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[80.230.25.21]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-488c5ceb914sm36669425e9.3.2026.04.08.07.33.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Apr 2026 07:33:20 -0700 (PDT) Date: Wed, 8 Apr 2026 10:33:17 -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: <20260408103237-mutt-send-email-mst@kernel.org> References: <2026040856-ploy-antiviral-fecc@gregkh> <20260408134351.1100654-1-sashal@kernel.org> <20260408095309-mutt-send-email-mst@kernel.org> <20260408101810-mutt-send-email-mst@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: On Wed, Apr 08, 2026 at 10:24:14AM -0400, Sasha Levin wrote: > On Wed, Apr 08, 2026 at 10:20:50AM -0400, Michael S. Tsirkin wrote: > > On Wed, Apr 08, 2026 at 10:15:48AM -0400, Sasha Levin wrote: > > > On Wed, Apr 08, 2026 at 09:54:33AM -0400, Michael S. Tsirkin wrote: > > > > 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? > > > > > > Probably, but changing the commit subject will just create more confusion. > > > > > > -- > > > Thanks, > > > Sasha > > > > It's not just the subject. The commit log says: > > > > Also the value 40 is a spec minimum, not a spec maximum. > > > > but the changed patch seems to treat it as a maximum: > > > > + vi->rss_key_size = min_t(u16, key_sz, VIRTIO_NET_RSS_MAX_KEY_SIZE); > > > > > > so unless I misread the code, the value is never > 40. > > I tried to explain it here: https://lore.kernel.org/all/adZitVex9UGVyH-V@laps/ > > -- > Thanks, > Sasha OK let us take the discussion there.