redonkable
/
alistair23-linux
1
0
Fork 0
Code Releases Activity

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>
alistair/sensors
Wanpeng Li 2020-03-13 11:55:18 +08:00 committed by Paolo Bonzini
parent 331b4de9a7
commit 041bc42ce2
1 changed files with 2 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
arch/x86/kvm/vmx/vmx.c
View File

@ -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)