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Subject[PATCH 2/2] drm/msm: Add modparam to allow vram carveout
Date
Using the GPU with a VRAM Carveout is a security vulnerability.
Nevertheless it is sometimes required, especially when no IOMMU
implementation is available for a certain platform.

Signed-off-by: Iskren Chernev <iskren.chernev@gmail.com>
---
drivers/gpu/drm/msm/adreno/a2xx_gpu.c | 6 ++++--
drivers/gpu/drm/msm/adreno/a3xx_gpu.c | 6 ++++--
drivers/gpu/drm/msm/adreno/a4xx_gpu.c | 6 ++++--
drivers/gpu/drm/msm/adreno/adreno_device.c | 4 ++++
drivers/gpu/drm/msm/adreno/adreno_gpu.h | 1 +
5 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a2xx_gpu.c b/drivers/gpu/drm/msm/adreno/a2xx_gpu.c
index 7e82c41a85f1a..bdc989183c648 100644
--- a/drivers/gpu/drm/msm/adreno/a2xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a2xx_gpu.c
@@ -534,8 +534,10 @@ struct msm_gpu *a2xx_gpu_init(struct drm_device *dev)

if (!gpu->aspace) {
dev_err(dev->dev, "No memory protection without MMU\n");
- ret = -ENXIO;
- goto fail;
+ if (!allow_vram_carveout) {
+ ret = -ENXIO;
+ goto fail;
+ }
}

return gpu;
diff --git a/drivers/gpu/drm/msm/adreno/a3xx_gpu.c b/drivers/gpu/drm/msm/adreno/a3xx_gpu.c
index 93da6683a8661..4534633fe7cdb 100644
--- a/drivers/gpu/drm/msm/adreno/a3xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a3xx_gpu.c
@@ -564,8 +564,10 @@ struct msm_gpu *a3xx_gpu_init(struct drm_device *dev)
* implement a cmdstream validator.
*/
DRM_DEV_ERROR(dev->dev, "No memory protection without IOMMU\n");
- ret = -ENXIO;
- goto fail;
+ if (!allow_vram_carveout) {
+ ret = -ENXIO;
+ goto fail;
+ }
}

icc_path = devm_of_icc_get(&pdev->dev, "gfx-mem");
diff --git a/drivers/gpu/drm/msm/adreno/a4xx_gpu.c b/drivers/gpu/drm/msm/adreno/a4xx_gpu.c
index c0be3a0f36b2c..82bebb40234de 100644
--- a/drivers/gpu/drm/msm/adreno/a4xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a4xx_gpu.c
@@ -692,8 +692,10 @@ struct msm_gpu *a4xx_gpu_init(struct drm_device *dev)
* implement a cmdstream validator.
*/
DRM_DEV_ERROR(dev->dev, "No memory protection without IOMMU\n");
- ret = -ENXIO;
- goto fail;
+ if (!allow_vram_carveout) {
+ ret = -ENXIO;
+ goto fail;
+ }
}

icc_path = devm_of_icc_get(&pdev->dev, "gfx-mem");
diff --git a/drivers/gpu/drm/msm/adreno/adreno_device.c b/drivers/gpu/drm/msm/adreno/adreno_device.c
index 87c8b033ad1a6..12e75ba360f95 100644
--- a/drivers/gpu/drm/msm/adreno/adreno_device.c
+++ b/drivers/gpu/drm/msm/adreno/adreno_device.c
@@ -18,6 +18,10 @@ bool snapshot_debugbus = false;
MODULE_PARM_DESC(snapshot_debugbus, "Include debugbus sections in GPU devcoredump (if not fused off)");
module_param_named(snapshot_debugbus, snapshot_debugbus, bool, 0600);

+bool allow_vram_carveout = false;
+MODULE_PARM_DESC(allow_vram_carveout, "Allow using VRAM Carveout, in place of IOMMU");
+module_param_named(allow_vram_carveout, allow_vram_carveout, bool, 0600);
+
static const struct adreno_info gpulist[] = {
{
.rev = ADRENO_REV(2, 0, 0, 0),
diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.h b/drivers/gpu/drm/msm/adreno/adreno_gpu.h
index c3775f79525a7..fe5444a1482ae 100644
--- a/drivers/gpu/drm/msm/adreno/adreno_gpu.h
+++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.h
@@ -18,6 +18,7 @@
#include "adreno_pm4.xml.h"

extern bool snapshot_debugbus;
+extern bool allow_vram_carveout;

enum {
ADRENO_FW_PM4 = 0,
--
2.29.2
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