The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 059a49aa2e25c58f90b50151f109dd3c4cdb3a47 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024041414-humming-alarm-eb41@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:

059a49aa2e25 ("virtio_net: Do not send RSS key if it is not supported") fb6e30a72539 ("net: ethtool: pass a pointer to parameters to get/set_rxfh ethtool ops") 02cbfba1add5 ("idpf: add ethtool callbacks") a5ab9ee0df0b ("idpf: add singleq start_xmit and napi poll") 3a8845af66ed ("idpf: add RX splitq napi poll support") c2d548cad150 ("idpf: add TX splitq napi poll support") 6818c4d5b3c2 ("idpf: add splitq start_xmit") d4d558718266 ("idpf: initialize interrupts and enable vport") 95af467d9a4e ("idpf: configure resources for RX queues") 1c325aac10a8 ("idpf: configure resources for TX queues") ce1b75d0635c ("idpf: add ptypes and MAC filter support") 0fe45467a104 ("idpf: add create vport and netdev configuration") 4930fbf419a7 ("idpf: add core init and interrupt request") 8077c727561a ("idpf: add controlq init and reset checks") e850efed5e15 ("idpf: add module register and probe functionality") b9335a757232 ("net/mlx5e: Make flow classification filters static") 4cab498f33f7 ("hv_netvsc: Allocate rx indirection table size dynamically") 4f3ed1293feb ("ixgbe: Allow flow hash to be set via ethtool") 2b30f8291a30 ("net: ethtool: add support for MAC Merge layer") 8580e16c28f3 ("net/ethtool: add netlink interface for the PLCA RS")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 059a49aa2e25c58f90b50151f109dd3c4cdb3a47 Mon Sep 17 00:00:00 2001 From: Breno Leitao leitao@debian.org Date: Wed, 3 Apr 2024 08:43:12 -0700 Subject: [PATCH] virtio_net: Do not send RSS key if it is not supported

There is a bug when setting the RSS options in virtio_net that can break the whole machine, getting the kernel into an infinite loop.

Running the following command in any QEMU virtual machine with virtionet will reproduce this problem:

# ethtool -X eth0 hfunc toeplitz

This is how the problem happens:

1) ethtool_set_rxfh() calls virtnet_set_rxfh()

2) virtnet_set_rxfh() calls virtnet_commit_rss_command()

3) virtnet_commit_rss_command() populates 4 entries for the rss scatter-gather

4) Since the command above does not have a key, then the last scatter-gatter entry will be zeroed, since rss_key_size == 0. sg_buf_size = vi->rss_key_size;

5) This buffer is passed to qemu, but qemu is not happy with a buffer with zero length, and do the following in virtqueue_map_desc() (QEMU function):

if (!sz) { virtio_error(vdev, "virtio: zero sized buffers are not allowed");

6) virtio_error() (also QEMU function) set the device as broken

vdev->broken = true;

7) Qemu bails out, and do not repond this crazy kernel.

8) The kernel is waiting for the response to come back (function virtnet_send_command())

9) The kernel is waiting doing the following :

while (!virtqueue_get_buf(vi->cvq, &tmp) && !virtqueue_is_broken(vi->cvq)) cpu_relax();

10) None of the following functions above is true, thus, the kernel loops here forever. Keeping in mind that virtqueue_is_broken() does not look at the qemu `vdev->broken`, so, it never realizes that the vitio is broken at QEMU side.

Fix it by not sending RSS commands if the feature is not available in the device.

Fixes: c7114b1249fa ("drivers/net/virtio_net: Added basic RSS support.") Cc: stable@vger.kernel.org Cc: qemu-devel@nongnu.org Signed-off-by: Breno Leitao leitao@debian.org Reviewed-by: Heng Qi hengqi@linux.alibaba.com Reviewed-by: Xuan Zhuo xuanzhuo@linux.alibaba.com Signed-off-by: David S. Miller davem@davemloft.net

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index c22d1118a133..115c3c5414f2 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -3807,6 +3807,7 @@ static int virtnet_set_rxfh(struct net_device *dev, struct netlink_ext_ack *extack) { struct virtnet_info *vi = netdev_priv(dev); + bool update = false; int i;

if (rxfh->hfunc != ETH_RSS_HASH_NO_CHANGE && @@ -3814,13 +3815,28 @@ static int virtnet_set_rxfh(struct net_device *dev, return -EOPNOTSUPP;

if (rxfh->indir) { + if (!vi->has_rss) + return -EOPNOTSUPP; + for (i = 0; i < vi->rss_indir_table_size; ++i) vi->ctrl->rss.indirection_table[i] = rxfh->indir[i]; + update = true; } - if (rxfh->key) - memcpy(vi->ctrl->rss.key, rxfh->key, vi->rss_key_size);

- virtnet_commit_rss_command(vi); + if (rxfh->key) { + /* If either _F_HASH_REPORT or _F_RSS are negotiated, the + * device provides hash calculation capabilities, that is, + * hash_key is configured. + */ + if (!vi->has_rss && !vi->has_rss_hash_report) + return -EOPNOTSUPP; + + memcpy(vi->ctrl->rss.key, rxfh->key, vi->rss_key_size); + update = true; + } + + if (update) + virtnet_commit_rss_command(vi);

return 0; } @@ -4729,13 +4745,15 @@ static int virtnet_probe(struct virtio_device *vdev) if (virtio_has_feature(vdev, VIRTIO_NET_F_HASH_REPORT)) vi->has_rss_hash_report = true;

- if (virtio_has_feature(vdev, VIRTIO_NET_F_RSS)) + if (virtio_has_feature(vdev, VIRTIO_NET_F_RSS)) { vi->has_rss = true;

- if (vi->has_rss || vi->has_rss_hash_report) { vi->rss_indir_table_size = virtio_cread16(vdev, offsetof(struct virtio_net_config, rss_max_indirection_table_length)); + } + + if (vi->has_rss || vi->has_rss_hash_report) { vi->rss_key_size = virtio_cread8(vdev, offsetof(struct virtio_net_config, rss_max_key_size));