Re: [PATCH 6.1.y] virtio_net: clamp rss_max_key_size to NETDEV_RSS_KEY_LEN

[Sasha Levin <sashal@kernel.org>]

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 <schalla@marvell.com>
>>
>> [ 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 <schalla@marvell.com>
>> Acked-by: Michael S. Tsirkin <mst@redhat.com>
>> Link: https://patch.msgid.link/20260326142344.1171317-1-schalla@marvell.com
>> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
>> [ 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