Re: [PATCH 1/6] x86: add kconfig symbols for assembler VAES and VPCLMULQDQ support

Eric Biggers
2024-03-26T08:18:18Z

On Tue, Mar 26, 2024 at 09:10:13AM +0100, Ingo Molnar wrote:
>
> * Eric Biggers <ebiggers@kernel.org> wrote:
>
> > From: Eric Biggers <ebiggers@google.com>
> >
> > Add config symbols AS_VAES and AS_VPCLMULQDQ that expose whether the
> > assembler supports the vector AES and carryless multiplication
> > cryptographic extensions.
> >
> > Signed-off-by: Eric Biggers <ebiggers@google.com>
> > ---
> > arch/x86/Kconfig.assembler | 10 ++++++++++
> > 1 file changed, 10 insertions(+)
> >
> > diff --git a/arch/x86/Kconfig.assembler b/arch/x86/Kconfig.assembler
> > index 8ad41da301e5..59aedf32c4ea 100644
> > --- a/arch/x86/Kconfig.assembler
> > +++ b/arch/x86/Kconfig.assembler
> > @@ -23,9 +23,19 @@ config AS_TPAUSE
> > config AS_GFNI
> > def_bool $(as-instr,vgf2p8mulb %xmm0$(comma)%xmm1$(comma)%xmm2)
> > help
> > Supported by binutils >= 2.30 and LLVM integrated assembler
> >
> > +config AS_VAES
> > + def_bool $(as-instr,vaesenc %ymm0$(comma)%ymm1$(comma)%ymm2)
> > + help
> > + Supported by binutils >= 2.30 and LLVM integrated assembler
>
> Nit: any reason it isn't called AS_VAESENC, like the instruction itself?
>
> The other new AS_ Kconfig symbols follow the same nomenclature:

The CPU feature flag is called VAES. It guards the vaesenc, vaesenclast,
vaesdec, and vaesdeclast instructions when used on ymm and zmm registers.

So the name AS_VAES seems fine as-is.

I think you may have been confused by AS_VPCLMULQDQ, because in that case the
feature happens to provides a single instruction with the same name as the CPU
feature flag.

- Eric