On Mon, Oct 09, 2023 at 11:08:52PM +0000, Raghavendra Rao Ananta wrote: > Add a helper, kvm_arm_get_num_counters(), to read the number > of counters from the arm_pmu associated to the VM. Make the > function global as upcoming patches will be interested to > know the value while setting the PMCR.N of the guest from > userspace. > > Signed-off-by: Raghavendra Rao Ananta <rananta@xxxxxxxxxx> > --- > arch/arm64/kvm/pmu-emul.c | 17 +++++++++++++++++ > include/kvm/arm_pmu.h | 6 ++++++ > 2 files changed, 23 insertions(+) > > diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c > index a161d6266a5c..84aa8efd9163 100644 > --- a/arch/arm64/kvm/pmu-emul.c > +++ b/arch/arm64/kvm/pmu-emul.c > @@ -873,6 +873,23 @@ static bool pmu_irq_is_valid(struct kvm *kvm, int irq) > return true; > } > > +/** > + * kvm_arm_get_num_counters - Get the number of general-purpose PMU counters. > + * @kvm: The kvm pointer > + */ > +int kvm_arm_get_num_counters(struct kvm *kvm) nit: the naming suggests this returns the configured number of PMCs, not the limit. Maybe kvm_arm_pmu_get_max_counters()? > +{ > + struct arm_pmu *arm_pmu = kvm->arch.arm_pmu; > + > + lockdep_assert_held(&kvm->arch.config_lock); > + > + /* > + * The arm_pmu->num_events considers the cycle counter as well. > + * Ignore that and return only the general-purpose counters. > + */ > + return arm_pmu->num_events - 1; > +} > + > static void kvm_arm_set_pmu(struct kvm *kvm, struct arm_pmu *arm_pmu) > { > lockdep_assert_held(&kvm->arch.config_lock); > diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h > index cd980d78b86b..672f3e9d7eea 100644 > --- a/include/kvm/arm_pmu.h > +++ b/include/kvm/arm_pmu.h > @@ -102,6 +102,7 @@ void kvm_vcpu_pmu_resync_el0(void); > > u8 kvm_arm_pmu_get_pmuver_limit(void); > int kvm_arm_set_default_pmu(struct kvm *kvm); > +int kvm_arm_get_num_counters(struct kvm *kvm); > > u64 kvm_vcpu_read_pmcr(struct kvm_vcpu *vcpu); > #else > @@ -181,6 +182,11 @@ static inline int kvm_arm_set_default_pmu(struct kvm *kvm) > return -ENODEV; > } > > +static inline int kvm_arm_get_num_counters(struct kvm *kvm) > +{ > + return -ENODEV; > +} > + > static inline u64 kvm_vcpu_read_pmcr(struct kvm_vcpu *vcpu) > { > return 0; > -- > 2.42.0.609.gbb76f46606-goog > -- Thanks, Oliver