[PATCH v2 0/2] KVM: arm64: Handle hidden FEAT_PMUv3 in ID_AA64DFR0_EL1

[Colton Lewis <coltonlewis@google.com>]

When userspace initializes a vCPU with KVM_ARM_VCPU_PMU_V3 and hides
FEAT_PMUv3 via ID_AA64DFR0_EL1.PMUVer, KVM hits a WARN_ONCE("Unknown PMU
version 0") during reset_pmevtyper() and continues to expose PMU system
registers instead of emulating guest accesses as UNDEF.

Patch 1 handles ID_AA64DFR0_EL1_PMUVer_NI in __kvm_pmu_event_mask() and
removes the redundant kvm_vcpu_has_pmu() check in reset_pmevtyper().
Patch 2 updates pmu_visibility() to check ID_AA64DFR0_EL1.PMUVer via
kvm_has_feat() so PMU registers are marked REG_HIDDEN when FEAT_PMUv3 is
not advertised.

Changes in v2:
- Handle ID_AA64DFR0_EL1_PMUVer_NI in __kvm_pmu_event_mask() and drop
  the kvm_vcpu_has_pmu() check in reset_pmevtyper() (Oliver)
- Drop Cc: stable@vger.kernel.org (Oliver)
- Add patch 2 to check ID_AA64DFR0_EL1.PMUVer in pmu_visibility()
  (Oliver)
- Link to v1: https://lore.kernel.org/r/20260929220411.3756519-1-coltonlewis@google.com

Colton Lewis (2):
  KVM: arm64: Handle ID_AA64DFR0_EL1.PMUVer == NI in
    __kvm_pmu_event_mask()
  KVM: arm64: Check ID_AA64DFR0_EL1.PMUVer in pmu_visibility()

 arch/arm64/kvm/pmu-emul.c | 5 ++++-
 arch/arm64/kvm/sys_regs.c | 6 +-----
 2 files changed, 5 insertions(+), 6 deletions(-)

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2.56.0.rc1.315.gc6ed9934b7-goog