Re: [PATCH v2] x86/cpu: Use SERIALIZE in sync_core() when available

[Borislav Petkov]

On Tue, Aug 04, 2020 at 09:58:25PM -0700, hpa@xxxxxxxxx wrote:
> Because why use an alternative to jump over one instruction?
>
> I personally would prefer to have the IRET put out of line

Can't yet - SERIALIZE CPUs are a minority at the moment.

> and have the call/jmp replaced by SERIALIZE inline.

Well, we could do:

	alternative_io("... IRET bunch", __ASM_SERIALIZE, X86_FEATURE_SERIALIZE, ...);

and avoid all kinds of jumping. Alternatives get padded so there
would be a couple of NOPs following when SERIALIZE gets patched in
but it shouldn't be a problem. I guess one needs to look at what gcc
generates...

-- 
Regards/Gruss,
    Boris.

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