From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Wanpeng Li <kernellwp@gmail.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>
Subject: Re: [PATCH v2 3/3] KVM: SVM: Fix disable pause loop exit/pause filtering capability on SVM
Date: Wed, 29 Jul 2020 14:20:54 +0200 [thread overview]
Message-ID: <87k0ymldg9.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <1595929506-9203-3-git-send-email-wanpengli@tencent.com>
Wanpeng Li <kernellwp@gmail.com> writes:
> From: Wanpeng Li <wanpengli@tencent.com>
>
> Commit 8566ac8b (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.
>
> We can observe 2.9% hackbench improvement for a 92 vCPUs guest on AMD
> Rome Server.
>
> Reported-by: Haiwei Li <lihaiwei@tencent.com>
> Tested-by: Haiwei Li <lihaiwei@tencent.com>
> Fixes: 8566ac8b (KVM: SVM: Implement pause loop exit logic in SVM)
> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> ---
> 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..c20f127 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 (pause_filter_count && !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_thresh)
> + kvm->arch.pause_in_guest = true;
Would it make sense to do
if (!pause_filter_count || !pause_filter_thresh)
kvm->arch.pause_in_guest = true;
here and simplify the condition in init_vmcb()?
> +
> if (avic) {
> int ret = avic_vm_init(kvm);
> if (ret)
--
Vitaly
next prev parent reply other threads:[~2020-07-29 12:21 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-28 9:45 [PATCH v2 1/3] KVM: LAPIC: Prevent setting the tscdeadline timer if the lapic is hw disabled Wanpeng Li
2020-07-28 9:45 ` [PATCH v2 2/3] KVM: LAPIC: Set the APIC_TDCR settable bits Wanpeng Li
2020-07-28 9:45 ` [PATCH v2 3/3] KVM: SVM: Fix disable pause loop exit/pause filtering capability on SVM Wanpeng Li
2020-07-29 12:20 ` Vitaly Kuznetsov [this message]
2020-07-30 0:56 ` Wanpeng Li
2020-07-30 11:16 ` Vitaly Kuznetsov
2020-07-31 3:18 ` Wanpeng Li
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