On Wed, Jul 22, 2026 at 03:03:16PM +0200, Cédric Le Goater wrote: > On 7/22/26 13:57, Daniel P. Berrangé via Devel wrote: > > Linux 7.1 has deprecated the AF_ALG crypto backend: > > > > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a67afb1884ba815079bd43d5c998e155e03b08b6 > > > > And has documented it to be always slower than userspace crypto: > > > > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5624ea54f3ba5c83d2e5503411a31a8be0278c1e > > > > as a result of dropping support for zero-copy and hardware > > accelerators: > > > > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7524070f26d8d347c26787dc297fb844baa26abf > > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ffdd2bc378953b525aca61902534e753f1f8e734 > > > > The main use case for the AF_ALG impl was to improve the performance > > of virtio-crypto with the cryptodev-backend-builtin driver. In > > practice this did not matter since 'cryptodev-backend-lkcf' can do > > offload to the kernel via the keyctl syscall, and 'cryptodev-vhost-user' > > can offload to an external process which can optionally integrate with > > hardware accelerators without kernel assistance. > > > > The AF_ALG backend has no user visible configuration options at runtime, > > it is unconditionally tried with any use of the cipher APIs. So it does > > not strictly have to go through the deprecation process, however, it is > > left available initially in case there was an unexpected use case that > > relies on it which may be faster with old kernels before the above Linux > > commits. > > > > Suggested-by: Thomas Huth <[email protected]> > > Signed-off-by: Daniel P. Berrangé <[email protected]> > > --- > > docs/about/deprecated.rst | 21 +++++++++++++++++++++ > > meson.build | 6 ++++++ > > 2 files changed, 27 insertions(+) > > > > diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst > > index 0c656a968f..54b2662752 100644 > > --- a/docs/about/deprecated.rst > > +++ b/docs/about/deprecated.rst > > @@ -416,6 +416,27 @@ ABI is long-obsolete. We are therefore deprecating > > both OABI support > > and NWFPE emulation, and they will be removed in a future QEMU > > release. > > +Build features > > +-------------- > > + > > +Crypto AF_ALG backend > > +--------------------- > > > Crypto AF_ALG backend (since 11.1) > '''''''''''''''''''''''''''''''''' > > ?
Oppps, yes, of course it needs a version :-) > > With that, > > Reviewed-by: Cédric Le Goater <[email protected]> > With regards, Daniel -- |: https://berrange.com ~~ https://hachyderm.io/@berrange :| |: https://libvirt.org ~~ https://entangle-photo.org :| |: https://pixelfed.art/berrange ~~ https://fstop138.berrange.com :|
