Intel GVT-g guest support
  29  *
  30  * Intel GVT-g is a graphics virtualization technology which shares the
  31  * GPU among multiple virtual machines on a time-sharing basis. Each
  32  * virtual machine is presented a virtual GPU (vGPU), which has equivalent
  33  * features as the underlying physical GPU (pGPU), so i915 driver can run
  34  * seamlessly in a virtual machine. This file provides vGPU specific
  35  * optimizations when running in a virtual machine, to reduce the complexity
  36  * of vGPU emulation and to improve the overall performance.
  37  *
  38  * A primary function introduced here is so-called "address space ballooning"
  39  * technique. Intel GVT-g partitions global graphics memory among multiple VMs,
  40  * so each VM can directly access a portion of the memory without hypervisor's
  41  * intervention, e.g. filling textures or queuing commands. However with the
  42  * partitioning an unmodified i915 driver would assume a smaller graphics
  43  * memory starting from address ZERO, then requires vGPU emulation module to
  44  * translate the graphics address between 'guest view' and 'host view', for
  45  * all registers and command opcodes which contain a graphics memory address.
  46  * To reduce the complexity, Intel GVT-g introduces "address space ballooning",
  47  * by telling the exact partitioning knowledge to each guest i915 driver, which
  48  * then reserves and prevents non-allocated portions from allocation. Thus vGPU
  49  * emulation module only needs to scan and validate graphics addresses without
  50  * complexity of address translation.
  51  *
  52  */
  53
  54 /**
  55  * i915_check_vgpu - detect virtual GPU
  56  * @dev_priv: i915 device private
  57  *
  58  * This function is called at the initialization stage, to detect whether
  59  * running on a vGPU.
  60  */
  61 void i915_check_vgpu(struct drm_i915_private *dev_priv)
  62 {
  63         u64 magic;
  64         u16 version_major;
  65
  66         BUILD_BUG_ON(sizeof(struct vgt_if) != VGT_PVINFO_SIZE);
  67
  68         magic = __raw_i915_read64(dev_priv, vgtif_reg(magic));
  69         if (magic != VGT_MAGIC)
  70                 return;
  71
  72         version_major = __raw_i915_read16(dev_priv, vgtif_reg(version_major));
  73         if (version_major < VGT_VERSION_MAJOR) {
  74                 DRM_INFO("VGT interface version mismatch!\n");
  75                 return;
  76         }
  77
  78         dev_priv->vgpu.active = true;
  79         DRM_INFO("Virtual GPU for Intel GVT-g detected.\n");
  80 }
  81
  82 struct _balloon_info_ {
  83         /*
  84          * There are up to 2 regions per mappable/unmappable graphic
  85          * memory that might be ballooned. Here, index 0/1 is for mappable
  86          * graphic memory, 2/3 for unmappable graphic memory.
  87          */
  88         struct drm_mm_node space[4];
  89 };
  90
  91 static struct _balloon_info_ bl_info;
  92
  93 static void vgt_deballoon_space(struct i915_ggtt *ggtt,
  94                                 struct drm_mm_node *node)
  95 {
  96         DRM_DEBUG_DRIVER("deballoon space: range [0x%llx - 0x%llx] %llu KiB.\n",
  97                          node->start,
  98                          node->start + node->size,
  99                          node->size / 1024);
 100
 101         ggtt->base.reserved -= node->size;
 102         drm_mm_remove_node(node);
 103 }
 104
 105 /**
 106  * intel_vgt_deballoon - deballoon reserved graphics address trunks
 107  * @dev_priv: i915 device private data
 108  *
 109  * This function is called to deallocate the ballooned-out graphic memory, when
 110  * driver is unloaded or when ballooning fails.
 111  */
 112 void intel_vgt_deballoon(struct drm_i915_private *dev_priv)
 113 {
 114         int i;
 115
 116         if (!intel_vgpu_active(dev_priv))
 117                 return;
 118
 119         DRM_DEBUG("VGT deballoon.\n");
 120
 121         for (i = 0; i < 4; i++)
 122                 vgt_deballoon_space(&dev_priv->ggtt, &bl_info.space[i]);
 123 }
 124
 125 static int vgt_balloon_space(struct i915_ggtt *ggtt,
 126                              struct drm_mm_node *node,
 127                              unsigned long start, unsigned long end)
 128 {
 129         unsigned long size = end - start;
 130         int ret;
 131
 132         if (start >= end)
 133                 return -EINVAL;
 134
 135         DRM_INFO("balloon space: range [ 0x%lx - 0x%lx ] %lu KiB.\n",
 136                  start, end, size / 1024);
 137         ret = i915_gem_gtt_reserve(&ggtt->base, node,
 138                                    size, start, I915_COLOR_UNEVICTABLE,
 139                                    0);
 140         if (!ret)
 141                 ggtt->base.reserved += size;
 142
 143         return ret;
 144 }
 145
 146 /**
 147  * intel_vgt_balloon - balloon out reserved graphics address trunks
 148  * @dev_priv: i915 device private data
 149  *
 150  * This function is called at the initialization stage, to balloon out the
 151  * graphic address space allocated to other vGPUs, by marking these spaces as
 152  * reserved. The ballooning related knowledge(starting address and size of
 153  * the mappable/unmappable graphic memory) is described in the vgt_if structure
 154  * in a reserved mmio range.
 155  *
 156  * To give an example, the drawing below depicts one typical scenario after
 157  * ballooning. Here the vGPU1 has 2 pieces of graphic address spaces ballooned
 158  * out each for the mappable and the non-mappable part. From the vGPU1 point of
 159  * view, the total size is the same as the physical one, with the start address
 160  * of its graphic space being zero. Yet there are some portions ballooned out(
 161  * the shadow part, which are marked as reserved by drm allocator). From the
 162  * host point of view, the graphic address space is partitioned by multiple
 163  * vGPUs in different VMs. ::
 164  *
 165  *                         vGPU1 view         Host view
 166  *              0 ------> +-----------+     +-----------+
 167  *                ^       |###########|     |   vGPU3   |
 168  *                |       |###########|     +-----------+
 169  *                |       |###########|     |   vGPU2   |
 170  *                |       +-----------+     +-----------+
 171  *         mappable GM    | available | ==> |   vGPU1   |
 172  *                |       +-----------+     +-----------+
 173  *                |       |###########|     |           |
 174  *                v       |###########|     |   Host    |
 175  *                +=======+===========+     +===========+
 176  *                ^       |###########|     |   vGPU3   |
 177  *                |       |###########|     +-----------+
 178  *                |       |###########|     |   vGPU2   |
 179  *                |       +-----------+     +-----------+
 180  *       unmappable GM    | available | ==> |   vGPU1   |
 181  *                |       +-----------+     +-----------+
 182  *                |       |###########|     |           |
 183  *                |       |###########|     |   Host    |
 184  *                v       |###########|     |           |
 185  *  total GM size ------> +-----------+     +-----------+
 186  *
 187  * Returns:
 188  * zero on success, non-zero if configuration invalid or ballooning failed
 189  */
 190 int intel_vgt_balloon(struct drm_i915_private *dev_priv)
 191 {
 192         struct i915_ggtt *ggtt = &dev_priv->ggtt;
 193         unsigned long ggtt_end = ggtt->base.total;
 194
 195         unsigned long mappable_base, mappable_size, mappable_end;
 196         unsigned long unmappable_base, unmappable_size, unmappable_end;
 197         int ret;
 198
 199         if (!intel_vgpu_active(dev_priv))
 200                 return 0;
 201
 202         mappable_base = I915_READ(vgtif_reg(avail_rs.mappable_gmadr.base));
 203         mappable_size = I915_READ(vgtif_reg(avail_rs.mappable_gmadr.size));
 204         unmappable_base = I915_READ(vgtif_reg(avail_rs.nonmappable_gmadr.base));
 205         unmappable_size = I915_READ(vgtif_reg(avail_rs.nonmappable_gmadr.size));
 206
 207         mappable_end = mappable_base + mappable_size;
 208         unmappable_end = unmappable_base + unmappable_size;
 209
 210         DRM_INFO("VGT ballooning configuration:\n");
 211         DRM_INFO("Mappable graphic memory: base 0x%lx size %ldKiB\n",
 212                  mappable_base, mappable_size / 1024);
 213         DRM_INFO("Unmappable graphic memory: base 0x%lx size %ldKiB\n",
 214                  unmappable_base, unmappable_size / 1024);
 215
 216         if (mappable_end > ggtt->mappable_end ||
 217             unmappable_base < ggtt->mappable_end ||
 218             unmappable_end > ggtt_end) {
 219                 DRM_ERROR("Invalid ballooning configuration!\n");
 220                 return -EINVAL;
 221         }
 222
 223         /* Unmappable graphic memory ballooning */
 224         if (unmappable_base > ggtt->mappable_end) {
 225                 ret = vgt_balloon_space(ggtt, &bl_info.space[2],
 226                                         ggtt->mappable_end, unmappable_base);
 227
 228                 if (ret)
 229                         goto err;
 230         }
 231
 232         if (unmappable_end < ggtt_end) {
 233                 ret = vgt_balloon_space(ggtt, &bl_info.space[3],
 234                                         unmappable_end, ggtt_end);
 235                 if (ret)
 236                         goto err_upon_mappable;
 237         }
 238
 239         /* Mappable graphic memory ballooning */
 240         if (mappable_base) {
 241                 ret = vgt_balloon_space(ggtt, &bl_info.space[0],
 242                                         0, mappable_base);
 243
 244                 if (ret)
 245                         goto err_upon_unmappable;
 246         }
 247
 248         if (mappable_end < ggtt->mappable_end) {
 249                 ret = vgt_balloon_space(ggtt, &bl_info.space[1],
 250                                         mappable_end, ggtt->mappable_end);
 251
 252                 if (ret)
 253                         goto err_below_mappable;
 254         }
 255
 256         DRM_INFO("VGT balloon successfully\n");
 257         return 0;
 258
 259 err_below_mappable:
 260         vgt_deballoon_space(ggtt, &bl_info.space[0]);
 261 err_upon_unmappable:
 262         vgt_deballoon_space(ggtt, &bl_info.space[3]);
 263 err_upon_mappable:
 264         vgt_deballoon_space(ggtt, &bl_info.space[2]);
 265 err:
 266         DRM_ERROR("VGT balloon fail\n");
 267         return ret;
 268 }