Re: [PATCH] virtio_net: Do not send RSS key if it is not supported
From: Heng Qi
Date: Mon Mar 25 2024 - 11:16:42 EST
在 2024/3/25 下午7:35, Xuan Zhuo 写道:
On Mon, 25 Mar 2024 04:26:08 -0700, Breno Leitao <leitao@xxxxxxxxxx> wrote:
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;
+
Should we check has_rss_hash_report?
Hi, Breno.
You can refer to the following modification. It is worth noting
that \field{rss_max_indirection_table_length} should only be
accessed if VIRTIO_NET_F_RSS is negotiated, which I have
modified below:
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 727c874..fb4c438 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -3836,10 +3836,16 @@ static int virtnet_set_rxfh(struct net_device *dev,
struct virtnet_info *vi = netdev_priv(dev);
int i;
+ if (!vi->has_rss && !vi->has_rss_hash_report)
+ return -EOPNOTSUPP;
+
if (rxfh->hfunc != ETH_RSS_HASH_NO_CHANGE &&
rxfh->hfunc != ETH_RSS_HASH_TOP)
return -EOPNOTSUPP;
+ if (rxfh->indir && !vi->has_rss)
+ return -EINVAL;
+
if (rxfh->indir) {
for (i = 0; i < vi->rss_indir_table_size; ++i)
vi->ctrl->rss.indirection_table[i] =
rxfh->indir[i];
@@ -4757,13 +4763,14 @@ 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));
Regards,
Heng
@Heng Qi
Could you help us?
Thanks.
if (rxfh->hfunc != ETH_RSS_HASH_NO_CHANGE &&
rxfh->hfunc != ETH_RSS_HASH_TOP)
return -EOPNOTSUPP;
Thanks!