drm/radeon/kms: check if vm is supported in VA ioctl

Add a VM manager enabled field and use it to check if
vm is enabled.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: jglisse@redhat.com
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/radeon_gem.c b/drivers/gpu/drm/radeon/radeon_gem.c
index 003eeec..7337850 100644
--- a/drivers/gpu/drm/radeon/radeon_gem.c
+++ b/drivers/gpu/drm/radeon/radeon_gem.c
@@ -404,6 +404,11 @@
 	u32 invalid_flags;
 	int r = 0;
 
+	if (!rdev->vm_manager.enabled) {
+		args->operation = RADEON_VA_RESULT_ERROR;
+		return -ENOTTY;
+	}
+
 	/* !! DONT REMOVE !!
 	 * We don't support vm_id yet, to be sure we don't have have broken
 	 * userspace, reject anyone trying to use non 0 value thus moving