> -----Original Message----- > From: kvm-owner@xxxxxxxxxxxxxxx [mailto:kvm-owner@xxxxxxxxxxxxxxx] On > Behalf Of Wei Wang > Sent: Thursday, September 20, 2018 6:06 PM > To: linux-kernel@xxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; pbonzini@xxxxxxxxxx; > ak@xxxxxxxxxxxxxxx > Cc: kan.liang@xxxxxxxxx; peterz@xxxxxxxxxxxxx; mingo@xxxxxxxxxx; > rkrcmar@xxxxxxxxxx; like.xu@xxxxxxxxx; wei.w.wang@xxxxxxxxx; > jannh@xxxxxxxxxx; Gonglei (Arei) <arei.gonglei@xxxxxxxxxx> > Subject: [PATCH v3 0/5] Guest LBR Enabling > > Last Branch Recording (LBR) is a performance monitor unit (PMU) feature > on Intel CPUs that captures branch related info. This patch series enables > this feature to KVM guests. > > Here is a conclusion of the fundamental methods that we use: > 1) the LBR feature is enabled per guest via QEMU setting of > KVM_CAP_X86_GUEST_LBR; Did you send the QEMU parts for guest LBR support? Thanks, -Gonglei > 2) the LBR stack is passed through to the guest for direct accesses after > the guest's first access to any of the lbr related MSRs; > 3) When the guest uses the LBR feature with the user callstack mode, the > host will help save/resotre the LBR stack when the vCPU is scheduled > out/in. > > ChangeLog: > v2->v3: > - replaces the pv approach with a lazy save approach to saving the lbr > stack on vCPU switching; > - destroy the host side perf event if the guest is torn down; > - remove the unnecessary event->pmu->stop() before calling > perf_event_release_kernel(). > v1->v2: > - add the per guest LBR capability, KVM_CAP_X86_GUEST_LBR; > - save/restore the LBR stack conditionally on the vCPU thread context > switching, instead of on VMX transitions; > - expose MSR_IA32_PERF_CAPABILITIES to the guest. > > Like Xu (1): > KVM/x86/vPMU: Add APIs to support host save/restore the guest lbr > stack > > Wei Wang (4): > perf/x86: add a function to get the lbr stack > KVM/x86: KVM_CAP_X86_GUEST_LBR > KVM/x86: expose MSR_IA32_PERF_CAPABILITIES to the guest > KVM/x86/lbr: lazy save the guest lbr stack > > arch/x86/events/intel/lbr.c | 49 ++++++++++++- > arch/x86/events/perf_event.h | 1 + > arch/x86/include/asm/kvm_host.h | 7 ++ > arch/x86/include/asm/perf_event.h | 22 ++++++ > arch/x86/kvm/cpuid.c | 2 +- > arch/x86/kvm/pmu.h | 8 +++ > arch/x86/kvm/pmu_intel.c | 41 +++++++++++ > arch/x86/kvm/vmx.c | 144 > ++++++++++++++++++++++++++++++++++++++ > arch/x86/kvm/x86.c | 10 +++ > include/uapi/linux/kvm.h | 1 + > 10 files changed, 281 insertions(+), 4 deletions(-) > > -- > 2.7.4
