drm/nouveau/bar/gf100: ensure BAR is mapped

commit 12e08beb upstream.

If the BAR is zero size, it indicates it was never successfully mapped.
Ensure that the BAR is valid during initialization before attempting to
use it.
Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Sushma Kalakota <sushmax.kalakota@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/gpu/drm/nouveau/nvkm/subdev/bar/gf100.c

@@ -94,6 +94,8 @@ gf100_bar_oneinit_bar(struct gf100_bar *bar, struct gf100_barN *bar_vm,
 		return ret;
 
 	bar_len = device->func->resource_size(device, bar_nr);
+	if (!bar_len)
+		return -ENOMEM;
 	if (bar_nr == 3 && bar->bar2_halve)
 		bar_len >>= 1;