Re: [PATCH v3 0/7] running kernel mode SIMD with softirqs disabled

[Eric Biggers <ebiggers@kernel.org>]

On Wed, May 12, 2021 at 08:44:32PM +0200, Ard Biesheuvel wrote:
> This is a follow-up to [0], but given that the arm64 architectural
> pieces have been merged for arm64, the only remaining changes are crypto
> specific. Therefore, the audience has been reduced to those people who
> are likely to care about these specifics.
> 
> Patch #1 addresses an issue in the skcipher walker which doesn't handle
> zero sized AEAD inputs entirely consistently, which is uncovered by the
> change in patch #7.
> 
> Patches #2 and #3 add some sanity checks to the public AEAD and skcipher
> APIs to limit their availibility to either task or softirq context
> (which is the only way in which they are currently being used). Adding
> this restriction permits the arm64 crypto code to get rid of all scalar
> fallbacks, given that on this architecture, softirqs are no longer
> served while the SIMD unit is being used in kernel mode, which means
> that the scalar fallbacks are never needed. These are removed in the
> remaining 4 patches.
> 
> [0] https://lore.kernel.org/linux-arm-kernel/20210302090118.30666-1-ardb@kernel.org/

Did you check whether any updates to the self-tests in testmgr.c are warranted?
Specifically, is disabling the use of SIMD for testing still something that
makes sense?

- Eric