From 3bc06da858ef17cfe94b49efc0d9713727012835 Mon Sep 17 00:00:00 2001 From: Brett Creeley Date: Thu, 16 Apr 2026 14:21:21 -0700 Subject: [PATCH] virtio_net: sync rss_trailer.max_tx_vq on queue_pairs change via VQ_PAIRS_SET When netif_is_rxfh_configured() is true (i.e., the user has explicitly configured the RSS indirection table), virtnet_set_queues() skips the RSS update path and falls through to the VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET command to change the number of queue pairs. However, it does not update vi->rss_trailer.max_tx_vq to reflect the new queue_pairs value. This causes a mismatch between vi->curr_queue_pairs and vi->rss_trailer.max_tx_vq. Any subsequent RSS reconfiguration (e.g., via ethtool -X) calls virtnet_commit_rss_command(), which sends the stale max_tx_vq to the device, silently reverting the queue count. Reproduction: 1. User configured RSS ethtool -X eth0 equal 8 2. VQ_PAIRS_SET path; max_tx_vq stays 16 ethtool -L eth0 combined 12 3. RSS commit uses max_tx_vq=16 instead of 12 ethtool -X eth0 equal 4 Fix this by updating vi->rss_trailer.max_tx_vq after a successful VQ_PAIRS_SET command when RSS is enabled, keeping it in sync with curr_queue_pairs. Fixes: 50bfcaedd78e ("virtio_net: Update rss when set queue") Signed-off-by: Brett Creeley Acked-by: Michael S. Tsirkin Link: https://patch.msgid.link/20260416212121.29073-1-brett.creeley@amd.com Signed-off-by: Jakub Kicinski --- drivers/net/virtio_net.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index bfb566fecb92..f4adcfee7a80 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -3759,6 +3759,12 @@ static int virtnet_set_queues(struct virtnet_info *vi, u16 queue_pairs) queue_pairs); return -EINVAL; } + + /* Keep max_tx_vq in sync so that a later RSS command does not + * revert queue_pairs to a stale value. + */ + if (vi->has_rss) + vi->rss_trailer.max_tx_vq = cpu_to_le16(queue_pairs); succ: vi->curr_queue_pairs = queue_pairs; if (dev->flags & IFF_UP) {