Re: [PATCH] KVM: SVM: Analyze is_guest_mode() in svm_vcpu_run()

[Haiwei Li]

On 20/9/15 04:43, Krish Sadhukhan wrote:
> On 9/13/20 11:55 PM, Wanpeng Li wrote:
> > From: Wanpeng Li <wanpengli@xxxxxxxxxxx>
> >
> > Analyze is_guest_mode() in svm_vcpu_run() instead of 
> > svm_exit_handlers_fastpath()
> > in conformity with VMX version.
> >
> > Suggested-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> > Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
> > ---
> >   arch/x86/kvm/svm/svm.c | 7 +++++--
> >   1 file changed, 5 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> > index 3da5b2f..009035a 100644
> > --- a/arch/x86/kvm/svm/svm.c
> > +++ b/arch/x86/kvm/svm/svm.c
> > @@ -3393,8 +3393,7 @@ static void svm_cancel_injection(struct kvm_vcpu 
> > *vcpu)
> >   static fastpath_t svm_exit_handlers_fastpath(struct kvm_vcpu *vcpu)
> >   {
> > -    if (!is_guest_mode(vcpu) &&
> > -        to_svm(vcpu)->vmcb->control.exit_code == SVM_EXIT_MSR &&
> > +    if (to_svm(vcpu)->vmcb->control.exit_code == SVM_EXIT_MSR &&
> >           to_svm(vcpu)->vmcb->control.exit_info_1)
> >           return handle_fastpath_set_msr_irqoff(vcpu);
> > @@ -3580,6 +3579,10 @@ static __no_kcsan fastpath_t 
> > svm_vcpu_run(struct kvm_vcpu *vcpu)
> >           svm_handle_mce(svm);
> >       svm_complete_interrupts(svm);
> > +
> > +    if (is_guest_mode(vcpu))
> > +        return EXIT_FASTPATH_NONE;
> > +
> >       exit_fastpath = svm_exit_handlers_fastpath(vcpu);
> >       return exit_fastpath;
>
> Not related to your changes, but should we get rid of the variable 
> 'exit_fastpath' and just do,
>
>          return svm_exit_handler_fastpath(vcpu);
>
> It seems the variable isn't used anywhere else and svm_vcpu_run() 
> doesn't return from anywhere else either.
>
> Also, svm_exit_handlers_fastpath() doesn't have any other caller. Should 
> we get rid of it as well ?

I will do this soon, thanks.