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11 * The above copyright notice and this permission notice (including the next
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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,
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24 #include "intel_drv.h"
25 #include "i915_vgpu.h"
28 * DOC: Intel GVT-g guest support
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.
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.
55 * i915_check_vgpu - detect virtual GPU
56 * @dev_priv: i915 device private
58 * This function is called at the initialization stage, to detect whether
61 void i915_check_vgpu(struct drm_i915_private *dev_priv)
63 struct intel_uncore *uncore = &dev_priv->uncore;
67 BUILD_BUG_ON(sizeof(struct vgt_if) != VGT_PVINFO_SIZE);
69 magic = __raw_uncore_read64(uncore, vgtif_reg(magic));
70 if (magic != VGT_MAGIC)
73 version_major = __raw_uncore_read16(uncore, vgtif_reg(version_major));
74 if (version_major < VGT_VERSION_MAJOR) {
75 DRM_INFO("VGT interface version mismatch!\n");
79 dev_priv->vgpu.caps = __raw_uncore_read32(uncore, vgtif_reg(vgt_caps));
81 dev_priv->vgpu.active = true;
82 DRM_INFO("Virtual GPU for Intel GVT-g detected.\n");
85 bool intel_vgpu_has_full_ppgtt(struct drm_i915_private *dev_priv)
87 return dev_priv->vgpu.caps & VGT_CAPS_FULL_PPGTT;
90 struct _balloon_info_ {
92 * There are up to 2 regions per mappable/unmappable graphic
93 * memory that might be ballooned. Here, index 0/1 is for mappable
94 * graphic memory, 2/3 for unmappable graphic memory.
96 struct drm_mm_node space[4];
99 static struct _balloon_info_ bl_info;
101 static void vgt_deballoon_space(struct i915_ggtt *ggtt,
102 struct drm_mm_node *node)
104 if (!drm_mm_node_allocated(node))
107 DRM_DEBUG_DRIVER("deballoon space: range [0x%llx - 0x%llx] %llu KiB.\n",
109 node->start + node->size,
112 ggtt->vm.reserved -= node->size;
113 drm_mm_remove_node(node);
117 * intel_vgt_deballoon - deballoon reserved graphics address trunks
118 * @dev_priv: i915 device private data
120 * This function is called to deallocate the ballooned-out graphic memory, when
121 * driver is unloaded or when ballooning fails.
123 void intel_vgt_deballoon(struct drm_i915_private *dev_priv)
127 if (!intel_vgpu_active(dev_priv))
130 DRM_DEBUG("VGT deballoon.\n");
132 for (i = 0; i < 4; i++)
133 vgt_deballoon_space(&dev_priv->ggtt, &bl_info.space[i]);
136 static int vgt_balloon_space(struct i915_ggtt *ggtt,
137 struct drm_mm_node *node,
138 unsigned long start, unsigned long end)
140 unsigned long size = end - start;
146 DRM_INFO("balloon space: range [ 0x%lx - 0x%lx ] %lu KiB.\n",
147 start, end, size / 1024);
148 ret = i915_gem_gtt_reserve(&ggtt->vm, node,
149 size, start, I915_COLOR_UNEVICTABLE,
152 ggtt->vm.reserved += size;
158 * intel_vgt_balloon - balloon out reserved graphics address trunks
159 * @dev_priv: i915 device private data
161 * This function is called at the initialization stage, to balloon out the
162 * graphic address space allocated to other vGPUs, by marking these spaces as
163 * reserved. The ballooning related knowledge(starting address and size of
164 * the mappable/unmappable graphic memory) is described in the vgt_if structure
165 * in a reserved mmio range.
167 * To give an example, the drawing below depicts one typical scenario after
168 * ballooning. Here the vGPU1 has 2 pieces of graphic address spaces ballooned
169 * out each for the mappable and the non-mappable part. From the vGPU1 point of
170 * view, the total size is the same as the physical one, with the start address
171 * of its graphic space being zero. Yet there are some portions ballooned out(
172 * the shadow part, which are marked as reserved by drm allocator). From the
173 * host point of view, the graphic address space is partitioned by multiple
174 * vGPUs in different VMs. ::
176 * vGPU1 view Host view
177 * 0 ------> +-----------+ +-----------+
178 * ^ |###########| | vGPU3 |
179 * | |###########| +-----------+
180 * | |###########| | vGPU2 |
181 * | +-----------+ +-----------+
182 * mappable GM | available | ==> | vGPU1 |
183 * | +-----------+ +-----------+
184 * | |###########| | |
185 * v |###########| | Host |
186 * +=======+===========+ +===========+
187 * ^ |###########| | vGPU3 |
188 * | |###########| +-----------+
189 * | |###########| | vGPU2 |
190 * | +-----------+ +-----------+
191 * unmappable GM | available | ==> | vGPU1 |
192 * | +-----------+ +-----------+
193 * | |###########| | |
194 * | |###########| | Host |
195 * v |###########| | |
196 * total GM size ------> +-----------+ +-----------+
199 * zero on success, non-zero if configuration invalid or ballooning failed
201 int intel_vgt_balloon(struct drm_i915_private *dev_priv)
203 struct i915_ggtt *ggtt = &dev_priv->ggtt;
204 unsigned long ggtt_end = ggtt->vm.total;
206 unsigned long mappable_base, mappable_size, mappable_end;
207 unsigned long unmappable_base, unmappable_size, unmappable_end;
210 if (!intel_vgpu_active(dev_priv))
213 mappable_base = I915_READ(vgtif_reg(avail_rs.mappable_gmadr.base));
214 mappable_size = I915_READ(vgtif_reg(avail_rs.mappable_gmadr.size));
215 unmappable_base = I915_READ(vgtif_reg(avail_rs.nonmappable_gmadr.base));
216 unmappable_size = I915_READ(vgtif_reg(avail_rs.nonmappable_gmadr.size));
218 mappable_end = mappable_base + mappable_size;
219 unmappable_end = unmappable_base + unmappable_size;
221 DRM_INFO("VGT ballooning configuration:\n");
222 DRM_INFO("Mappable graphic memory: base 0x%lx size %ldKiB\n",
223 mappable_base, mappable_size / 1024);
224 DRM_INFO("Unmappable graphic memory: base 0x%lx size %ldKiB\n",
225 unmappable_base, unmappable_size / 1024);
227 if (mappable_end > ggtt->mappable_end ||
228 unmappable_base < ggtt->mappable_end ||
229 unmappable_end > ggtt_end) {
230 DRM_ERROR("Invalid ballooning configuration!\n");
234 /* Unmappable graphic memory ballooning */
235 if (unmappable_base > ggtt->mappable_end) {
236 ret = vgt_balloon_space(ggtt, &bl_info.space[2],
237 ggtt->mappable_end, unmappable_base);
243 if (unmappable_end < ggtt_end) {
244 ret = vgt_balloon_space(ggtt, &bl_info.space[3],
245 unmappable_end, ggtt_end);
247 goto err_upon_mappable;
250 /* Mappable graphic memory ballooning */
252 ret = vgt_balloon_space(ggtt, &bl_info.space[0],
256 goto err_upon_unmappable;
259 if (mappable_end < ggtt->mappable_end) {
260 ret = vgt_balloon_space(ggtt, &bl_info.space[1],
261 mappable_end, ggtt->mappable_end);
264 goto err_below_mappable;
267 DRM_INFO("VGT balloon successfully\n");
271 vgt_deballoon_space(ggtt, &bl_info.space[0]);
273 vgt_deballoon_space(ggtt, &bl_info.space[3]);
275 vgt_deballoon_space(ggtt, &bl_info.space[2]);
277 DRM_ERROR("VGT balloon fail\n");