linux-kernel - [PATCH 0/2] KVM: x86/pmu: Globally enable GP counters at "RESET"

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Message-ID: <20240309013641.1413400-1-seanjc@google.com>
Date: Fri,  8 Mar 2024 17:36:39 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Babu Moger <babu.moger@....com>, Sandipan Das <sandipan.das@....com>, 
	Like Xu <like.xu.linux@...il.com>, Mingwei Zhang <mizhang@...gle.com>, 
	Dapeng Mi <dapeng1.mi@...ux.intel.com>
Subject: [PATCH 0/2] KVM: x86/pmu: Globally enable GP counters at "RESET"

Globally enable GP counters in PERF_GLOBAL_CTRL when refreshing a vCPU's
PMU to emulate the architecturally defined post-RESET behavior of the MSR.

Extend pmu_counters_test.c to verify the behavior.

Note, this is slightly different than what I "posted" before: it keeps
PERF_GLOBAL_CTRL '0' if there are no counters.  That's technically not
what the SDM dictates, but I went with the common sense route of
interpreting the SDM to mean "globally enable all GP counters".

I figured it was much more likely that the SDM writers didn't think
about virtual CPUs that can have a PMU without any GP counters, versus
Intel really wanting to set _all_ bits in PERF_GLOBAL_CTRL :-)

Sean Christopherson (2):
  KVM: x86/pmu: Set enable bits for GP counters in PERF_GLOBAL_CTRL at
    "RESET"
  KVM: selftests: Verify post-RESET value of PERF_GLOBAL_CTRL in PMCs
    test

 arch/x86/kvm/pmu.c                            | 16 +++++++++++++--
 .../selftests/kvm/x86_64/pmu_counters_test.c  | 20 ++++++++++++++++++-
 2 files changed, 33 insertions(+), 3 deletions(-)


base-commit: 964d0c614c7f71917305a5afdca9178fe8231434
-- 
2.44.0.278.ge034bb2e1d-goog