linux-kernel - RE: [PATCH v3 03/11] KVM: SVM: Change intercept

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Date:   Thu, 30 Jul 2020 17:41:52 -0500
From:   Babu Moger <babu.moger@....com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Jim Mattson <jmattson@...gle.com>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        kvm list <kvm@...r.kernel.org>, Joerg Roedel <joro@...tes.org>,
        the arch/x86 maintainers <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: RE: [PATCH v3 03/11] KVM: SVM: Change intercept_dr to generic
 intercepts



> -----Original Message-----
> From: kvm-owner@...r.kernel.org <kvm-owner@...r.kernel.org> On Behalf
> Of Babu Moger
> Sent: Thursday, July 30, 2020 11:38 AM
> To: Paolo Bonzini <pbonzini@...hat.com>; Jim Mattson
> <jmattson@...gle.com>
> Cc: Vitaly Kuznetsov <vkuznets@...hat.com>; Wanpeng Li
> <wanpengli@...cent.com>; Sean Christopherson
> <sean.j.christopherson@...el.com>; kvm list <kvm@...r.kernel.org>; Joerg
> Roedel <joro@...tes.org>; the arch/x86 maintainers <x86@...nel.org>; LKML
> <linux-kernel@...r.kernel.org>; Ingo Molnar <mingo@...hat.com>; Borislav
> Petkov <bp@...en8.de>; H . Peter Anvin <hpa@...or.com>; Thomas Gleixner
> <tglx@...utronix.de>
> Subject: RE: [PATCH v3 03/11] KVM: SVM: Change intercept_dr to generic
> intercepts
> 
> 
> 
> > -----Original Message-----
> > From: Paolo Bonzini <pbonzini@...hat.com>
> > Sent: Wednesday, July 29, 2020 6:12 PM
> > To: Jim Mattson <jmattson@...gle.com>; Moger, Babu
> > <Babu.Moger@....com>
> > Cc: Vitaly Kuznetsov <vkuznets@...hat.com>; Wanpeng Li
> > <wanpengli@...cent.com>; Sean Christopherson
> > <sean.j.christopherson@...el.com>; kvm list <kvm@...r.kernel.org>;
> > Joerg Roedel <joro@...tes.org>; the arch/x86 maintainers
> > <x86@...nel.org>; LKML <linux-kernel@...r.kernel.org>; Ingo Molnar
> > <mingo@...hat.com>; Borislav Petkov <bp@...en8.de>; H . Peter Anvin
> > <hpa@...or.com>; Thomas Gleixner <tglx@...utronix.de>
> > Subject: Re: [PATCH v3 03/11] KVM: SVM: Change intercept_dr to generic
> > intercepts
> >
> > On 29/07/20 01:59, Jim Mattson wrote:
> > >>         case SVM_EXIT_READ_DR0 ... SVM_EXIT_WRITE_DR7: {
> > >> -               u32 bit = 1U << (exit_code - SVM_EXIT_READ_DR0);
> > >> -               if (svm->nested.ctl.intercept_dr & bit)
> > >> +               if (__is_intercept(&svm->nested.ctl.intercepts,
> > >> + exit_code))
> > > Can I assume that all of these __<function> calls will become
> > > <function> calls when the grand unification is done? (Maybe I should
> > > just look ahead.)
> > >
> >
> > The <function> calls are reserved for the active VMCB while these take a
> vector.
> > Probably it would be nicer to call them vmcb_{set,clr,is}_intercept
> > and make them take a struct vmcb_control_area*, but apart from that
> > the concept is fine
> >
> > Once we do the vmcb01/vmcb02/vmcb12 work, there will not be anymore
> > &svm->nested.ctl (replaced by &svm->nested.vmcb12->ctl) and we will be
> > able to change them to take a struct vmcb*.  Then is_intercept would
> > for example be
> > simply:
> Yea. True. It makes the code even cleaner. Also we can avoid calling
> recalc_intercepts every time we set or clear a bit inside the same function(like
> init_vmcb).
> 
> Let me try to understand.
> 
> vmcb01 is &svm->vmcb->control;l
> vmcb02 is &svm->nested.hsave->control
> vmcb12 is  &svm->nested.ctl;
> 
> The functions set_intercept and clr_intercept calls get_host_vmcb to get the
> vmcb address.

I will move the get_host_vmcb inside the caller and then call
vmcb_set_intercept/vmcb_clr_intercept/vmcb_is_intercept directly.
I will re post the series. This will change the whole series a little bit.

Jim has already reviewed some of the patches. But I probably cannot use
"Reviewed-by" if I change the patches too much. thanks

> 
> static inline struct vmcb *get_host_vmcb(struct vcpu_svm *svm) {
>         if (is_guest_mode(&svm->vcpu))
>                 return svm->nested.hsave;
>         else
>                 return svm->vmcb;
> }
> 
> I need to study little bit when is_guest_mode Is on or off.  Let me take a look at.


> 
> Thanks
> 
> >
> > 	return vmcb_is_intercept(svm->vmcb, nr);
> >
> > as expected.
> >
> > Paolo