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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <87zgwh7p7r.fsf@vitty.brq.redhat.com>
Date:   Wed, 26 May 2021 12:40:24 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Maxim Levitsky <mlevitsk@...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

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"

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);
>
>

-- 
Vitaly