On Fri, 29 Jun 2018 at 18:45, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > > On 29/06/2018 11:51, Wanpeng Li wrote: > > From: Wanpeng Li <wanpengli@xxxxxxxxxxx> > > > > Using hypercall to send IPIs by one vmexit instead of one by one for > > xAPIC/x2APIC physical mode and one vmexit per-cluster for x2APIC cluster > > mode. > > > > Even if enable qemu interrupt remapping and PV TLB Shootdown, I can still > > observe ~14% performance boost by ebizzy benchmark for 64 vCPUs VM, the > > total msr-induced vmexits reduce ~70%. > > > > Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> > > Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx> > > Cc: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> > > Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx> > > --- > > Documentation/virtual/kvm/cpuid.txt | 4 ++++ > > arch/x86/kvm/cpuid.c | 3 ++- > > arch/x86/kvm/x86.c | 25 +++++++++++++++++++++++++ > > include/uapi/linux/kvm_para.h | 1 + > > 4 files changed, 32 insertions(+), 1 deletion(-) > > > > diff --git a/Documentation/virtual/kvm/cpuid.txt b/Documentation/virtual/kvm/cpuid.txt > > index ab022dc..d72359f 100644 > > --- a/Documentation/virtual/kvm/cpuid.txt > > +++ b/Documentation/virtual/kvm/cpuid.txt > > @@ -62,6 +62,10 @@ KVM_FEATURE_ASYNC_PF_VMEXIT || 10 || paravirtualized async PF VM exit > > || || can be enabled by setting bit 2 > > || || when writing to msr 0x4b564d02 > > ------------------------------------------------------------------------------ > > +KVM_FEATURE_PV_SEND_IPI || 11 || guest checks this feature bit > > + || || before enabling paravirtualized > > + || || send IPIs. > > It's not "enabling" but "using". You also need to document the > hypercall itself. Will fix it in v2. Regards, Wanpeng Li
