linux-kernel - Re: [PATCH] KVM: x86: Expose Predictive Store Forwarding Disable

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Message-ID: <e3718025-682d-469c-eac9-b4995e91dc11@redhat.com>
Date:   Wed, 24 Aug 2022 19:13:50 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Jim Mattson <jmattson@...gle.com>, Babu Moger <babu.moger@....com>
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, x86@...nel.org,
        hpa@...or.com, seanjc@...gle.com, vkuznets@...hat.com,
        wanpengli@...cent.com, joro@...tes.org, tony.luck@...el.com,
        peterz@...radead.org, kyung.min.park@...el.com, wei.huang2@....com,
        jgross@...e.com, andrew.cooper3@...rix.com,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH] KVM: x86: Expose Predictive Store Forwarding Disable

On 8/23/22 23:26, Jim Mattson wrote:
> For consistency, should this feature be renamed AMD_PSFD, now that
> Intel is enumerating PSFD with CPUID.(EAX=7,ECX=2):EDX.PSFD[bit 0]?
> Seehttps://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/technical-documentation/cpuid-enumeration-and-architectural-msrs.html.
> 
> And, Paolo, why are we carrying X86_FEATURE_PSFD as a private #define
> in KVM rather than putting it where it belongs in cpufeatures.h?
> 

Borislav asked to not show psfd in /proc/cpuinfo, because Linux had
decided not to control PSF separately; instead it just piggybacked
on SSBD which should disable PSF as well.  Honestly I disagree but
it's not my area of maintenance.

Paolo