Wanpeng Li <kernellwp@xxxxxxxxx> writes:
> From: Wanpeng Li <wanpengli@xxxxxxxxxxx>
>
> 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@xxxxxxxxxxx>
> Tested-by: Haiwei Li <lihaiwei@xxxxxxxxxxx>
> Fixes: 8566ac8b (KVM: SVM: Implement pause loop exit logic in SVM)
> Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
> ---
> 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
