[PATCH v9 00/12] KVM: x86/pmu: Add hardware Topdown metrics support

[Zide Chen <zide.chen@intel.com>]

Previous revisions were missing two things that are now addressed:

- A previous comment incorrectly claimed that MSR_PERF_METRICS bits
  [63:32] are ignored on hardware that only implements level-1 metrics;
  patch 10/12 fixes this by rejecting such writes.

- Patch 11/12 adds support for RDPMC Metrics Clear Mode. Without
  this feature, for user programs using RDPMC directly, the counter
  has to be reset explicitly using ioctl:

  ioctl(perf_fd, PERF_EVENT_IOC_RESET, 0);

Tests: besides the tests mentioned on v8 cover letter, tested RDPMC
Metrics Clear on a DMR machine, and tested Topdown metrics on nested
setup on top of the vPMU support series [1].

perf tool misidentifies "cpu/slots,metrics_clear=1/" as not being the
slots event, so it inserts an additional slots event into the group;
event scheduling then fails because the group needs fixed counter 3
(SLOTS) twice:

  $ perf stat -e "{cpu/slots,metrics_clear=1/,cpu/topdown-retiring/}" -- sleep 1
    WARNING: events were regrouped to match PMUs
           <not counted>      slots
         <not supported>      cpu/slots,metrics_clear=1/
           <not counted>      cpu/topdown-retiring/

A fix for this perf tool bug is posted at [2].

New patches:
patch 8/12: Add INTEL_TD_METRIC_FIELD_BITS for code cleanup.
patch 9/12: perf/x86: Expose number of Topdown metric events to KVM.
patch 10/12: Reject writes to reserved MSR_PERF_METRICS bits.
patch 11/12: Support RDPMC Metrics Clear Mode.

Minor non-logical changes to existing patches:
patch 5/12: Remove the incorrect comment about writing to PERF_METRICS.
patch 7/12: Remove references to Metrics Clear from the changelog.

Patch 11/12 could be folded into patch 5/12, but I kept them separate
because patches 1-8 were already well reviewed, and keeping them
unchanged should make reviewing v9 easier.

Rebased to kvm-x86/next: 70c944caf570fda2d79baa71435589a8db39f048

v8: https://lore.kernel.org/kvm/20260817183143.226156-1-zide.chen@intel.com/
QEMU:  https://lore.kernel.org/qemu-devel/20260604025546.19378-7-zide.chen@intel.com/

[1] https://lore.kernel.org/kvm/20260827223755.143247-1-zide.chen@intel.com/
[2] https://lore.kernel.org/linux-perf-users/20260917182525.3DE801F000FF@smtp.kernel.org/T/#t

Dapeng Mi (2):
  KVM: x86/pmu: Support Intel fixed counter 3 on mediated vPMU
  KVM: x86/pmu: Support PERF_METRICS MSR in mediated vPMU

Mingwei Zhang (1):
  KVM: x86/pmu: Snapshot host IA32_PERF_CAPABILITIES in kvm_host

Zide Chen (9):
  KVM: x86/pmu: Do not map fixed counters >= 3 to generic perf events
  KVM: x86/pmu: Rename and move vcpu_get_perf_capabilities() to pmu.h
  KVM: x86/pmu: Move RDPMC emulation into per-vendor callbacks
  KVM: x86/pmu: Emulate RDPMC on performance metrics
  KVM: selftests: Add PERF_METRICS and fixed counter 3 tests
  perf/x86: Add INTEL_TD_METRIC_FIELD_{BITS,MASK} constants
  perf/x86: Expose number of Topdown metric events to KVM
  KVM: x86/pmu: Reject writes to reserved MSR_PERF_METRICS bits
  KVM: x86/pmu: Support RDPMC Metrics Clear Mode

 arch/x86/events/core.c                        |   1 +
 arch/x86/events/intel/core.c                  |   8 +-
 arch/x86/include/asm/kvm-x86-pmu-ops.h        |   2 +-
 arch/x86/include/asm/kvm_host.h               |   5 +-
 arch/x86/include/asm/msr-index.h              |   2 +
 arch/x86/include/asm/perf_event.h             |   5 +
 arch/x86/kvm/msrs.c                           |  10 +-
 arch/x86/kvm/pmu.c                            |  37 +++--
 arch/x86/kvm/pmu.h                            |  17 ++-
 arch/x86/kvm/svm/pmu.c                        |  13 +-
 arch/x86/kvm/vmx/nested.c                     |   2 +
 arch/x86/kvm/vmx/pmu_intel.c                  | 132 +++++++++++++++---
 arch/x86/kvm/vmx/pmu_intel.h                  |  12 +-
 arch/x86/kvm/vmx/vmx.c                        |  19 ++-
 arch/x86/kvm/x86.c                            |   4 +
 tools/arch/x86/include/asm/msr-index.h        |   1 +
 tools/testing/selftests/kvm/include/x86/pmu.h |   3 +
 .../selftests/kvm/x86/pmu_counters_test.c     |  97 ++++++++++++-
 18 files changed, 303 insertions(+), 67 deletions(-)

-- 
2.55.0