Release 4.7 drivers/gpu/drm/i915/i915_vgpu.c
/*
* 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: drm device *
*
* This function is called at the initialization stage, to detect whether
* running on a vGPU.
*/
void i915_check_vgpu(struct drm_device *dev)
{
struct drm_i915_private *dev_priv = to_i915(dev);
uint64_t magic;
uint32_t version;
BUILD_BUG_ON(sizeof(struct vgt_if) != VGT_PVINFO_SIZE);
if (!IS_HASWELL(dev))
return;
magic = __raw_i915_read64(dev_priv, vgtif_reg(magic));
if (magic != VGT_MAGIC)
return;
version = INTEL_VGT_IF_VERSION_ENCODE(
__raw_i915_read16(dev_priv, vgtif_reg(version_major)),
__raw_i915_read16(dev_priv, vgtif_reg(version_minor)));
if (version != INTEL_VGT_IF_VERSION) {
DRM_INFO("VGT interface version mismatch!\n");
return;
}
dev_priv->vgpu.active = true;
DRM_INFO("Virtual GPU for Intel GVT-g detected.\n");
}
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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
*
* This function is called to deallocate the ballooned-out graphic memory, when
* driver is unloaded or when ballooning fails.
*/
void intel_vgt_deballoon(void)
{
int i;
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));
}
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static int vgt_balloon_space(struct drm_mm *mm,
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);
node->start = start;
node->size = size;
return drm_mm_reserve_node(mm, node);
}
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/**
* intel_vgt_balloon - balloon out reserved graphics address trunks
* @dev: drm device
*
* 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_device *dev)
{
struct drm_i915_private *dev_priv = to_i915(dev);
struct i915_ggtt *ggtt = &dev_priv->ggtt;
unsigned long ggtt_end = ggtt->base.start + ggtt->base.total;
unsigned long mappable_base, mappable_size, mappable_end;
unsigned long unmappable_base, unmappable_size, unmappable_end;
int ret;
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_base < ggtt->base.start ||
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->base.mm,
&bl_info.space[2],
ggtt->mappable_end,
unmappable_base);
if (ret)
goto err;
}
/*
* No need to partition out the last physical page,
* because it is reserved to the guard page.
*/
if (unmappable_end < ggtt_end - PAGE_SIZE) {
ret = vgt_balloon_space(&ggtt->base.mm,
&bl_info.space[3],
unmappable_end,
ggtt_end - PAGE_SIZE);
if (ret)
goto err;
}
/* Mappable graphic memory ballooning */
if (mappable_base > ggtt->base.start) {
ret = vgt_balloon_space(&ggtt->base.mm,
&bl_info.space[0],
ggtt->base.start, mappable_base);
if (ret)
goto err;
}
if (mappable_end < ggtt->mappable_end) {
ret = vgt_balloon_space(&ggtt->base.mm,
&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();
return ret;
}
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