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virtio_net: clamp rss_max_key_size to NETDEV_RSS_KEY_LEN

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rss_max_key_size in the virtio spec is the maximum key size supported by
the device, not a mandatory size the driver must use. Also the value 40
is a spec minimum, not a spec maximum.

The current code rejects RSS and can fail probe when the device reports a
larger rss_max_key_size than the driver buffer limit. Instead, clamp the
effective key length to min(device rss_max_key_size, NETDEV_RSS_KEY_LEN)
and keep RSS enabled.

This keeps probe working on devices that advertise larger maximum key sizes
while respecting the netdev RSS key buffer size limit.

Fixes: 3f7d9c1964 ("virtio_net: Add hash_key_length check")
Cc: stable@vger.kernel.org
Signed-off-by: Srujana Challa <schalla@marvell.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Link: https://patch.msgid.link/20260326142344.1171317-1-schalla@marvell.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Srujana Challa
2026-03-26 19:53:44 +05:30
committed by Jakub Kicinski
parent d64cb81dcb
commit b4e5f04c58
1 changed files with 9 additions and 11 deletions
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20
drivers/net/virtio_net.c
View File

@@ -381,8 +381,6 @@ struct receive_queue {
struct xdp_buff **xsk_buffs;
};
#define VIRTIO_NET_RSS_MAX_KEY_SIZE 40
/* Control VQ buffers: protected by the rtnl lock */
struct control_buf {
struct virtio_net_ctrl_hdr hdr;
@@ -486,7 +484,7 @@ struct virtnet_info {
/* Must be last as it ends in a flexible-array member. */
TRAILING_OVERLAP(struct virtio_net_rss_config_trailer, rss_trailer, hash_key_data,
u8 rss_hash_key_data[VIRTIO_NET_RSS_MAX_KEY_SIZE];
u8 rss_hash_key_data[NETDEV_RSS_KEY_LEN];
);
};
static_assert(offsetof(struct virtnet_info, rss_trailer.hash_key_data) ==
@@ -6708,6 +6706,7 @@ static int virtnet_probe(struct virtio_device *vdev)
struct virtnet_info *vi;
u16 max_queue_pairs;
int mtu = 0;
u16 key_sz;
/* Find if host supports multiqueue/rss virtio_net device */
max_queue_pairs = 1;
@@ -6842,14 +6841,13 @@ static int virtnet_probe(struct virtio_device *vdev)
}
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));
if (vi->rss_key_size > VIRTIO_NET_RSS_MAX_KEY_SIZE) {
dev_err(&vdev->dev, "rss_max_key_size=%u exceeds the limit %u.\n",
vi->rss_key_size, VIRTIO_NET_RSS_MAX_KEY_SIZE);
err = -EINVAL;
goto free;
}
key_sz = virtio_cread8(vdev, offsetof(struct virtio_net_config, rss_max_key_size));
vi->rss_key_size = min_t(u16, key_sz, NETDEV_RSS_KEY_LEN);
if (key_sz > vi->rss_key_size)
dev_warn(&vdev->dev,
"rss_max_key_size=%u exceeds driver limit %u, clamping\n",
key_sz, vi->rss_key_size);
vi->rss_hash_types_supported =
virtio_cread32(vdev, offsetof(struct virtio_net_config, supported_hash_types));