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

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Date:   Wed, 26 May 2021 12:57:13 +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 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?

For the code:

Reviewed-by: Maxim Levitsky <mlevitsk@...hat.com>

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);