drm/radeon: Fail fb creation from imported dma-bufs.

BugLink: http://bugs.launchpad.net/bugs/1764666

[ Upstream commit a294043b ]

Any use of the framebuffer will migrate it to VRAM, which is not sensible for
an imported dma-buf.

v2: Use DRM_DEBUG_KMS to prevent userspace accidentally spamming dmesg.
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christopher James Halse Rogers <christopher.halse.rogers@canonical.com>
CC: amd-gfx@lists.freedesktop.org
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

drivers/gpu/drm/radeon/radeon_display.c

@@ -1374,6 +1374,12 @@ radeon_user_framebuffer_create(struct drm_device *dev,
 		return ERR_PTR(-ENOENT);
 	}
 
+	/* Handle is imported dma-buf, so cannot be migrated to VRAM for scanout */
+	if (obj->import_attach) {
+		DRM_DEBUG_KMS("Cannot create framebuffer from imported dma_buf\n");
+		return ERR_PTR(-EINVAL);
+	}
+
 	radeon_fb = kzalloc(sizeof(*radeon_fb), GFP_KERNEL);
 	if (radeon_fb == NULL) {
 		drm_gem_object_unreference_unlocked(obj);