RE: [PATCH v3 03/11] KVM: SVM: Change intercept_dr to generic intercepts

Babu Moger
2020-07-30T22:42:02Z

> -----Original Message-----
> From: kvm-owner@vger.kernel.org <kvm-owner@vger.kernel.org> On Behalf
> Of Babu Moger
> Sent: Thursday, July 30, 2020 11:38 AM
> To: Paolo Bonzini <pbonzini@redhat.com>; Jim Mattson
> <jmattson@google.com>
> Cc: Vitaly Kuznetsov <vkuznets@redhat.com>; Wanpeng Li
> <wanpengli@tencent.com>; Sean Christopherson
> <sean.j.christopherson@intel.com>; kvm list <kvm@vger.kernel.org>; Joerg
> Roedel <joro@8bytes.org>; the arch/x86 maintainers <x86@kernel.org>; LKML
> <linux-kernel@vger.kernel.org>; Ingo Molnar <mingo@redhat.com>; Borislav
> Petkov <bp@alien8.de>; H . Peter Anvin <hpa@zytor.com>; Thomas Gleixner
> <tglx@linutronix.de>
> Subject: RE: [PATCH v3 03/11] KVM: SVM: Change intercept_dr to generic
> intercepts
>
>
>
> > -----Original Message-----
> > From: Paolo Bonzini <pbonzini@redhat.com>
> > Sent: Wednesday, July 29, 2020 6:12 PM
> > To: Jim Mattson <jmattson@google.com>; Moger, Babu
> > <Babu.Moger@amd.com>
> > Cc: Vitaly Kuznetsov <vkuznets@redhat.com>; Wanpeng Li
> > <wanpengli@tencent.com>; Sean Christopherson
> > <sean.j.christopherson@intel.com>; kvm list <kvm@vger.kernel.org>;
> > Joerg Roedel <joro@8bytes.org>; the arch/x86 maintainers
> > <x86@kernel.org>; LKML <linux-kernel@vger.kernel.org>; Ingo Molnar
> > <mingo@redhat.com>; Borislav Petkov <bp@alien8.de>; H . Peter Anvin
> > <hpa@zytor.com>; Thomas Gleixner <tglx@linutronix.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