linux-kernel - Re: [PATCH 03/19] Revert "KVM: SVM: Introduce hybrid-AVIC mode"

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Message-ID: <YxCzsFXy/sNYF0Ac@google.com>
Date:   Thu, 1 Sep 2022 13:29:20 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Maxim Levitsky <mlevitsk@...hat.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
        Li RongQing <lirongqing@...du.com>
Subject: Re: [PATCH 03/19] Revert "KVM: SVM: Introduce hybrid-AVIC mode"

On Thu, Sep 01, 2022, Maxim Levitsky wrote:
> On Wed, 2022-08-31 at 19:12 +0000, Sean Christopherson wrote:
> > On Wed, Aug 31, 2022, Maxim Levitsky wrote:
> > > If you are really hell bent on not having that MMIO exposed, then I say we
> > > can just disable the AVIC memslot, and keep AVIC enabled in this case - this
> > > should make us both happy.
> > 
> > I don't think that will work though, as I don't think it's possible to tell hardware
> > not to accelerate AVIC accesses.  I.e. KVM can squash the unaccelerated traps, but
> > anything that is handled by hardware will still go through.
> 
> Nope! Remember why do we have that APIC private memslot?

Heh, I finally understood what you were suggesting two minutes after I woke up
this morning.   Apparently I needed to sleep on it?