On 2025/06/15 7:44, Konstantin Shkolnyy wrote:
After commit 0caed25cd171 vhost_vdpa_net_load_vlan() started seeing
VIRTIO_NET_F_CTRL_VLAN flag and making 4096 calls to the kernel with
VIRTIO_NET_CTRL_VLAN_ADD command. However, it forgot to convert the
16-bit VLAN IDs to LE format. On BE machine, the kernel calls failed
when they saw "VLAN IDs" greater than 4095, and QEMU then said:
"unable to start vhost net: 5: falling back on userspace virtio", and
VDPA became disabled.
Please add the Fixes: tag to refer the commit; see:
docs/devel/submitting-a-patch.rst
Convert the VLAN ID to LE before putting it into virtio queue.
Signed-off-by: Konstantin Shkolnyy <k...@linux.ibm.com>
---
net/vhost-vdpa.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index 58d738945d..99c9eb42b9 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -1173,9 +1173,10 @@ static int
vhost_vdpa_net_load_single_vlan(VhostVDPAState *s,
struct iovec *in_cursor,
uint16_t vid)
{
+ __le16 vid_le = cpu_to_le16(vid);
docs/devel/style.rst says:
Don't use Linux kernel internal types like u32, __u32 or __le32.
It's unfortunate that QEMU lacks endian types and a checker for them;
such a checker could not have caught this particular case, but can catch
other similar bugs.
Regards,
Akihiko Odaki
const struct iovec data = {
- .iov_base = &vid,
- .iov_len = sizeof(vid),
+ .iov_base = &vid_le,
+ .iov_len = sizeof(vid_le),
};
ssize_t r = vhost_vdpa_net_load_cmd(s, out_cursor, in_cursor,
VIRTIO_NET_CTRL_VLAN,
