[V5,00/10] KVM: x86: Add AMD Guest PerfMonV2 PMU support

Message

Like Xu April 10, 2023, 10:50 a.m. UTC

Starting with Zen4, core PMU on AMD platforms such as Genoa and
Ryzen-7000 will support PerfMonV2, and it is also compatible with
legacy PERFCTR_CORE behavior and MSR addresses.

If you don't have access to the hardware specification, the commits
d6d0c7f681fd..7685665c390d for host perf can also bring a quick
overview. Its main change is the addition of three MSR's equivalent
to Intel V2, namely global_ctrl, global_status, global_status_clear.

It is worth noting that this feature is very attractive for reducing the
overhead of PMU virtualization, since multiple MSR accesses to multiple
counters will be replaced by a single access to the global register,
plus more accuracy gain when multiple guest counters are used.

All related testcases are passed on a Genoa box.
Please feel free to run more tests, add more or share comments.

Patch 0001-0007 could be applied earlier, which may help reduce
the burden on industrious reviewers.

Previous:
https://lore.kernel.org/kvm/[e-mail]/

V4 -> V5 Changelog:
- Avoid pronouns in the changelogs and comments; (Sean)
- Drop the assumption that KVM can blindly set v2 without changes; (Sean)
- Grab host CPUID and clear here (instead of setting); (Sean)
- Clarification of behaviours from spec-defined and HW observations; (Sean)
- Drop the use of the intermediate "entry"; (Sean)
- Use BUILD_BUG_ON() to avoid potential null-pointer deref bug; (Sean)
- Add a patch to cap nr_arch_gp_counters in the common flow; (Sean)
- Add sanitize check for pmu->nr_arch_gp_counters; (Sean)
- Rewrite changelogs which doesn't depend on the shortlog; (Sean)
- State what the patch actually does, not "should do"; (Sean)
- Drop the useless multiple line comment; (Sean)
- Apply a better short log; (Sean)
- Drop the performance blurb; (Sean)
- Drop the "The", i.e. just "AMD PerfMonV2 defines ..."; (Sean)
- s/hanlders/handlers; (Sean)
- s/intel/Intel; (Sean)
- Drop useless message on pmc_is_globally_enabled(); (Sean)
- Tweak "return 1" to follow the patterns for other MSR helpers; (Sean)
- Add assumptions about reusing global_ovf_ctrl_mask; (Sean)

Like Xu (10):
  KVM: x86/pmu: Expose reprogram_counters() in pmu.h
  KVM: x86/pmu: Return #GP if user sets the GLOBAL_STATUS reserved bits
  KVM: x86/pmu: Make part of the Intel v2 PMU MSRs handling x86 generic
  KVM: x86: Explicitly zero cpuid "0xa" leaf when PMU is disabled
  KVM: x86/pmu: Disable vPMU if the minimum num of counters isn't met
  KVM: x86/pmu: Forget PERFCTR_CORE if the min num of counters isn't met
  KVM: x86/pmu: Constrain the num of guest counters with kvm_pmu_cap
  KVM: x86/cpuid: Add a KVM-only leaf to redirect AMD PerfMonV2 flag
  KVM: x86/svm/pmu: Add AMD PerfMonV2 support
  KVM: x86/cpuid: Add AMD CPUID ExtPerfMonAndDbg leaf 0x80000022

 arch/x86/include/asm/kvm-x86-pmu-ops.h |  1 -
 arch/x86/kvm/cpuid.c                   | 30 +++++++++-
 arch/x86/kvm/pmu.c                     | 83 +++++++++++++++++++++++---
 arch/x86/kvm/pmu.h                     | 32 +++++++++-
 arch/x86/kvm/reverse_cpuid.h           |  7 +++
 arch/x86/kvm/svm/pmu.c                 | 67 +++++++++++++++------
 arch/x86/kvm/svm/svm.c                 | 19 +++++-
 arch/x86/kvm/vmx/pmu_intel.c           | 32 ++--------
 arch/x86/kvm/x86.c                     | 10 ++++
 9 files changed, 221 insertions(+), 60 deletions(-)


base-commit: dfdeda67ea2dac57d2d7506d65cfe5a0878ad285