drm/vmwgfx: Fix vmw_du_get_cursor_mob fencing of newly-created MOBs

The fencing of MOB creation used in vmw_du_get_cursor_mob was incompatible
with register-based device communication employed by this routine. As a
result cursor MOB creation was racy, leading to potentially broken/missing
mouse cursor on desktops using CursorMob device feature.

Fixes: 53bc3f6f ("drm/vmwgfx: Clean up cursor mobs")
Signed-off-by: Martin Krastev <martin.krastev@broadcom.com>
Reviewed-by: Maaz Mombasawala <maaz.mombasawala@broadcom.com>
Reviewed-by: Zack Rusin <zack.rusin@broadcom.com>
Signed-off-by: Zack Rusin <zack.rusin@broadcom.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240126200804.732454-5-zack.rusin@broadcom.com

drivers/gpu/drm/vmwgfx/vmwgfx_kms.c

@@ -273,6 +273,7 @@ static int vmw_du_get_cursor_mob(struct vmw_cursor_plane *vcp,
 	u32 size = vmw_du_cursor_mob_size(vps->base.crtc_w, vps->base.crtc_h);
 	u32 i;
 	u32 cursor_max_dim, mob_max_size;
+	struct vmw_fence_obj *fence = NULL;
 	int ret;
 
 	if (!dev_priv->has_mob ||
@@ -314,7 +315,15 @@ static int vmw_du_get_cursor_mob(struct vmw_cursor_plane *vcp,
 	if (ret != 0)
 		goto teardown;
 
-	vmw_bo_fence_single(&vps->cursor.bo->tbo, NULL);
+	ret = vmw_execbuf_fence_commands(NULL, dev_priv, &fence, NULL);
+	if (ret != 0) {
+		ttm_bo_unreserve(&vps->cursor.bo->tbo);
+		goto teardown;
+	}
+
+	dma_fence_wait(&fence->base, false);
+	dma_fence_put(&fence->base);
+
 	ttm_bo_unreserve(&vps->cursor.bo->tbo);
 	return 0;