Messages in this thread Patch in this message | | | From | Wanpeng Li <> | Subject | [PATCH v3 5/5] KVM: VMX: Handle preemption timer fastpath | Date | Fri, 24 Apr 2020 14:22:44 +0800 |
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From: Wanpeng Li <wanpengli@tencent.com>
This patch implements handle preemption timer fastpath, after timer fire due to VMX-preemption timer counts down to zero, handle it as soon as possible and vmentry immediately without checking various kvm stuff when possible.
Testing on SKX Server.
cyclictest in guest(w/o mwait exposed, adaptive advance lapic timer is default -1):
5540.5ns -> 4602ns 17%
kvm-unit-test/vmexit.flat:
w/o avanced timer: tscdeadline_immed: 2885 -> 2431.25 15.7% tscdeadline: 5668.75 -> 5188.5 8.4%
w/ adaptive advance timer default -1: tscdeadline_immed: 2965.25 -> 2520 15.0% tscdeadline: 4663.75 -> 4537 2.7%
Tested-by: Haiwei Li <lihaiwei@tencent.com> Cc: Haiwei Li <lihaiwei@tencent.com> Signed-off-by: Wanpeng Li <wanpengli@tencent.com> --- arch/x86/kvm/vmx/vmx.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index d21b66b..028967a 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6560,12 +6560,28 @@ void vmx_update_host_rsp(struct vcpu_vmx *vmx, unsigned long host_rsp) } } +static enum exit_fastpath_completion handle_fastpath_preemption_timer(struct kvm_vcpu *vcpu) +{ + struct vcpu_vmx *vmx = to_vmx(vcpu); + + if (!vmx->req_immediate_exit && + !unlikely(vmx->loaded_vmcs->hv_timer_soft_disabled)) { + kvm_lapic_expired_hv_timer(vcpu); + trace_kvm_exit(EXIT_REASON_PREEMPTION_TIMER, vcpu, KVM_ISA_VMX); + return EXIT_FASTPATH_CONT_RUN; + } + + return EXIT_FASTPATH_NONE; +} + static enum exit_fastpath_completion vmx_exit_handlers_fastpath(struct kvm_vcpu *vcpu) { if (!is_guest_mode(vcpu) && vcpu->arch.apicv_active) { switch (to_vmx(vcpu)->exit_reason) { case EXIT_REASON_MSR_WRITE: return handle_fastpath_set_msr_irqoff(vcpu); + case EXIT_REASON_PREEMPTION_TIMER: + return handle_fastpath_preemption_timer(vcpu); default: return EXIT_FASTPATH_NONE; } -- 2.7.4
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