diff options
| author | Boris Brezillon <boris.brezillon@collabora.com> | 2025-11-07 18:12:14 +0100 |
|---|---|---|
| committer | Steven Price <steven.price@arm.com> | 2025-11-10 14:56:06 +0000 |
| commit | 576c930e5e7dcb937648490611a83f1bf0171048 (patch) | |
| tree | ef6a703e49d2a5b99ea030a96fb0fd601ae14cd5 | |
| parent | eef295a8508202e750e4f103a97447f3c9d5e3d0 (diff) | |
drm/panthor: Flush shmem writes before mapping buffers CPU-uncached
The shmem layer zeroes out the new pages using cached mappings, and if
we don't CPU-flush we might leave dirty cachelines behind, leading to
potential data leaks and/or asynchronous buffer corruption when dirty
cachelines are evicted.
Fixes: 8a1cc07578bf ("drm/panthor: Add GEM logical block")
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Link: https://patch.msgid.link/20251107171214.1186299-1-boris.brezillon@collabora.com
| -rw-r--r-- | drivers/gpu/drm/panthor/panthor_gem.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c index 156c7a0b62a2..3f43686f0195 100644 --- a/drivers/gpu/drm/panthor/panthor_gem.c +++ b/drivers/gpu/drm/panthor/panthor_gem.c @@ -288,6 +288,23 @@ panthor_gem_create_with_handle(struct drm_file *file, panthor_gem_debugfs_set_usage_flags(bo, 0); + /* If this is a write-combine mapping, we query the sgt to force a CPU + * cache flush (dma_map_sgtable() is called when the sgt is created). + * This ensures the zero-ing is visible to any uncached mapping created + * by vmap/mmap. + * FIXME: Ideally this should be done when pages are allocated, not at + * BO creation time. + */ + if (shmem->map_wc) { + struct sg_table *sgt; + + sgt = drm_gem_shmem_get_pages_sgt(shmem); + if (IS_ERR(sgt)) { + ret = PTR_ERR(sgt); + goto out_put_gem; + } + } + /* * Allocate an id of idr table where the obj is registered * and handle has the id what user can see. @@ -296,6 +313,7 @@ panthor_gem_create_with_handle(struct drm_file *file, if (!ret) *size = bo->base.base.size; +out_put_gem: /* drop reference from allocate - handle holds it now. */ drm_gem_object_put(&shmem->base); |