linux-kernel - Re: [PATCH v2 4/5] KVM: x86: Invert APICv/AVIC enablement check

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Message-ID: <5ab4b9159e25c3c605c736b9d2338e6e68b7eb56.camel@redhat.com>
Date:   Wed, 26 May 2021 14:11:13 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>, kvm@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Kechen Lu <kechenl@...dia.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/5] KVM: x86: Invert APICv/AVIC enablement check

On Wed, 2021-05-26 at 12:40 +0200, Vitaly Kuznetsov wrote:
> Maxim Levitsky <mlevitsk@...hat.com> writes:
> 
> > On Tue, 2021-05-18 at 16:43 +0200, Vitaly Kuznetsov wrote:
> > > Now that APICv/AVIC enablement is kept in common 'enable_apicv' variable,
> > > there's no need to call kvm_apicv_init() from vendor specific code.
> > > 
> > > No functional change intended.
> > 
> > Minor nitpick: I don't see any invert here, but rather
> > a unification of SVM/VMX virtual apic enablement code.
> > Maybe update the subject a bit?
> 
> It is a bit umbiguous in v2, I agree (v1 used hooks in vendor-specific
> code so instead of calling to vendor-neutral kvm_apicv_init() from
> vendor-specific svm_vm_init()/vmx_vm_init(), we were calling
> vendor-specific hooks from vendor-neutral kvm_apicv_init(), thus
> 'invert'. We can update the subject to something like
> 
> "KVM: x86: Drop vendor specific functions for APICv/AVIC enablement"

Yep, this subject line looks great.
Thanks!

Best regards,
	Maxim Levitsky

> 
> or something like that.
> 
> > For the code:
> > 
> > Reviewed-by: Maxim Levitsky <mlevitsk@...hat.com>
> > 
> 
> Thanks!
> 
> > Best regards,
> > 	Maxim Levitsky
> > 
> > > Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
> > > ---
> > >  arch/x86/include/asm/kvm_host.h | 1 -
> > >  arch/x86/kvm/svm/svm.c          | 1 -
> > >  arch/x86/kvm/vmx/vmx.c          | 1 -
> > >  arch/x86/kvm/x86.c              | 6 +++---
> > >  4 files changed, 3 insertions(+), 6 deletions(-)
> > > 
> > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> > > index a2197fcf0e7c..bf5807d35339 100644
> > > --- a/arch/x86/include/asm/kvm_host.h
> > > +++ b/arch/x86/include/asm/kvm_host.h
> > > @@ -1662,7 +1662,6 @@ gpa_t kvm_mmu_gva_to_gpa_system(struct kvm_vcpu *vcpu, gva_t gva,
> > >  				struct x86_exception *exception);
> > >  
> > >  bool kvm_apicv_activated(struct kvm *kvm);
> > > -void kvm_apicv_init(struct kvm *kvm, bool enable);
> > >  void kvm_vcpu_update_apicv(struct kvm_vcpu *vcpu);
> > >  void kvm_request_apicv_update(struct kvm *kvm, bool activate,
> > >  			      unsigned long bit);
> > > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> > > index 0d6ec34d1e4b..84f58e8b2f49 100644
> > > --- a/arch/x86/kvm/svm/svm.c
> > > +++ b/arch/x86/kvm/svm/svm.c
> > > @@ -4438,7 +4438,6 @@ static int svm_vm_init(struct kvm *kvm)
> > >  			return ret;
> > >  	}
> > >  
> > > -	kvm_apicv_init(kvm, enable_apicv);
> > >  	return 0;
> > >  }
> > >  
> > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> > > index 5e9ba10e9c2d..697dd54c7df8 100644
> > > --- a/arch/x86/kvm/vmx/vmx.c
> > > +++ b/arch/x86/kvm/vmx/vmx.c
> > > @@ -7000,7 +7000,6 @@ static int vmx_vm_init(struct kvm *kvm)
> > >  			break;
> > >  		}
> > >  	}
> > > -	kvm_apicv_init(kvm, enable_apicv);
> > >  	return 0;
> > >  }
> > >  
> > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > > index 23fdbba6b394..22a1e2b438c3 100644
> > > --- a/arch/x86/kvm/x86.c
> > > +++ b/arch/x86/kvm/x86.c
> > > @@ -8345,16 +8345,15 @@ bool kvm_apicv_activated(struct kvm *kvm)
> > >  }
> > >  EXPORT_SYMBOL_GPL(kvm_apicv_activated);
> > >  
> > > -void kvm_apicv_init(struct kvm *kvm, bool enable)
> > > +static void kvm_apicv_init(struct kvm *kvm)
> > >  {
> > > -	if (enable)
> > > +	if (enable_apicv)
> > >  		clear_bit(APICV_INHIBIT_REASON_DISABLE,
> > >  			  &kvm->arch.apicv_inhibit_reasons);
> > >  	else
> > >  		set_bit(APICV_INHIBIT_REASON_DISABLE,
> > >  			&kvm->arch.apicv_inhibit_reasons);
> > >  }
> > > -EXPORT_SYMBOL_GPL(kvm_apicv_init);
> > >  
> > >  static void kvm_sched_yield(struct kvm_vcpu *vcpu, unsigned long dest_id)
> > >  {
> > > @@ -10739,6 +10738,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
> > >  	INIT_DELAYED_WORK(&kvm->arch.kvmclock_update_work, kvmclock_update_fn);
> > >  	INIT_DELAYED_WORK(&kvm->arch.kvmclock_sync_work, kvmclock_sync_fn);
> > >  
> > > +	kvm_apicv_init(kvm);
> > >  	kvm_hv_init_vm(kvm);
> > >  	kvm_page_track_init(kvm);
> > >  	kvm_mmu_init_vm(kvm);