diff options
| author | Marc Zyngier <maz@kernel.org> | 2025-02-17 10:17:20 +0000 |
|---|---|---|
| committer | Marc Zyngier <maz@kernel.org> | 2025-04-11 12:58:51 +0100 |
| commit | c8823e51b534d490ec27d372596eb35d2bb7193c (patch) | |
| tree | 4372b3b83fb68b0ed56ca3a5a246f66f8ee0503f /arch/arm64/kvm/pmu-emul.c | |
| parent | f12b54d7c24388886277598236b3eeea5c68eec4 (diff) | |
KVM: arm64: Fix MDCR_EL2.HPMN reset value
The MDCR_EL2 documentation indicates that the HPMN field has
the following behaviour:
"On a Warm reset, this field resets to the expression NUM_PMU_COUNTERS."
However, it appears we reset it to zero, which is not very useful.
Add a reset helper for MDCR_EL2, and handle the case where userspace
changes the target PMU, which may force us to change HPMN again.
Reported-by: Joey Gouly <joey.gouly@arm.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Diffstat (limited to 'arch/arm64/kvm/pmu-emul.c')
| -rw-r--r-- | arch/arm64/kvm/pmu-emul.c | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c index 60b5a5e4a6c5..2df54508f5ae 100644 --- a/arch/arm64/kvm/pmu-emul.c +++ b/arch/arm64/kvm/pmu-emul.c @@ -1027,12 +1027,30 @@ u8 kvm_arm_pmu_get_max_counters(struct kvm *kvm) return bitmap_weight(arm_pmu->cntr_mask, ARMV8_PMU_MAX_GENERAL_COUNTERS); } +static void kvm_arm_set_nr_counters(struct kvm *kvm, unsigned int nr) +{ + kvm->arch.nr_pmu_counters = nr; + + /* Reset MDCR_EL2.HPMN behind the vcpus' back... */ + if (test_bit(KVM_ARM_VCPU_HAS_EL2, kvm->arch.vcpu_features)) { + struct kvm_vcpu *vcpu; + unsigned long i; + + kvm_for_each_vcpu(i, vcpu, kvm) { + u64 val = __vcpu_sys_reg(vcpu, MDCR_EL2); + val &= ~MDCR_EL2_HPMN; + val |= FIELD_PREP(MDCR_EL2_HPMN, kvm->arch.nr_pmu_counters); + __vcpu_sys_reg(vcpu, MDCR_EL2) = val; + } + } +} + static void kvm_arm_set_pmu(struct kvm *kvm, struct arm_pmu *arm_pmu) { lockdep_assert_held(&kvm->arch.config_lock); kvm->arch.arm_pmu = arm_pmu; - kvm->arch.nr_pmu_counters = kvm_arm_pmu_get_max_counters(kvm); + kvm_arm_set_nr_counters(kvm, kvm_arm_pmu_get_max_counters(kvm)); } /** |