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[80.230.25.21]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b9c3d0287b5sm650668966b.56.2026.04.08.06.54.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Apr 2026 06:54:36 -0700 (PDT) Date: Wed, 8 Apr 2026 09:54:33 -0400 From: "Michael S. Tsirkin" To: Sasha Levin Cc: stable@vger.kernel.org, Srujana Challa , Jakub Kicinski Subject: Re: [PATCH 6.1.y] virtio_net: clamp rss_max_key_size to NETDEV_RSS_KEY_LEN Message-ID: <20260408095309-mutt-send-email-mst@kernel.org> References: <2026040856-ploy-antiviral-fecc@gregkh> <20260408134351.1100654-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260408134351.1100654-1-sashal@kernel.org> On Wed, Apr 08, 2026 at 09:43:51AM -0400, Sasha Levin wrote: > From: Srujana Challa > > [ Upstream commit b4e5f04c58a29c499faa85d12952ca9a4faf1cb9 ] > > 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: 3f7d9c1964fc ("virtio_net: Add hash_key_length check") > Cc: stable@vger.kernel.org > Signed-off-by: Srujana Challa > Acked-by: Michael S. Tsirkin > Link: https://patch.msgid.link/20260326142344.1171317-1-schalla@marvell.com > Signed-off-by: Jakub Kicinski > [ changed clamp target from NETDEV_RSS_KEY_LEN to VIRTIO_NET_RSS_MAX_KEY_SIZE ] Does this not make the subject and the commit log misleading? > Signed-off-by: Sasha Levin > --- > drivers/net/virtio_net.c | 16 ++++++++-------- > 1 file changed, 8 insertions(+), 8 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 9ee3465082c5a..0fcd662d15d51 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -3796,6 +3796,7 @@ 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; > @@ -3915,14 +3916,13 @@ 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, VIRTIO_NET_RSS_MAX_KEY_SIZE); > + 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)); > -- > 2.53.0