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Date: Mon, 25 Mar 2024 20:34:32 +0800
From: Heng Qi <hengqi@...ux.alibaba.com>
To: Breno Leitao <leitao@...ian.org>, Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Cc: rbc@...a.com, riel@...riel.com, stable@...r.kernel.org,
qemu-devel@...gnu.org,
"open list:VIRTIO CORE AND NET DRIVERS" <virtualization@...ts.linux.dev>,
"open list:NETWORKING DRIVERS" <netdev@...r.kernel.org>,
open list <linux-kernel@...r.kernel.org>, "Michael S. Tsirkin"
<mst@...hat.com>, Jason Wang <jasowang@...hat.com>,
"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
Andrew Melnychenko <andrew@...nix.com>
Subject: Re: [PATCH] virtio_net: Do not send RSS key if it is not supported
在 2024/3/25 下午7:35, Xuan Zhuo 写道:
> On Mon, 25 Mar 2024 04:26:08 -0700, Breno Leitao <leitao@...ian.org> 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@...ian.org> 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@...ian.org> 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!
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