drm/nouveau/gem: return only valid domain when there's only one

On nv50+, we restrict the valid domains to just the one where the buffer
was originally created. However after the buffer is evicted to system
memory, we might move it back to a different domain that was not
originally valid. When sharing the buffer and retrieving its GEM_INFO
data, we still want the domain that will be valid for this buffer in a
pushbuf, not the one where it currently happens to be.

This resolves fdo#92504 and several others. These are due to suspend
evicting all buffers, making it more likely that they temporarily end up
in the wrong place.

Cc: stable@vger.kernel.org
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92504
Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_gem.c

@@ -227,11 +227,12 @@ nouveau_gem_info(struct drm_file *file_priv, struct drm_gem_object *gem,
 	struct nouveau_bo *nvbo = nouveau_gem_object(gem);
 	struct nvkm_vma *vma;
 
-	if (nvbo->bo.mem.mem_type == TTM_PL_TT)
+	if (is_power_of_2(nvbo->valid_domains))
+		rep->domain = nvbo->valid_domains;
+	else if (nvbo->bo.mem.mem_type == TTM_PL_TT)
 		rep->domain = NOUVEAU_GEM_DOMAIN_GART;
 	else
 		rep->domain = NOUVEAU_GEM_DOMAIN_VRAM;
-
 	rep->offset = nvbo->bo.offset;
 	if (cli->vm) {
 		vma = nouveau_bo_vma_find(nvbo, cli->vm);