Re: [PATCH 6/6] docs: deprecate virtio-crypto

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Aug 19, 2026 at 10:22:06AM +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
> deprecate the sub-system with a view to removing it in a couple of
> cycles.
> 
> Link: https://gitlab.com/qemu-project/qemu/-/work_items/3625
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> Cc: Gonglei <arei.gonglei@huawei.com>

Let's see what Gonglei thinks.

> ---
>  docs/about/deprecated.rst | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst
> index 0c656a968fc..3c22981fc8a 100644
> --- a/docs/about/deprecated.rst
> +++ b/docs/about/deprecated.rst
> @@ -276,6 +276,20 @@ future release. Where no 'dh-params.pem' file is provided, the DH
>  parameters will be automatically negotiated in accordance with
>  RFC7919.
>  
> +Devices
> +-------
> +
> +``virtio-crypto`` (since 11.2)
> +''''''''''''''''''''''''''''''
> +
> +The ``virtio-crypto`` device emulation is quite complex code with a
> +number of known flaws. It has never been migratable so is unlikely to
> +be used in any serious virtualization setting. With most modern
> +systems supporting on-CPU cryptography acceleration via their
> +ISAs sets

ISA sets?

> the need for off-CPU acceleration is also reduced. Add to
> +that the kernel has recently removed the ability to use off-CPU
> +acceleration

did it really? I thought it's just for af_alg?

and putting "recently" into cde will not age well.

> suggests the time for this sort of off-load has passed.
> +
>  Device options
>  --------------
>  
> 
> -- 
> 2.47.3