Optimize code used by, or which impacts, kvm_pmu_trigger_event() to try and make a dent in the overhead of emulating PMU events in software, which is quite noticeable due to it kicking in anytime the guest has a vPMU and KVM is skipping an instruction. Note, Jim has a proposal/idea[*] (that I supported) to make kvm_pmu_trigger_event() even more performant. I opted not to do that as it's a bit more invasive, and I started chewing on this not so much because I care _that_ much about performance, but because it irritates me that the PMU code makes things way harder than they need to be. Note #2, this applies on top of my other two PMU series: https://lore.kernel.org/all/20231103230541.352265-1-seanjc@xxxxxxxxxx https://lore.kernel.org/all/20231110021306.1269082-1-seanjc@xxxxxxxxxx Those series fix actual functional issues, i.e. I'll definitely apply them first (there's definitely no rush on this one). [*] https://lore.kernel.org/all/CALMp9eQGqqo66fQGwFJMc3y+9XdUrL7ageE8kvoAOV6NJGfJpw@xxxxxxxxxxxxxx Sean Christopherson (10): KVM: x86/pmu: Zero out PMU metadata on AMD if PMU is disabled KVM: x86/pmu: Add common define to capture fixed counters offset KVM: x86/pmu: Move pmc_idx => pmc translation helper to common code KVM: x86/pmu: Snapshot and clear reprogramming bitmap before reprogramming KVM: x86/pmu: Add macros to iterate over all PMCs given a bitmap KVM: x86/pmu: Process only enabled PMCs when emulating events in software KVM: x86/pmu: Snapshot event selectors that KVM emulates in software KVM: x86/pmu: Expand the comment about what bits are check emulating events KVM: x86/pmu: Check eventsel first when emulating (branch) insns retired KVM: x86/pmu: Avoid CPL lookup if PMC enabline for USER and KERNEL is the same arch/x86/include/asm/kvm-x86-pmu-ops.h | 1 - arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/pmu.c | 143 +++++++++++++++---------- arch/x86/kvm/pmu.h | 52 ++++++++- arch/x86/kvm/svm/pmu.c | 7 +- arch/x86/kvm/vmx/nested.c | 2 +- arch/x86/kvm/vmx/pmu_intel.c | 44 ++------ arch/x86/kvm/x86.c | 6 +- 8 files changed, 154 insertions(+), 102 deletions(-) base-commit: ef1883475d4a24d8eaebb84175ed46206a688103 -- 2.42.0.869.gea05f2083d-goog
