linux-kernel - Re: [PATCH 6/9] KVM: x86: Provide paravirtualized flush_tlb

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Date:   Wed, 26 Jun 2019 11:21:54 -0700
From:   Andy Lutomirski <luto@...nel.org>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>
Cc:     Andy Lutomirski <luto@...nel.org>, Nadav Amit <namit@...are.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "the arch/x86 maintainers" <x86@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>
Subject: Re: [PATCH 6/9] KVM: x86: Provide paravirtualized flush_tlb_multi()

On Wed, Jun 26, 2019 at 10:41 AM Vitaly Kuznetsov <vkuznets@...hat.com> wrote:
>
> Andy Lutomirski <luto@...nel.org> writes:
>
> > All this being said, do we currently have any system that supports
> > PCID *and* remote flushes?  I guess KVM has some mechanism, but I'm
> > not that familiar with its exact capabilities.  If I remember right,
> > Hyper-V doesn't expose PCID yet.
> >
>
> It already does (and support it to certain extent), see
>
> commit 617ab45c9a8900e64a78b43696c02598b8cad68b
> Author: Vitaly Kuznetsov <vkuznets@...hat.com>
> Date:   Wed Jan 24 11:36:29 2018 +0100
>
>     x86/hyperv: Stop suppressing X86_FEATURE_PCID
>

Hmm.  Once the dust settles from Nadav's patches, I think we should
see about supporting it better :)