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[80.230.79.166]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-483bd6f19f5sm143757215e9.1.2026.02.25.02.03.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Feb 2026 02:03:53 -0800 (PST) Date: Wed, 25 Feb 2026 05:03:50 -0500 From: "Michael S. Tsirkin" To: Srujana Challa Cc: netdev@vger.kernel.org, virtualization@lists.linux.dev, pabeni@redhat.com, jasowang@redhat.com, xuanzhuo@linux.alibaba.com, eperezma@redhat.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, ndabilpuram@marvell.com, kshankar@marvell.com, stable@vger.kernel.org Subject: Re: [PATCH net,v4,1/2] virtio_net: Improve RSS key size validation and use NETDEV_RSS_KEY_LEN Message-ID: <20260225050154-mutt-send-email-mst@kernel.org> References: <20260224065850.962826-1-schalla@marvell.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <20260224065850.962826-1-schalla@marvell.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: d0B0-5jhv32KP-MV-QDhrNzJQF5y1TitdHmBiLQrLkM_1772013835 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Tue, Feb 24, 2026 at 12:28:49PM +0530, Srujana Challa wrote: > Replace hardcoded RSS max key size limit with NETDEV_RSS_KEY_LEN to > align with kernel's standard RSS key length. Add validation for RSS > key size against spec minimum (40 bytes) and driver maximum. When > validation fails, gracefully disable RSS features and continue > initialization rather than failing completely. > > Cc: stable@vger.kernel.org > Fixes: 3f7d9c1964fc ("virtio_net: Add hash_key_length check") > Signed-off-by: Srujana Challa --- should come here before changelog. > v3: > - Moved RSS key validation checks to virtnet_validate. > - Add fixes: tag and CC -stable > v4: > - Use NETDEV_RSS_KEY_LEN instead of type_max for the maximum rss key size. > --- > drivers/net/virtio_net.c | 34 ++++++++++++++++++++++++---------- > 1 file changed, 24 insertions(+), 10 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index db88dcaefb20..eeefe8abc122 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -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) == > @@ -6627,6 +6625,29 @@ static int virtnet_validate(struct virtio_device *vdev) > __virtio_clear_bit(vdev, VIRTIO_NET_F_STANDBY); > } > > + if (virtio_has_feature(vdev, VIRTIO_NET_F_RSS) || > + virtio_has_feature(vdev, VIRTIO_NET_F_HASH_REPORT)) { > + u8 key_sz = virtio_cread8(vdev, > + offsetof(struct virtio_net_config, > + rss_max_key_size)); > + /* Spec requires at least 40 bytes */ > +#define VIRTIO_NET_RSS_MIN_KEY_SIZE 40 > + if (key_sz < VIRTIO_NET_RSS_MIN_KEY_SIZE) { > + dev_warn(&vdev->dev, > + "rss_max_key_size=%u is less than spec minimum %u, disabling RSS\n", > + key_sz, VIRTIO_NET_RSS_MIN_KEY_SIZE); > + __virtio_clear_bit(vdev, VIRTIO_NET_F_RSS); > + __virtio_clear_bit(vdev, VIRTIO_NET_F_HASH_REPORT); > + } > + if (key_sz > NETDEV_RSS_KEY_LEN) { > + dev_warn(&vdev->dev, > + "rss_max_key_size=%u exceeds driver limit %u, disabling RSS\n", > + key_sz, NETDEV_RSS_KEY_LEN); > + __virtio_clear_bit(vdev, VIRTIO_NET_F_RSS); > + __virtio_clear_bit(vdev, VIRTIO_NET_F_HASH_REPORT); you flipped the logic here and it makes no sense now. Did you test this path? So if device is powerful and supports a very big key size then... we disable the feature? how does this make sense? > + } > + } > + > return 0; > } > > @@ -6839,13 +6860,6 @@ 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; > - } > - > vi->rss_hash_types_supported = > virtio_cread32(vdev, offsetof(struct virtio_net_config, supported_hash_types)); > vi->rss_hash_types_supported &= > -- > 2.25.1