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| author | Wanpeng Li <wanpengli@tencent.com> | 2020-03-13 11:55:18 +0800 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-03-16 17:58:58 +0100 |
| commit | 041bc42ce2d0efac3b85bbb81dea8c74b81f4ef9 (patch) | |
| tree | a77a59dc86fd997e0b105ab004edc9b86d63a625 /arch/x86/kvm | |
| parent | 331b4de9a7e780f9648ced959c08f4d593aa2e7b (diff) | |
| download | linux-041bc42ce2d0efac3b85bbb81dea8c74b81f4ef9.tar.gz linux-041bc42ce2d0efac3b85bbb81dea8c74b81f4ef9.tar.bz2 linux-041bc42ce2d0efac3b85bbb81dea8c74b81f4ef9.zip | |
KVM: VMX: Micro-optimize vmexit time when not exposing PMU
PMU is not exposed to guest by most of products from cloud providers since the
bad performance of PMU emulation and security concern. However, it calls
perf_guest_switch_get_msrs() and clear_atomic_switch_msr() unconditionally
even if PMU is not exposed to the guest before each vmentry.
~2% vmexit time reduced can be observed by kvm-unit-tests/vmexit.flat on my
SKX server.
Before patch:
vmcall 1559
After patch:
vmcall 1529
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm')
| -rw-r--r-- | arch/x86/kvm/vmx/vmx.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index e961633182f8..b447d66f44e6 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6549,7 +6549,8 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu) pt_guest_enter(vmx); - atomic_switch_perf_msrs(vmx); + if (vcpu_to_pmu(vcpu)->version) + atomic_switch_perf_msrs(vmx); atomic_switch_umwait_control_msr(vmx); if (enable_preemption_timer) |