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         uint64_t magic;
  64         uint32_t version;
  65
  66         BUILD_BUG_ON(sizeof(struct vgt_if) != VGT_PVINFO_SIZE);
  67
  68         if (!IS_HASWELL(dev_priv))
  69                 return;
  70
  71         magic = __raw_i915_read64(dev_priv, vgtif_reg(magic));
  72         if (magic != VGT_MAGIC)
  73                 return;
  74
  75         version = INTEL_VGT_IF_VERSION_ENCODE(
  76                 __raw_i915_read16(dev_priv, vgtif_reg(version_major)),
  77                 __raw_i915_read16(dev_priv, vgtif_reg(version_minor)));
  78         if (version != INTEL_VGT_IF_VERSION) {
  79                 DRM_INFO("VGT interface version mismatch!\n");
  80                 return;
  81         }
  82
  83         dev_priv->vgpu.active = true;
  84         DRM_INFO("Virtual GPU for Intel GVT-g detected.\n");
  85 }
  86
  87 struct _balloon_info_ {
  88         /*
  89          * There are up to 2 regions per mappable/unmappable graphic
  90          * memory that might be ballooned. Here, index 0/1 is for mappable
  91          * graphic memory, 2/3 for unmappable graphic memory.
  92          */
  93         struct drm_mm_node space[4];
  94 };
  95
  96 static struct _balloon_info_ bl_info;
  97
  98 /**
  99  * intel_vgt_deballoon - deballoon reserved graphics address trunks
 100  *
 101  * This function is called to deallocate the ballooned-out graphic memory, when
 102  * driver is unloaded or when ballooning fails.
 103  */
 104 void intel_vgt_deballoon(struct drm_i915_private *dev_priv)
 105 {
 106         int i;
 107
 108         if (!intel_vgpu_active(dev_priv))
 109                 return;
 110
 111         DRM_DEBUG("VGT deballoon.\n");
 112
 113         for (i = 0; i < 4; i++) {
 114                 if (bl_info.space[i].allocated)
 115                         drm_mm_remove_node(&bl_info.space[i]);
 116         }
 117
 118         memset(&bl_info, 0, sizeof(bl_info));
 119 }
 120
 121 static int vgt_balloon_space(struct drm_mm *mm,
 122                              struct drm_mm_node *node,
 123                              unsigned long start, unsigned long end)
 124 {
 125         unsigned long size = end - start;
 126
 127         if (start == end)
 128                 return -EINVAL;
 129
 130         DRM_INFO("balloon space: range [ 0x%lx - 0x%lx ] %lu KiB.\n",
 131                  start, end, size / 1024);
 132
 133         node->start = start;
 134         node->size = size;
 135
 136         return drm_mm_reserve_node(mm, node);
 137 }
 138
 139 /**
 140  * intel_vgt_balloon - balloon out reserved graphics address trunks
 141  * @dev: drm device
 142  *
 143  * This function is called at the initialization stage, to balloon out the
 144  * graphic address space allocated to other vGPUs, by marking these spaces as
 145  * reserved. The ballooning related knowledge(starting address and size of
 146  * the mappable/unmappable graphic memory) is described in the vgt_if structure
 147  * in a reserved mmio range.
 148  *
 149  * To give an example, the drawing below depicts one typical scenario after
 150  * ballooning. Here the vGPU1 has 2 pieces of graphic address spaces ballooned
 151  * out each for the mappable and the non-mappable part. From the vGPU1 point of
 152  * view, the total size is the same as the physical one, with the start address
 153  * of its graphic space being zero. Yet there are some portions ballooned out(
 154  * the shadow part, which are marked as reserved by drm allocator). From the
 155  * host point of view, the graphic address space is partitioned by multiple
 156  * vGPUs in different VMs. ::
 157  *
 158  *                        vGPU1 view         Host view
 159  *             0 ------> +-----------+     +-----------+
 160  *               ^       |###########|     |   vGPU3   |
 161  *               |       |###########|     +-----------+
 162  *               |       |###########|     |   vGPU2   |
 163  *               |       +-----------+     +-----------+
 164  *        mappable GM    | available | ==> |   vGPU1   |
 165  *               |       +-----------+     +-----------+
 166  *               |       |###########|     |           |
 167  *               v       |###########|     |   Host    |
 168  *               +=======+===========+     +===========+
 169  *               ^       |###########|     |   vGPU3   |
 170  *               |       |###########|     +-----------+
 171  *               |       |###########|     |   vGPU2   |
 172  *               |       +-----------+     +-----------+
 173  *      unmappable GM    | available | ==> |   vGPU1   |
 174  *               |       +-----------+     +-----------+
 175  *               |       |###########|     |           |
 176  *               |       |###########|     |   Host    |
 177  *               v       |###########|     |           |
 178  * total GM size ------> +-----------+     +-----------+
 179  *
 180  * Returns:
 181  * zero on success, non-zero if configuration invalid or ballooning failed
 182  */
 183 int intel_vgt_balloon(struct drm_i915_private *dev_priv)
 184 {
 185         struct i915_ggtt *ggtt = &dev_priv->ggtt;
 186         unsigned long ggtt_end = ggtt->base.start + ggtt->base.total;
 187
 188         unsigned long mappable_base, mappable_size, mappable_end;
 189         unsigned long unmappable_base, unmappable_size, unmappable_end;
 190         int ret;
 191
 192         if (!intel_vgpu_active(dev_priv))
 193                 return 0;
 194
 195         mappable_base = I915_READ(vgtif_reg(avail_rs.mappable_gmadr.base));
 196         mappable_size = I915_READ(vgtif_reg(avail_rs.mappable_gmadr.size));
 197         unmappable_base = I915_READ(vgtif_reg(avail_rs.nonmappable_gmadr.base));
 198         unmappable_size = I915_READ(vgtif_reg(avail_rs.nonmappable_gmadr.size));
 199
 200         mappable_end = mappable_base + mappable_size;
 201         unmappable_end = unmappable_base + unmappable_size;
 202
 203         DRM_INFO("VGT ballooning configuration:\n");
 204         DRM_INFO("Mappable graphic memory: base 0x%lx size %ldKiB\n",
 205                  mappable_base, mappable_size / 1024);
 206         DRM_INFO("Unmappable graphic memory: base 0x%lx size %ldKiB\n",
 207                  unmappable_base, unmappable_size / 1024);
 208
 209         if (mappable_base < ggtt->base.start ||
 210             mappable_end > ggtt->mappable_end ||
 211             unmappable_base < ggtt->mappable_end ||
 212             unmappable_end > ggtt_end) {
 213                 DRM_ERROR("Invalid ballooning configuration!\n");
 214                 return -EINVAL;
 215         }
 216
 217         /* Unmappable graphic memory ballooning */
 218         if (unmappable_base > ggtt->mappable_end) {
 219                 ret = vgt_balloon_space(&ggtt->base.mm,
 220                                         &bl_info.space[2],
 221                                         ggtt->mappable_end,
 222                                         unmappable_base);
 223
 224                 if (ret)
 225                         goto err;
 226         }
 227
 228         /*
 229          * No need to partition out the last physical page,
 230          * because it is reserved to the guard page.
 231          */
 232         if (unmappable_end < ggtt_end - PAGE_SIZE) {
 233                 ret = vgt_balloon_space(&ggtt->base.mm,
 234                                         &bl_info.space[3],
 235                                         unmappable_end,
 236                                         ggtt_end - PAGE_SIZE);
 237                 if (ret)
 238                         goto err;
 239         }
 240
 241         /* Mappable graphic memory ballooning */
 242         if (mappable_base > ggtt->base.start) {
 243                 ret = vgt_balloon_space(&ggtt->base.mm,
 244                                         &bl_info.space[0],
 245                                         ggtt->base.start, mappable_base);
 246
 247                 if (ret)
 248                         goto err;
 249         }
 250
 251         if (mappable_end < ggtt->mappable_end) {
 252                 ret = vgt_balloon_space(&ggtt->base.mm,
 253                                         &bl_info.space[1],
 254                                         mappable_end,
 255                                         ggtt->mappable_end);
 256
 257                 if (ret)
 258                         goto err;
 259         }
 260
 261         DRM_INFO("VGT balloon successfully\n");
 262         return 0;
 263
 264 err:
 265         DRM_ERROR("VGT balloon fail\n");
 266         intel_vgt_deballoon(dev_priv);
 267         return ret;
 268 }