[PATCH v2 0/7] KVM: x86/pmu: Fix some corner cases including Intel PEBS

Like Xu
2022-07-21T10:36:01Z

Good well-designed tests can help us find more bugs, especially when
the test steps differ from the Linux kernel behaviour in terms of the
timing of access to virtualized hw resources.

A new guest PEBS kvm-unit-test constructs a number of typical and
corner use cases to demonstrate how fragile the earlier PEBS
enabling patch set is. I prefer to reveal these flaws and fix them
myself before we receive complaints from projects that rely on it.

In this patch series, there is one small optimization (006), one hardware
surprise (002), and most of these fixes have stepped on my little toes.

Please feel free to run tests, add more or share comments.

Previous:
https://lore.kernel.org/kvm/20220713122507.29236-1-likexu@tencent.com/

V1 -> V2 Changelog:
- For 3/7, use "hw_idx > -1" and add comment; (Sean)
- For 4/7, refine commit message and add comment; (Sean)
- For 6/7, inline reprogram_counter() and restrict pmc->current_config;

Like Xu (7):
perf/x86/core: Update x86_pmu.pebs_capable for ICELAKE_{X,D}
perf/x86/core: Completely disable guest PEBS via guest's global_ctrl
KVM: x86/pmu: Avoid setting BIT_ULL(-1) to pmu->host_cross_mapped_mask
KVM: x86/pmu: Don't generate PEBS records for emulated instructions
KVM: x86/pmu: Avoid using PEBS perf_events for normal counters
KVM: x86/pmu: Defer reprogram_counter() to kvm_pmu_handle_event()
KVM: x86/pmu: Defer counter emulated overflow via pmc->stale_counter

arch/x86/events/intel/core.c | 4 ++-
arch/x86/include/asm/kvm_host.h | 6 +++--
arch/x86/kvm/pmu.c | 47 +++++++++++++++++++++------------
arch/x86/kvm/pmu.h | 6 ++++-
arch/x86/kvm/svm/pmu.c | 2 +-
arch/x86/kvm/vmx/pmu_intel.c | 30 ++++++++++-----------
6 files changed, 58 insertions(+), 37 deletions(-)

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2.37.1