linux-kernel - Re: [PATCH v3 1/2] x86: KVM: Advertise FSRS and FSRC on AMD to userspace

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Message-ID: <20250411094210.GJZ_jj8sSbUydxrv2o@fat_crate.local>
Date: Fri, 11 Apr 2025 11:42:10 +0200
From: Borislav Petkov <bp@...en8.de>
To: Maksim Davydov <davydov-max@...dex-team.ru>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, x86@...nel.org,
	babu.moger@....com, seanjc@...gle.com, mingo@...hat.com,
	tglx@...utronix.de, dave.hansen@...ux.intel.com, hpa@...or.com,
	jmattson@...gle.com, pbonzini@...hat.com
Subject: Re: [PATCH v3 1/2] x86: KVM: Advertise FSRS and FSRC on AMD to
 userspace

On Wed, Dec 04, 2024 at 04:43:44PM +0300, Maksim Davydov wrote:
> Fast short REP STOSB and fast short CMPSB support on AMD processors are
> provided in other CPUID function in comparison with Intel processors:
> * FSRS: 10 bit in 0x80000021_EAX
> * FSRC: 11 bit in 0x80000021_EAX
> 
> AMD bit numbers differ from existing definition of FSRC and
> FSRS. So, the new appropriate values have to be added with new names.
> 
> It's safe to advertise these features to userspace because they are a part
> of CPU model definition and they can't be disabled (as existing Intel
> features).
> 
> Fixes: 2a4209d6a9cb ("KVM: x86: Advertise fast REP string features inherent to the CPU")

Why is there a Fixes tag here?

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette