drm/vmwgfx: Fix subresource updates with new contexts

The has_dx variable was only set during the initialization which
meant that UPDATE_SUBRESOURCE was never used. We were emulating it
with UPDATE_GB_IMAGE but that's always been a stop-gap. Instead
of has_dx which has been deprecated a long time ago we need to check
for whether shader model 4.0 or newer is available to the device.
Signed-off-by: Zack Rusin <zackr@vmware.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Reviewed-by: Martin Krastev <krastevm@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210609172307.131929-4-zackr@vmware.com

drivers/gpu/drm/vmwgfx/vmwgfx_surface.c

@@ -1872,7 +1872,6 @@ static void vmw_surface_dirty_range_add(struct vmw_resource *res, size_t start,
 static int vmw_surface_dirty_sync(struct vmw_resource *res)
 {
 	struct vmw_private *dev_priv = res->dev_priv;
-	bool has_dx = 0;
 	u32 i, num_dirty;
 	struct vmw_surface_dirty *dirty =
 		(struct vmw_surface_dirty *) res->dirty;
@@ -1899,7 +1898,7 @@ static int vmw_surface_dirty_sync(struct vmw_resource *res)
 	if (!num_dirty)
 		goto out;
 
-	alloc_size = num_dirty * ((has_dx) ? sizeof(*cmd1) : sizeof(*cmd2));
+	alloc_size = num_dirty * ((has_sm4_context(dev_priv)) ? sizeof(*cmd1) : sizeof(*cmd2));
 	cmd = VMW_CMD_RESERVE(dev_priv, alloc_size);
 	if (!cmd)
 		return -ENOMEM;
@@ -1917,7 +1916,7 @@ static int vmw_surface_dirty_sync(struct vmw_resource *res)
 		 * DX_UPDATE_SUBRESOURCE is aware of array surfaces.
 		 * UPDATE_GB_IMAGE is not.
 		 */
-		if (has_dx) {
+		if (has_sm4_context(dev_priv)) {
 			cmd1->header.id = SVGA_3D_CMD_DX_UPDATE_SUBRESOURCE;
 			cmd1->header.size = sizeof(cmd1->body);
 			cmd1->body.sid = res->id;