Maximum value for tx_queue_size depends on the backend type.
1024 for vDPA/vhost-user, 256 for all the others.
The value is returned by virtio_net_max_tx_queue_size() to set the
parameter:
n->net_conf.tx_queue_size = MIN(virtio_net_max_tx_queue_size(n),
n->net_conf.tx_queue_size);
But the parameter checking uses VIRTQUEUE_MAX_SIZE (1024).
So the parameter is silently ignored and ethtool reports a different
value than the one provided by the user.
... -netdev tap,... -device virtio-net,tx_queue_size=1024
# ethtool -g enp0s2
Ring parameters for enp0s2:
Pre-set maximums:
RX: 256
RX Mini: n/a
RX Jumbo: n/a
TX: 256
Current hardware settings:
RX: 256
RX Mini: n/a
RX Jumbo: n/a
TX: 256
... -netdev vhost-user,... -device virtio-net,tx_queue_size=2048
Invalid tx_queue_size (= 2048), must be a power of 2 between 256 and 1024
With this patch the correct maximum value is checked and displayed.
For vDPA/vhost-user:
Invalid tx_queue_size (= 2048), must be a power of 2 between 256 and 1024
For all the others:
Invalid tx_queue_size (= 512), must be a power of 2 between 256 and 256
Fixes: 2eef278b9e63 ("virtio-net: fix tx queue size for !vhost-user")
Cc: mst@redhat.com
Cc: qemu-stable@nongnu.org
Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
4271f40383