[v2,00/12] KVM: x86/pmu: Get rid of PERF_TYPE_HARDWAR and other minor fixes

Message

Like Xu March 2, 2022, 11:13 a.m. UTC

Hi,

This is a follow up to [0]. By keeping the same semantics of eventsel
for gp and fixed counters, the reprogram code could be made more
symmetrical, simpler and even faster [1], and it also fixes the
obsolescence amd_event_mapping issue [2].

One of the notable changes is that we ended up removing the
reprogram_{gp, fixed}_counter() functions and replacing it with the
merged reprogram_counter(), where KVM programs pmc->perf_event
with only the PERF_TYPE_RAW type for any type of counter
(suggested by Jim as well).  PeterZ confirmed the idea, "think so;
the HARDWARE is just a convenience wrapper over RAW IIRC". 

Practically, this change drops the guest pmu support on the hosts without
X86_FEATURE_ARCH_PERFMON  (the oldest Pentium 4), where the
PERF_TYPE_HARDWAR is intentionally introduced so that hosts can
map the architectural guest PMU events to their own.

Some code refactoring helps to review key changes more easily.
Patches are based on top of kvm/master (ec756e40e271).

The 11nd patch removes the call trace in the commit message while we still
think that kvm->arch.pmu_event_filter requires SRCU protection in terms
of pmu_event_filter functionality, similar to "kvm->arch.msr_filter".

Patch 0012 is trying to expose some reserved bits for Milan use only, and
the related discussion can be seen here [3], thanks to Jim and Ravikumar.

Please check more details in each commit and feel free to comment.

[0] https://lore.kernel.org/kvm/[e-mail]/
[1] https://lore.kernel.org/kvm/[e-mail]/
[2] https://lore.kernel.org/kvm/[e-mail]/
[3] https://lore.kernel.org/kvm/[e-mail]/

Thanks,

v1: https://lore.kernel.org/kvm/[e-mail]/
v1 -> v2 Changelog:
- Get all the vPMC tests I have on hand to pass;
- Update obsolete AMD PMU comments; (Jim)
- Fix my carelessness for [-Wconstant-logical-operand] in 0009; (0day)
- Add "u64 new_config" to reuse perf_event for fixed CTRs; (0day)
- Add patch 0012 to attract attention to review;

Like Xu (12):
  KVM: x86/pmu: Update comments for AMD gp counters
  KVM: x86/pmu: Extract check_pmu_event_filter() from the same semantics
  KVM: x86/pmu: Pass only "struct kvm_pmc *pmc" to reprogram_counter()
  KVM: x86/pmu: Drop "u64 eventsel" for reprogram_gp_counter()
  KVM: x86/pmu: Drop "u8 ctrl, int idx" for reprogram_fixed_counter()
  KVM: x86/pmu: Use only the uniformly exported interface
    reprogram_counter()
  KVM: x86/pmu: Use PERF_TYPE_RAW to merge reprogram_{gp,
    fixed}counter()
  perf: x86/core: Add interface to query perfmon_event_map[] directly
  KVM: x86/pmu: Replace pmc_perf_hw_id() with perf_get_hw_event_config()
  KVM: x86/pmu: Drop amd_event_mapping[] in the KVM context
  KVM: x86/pmu: Protect kvm->arch.pmu_event_filter with SRCU
  KVM: x86/pmu: Clear reserved bit PERF_CTL2[43] for AMD erratum 1292

 arch/x86/events/core.c            |  11 ++
 arch/x86/include/asm/perf_event.h |   6 +
 arch/x86/kvm/pmu.c                | 182 ++++++++++++------------------
 arch/x86/kvm/pmu.h                |   6 +-
 arch/x86/kvm/svm/pmu.c            |  57 ++++------
 arch/x86/kvm/vmx/pmu_intel.c      |  64 ++++++-----
 6 files changed, 149 insertions(+), 177 deletions(-)