linux-kernel - Re: [PATCH v2 2/7] KVM: nSVM: rename nested 'vmcb' to vmcb12

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Message-ID: <53b774c8f3ae94fb5161ee6d3005ac3b04f63052.camel@redhat.com>
Date:   Mon, 24 Aug 2020 14:37:53 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     Jim Mattson <jmattson@...gle.com>
Cc:     kvm list <kvm@...r.kernel.org>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" 
        <linux-kernel@...r.kernel.org>, "H. Peter Anvin" <hpa@...or.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Joerg Roedel <joro@...tes.org>,
        Wanpeng Li <wanpengli@...cent.com>,
        Borislav Petkov <bp@...en8.de>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [PATCH v2 2/7] KVM: nSVM: rename nested 'vmcb' to vmcb12_gpa in
 few places

On Thu, 2020-08-20 at 14:00 -0700, Jim Mattson wrote:
> On Thu, Aug 20, 2020 at 6:33 AM Maxim Levitsky <mlevitsk@...hat.com> wrote:
> > No functional changes.
> > 
> > Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
> > ---
> >  arch/x86/kvm/svm/nested.c | 10 +++++-----
> >  arch/x86/kvm/svm/svm.c    | 13 +++++++------
> >  arch/x86/kvm/svm/svm.h    |  2 +-
> >  3 files changed, 13 insertions(+), 12 deletions(-)
> > 
> > diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
> > index fb68467e6049..f5b17920a2ca 100644
> > --- a/arch/x86/kvm/svm/nested.c
> > +++ b/arch/x86/kvm/svm/nested.c
> > @@ -431,7 +431,7 @@ int enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
> For consistency, should the vmcb_gpa argument be renamed to vmcb12_gpa as well?

I went over all nested.c and renamed all mentions of vmcb which refer to guest's vmcb to vmcb12,
and mentions of nested_vmcb to vmcb12 as well. I hope I didn't made this patch too much larger.
I updated the patch subject too.
> 
> 
> > @@ -579,7 +579,7 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
> > 
> >         /* Exit Guest-Mode */
> >         leave_guest_mode(&svm->vcpu);
> > -       svm->nested.vmcb = 0;
> > +       svm->nested.vmcb12_gpa = 0;
> Perhaps in a follow-up change, this could be set to an illegal value
> rather than 0?
Or rather not reset this address at all, as I did later in the 
caching pathes which I dropped for now.

> 
> 
> > @@ -1018,7 +1018,7 @@ static int svm_get_nested_state(struct kvm_vcpu *vcpu,
> > 
> >         /* First fill in the header and copy it out.  */
> >         if (is_guest_mode(vcpu)) {
> > -               kvm_state.hdr.svm.vmcb_pa = svm->nested.vmcb;
> > +               kvm_state.hdr.svm.vmcb_pa = svm->nested.vmcb12_gpa;
> It's unfortunate that we have "_pa" on the LHS on "_gpa" on the RHS. Oh, well.
I was afraid to touch this struct since it is user visible. I noticed it.

> 
> 
> > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> > index 562a79e3e63a..d33013b9b4d7 100644
> > --- a/arch/x86/kvm/svm/svm.c
> > +++ b/arch/x86/kvm/svm/svm.c
> > @@ -1102,7 +1102,7 @@ static void init_vmcb(struct vcpu_svm *svm)
> >         }
> >         svm->asid_generation = 0;
> > 
> > -       svm->nested.vmcb = 0;
> > +       svm->nested.vmcb12_gpa = 0;
> Here, too, perhaps this could be changed from 0 to an illegal value in
> a follow-up change.
> 
> Reviewed-by: Jim Mattson <jmattson@...gle.com>
> 

Thanks for the review,
	Best regards,
		Maxim Levitsky