The Architectural Last Branch Records (LBRs) is published in the 319433-040 release of Intel Architecture Instruction Set Extensions and Future Features Programming Reference[0]. The main advantages of Arch LBR are [1]: - Faster context switching due to XSAVES support and faster reset of LBR MSRs via the new DEPTH MSR - Faster LBR read for a non-PEBS event due to XSAVES support, which lowers the overhead of the NMI handler. - Linux kernel can support the LBR features without knowing the model number of the current CPU. >From end user's point of view, the usage of Arch LBR is the same as the Legacy LBR that has been merged in the mainline. [0] https://software.intel.com/content/www/us/en/develop/download/intel-architecture-instruction-set-extensions-and-future-features-programming-reference.html [1] https://lore.kernel.org/lkml/1593780569-62993-1-git-send-email-kan.liang@xxxxxxxxxxxxxxx/ Note: to make the patchset buildable with kernel tree, this series includes 3 queued CET patches from Paolo's queued branch. Previous version: v4: https://lkml.kernel.org/kvm/20210510081535.94184-1-like.xu@xxxxxxxxxxxxxxx/ Like Xu (6): perf/x86/intel: Fix the comment about guest LBR support on KVM perf/x86/lbr: Simplify the exposure check for the LBR_INFO registers KVM: vmx/pmu: Emulate MSR_ARCH_LBR_DEPTH for guest Arch LBR KVM: vmx/pmu: Emulate MSR_ARCH_LBR_CTL for guest Arch LBR KVM: x86: Refine the matching and clearing logic for supported_xss KVM: x86: Add XSAVE Support for Architectural LBR Sean Christopherson (1): KVM: x86: Report XSS as an MSR to be saved if there are supported features Yang Weijiang (6): KVM: x86: Add arch LBR MSRs to msrs_to_save_all list KVM: x86/vmx: Save/Restore host MSR_ARCH_LBR_CTL state KVM: x86/pmu: Refactor code to support guest Arch LBR KVM: x86: Refresh CPUID on writes to MSR_IA32_XSS KVM: x86/vmx: Check Arch LBR config when return perf capabilities KVM: x86/cpuid: Advise Arch LBR feature in CPUID arch/x86/events/intel/core.c | 3 +- arch/x86/events/intel/lbr.c | 6 +- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/include/asm/msr-index.h | 1 + arch/x86/include/asm/vmx.h | 4 ++ arch/x86/kvm/cpuid.c | 44 ++++++++++-- arch/x86/kvm/vmx/capabilities.h | 25 ++++--- arch/x86/kvm/vmx/pmu_intel.c | 114 +++++++++++++++++++++++++++---- arch/x86/kvm/vmx/vmx.c | 50 ++++++++++++-- arch/x86/kvm/vmx/vmx.h | 4 ++ arch/x86/kvm/x86.c | 24 ++++++- 11 files changed, 237 insertions(+), 39 deletions(-) -- 2.21.1
