Hello Xuan,
On Mon, Mar 25, 2024 at 01:57:53PM +0800, Xuan Zhuo wrote:
> On Fri, 22 Mar 2024 03:21:21 -0700, Breno Leitao <leitao@xxxxxxxxxx> wrote:
> > Hello Xuan,
> >
> > On Fri, Mar 22, 2024 at 10:00:22AM +0800, Xuan Zhuo wrote:
> > > On Thu, 21 Mar 2024 09:54:30 -0700, Breno Leitao <leitao@xxxxxxxxxx> wrote:
> >
> > > > 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;
> > >
> > >
> > >
> > > 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));
> > > vi->rss_key_size =
> > > virtio_cread8(vdev, offsetof(struct virtio_net_config, rss_max_key_size));
> > >
> > > vi->rss_hash_types_supported =
> > > virtio_cread32(vdev, offsetof(struct virtio_net_config, supported_hash_types));
> > > vi->rss_hash_types_supported &=
> > > ~(VIRTIO_NET_RSS_HASH_TYPE_IP_EX |
> > > VIRTIO_NET_RSS_HASH_TYPE_TCP_EX |
> > > VIRTIO_NET_RSS_HASH_TYPE_UDP_EX);
> > >
> > > dev->hw_features |= NETIF_F_RXHASH;
> > > }
> > >
> > >
> > > vi->rss_key_size is initiated here, I wonder if there is something wrong?
> >
> > Not really, the code above is never executed (in my machines). This is
> > because `vi->has_rss` and `vi->has_rss_hash_report` are both unset.
> >
> > Looking further, vdev does not have the VIRTIO_NET_F_RSS and
> > VIRTIO_NET_F_HASH_REPORT features.
> >
> > Also, when I run `ethtool -x`, I got:
> >
> > # ethtool -x eth0
> > RX flow hash indirection table for eth0 with 1 RX ring(s):
> > Operation not supported
> > RSS hash key:
> > Operation not supported
> > RSS hash function:
> > toeplitz: on
> > xor: off
> > crc32: off
>
>
> The spec saies:
> Note that if the device offers VIRTIO_NET_F_HASH_REPORT, even if it
> supports only one pair of virtqueues, it MUST support at least one of
> commands of VIRTIO_NET_CTRL_MQ class to configure reported hash
> parameters:
>
> If the device offers VIRTIO_NET_F_RSS, it MUST support
> VIRTIO_NET_CTRL_MQ_RSS_CONFIG command per 5.1.6.5.7.1.
>
> Otherwise the device MUST support VIRTIO_NET_CTRL_MQ_HASH_CONFIG command
> per 5.1.6.5.6.4.
>
>
> So if we have not anyone of `vi->has_rss` and `vi->has_rss_hash_report`,
> we should return from virtnet_set_rxfh directly.
Makes sense. Although it is not clear to me how vi->has_rss_hash_report
is related here, but, I am convinced that we shouldn't do any RSS
operation if the device doesn't have the RSS feature, i.e, vi->has_rss
is false.
That said, I am thinking about something like this. How does it sound?
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 5a7700b103f8..8c1ad7361cf2 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -3780,6 +3780,9 @@ static int virtnet_set_rxfh(struct net_device *dev,
struct virtnet_info *vi = netdev_priv(dev);
int i;
+ if (!vi->has_rss)
+ return -EOPNOTSUPP;
+
if (rxfh->hfunc != ETH_RSS_HASH_NO_CHANGE &&
rxfh->hfunc != ETH_RSS_HASH_TOP)
return -EOPNOTSUPP;
Thanks!
