Michael S. Tsirkin
2023-Aug-10 08:51 UTC
[PATCH] virtio-net: Zero max_tx_vq field for VIRTIO_NET_CTRL_MQ_HASH_CONFIG case
On Thu, Aug 10, 2023 at 11:15:57AM +0800, Hawkins Jiawei wrote:> Kernel uses `struct virtio_net_ctrl_rss` to save command-specific-data > for both the VIRTIO_NET_CTRL_MQ_HASH_CONFIG and > VIRTIO_NET_CTRL_MQ_RSS_CONFIG commands. > > According to the VirtIO standard, "Field reserved MUST contain zeroes. > It is defined to make the structure to match the layout of > virtio_net_rss_config structure, defined in 5.1.6.5.7.". > > Yet for the VIRTIO_NET_CTRL_MQ_HASH_CONFIG command case, the `max_tx_vq` > field in struct virtio_net_ctrl_rss, which corresponds to the > `reserved` field in struct virtio_net_hash_config, is not zeroed, > thereby violating the VirtIO standard. > > This patch solves this problem by zeroing this field in > virtnet_init_default_rss(). > > Signed-off-by: Hawkins Jiawei <yin31149 at gmail.com>Fixes: c7114b1249fa ("drivers/net/virtio_net: Added basic RSS support.") Cc: Andrew Melnychenko <andrew at daynix.com> Acked-by: Michael S. Tsirkin <mst at redhat.com> And this is stable material I believe.> --- > > TestStep > =======> 1. Boot QEMU with one virtio-net-pci net device with `mq` and `hash` > feature on, command line like: > -netdev tap,vhost=off,... > -device virtio-net-pci,mq=on,hash=on,... > > 2. Trigger VIRTIO_NET_CTRL_MQ_HASH_CONFIG command in guest, command > line like: > ethtool -K eth0 rxhash on > > Without this patch, in virtnet_commit_rss_command(), we can see the > `max_tx_vq` field is 1 in gdb like below: > > pwndbg> p vi->ctrl->rss > $1 = { > hash_types = 63, > indirection_table_mask = 0, > unclassified_queue = 0, > indirection_table = {0 <repeats 128 times>}, > max_tx_vq = 1, > hash_key_length = 40 '(', > ... > } > > With this patch, in virtnet_commit_rss_command(), we can see the > `max_tx_vq` field is 0 in gdb like below: > > pwndbg> p vi->ctrl->rss > $1 = { > hash_types = 63, > indirection_table_mask = 0, > unclassified_queue = 0, > indirection_table = {0 <repeats 128 times>}, > max_tx_vq = 0, > hash_key_length = 40 '(', > ... > } > > drivers/net/virtio_net.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 1270c8d23463..8db38634ae82 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -2761,7 +2761,7 @@ static void virtnet_init_default_rss(struct virtnet_info *vi) > vi->ctrl->rss.indirection_table[i] = indir_val; > } > > - vi->ctrl->rss.max_tx_vq = vi->curr_queue_pairs; > + vi->ctrl->rss.max_tx_vq = vi->has_rss ? vi->curr_queue_pairs : 0; > vi->ctrl->rss.hash_key_length = vi->rss_key_size; > > netdev_rss_key_fill(vi->ctrl->rss.key, vi->rss_key_size); > -- > 2.34.1