linux-kernel - Re: [PATCH 6/6] KVM: VMX: Move VERW closer to VMentry for MDS mitigation

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Message-ID: <20231023211647.lgebgvt622zemg6y@desk>
Date:   Mon, 23 Oct 2023 14:17:25 -0700
From:   Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
To:     Josh Poimboeuf <jpoimboe@...nel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Jonathan Corbet <corbet@....net>,
        Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>, tony.luck@...el.com,
        ak@...ux.intel.com, tim.c.chen@...ux.intel.com,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        kvm@...r.kernel.org,
        Alyssa Milburn <alyssa.milburn@...ux.intel.com>,
        Daniel Sneddon <daniel.sneddon@...ux.intel.com>,
        antonio.gomez.iglesias@...ux.intel.com
Subject: Re: [PATCH  6/6] KVM: VMX: Move VERW closer to VMentry for MDS
 mitigation

On Mon, Oct 23, 2023 at 11:56:43AM -0700, Josh Poimboeuf wrote:
> On Fri, Oct 20, 2023 at 01:45:29PM -0700, Pawan Gupta wrote:
> > @@ -31,6 +32,8 @@
> >  #define VCPU_R15	__VCPU_REGS_R15 * WORD_SIZE
> >  #endif
> >  
> > +#define GUEST_CLEAR_CPU_BUFFERS		USER_CLEAR_CPU_BUFFERS
> 
> I don't think the extra macro buys anything here.

Using USER_CLEAR_CPU_BUFFERS in the VMentry path didn't feel right. But,
after "USER_" is gone as per your comment on 2/6 patch,
GUEST_CLEAR_CPU_BUFFERS can also go away.