sys/dev/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: drm device *
  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_device *dev)
  62 {
  63         struct drm_i915_private *dev_priv = to_i915(dev);
  64         uint64_t magic;
  65         uint32_t version;
  66
  67         BUILD_BUG_ON(sizeof(struct vgt_if) != VGT_PVINFO_SIZE);
  68
  69         if (!IS_HASWELL(dev))
  70                 return;
  71
  72         magic = __raw_i915_read64(dev_priv, vgtif_reg(magic));
  73         if (magic != VGT_MAGIC)
  74                 return;
  75
  76         version = INTEL_VGT_IF_VERSION_ENCODE(
  77                 __raw_i915_read16(dev_priv, vgtif_reg(version_major)),
  78                 __raw_i915_read16(dev_priv, vgtif_reg(version_minor)));
  79         if (version != INTEL_VGT_IF_VERSION) {
  80                 DRM_INFO("VGT interface version mismatch!\n");
  81                 return;
  82         }
  83
  84         dev_priv->vgpu.active = true;
  85         DRM_INFO("Virtual GPU for Intel GVT-g detected.\n");
  86 }
  87
  88 struct _balloon_info_ {
  89         /*
  90          * There are up to 2 regions per mappable/unmappable graphic
  91          * memory that might be ballooned. Here, index 0/1 is for mappable
  92          * graphic memory, 2/3 for unmappable graphic memory.
  93          */
  94         struct drm_mm_node space[4];
  95 };
  96
  97 static struct _balloon_info_ bl_info;
  98
  99 /**
 100  * intel_vgt_deballoon - deballoon reserved graphics address trunks
 101  *
 102  * This function is called to deallocate the ballooned-out graphic memory, when
 103  * driver is unloaded or when ballooning fails.
 104  */
 105 void intel_vgt_deballoon(void)
 106 {
 107         int i;
 108
 109         DRM_DEBUG("VGT deballoon.\n");
 110
 111         for (i = 0; i < 4; i++) {
 112                 if (bl_info.space[i].allocated)
 113                         drm_mm_remove_node(&bl_info.space[i]);
 114         }
 115
 116         memset(&bl_info, 0, sizeof(bl_info));
 117 }
 118
 119 static int vgt_balloon_space(struct drm_mm *mm,
 120                              struct drm_mm_node *node,
 121                              unsigned long start, unsigned long end)
 122 {
 123         unsigned long size = end - start;
 124
 125         if (start == end)
 126                 return -EINVAL;
 127
 128         DRM_INFO("balloon space: range [ 0x%lx - 0x%lx ] %lu KiB.\n",
 129                  start, end, size / 1024);
 130
 131         node->start = start;
 132         node->size = size;
 133
 134         return drm_mm_reserve_node(mm, node);
 135 }
 136
 137 /**
 138  * intel_vgt_balloon - balloon out reserved graphics address trunks
 139  * @dev: drm device
 140  *
 141  * This function is called at the initialization stage, to balloon out the
 142  * graphic address space allocated to other vGPUs, by marking these spaces as
 143  * reserved. The ballooning related knowledge(starting address and size of
 144  * the mappable/unmappable graphic memory) is described in the vgt_if structure
 145  * in a reserved mmio range.
 146  *
 147  * To give an example, the drawing below depicts one typical scenario after
 148  * ballooning. Here the vGPU1 has 2 pieces of graphic address spaces ballooned
 149  * out each for the mappable and the non-mappable part. From the vGPU1 point of
 150  * view, the total size is the same as the physical one, with the start address
 151  * of its graphic space being zero. Yet there are some portions ballooned out(
 152  * the shadow part, which are marked as reserved by drm allocator). From the
 153  * host point of view, the graphic address space is partitioned by multiple
 154  * vGPUs in different VMs.
 155  *
 156  *                        vGPU1 view         Host view
 157  *             0 ------> +-----------+     +-----------+
 158  *               ^       |///////////|     |   vGPU3   |
 159  *               |       |///////////|     +-----------+
 160  *               |       |///////////|     |   vGPU2   |
 161  *               |       +-----------+     +-----------+
 162  *        mappable GM    | available | ==> |   vGPU1   |
 163  *               |       +-----------+     +-----------+
 164  *               |       |///////////|     |           |
 165  *               v       |///////////|     |   Host    |
 166  *               +=======+===========+     +===========+
 167  *               ^       |///////////|     |   vGPU3   |
 168  *               |       |///////////|     +-----------+
 169  *               |       |///////////|     |   vGPU2   |
 170  *               |       +-----------+     +-----------+
 171  *      unmappable GM    | available | ==> |   vGPU1   |
 172  *               |       +-----------+     +-----------+
 173  *               |       |///////////|     |           |
 174  *               |       |///////////|     |   Host    |
 175  *               v       |///////////|     |           |
 176  * total GM size ------> +-----------+     +-----------+
 177  *
 178  * Returns:
 179  * zero on success, non-zero if configuration invalid or ballooning failed
 180  */
 181 int intel_vgt_balloon(struct drm_device *dev)
 182 {
 183         struct drm_i915_private *dev_priv = to_i915(dev);
 184         struct i915_ggtt *ggtt = &dev_priv->ggtt;
 185         unsigned long ggtt_end = ggtt->base.start + ggtt->base.total;
 186
 187         unsigned long mappable_base, mappable_size, mappable_end;
 188         unsigned long unmappable_base, unmappable_size, unmappable_end;
 189         int ret;
 190
 191         mappable_base = I915_READ(vgtif_reg(avail_rs.mappable_gmadr.base));
 192         mappable_size = I915_READ(vgtif_reg(avail_rs.mappable_gmadr.size));
 193         unmappable_base = I915_READ(vgtif_reg(avail_rs.nonmappable_gmadr.base));
 194         unmappable_size = I915_READ(vgtif_reg(avail_rs.nonmappable_gmadr.size));
 195
 196         mappable_end = mappable_base + mappable_size;
 197         unmappable_end = unmappable_base + unmappable_size;
 198
 199         DRM_INFO("VGT ballooning configuration:\n");
 200         DRM_INFO("Mappable graphic memory: base 0x%lx size %ldKiB\n",
 201                  mappable_base, mappable_size / 1024);
 202         DRM_INFO("Unmappable graphic memory: base 0x%lx size %ldKiB\n",
 203                  unmappable_base, unmappable_size / 1024);
 204
 205         if (mappable_base < ggtt->base.start ||
 206             mappable_end > ggtt->mappable_end ||
 207             unmappable_base < ggtt->mappable_end ||
 208             unmappable_end > ggtt_end) {
 209                 DRM_ERROR("Invalid ballooning configuration!\n");
 210                 return -EINVAL;
 211         }
 212
 213         /* Unmappable graphic memory ballooning */
 214         if (unmappable_base > ggtt->mappable_end) {
 215                 ret = vgt_balloon_space(&ggtt->base.mm,
 216                                         &bl_info.space[2],
 217                                         ggtt->mappable_end,
 218                                         unmappable_base);
 219
 220                 if (ret)
 221                         goto err;
 222         }
 223
 224         /*
 225          * No need to partition out the last physical page,
 226          * because it is reserved to the guard page.
 227          */
 228         if (unmappable_end < ggtt_end - PAGE_SIZE) {
 229                 ret = vgt_balloon_space(&ggtt->base.mm,
 230                                         &bl_info.space[3],
 231                                         unmappable_end,
 232                                         ggtt_end - PAGE_SIZE);
 233                 if (ret)
 234                         goto err;
 235         }
 236
 237         /* Mappable graphic memory ballooning */
 238         if (mappable_base > ggtt->base.start) {
 239                 ret = vgt_balloon_space(&ggtt->base.mm,
 240                                         &bl_info.space[0],
 241                                         ggtt->base.start, mappable_base);
 242
 243                 if (ret)
 244                         goto err;
 245         }
 246
 247         if (mappable_end < ggtt->mappable_end) {
 248                 ret = vgt_balloon_space(&ggtt->base.mm,
 249                                         &bl_info.space[1],
 250                                         mappable_end,
 251                                         ggtt->mappable_end);
 252
 253                 if (ret)
 254                         goto err;
 255         }
 256
 257         DRM_INFO("VGT balloon successfully\n");
 258         return 0;
 259
 260 err:
 261         DRM_ERROR("VGT balloon fail\n");
 262         intel_vgt_deballoon();
 263         return ret;
 264 }