linux-kernel - Re: [PATCH v3 3/3] KVM: SVM: Fix disable pause loop exit/pause filtering capability on SVM

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Message-ID: <ae8bf85f-00ee-c59c-e543-e0364481526c@redhat.com>
Date:   Fri, 31 Jul 2020 09:21:27 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Wanpeng Li <kernellwp@...il.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>
Subject: Re: [PATCH v3 3/3] KVM: SVM: Fix disable pause loop exit/pause
 filtering capability on SVM

On 31/07/20 05:12, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@...cent.com>
> 
> 'Commit 8566ac8b8e7c ("KVM: SVM: Implement pause loop exit logic in SVM")' 
> drops disable pause loop exit/pause filtering capability completely, I 
> guess it is a merge fault by Radim since disable vmexits capabilities and 
> pause loop exit for SVM patchsets are merged at the same time. This patch 
> reintroduces the disable pause loop exit/pause filtering capability support.
> 
> Reported-by: Haiwei Li <lihaiwei@...cent.com>
> Tested-by: Haiwei Li <lihaiwei@...cent.com>
> Fixes: 8566ac8b (KVM: SVM: Implement pause loop exit logic in SVM)
> Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
> ---
> v2 -> v3:
>  * simplify the condition in init_vmcb() 
> 
>  arch/x86/kvm/svm/svm.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index c0da4dd..bf77f90 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -1090,7 +1090,7 @@ static void init_vmcb(struct vcpu_svm *svm)
>  	svm->nested.vmcb = 0;
>  	svm->vcpu.arch.hflags = 0;
>  
> -	if (pause_filter_count) {
> +	if (!kvm_pause_in_guest(svm->vcpu.kvm)) {
>  		control->pause_filter_count = pause_filter_count;
>  		if (pause_filter_thresh)
>  			control->pause_filter_thresh = pause_filter_thresh;
> @@ -2693,7 +2693,7 @@ static int pause_interception(struct vcpu_svm *svm)
>  	struct kvm_vcpu *vcpu = &svm->vcpu;
>  	bool in_kernel = (svm_get_cpl(vcpu) == 0);
>  
> -	if (pause_filter_thresh)
> +	if (!kvm_pause_in_guest(vcpu->kvm))
>  		grow_ple_window(vcpu);
>  
>  	kvm_vcpu_on_spin(vcpu, in_kernel);
> @@ -3780,7 +3780,7 @@ static void svm_handle_exit_irqoff(struct kvm_vcpu *vcpu)
>  
>  static void svm_sched_in(struct kvm_vcpu *vcpu, int cpu)
>  {
> -	if (pause_filter_thresh)
> +	if (!kvm_pause_in_guest(vcpu->kvm))
>  		shrink_ple_window(vcpu);
>  }
>  
> @@ -3958,6 +3958,9 @@ static void svm_vm_destroy(struct kvm *kvm)
>  
>  static int svm_vm_init(struct kvm *kvm)
>  {
> +	if (!pause_filter_count || !pause_filter_thresh)
> +		kvm->arch.pause_in_guest = true;
> +
>  	if (avic) {
>  		int ret = avic_vm_init(kvm);
>  		if (ret)
> 

Queued all three, thanks.  Please do send a testcase for patch 1
however, I only queued it in order to have it in 5.8.

Paolo