Linux Virtualization - Feb 2020 - [PATCH] drm/virtio: fix error check

The >= compare op must happen in cpu byte order, doing it in
little endian fails on big endian machines like s390.

Reported-by: Sebastian Mitterle <smitterl at redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel at redhat.com>
---
 drivers/gpu/drm/virtio/virtgpu_vq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c
b/drivers/gpu/drm/virtio/virtgpu_vq.c
index cfe9c54f87a3..67caecde623e 100644
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c
+++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
@@ -222,7 +222,7 @@ void virtio_gpu_dequeue_ctrl_func(struct work_struct *work)
 		trace_virtio_gpu_cmd_response(vgdev->ctrlq.vq, resp);
 
 		if (resp->type != cpu_to_le32(VIRTIO_GPU_RESP_OK_NODATA)) {
-			if (resp->type >= cpu_to_le32(VIRTIO_GPU_RESP_ERR_UNSPEC)) {
+			if (le32_to_cpu(resp->type) >= VIRTIO_GPU_RESP_ERR_UNSPEC) {
 				struct virtio_gpu_ctrl_hdr *cmd;
 				cmd = virtio_gpu_vbuf_ctrl_hdr(entry);
 				DRM_ERROR_RATELIMITED("response 0x%x (command 0x%x)\n",
-- 
2.18.2

On Fri, 14 Feb 2020 09:01:00 +0100
Gerd Hoffmann <kraxel at redhat.com> wrote:
> The >= compare op must happen in cpu byte order, doing it in
> little endian fails on big endian machines like s390.
> 
> Reported-by: Sebastian Mitterle <smitterl at redhat.com>
> Signed-off-by: Gerd Hoffmann <kraxel at redhat.com>
> ---
>  drivers/gpu/drm/virtio/virtgpu_vq.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c
b/drivers/gpu/drm/virtio/virtgpu_vq.c
> index cfe9c54f87a3..67caecde623e 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_vq.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
> @@ -222,7 +222,7 @@ void virtio_gpu_dequeue_ctrl_func(struct work_struct
*work)
>  		trace_virtio_gpu_cmd_response(vgdev->ctrlq.vq, resp);
>  
>  		if (resp->type != cpu_to_le32(VIRTIO_GPU_RESP_OK_NODATA)) {
> -			if (resp->type >= cpu_to_le32(VIRTIO_GPU_RESP_ERR_UNSPEC)) {
> +			if (le32_to_cpu(resp->type) >= VIRTIO_GPU_RESP_ERR_UNSPEC) {
>  				struct virtio_gpu_ctrl_hdr *cmd;
>  				cmd = virtio_gpu_vbuf_ctrl_hdr(entry);
>  				DRM_ERROR_RATELIMITED("response 0x%x (command 0x%x)\n",
Reviewed-by: Cornelia Huck <cohuck at redhat.com>

Endianness continues to be fun.