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20 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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
)
66 BUILD_BUG_ON(sizeof(struct vgt_if
) != VGT_PVINFO_SIZE
);
68 if (!IS_HASWELL(dev_priv
))
71 magic
= __raw_i915_read64(dev_priv
, vgtif_reg(magic
));
72 if (magic
!= VGT_MAGIC
)
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");
83 dev_priv
->vgpu
.active
= true;
84 DRM_INFO("Virtual GPU for Intel GVT-g detected.\n");
87 struct _balloon_info_
{
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.
93 struct drm_mm_node space
[4];
96 static struct _balloon_info_ bl_info
;
99 * intel_vgt_deballoon - deballoon reserved graphics address trunks
100 * @dev_priv: i915 device private data
102 * This function is called to deallocate the ballooned-out graphic memory, when
103 * driver is unloaded or when ballooning fails.
105 void intel_vgt_deballoon(struct drm_i915_private
*dev_priv
)
109 if (!intel_vgpu_active(dev_priv
))
112 DRM_DEBUG("VGT deballoon.\n");
114 for (i
= 0; i
< 4; i
++) {
115 if (bl_info
.space
[i
].allocated
)
116 drm_mm_remove_node(&bl_info
.space
[i
]);
119 memset(&bl_info
, 0, sizeof(bl_info
));
122 static int vgt_balloon_space(struct drm_mm
*mm
,
123 struct drm_mm_node
*node
,
124 unsigned long start
, unsigned long end
)
126 unsigned long size
= end
- start
;
131 DRM_INFO("balloon space: range [ 0x%lx - 0x%lx ] %lu KiB.\n",
132 start
, end
, size
/ 1024);
137 return drm_mm_reserve_node(mm
, node
);
141 * intel_vgt_balloon - balloon out reserved graphics address trunks
142 * @dev_priv: i915 device private data
144 * This function is called at the initialization stage, to balloon out the
145 * graphic address space allocated to other vGPUs, by marking these spaces as
146 * reserved. The ballooning related knowledge(starting address and size of
147 * the mappable/unmappable graphic memory) is described in the vgt_if structure
148 * in a reserved mmio range.
150 * To give an example, the drawing below depicts one typical scenario after
151 * ballooning. Here the vGPU1 has 2 pieces of graphic address spaces ballooned
152 * out each for the mappable and the non-mappable part. From the vGPU1 point of
153 * view, the total size is the same as the physical one, with the start address
154 * of its graphic space being zero. Yet there are some portions ballooned out(
155 * the shadow part, which are marked as reserved by drm allocator). From the
156 * host point of view, the graphic address space is partitioned by multiple
157 * vGPUs in different VMs. ::
159 * vGPU1 view Host view
160 * 0 ------> +-----------+ +-----------+
161 * ^ |###########| | vGPU3 |
162 * | |###########| +-----------+
163 * | |###########| | vGPU2 |
164 * | +-----------+ +-----------+
165 * mappable GM | available | ==> | vGPU1 |
166 * | +-----------+ +-----------+
167 * | |###########| | |
168 * v |###########| | Host |
169 * +=======+===========+ +===========+
170 * ^ |###########| | vGPU3 |
171 * | |###########| +-----------+
172 * | |###########| | vGPU2 |
173 * | +-----------+ +-----------+
174 * unmappable GM | available | ==> | vGPU1 |
175 * | +-----------+ +-----------+
176 * | |###########| | |
177 * | |###########| | Host |
178 * v |###########| | |
179 * total GM size ------> +-----------+ +-----------+
182 * zero on success, non-zero if configuration invalid or ballooning failed
184 int intel_vgt_balloon(struct drm_i915_private
*dev_priv
)
186 struct i915_ggtt
*ggtt
= &dev_priv
->ggtt
;
187 unsigned long ggtt_end
= ggtt
->base
.start
+ ggtt
->base
.total
;
189 unsigned long mappable_base
, mappable_size
, mappable_end
;
190 unsigned long unmappable_base
, unmappable_size
, unmappable_end
;
193 if (!intel_vgpu_active(dev_priv
))
196 mappable_base
= I915_READ(vgtif_reg(avail_rs
.mappable_gmadr
.base
));
197 mappable_size
= I915_READ(vgtif_reg(avail_rs
.mappable_gmadr
.size
));
198 unmappable_base
= I915_READ(vgtif_reg(avail_rs
.nonmappable_gmadr
.base
));
199 unmappable_size
= I915_READ(vgtif_reg(avail_rs
.nonmappable_gmadr
.size
));
201 mappable_end
= mappable_base
+ mappable_size
;
202 unmappable_end
= unmappable_base
+ unmappable_size
;
204 DRM_INFO("VGT ballooning configuration:\n");
205 DRM_INFO("Mappable graphic memory: base 0x%lx size %ldKiB\n",
206 mappable_base
, mappable_size
/ 1024);
207 DRM_INFO("Unmappable graphic memory: base 0x%lx size %ldKiB\n",
208 unmappable_base
, unmappable_size
/ 1024);
210 if (mappable_base
< ggtt
->base
.start
||
211 mappable_end
> ggtt
->mappable_end
||
212 unmappable_base
< ggtt
->mappable_end
||
213 unmappable_end
> ggtt_end
) {
214 DRM_ERROR("Invalid ballooning configuration!\n");
218 /* Unmappable graphic memory ballooning */
219 if (unmappable_base
> ggtt
->mappable_end
) {
220 ret
= vgt_balloon_space(&ggtt
->base
.mm
,
230 * No need to partition out the last physical page,
231 * because it is reserved to the guard page.
233 if (unmappable_end
< ggtt_end
- PAGE_SIZE
) {
234 ret
= vgt_balloon_space(&ggtt
->base
.mm
,
237 ggtt_end
- PAGE_SIZE
);
242 /* Mappable graphic memory ballooning */
243 if (mappable_base
> ggtt
->base
.start
) {
244 ret
= vgt_balloon_space(&ggtt
->base
.mm
,
246 ggtt
->base
.start
, mappable_base
);
252 if (mappable_end
< ggtt
->mappable_end
) {
253 ret
= vgt_balloon_space(&ggtt
->base
.mm
,
262 DRM_INFO("VGT balloon successfully\n");
266 DRM_ERROR("VGT balloon fail\n");
267 intel_vgt_deballoon(dev_priv
);
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