summaryrefslogtreecommitdiff
path: root/drivers/gpu/drm/i915/i915_vgpu.c
blob: 2e739018fb4c69581832d49800c5364d02160fb5 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
/*
 * Copyright(c) 2011-2015 Intel Corporation. All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include "intel_drv.h"
#include "i915_vgpu.h"

/**
 * DOC: Intel GVT-g guest support
 *
 * Intel GVT-g is a graphics virtualization technology which shares the
 * GPU among multiple virtual machines on a time-sharing basis. Each
 * virtual machine is presented a virtual GPU (vGPU), which has equivalent
 * features as the underlying physical GPU (pGPU), so i915 driver can run
 * seamlessly in a virtual machine. This file provides vGPU specific
 * optimizations when running in a virtual machine, to reduce the complexity
 * of vGPU emulation and to improve the overall performance.
 *
 * A primary function introduced here is so-called "address space ballooning"
 * technique. Intel GVT-g partitions global graphics memory among multiple VMs,
 * so each VM can directly access a portion of the memory without hypervisor's
 * intervention, e.g. filling textures or queuing commands. However with the
 * partitioning an unmodified i915 driver would assume a smaller graphics
 * memory starting from address ZERO, then requires vGPU emulation module to
 * translate the graphics address between 'guest view' and 'host view', for
 * all registers and command opcodes which contain a graphics memory address.
 * To reduce the complexity, Intel GVT-g introduces "address space ballooning",
 * by telling the exact partitioning knowledge to each guest i915 driver, which
 * then reserves and prevents non-allocated portions from allocation. Thus vGPU
 * emulation module only needs to scan and validate graphics addresses without
 * complexity of address translation.
 *
 */

/**
 * i915_check_vgpu - detect virtual GPU
 * @dev_priv: i915 device private
 *
 * This function is called at the initialization stage, to detect whether
 * running on a vGPU.
 */
void i915_check_vgpu(struct drm_i915_private *dev_priv)
{
	u64 magic;
	u16 version_major;

	BUILD_BUG_ON(sizeof(struct vgt_if) != VGT_PVINFO_SIZE);

	magic = __raw_i915_read64(dev_priv, vgtif_reg(magic));
	if (magic != VGT_MAGIC)
		return;

	version_major = __raw_i915_read16(dev_priv, vgtif_reg(version_major));
	if (version_major < VGT_VERSION_MAJOR) {
		DRM_INFO("VGT interface version mismatch!\n");
		return;
	}

	dev_priv->vgpu.active = true;
	DRM_INFO("Virtual GPU for Intel GVT-g detected.\n");
}

struct _balloon_info_ {
	/*
	 * There are up to 2 regions per mappable/unmappable graphic
	 * memory that might be ballooned. Here, index 0/1 is for mappable
	 * graphic memory, 2/3 for unmappable graphic memory.
	 */
	struct drm_mm_node space[4];
};

static struct _balloon_info_ bl_info;

/**
 * intel_vgt_deballoon - deballoon reserved graphics address trunks
 * @dev_priv: i915 device private data
 *
 * This function is called to deallocate the ballooned-out graphic memory, when
 * driver is unloaded or when ballooning fails.
 */
void intel_vgt_deballoon(struct drm_i915_private *dev_priv)
{
	int i;

	if (!intel_vgpu_active(dev_priv))
		return;

	DRM_DEBUG("VGT deballoon.\n");

	for (i = 0; i < 4; i++) {
		if (bl_info.space[i].allocated)
			drm_mm_remove_node(&bl_info.space[i]);
	}

	memset(&bl_info, 0, sizeof(bl_info));
}

static int vgt_balloon_space(struct i915_ggtt *ggtt,
			     struct drm_mm_node *node,
			     unsigned long start, unsigned long end)
{
	unsigned long size = end - start;

	if (start >= end)
		return -EINVAL;

	DRM_INFO("balloon space: range [ 0x%lx - 0x%lx ] %lu KiB.\n",
		 start, end, size / 1024);
	return i915_gem_gtt_reserve(&ggtt->base, node,
				    size, start, I915_COLOR_UNEVICTABLE,
				    0);
}

/**
 * intel_vgt_balloon - balloon out reserved graphics address trunks
 * @dev_priv: i915 device private data
 *
 * This function is called at the initialization stage, to balloon out the
 * graphic address space allocated to other vGPUs, by marking these spaces as
 * reserved. The ballooning related knowledge(starting address and size of
 * the mappable/unmappable graphic memory) is described in the vgt_if structure
 * in a reserved mmio range.
 *
 * To give an example, the drawing below depicts one typical scenario after
 * ballooning. Here the vGPU1 has 2 pieces of graphic address spaces ballooned
 * out each for the mappable and the non-mappable part. From the vGPU1 point of
 * view, the total size is the same as the physical one, with the start address
 * of its graphic space being zero. Yet there are some portions ballooned out(
 * the shadow part, which are marked as reserved by drm allocator). From the
 * host point of view, the graphic address space is partitioned by multiple
 * vGPUs in different VMs. ::
 *
 *                         vGPU1 view         Host view
 *              0 ------> +-----------+     +-----------+
 *                ^       |###########|     |   vGPU3   |
 *                |       |###########|     +-----------+
 *                |       |###########|     |   vGPU2   |
 *                |       +-----------+     +-----------+
 *         mappable GM    | available | ==> |   vGPU1   |
 *                |       +-----------+     +-----------+
 *                |       |###########|     |           |
 *                v       |###########|     |   Host    |
 *                +=======+===========+     +===========+
 *                ^       |###########|     |   vGPU3   |
 *                |       |###########|     +-----------+
 *                |       |###########|     |   vGPU2   |
 *                |       +-----------+     +-----------+
 *       unmappable GM    | available | ==> |   vGPU1   |
 *                |       +-----------+     +-----------+
 *                |       |###########|     |           |
 *                |       |###########|     |   Host    |
 *                v       |###########|     |           |
 *  total GM size ------> +-----------+     +-----------+
 *
 * Returns:
 * zero on success, non-zero if configuration invalid or ballooning failed
 */
int intel_vgt_balloon(struct drm_i915_private *dev_priv)
{
	struct i915_ggtt *ggtt = &dev_priv->ggtt;
	unsigned long ggtt_end = ggtt->base.total;

	unsigned long mappable_base, mappable_size, mappable_end;
	unsigned long unmappable_base, unmappable_size, unmappable_end;
	int ret;

	if (!intel_vgpu_active(dev_priv))
		return 0;

	mappable_base = I915_READ(vgtif_reg(avail_rs.mappable_gmadr.base));
	mappable_size = I915_READ(vgtif_reg(avail_rs.mappable_gmadr.size));
	unmappable_base = I915_READ(vgtif_reg(avail_rs.nonmappable_gmadr.base));
	unmappable_size = I915_READ(vgtif_reg(avail_rs.nonmappable_gmadr.size));

	mappable_end = mappable_base + mappable_size;
	unmappable_end = unmappable_base + unmappable_size;

	DRM_INFO("VGT ballooning configuration:\n");
	DRM_INFO("Mappable graphic memory: base 0x%lx size %ldKiB\n",
		 mappable_base, mappable_size / 1024);
	DRM_INFO("Unmappable graphic memory: base 0x%lx size %ldKiB\n",
		 unmappable_base, unmappable_size / 1024);

	if (mappable_end > ggtt->mappable_end ||
	    unmappable_base < ggtt->mappable_end ||
	    unmappable_end > ggtt_end) {
		DRM_ERROR("Invalid ballooning configuration!\n");
		return -EINVAL;
	}

	/* Unmappable graphic memory ballooning */
	if (unmappable_base > ggtt->mappable_end) {
		ret = vgt_balloon_space(ggtt, &bl_info.space[2],
					ggtt->mappable_end, unmappable_base);

		if (ret)
			goto err;
	}

	if (unmappable_end < ggtt_end) {
		ret = vgt_balloon_space(ggtt, &bl_info.space[3],
					unmappable_end, ggtt_end);
		if (ret)
			goto err;
	}

	/* Mappable graphic memory ballooning */
	if (mappable_base) {
		ret = vgt_balloon_space(ggtt, &bl_info.space[0],
					0, mappable_base);

		if (ret)
			goto err;
	}

	if (mappable_end < ggtt->mappable_end) {
		ret = vgt_balloon_space(ggtt, &bl_info.space[1],
					mappable_end, ggtt->mappable_end);

		if (ret)
			goto err;
	}

	DRM_INFO("VGT balloon successfully\n");
	return 0;

err:
	DRM_ERROR("VGT balloon fail\n");
	intel_vgt_deballoon(dev_priv);
	return ret;
}