linux-kernel - Re: [PATCH v4 01/12] KVM: x86/mmu: helpers to return if KVM honors guest MTRRs

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Date:   Wed, 11 Oct 2023 09:47:28 +0800
From:   Yan Zhao <yan.y.zhao@...el.com>
To:     Sean Christopherson <seanjc@...gle.com>
CC:     Like Xu <like.xu.linux@...il.com>, <pbonzini@...hat.com>,
        <chao.gao@...el.com>, <kai.huang@...el.com>,
        <robert.hoo.linux@...il.com>, <yuan.yao@...ux.intel.com>,
        kvm list <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 01/12] KVM: x86/mmu: helpers to return if KVM honors
 guest MTRRs

On Tue, Oct 10, 2023 at 05:08:08PM -0700, Sean Christopherson wrote:
> On Tue, Oct 10, 2023, Yan Zhao wrote:
> > BTW, as param "kvm" is now removed from the helper, better to remove the word
> > "second" in comment in patch 4, i.e.
> > 
> > -        * So, specify the second parameter as true here to indicate
> > -        * non-coherent DMAs are/were involved and TDP zap might be
> > -        * necessary.
> > +        * So, specify the parameter as true here to indicate non-coherent
> > +        * DMAs are/were involved and TDP zap might be necessary.
> > 
> > Sorry and thanks a lot for helps on this series!
> 
> Heh, don't be sorry, it's not your fault I can't get this quite right.  Fixed
> up yet again, hopefully for the last time.  This is what I ended up with for the
> comment:
> 
> 	/*
> 	 * Non-coherent DMA assignment and de-assignment will affect
> 	 * whether KVM honors guest MTRRs and cause changes in memtypes
> 	 * in TDP.
> 	 * So, pass %true unconditionally to indicate non-coherent DMA was,
> 	 * or will be involved, and that zapping SPTEs might be necessary.
> 	 */
> 
> and the hashes:
> 
> [1/5] KVM: x86/mmu: Add helpers to return if KVM honors guest MTRRs
>       https://github.com/kvm-x86/linux/commit/1affe455d66d
> [2/5] KVM: x86/mmu: Zap SPTEs when CR0.CD is toggled iff guest MTRRs are honored
>       https://github.com/kvm-x86/linux/commit/7a18c7c2b69a
> [3/5] KVM: x86/mmu: Zap SPTEs on MTRR update iff guest MTRRs are honored
>       https://github.com/kvm-x86/linux/commit/9a3768191d95
> [4/5] KVM: x86/mmu: Zap KVM TDP when noncoherent DMA assignment starts/stops
>       https://github.com/kvm-x86/linux/commit/362ff6dca541
> [5/5] KVM: VMX: drop IPAT in memtype when CD=1 for KVM_X86_QUIRK_CD_NW_CLEARED
>       https://github.com/kvm-x86/linux/commit/c9f65a3f2d92

Looks good to me, thanks!