[PATCH 4/6 (v2)] drm/amdgpu: Refuse to pin or change acceptable domains of prime BOs to VRAM. (v2)

[raof at ubuntu.com]

From: Christopher James Halse Rogers <christopher.halse.rogers at canonical.com>

Migration to VRAM will break the sharing, resulting in rendering on the exporting GPU never becoming
visible on the importing GPU.

v2: Don't pin BOs to GTT. Instead, refuse to migrate them out of GTT.

Signed-off-by: Christopher James Halse Rogers <christopher.halse.rogers at canonical.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c    | 5 +++++
 drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 4 ++++
 2 files changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
index 106cf83c2e6b..bc5356d0a13d 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
@@ -679,6 +679,11 @@ int amdgpu_gem_op_ioctl(struct drm_device *dev, void *data,
 		break;
 	}
 	case AMDGPU_GEM_OP_SET_PLACEMENT:
+		if (robj->prime_shared_count && (args->value & AMDGPU_GEM_DOMAIN_VRAM)) {
+			r = -EINVAL;
+			amdgpu_bo_unreserve(robj);
+			break;
+		}
 		if (amdgpu_ttm_tt_get_usermm(robj->tbo.ttm)) {
 			r = -EPERM;
 			amdgpu_bo_unreserve(robj);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index be80a4a68d7b..323580740a74 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -665,6 +665,10 @@ int amdgpu_bo_pin_restricted(struct amdgpu_bo *bo, u32 domain,
 	if (WARN_ON_ONCE(min_offset > max_offset))
 		return -EINVAL;
 
+	/* A shared bo cannot be migrated to VRAM */
+	if (bo->prime_shared_count && (domain == AMDGPU_GEM_DOMAIN_VRAM))
+		return -EINVAL;
+
 	if (bo->pin_count) {
 		uint32_t mem_type = bo->tbo.mem.mem_type;
 
-- 
2.11.0