[PATCH 7/7 v2] drm/radeon: Refuse to migrate a prime BO to VRAM. (v2)

[raof at ubuntu.com]

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

BOs shared via dma-buf, either imported or exported, cannot sensibly be migrated to VRAM
without breaking the dma-buf sharing. Refuse userspace requests to migrate to VRAM,
ensure such BOs are not migrated during command submission, and refuse to pin them
to VRAM.

v2: Don't pin BOs in GTT. Instead, refuse to migrate BOs to VRAM.

Signed-off-by: Christopher James Halse Rogers <christopher.halse.rogers at canonical.com>
---
 drivers/gpu/drm/radeon/radeon_cs.c     | 10 ++++++++++
 drivers/gpu/drm/radeon/radeon_gem.c    |  4 ++++
 drivers/gpu/drm/radeon/radeon_object.c |  5 +++++
 3 files changed, 19 insertions(+)

diff --git a/drivers/gpu/drm/radeon/radeon_cs.c b/drivers/gpu/drm/radeon/radeon_cs.c
index a8442f7196d6..df6b58c08544 100644
--- a/drivers/gpu/drm/radeon/radeon_cs.c
+++ b/drivers/gpu/drm/radeon/radeon_cs.c
@@ -164,6 +164,16 @@ static int radeon_cs_parser_relocs(struct radeon_cs_parser *p)
 			p->relocs[i].allowed_domains = domain;
 		}
 
+		/* Objects shared as dma-bufs cannot be moved to VRAM */
+		if (p->relocs[i].robj->prime_shared_count) {
+			p->relocs[i].allowed_domains &= ~RADEON_GEM_DOMAIN_VRAM;
+			if (!p->relocs[i].allowed_domains) {
+				DRM_ERROR("BO associated with dma-buf cannot "
+					  "be moved to VRAM\n");
+				return -EINVAL;
+			}
+		}
+
 		p->relocs[i].tv.bo = &p->relocs[i].robj->tbo;
 		p->relocs[i].tv.shared = !r->write_domain;
 
diff --git a/drivers/gpu/drm/radeon/radeon_gem.c b/drivers/gpu/drm/radeon/radeon_gem.c
index 96683f5b2b1b..067ea7d7658a 100644
--- a/drivers/gpu/drm/radeon/radeon_gem.c
+++ b/drivers/gpu/drm/radeon/radeon_gem.c
@@ -120,6 +120,10 @@ static int radeon_gem_set_domain(struct drm_gem_object *gobj,
 			return r;
 		}
 	}
+	if (domain == RADEON_GEM_DOMAIN_VRAM && robj->prime_shared_count) {
+		/* A BO that is associated with a dma-buf cannot be sensibly migrated to VRAM */
+		return -EINVAL;
+	}
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/radeon/radeon_object.c b/drivers/gpu/drm/radeon/radeon_object.c
index 74b276060c20..bec2ec056de4 100644
--- a/drivers/gpu/drm/radeon/radeon_object.c
+++ b/drivers/gpu/drm/radeon/radeon_object.c
@@ -352,6 +352,11 @@ int radeon_bo_pin_restricted(struct radeon_bo *bo, u32 domain, u64 max_offset,
 
 		return 0;
 	}
+	if (bo->prime_shared_count && domain == RADEON_GEM_DOMAIN_VRAM) {
+		/* A BO shared as a dma-buf cannot be sensibly migrated to VRAM */
+		return -EINVAL;
+	}
+
 	radeon_ttm_placement_from_domain(bo, domain);
 	for (i = 0; i < bo->placement.num_placement; i++) {
 		/* force to pin into visible video ram */
-- 
2.11.0