On Mon, Aug 24, 2026 at 04:24:54PM +0100, Alex Bennée wrote:
We have outstanding guest exploitable bugs in the code which is fairly complex and needs some serious love to clean it up. As off-CPU cryptography acceleration seems to be waning in popularity lets just the deprecate the sub-system with a view to removing it in a couple of cycles.
We can also remove the backend code at that point as well.
Link: https://gitlab.com/qemu-project/qemu/-/work_items/3625 Reviewed-by: Mohamed Mediouni <mohamed@unpredictable.fr> Reviewed-by: Thomas Huth <thuth@redhat.com> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Acked-by: Michael S. Tsirkin <mst@redhat.com> I am assuming it will be merged with the rest of it?
--- v2 - mention the backend bits (only used by virtio-crypto) - use Gonglei's modified version of the text --- docs/about/deprecated.rst | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)
diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst index 0c656a968fc..05e4ce8cf16 100644 --- a/docs/about/deprecated.rst +++ b/docs/about/deprecated.rst @@ -276,6 +276,24 @@ future release. Where no 'dh-params.pem' file is provided, the DH parameters will be automatically negotiated in accordance with RFC7919.
+Devices +------- + +``virtio-crypto`` and cryptodev backends (since 11.2) +''''''''''''''''''''''''''''''''''''''''''''''''''''' + +The ``virtio-crypto`` device emulation is quite complex code with a +number of known flaws. It has never been migratable, so it is +unlikely to be used in any serious virtualization setting. Modern +ISAs provide on-CPU cryptography instructions (e.g. AES-NI/VAES, +armv8 crypto extensions), and the Linux kernel deprecated AF_ALG +and dropped its off-CPU accelerator support in Linux 7.2, removing +the primary userspace path for off-CPU crypto acceleration. The +time for this sort of off-load has passed. + +As this is the only device that uses the cryptodev backends these will +be removed at the same time the ``virtio-crypto`` device is. + Device options --------------
-- 2.47.3