Hi, Considering that developers are more likely to have access to AMD VMs and use vPMU inside guest, there's a dark cloud that needs to rain. The x86_64/pmu_event_filter_test always fails on Zen3 boxes: test_amd_deny_list: Branch instructions retired = 43 (expected 42) test_without_filter: Branch instructions retired = 43 (expected 42) test_member_allow_list: Branch instructions retired = 43 (expected 42) test_not_member_deny_list: Branch instructions retired = 43 (expected 42) ,which is not caused by the event_filter feature (otherwise it's zero). After some dubious guessing and microtesting on Zen3+ pmu hardware, we found that VMRUN or one of the instructions in __svm_vcpu_run() causes a guest-only enabled counter for counting guest instruction (in the pmu_event_filter case, the branch instruction) to always increase by one right after each vm_entry. This creates an inconsistency with the AMD64_EVENTSEL_GUESTONLY, where the vPMU user in the VM does not expect to see any counter changes due to the SVM transaction at all. This patch set provides a low overhead software fix until HW change arrives or simply no fix planned. Prerequisite: KVM: x86/pmu/misc: Fix a typo on kvm_pmu_request_counter_reprogam() KVM: x86/pmu: Prevent the PMU from counting disallowed events Please feel free to run more tests, add more or share comments. Thanks, Like Xu (5): KVM: x86/pmu: Emulate CTR overflow directly in kvm_pmu_handle_event() KVM: x86/pmu: Add a helper to check if pmc has PEBS mode enabled KVM: x86/pmu: Move the overflow of a normal counter out of PMI context KVM: x86/pmu: Reorder functions to reduce unnecessary declarations KVM: x86/pmu: Hide guest counter updates from the VMRUN instruction arch/x86/include/asm/kvm_host.h | 4 ++ arch/x86/kvm/pmu.c | 81 +++++++++++++++++++++------------ arch/x86/kvm/pmu.h | 37 +++++++++++++-- arch/x86/kvm/svm/pmu.c | 1 + arch/x86/kvm/svm/svm.c | 28 ++++++++++++ 5 files changed, 119 insertions(+), 32 deletions(-) base-commit: e79412ef245c53b2157458754327f39f43dd6a49 -- 2.39.2
