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 */
i915_check_vgpu(struct drm_i915_private * dev_priv)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 /**
94 * intel_vgt_deballoon - deballoon reserved graphics address trunks
95 * @dev_priv: i915 device private data
96 *
97 * This function is called to deallocate the ballooned-out graphic memory, when
98 * driver is unloaded or when ballooning fails.
99 */
intel_vgt_deballoon(struct drm_i915_private * dev_priv)100 void intel_vgt_deballoon(struct drm_i915_private *dev_priv)
101 {
102 int i;
103
104 if (!intel_vgpu_active(dev_priv))
105 return;
106
107 DRM_DEBUG("VGT deballoon.\n");
108
109 for (i = 0; i < 4; i++) {
110 if (bl_info.space[i].allocated)
111 drm_mm_remove_node(&bl_info.space[i]);
112 }
113
114 memset(&bl_info, 0, sizeof(bl_info));
115 }
116
vgt_balloon_space(struct drm_mm * mm,struct drm_mm_node * node,unsigned long start,unsigned long end)117 static int vgt_balloon_space(struct drm_mm *mm,
118 struct drm_mm_node *node,
119 unsigned long start, unsigned long end)
120 {
121 unsigned long size = end - start;
122
123 if (start == end)
124 return -EINVAL;
125
126 DRM_INFO("balloon space: range [ 0x%lx - 0x%lx ] %lu KiB.\n",
127 start, end, size / 1024);
128
129 node->start = start;
130 node->size = size;
131
132 return drm_mm_reserve_node(mm, node);
133 }
134
135 /**
136 * intel_vgt_balloon - balloon out reserved graphics address trunks
137 * @dev_priv: i915 device private data
138 *
139 * This function is called at the initialization stage, to balloon out the
140 * graphic address space allocated to other vGPUs, by marking these spaces as
141 * reserved. The ballooning related knowledge(starting address and size of
142 * the mappable/unmappable graphic memory) is described in the vgt_if structure
143 * in a reserved mmio range.
144 *
145 * To give an example, the drawing below depicts one typical scenario after
146 * ballooning. Here the vGPU1 has 2 pieces of graphic address spaces ballooned
147 * out each for the mappable and the non-mappable part. From the vGPU1 point of
148 * view, the total size is the same as the physical one, with the start address
149 * of its graphic space being zero. Yet there are some portions ballooned out(
150 * the shadow part, which are marked as reserved by drm allocator). From the
151 * host point of view, the graphic address space is partitioned by multiple
152 * vGPUs in different VMs. ::
153 *
154 * vGPU1 view Host view
155 * 0 ------> +-----------+ +-----------+
156 * ^ |###########| | vGPU3 |
157 * | |###########| +-----------+
158 * | |###########| | vGPU2 |
159 * | +-----------+ +-----------+
160 * mappable GM | available | ==> | vGPU1 |
161 * | +-----------+ +-----------+
162 * | |###########| | |
163 * v |###########| | Host |
164 * +=======+===========+ +===========+
165 * ^ |###########| | vGPU3 |
166 * | |###########| +-----------+
167 * | |###########| | vGPU2 |
168 * | +-----------+ +-----------+
169 * unmappable GM | available | ==> | vGPU1 |
170 * | +-----------+ +-----------+
171 * | |###########| | |
172 * | |###########| | Host |
173 * v |###########| | |
174 * total GM size ------> +-----------+ +-----------+
175 *
176 * Returns:
177 * zero on success, non-zero if configuration invalid or ballooning failed
178 */
intel_vgt_balloon(struct drm_i915_private * dev_priv)179 int intel_vgt_balloon(struct drm_i915_private *dev_priv)
180 {
181 struct i915_ggtt *ggtt = &dev_priv->ggtt;
182 unsigned long ggtt_end = ggtt->base.start + ggtt->base.total;
183
184 unsigned long mappable_base, mappable_size, mappable_end;
185 unsigned long unmappable_base, unmappable_size, unmappable_end;
186 int ret;
187
188 if (!intel_vgpu_active(dev_priv))
189 return 0;
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(dev_priv);
263 return ret;
264 }
265