Hi Reiji,
On 10/10/23 01:08, Raghavendra Rao Ananta wrote:
> From: Reiji Watanabe <reijiw@xxxxxxxxxx>
>
> Introduce new helper functions to set the guest's PMU
> (kvm->arch.arm_pmu) either to a default probed instance or to a
> caller requested one, and use it when the guest's PMU needs to
> be set. These helpers will make it easier for the following
> patches to modify the relevant code.
>
> No functional change intended.
>
> Signed-off-by: Reiji Watanabe <reijiw@xxxxxxxxxx>
> Signed-off-by: Raghavendra Rao Ananta <rananta@xxxxxxxxxx>
Reviewed-by: Eric Auger <eric.auger@xxxxxxxxxx>
Eric
> ---
> arch/arm64/kvm/pmu-emul.c | 50 +++++++++++++++++++++++++++------------
> 1 file changed, 35 insertions(+), 15 deletions(-)
>
> diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
> index 3afb281ed8d2..eb5dcb12dafe 100644
> --- a/arch/arm64/kvm/pmu-emul.c
> +++ b/arch/arm64/kvm/pmu-emul.c
> @@ -874,6 +874,36 @@ static bool pmu_irq_is_valid(struct kvm *kvm, int irq)
> return true;
> }
>
> +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_arm_set_default_pmu - No PMU set, get the default one.
> + * @kvm: The kvm pointer
> + *
> + * The observant among you will notice that the supported_cpus
> + * mask does not get updated for the default PMU even though it
> + * is quite possible the selected instance supports only a
> + * subset of cores in the system. This is intentional, and
> + * upholds the preexisting behavior on heterogeneous systems
> + * where vCPUs can be scheduled on any core but the guest
> + * counters could stop working.
> + */
> +static int kvm_arm_set_default_pmu(struct kvm *kvm)
> +{
> + struct arm_pmu *arm_pmu = kvm_pmu_probe_armpmu();
> +
> + if (!arm_pmu)
> + return -ENODEV;
> +
> + kvm_arm_set_pmu(kvm, arm_pmu);
> + return 0;
> +}
> +
> static int kvm_arm_pmu_v3_set_pmu(struct kvm_vcpu *vcpu, int pmu_id)
> {
> struct kvm *kvm = vcpu->kvm;
> @@ -893,7 +923,7 @@ static int kvm_arm_pmu_v3_set_pmu(struct kvm_vcpu *vcpu, int pmu_id)
> break;
> }
>
> - kvm->arch.arm_pmu = arm_pmu;
> + kvm_arm_set_pmu(kvm, arm_pmu);
> cpumask_copy(kvm->arch.supported_cpus, &arm_pmu->supported_cpus);
> ret = 0;
> break;
> @@ -917,20 +947,10 @@ int kvm_arm_pmu_v3_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
> return -EBUSY;
>
> if (!kvm->arch.arm_pmu) {
> - /*
> - * No PMU set, get the default one.
> - *
> - * The observant among you will notice that the supported_cpus
> - * mask does not get updated for the default PMU even though it
> - * is quite possible the selected instance supports only a
> - * subset of cores in the system. This is intentional, and
> - * upholds the preexisting behavior on heterogeneous systems
> - * where vCPUs can be scheduled on any core but the guest
> - * counters could stop working.
> - */
> - kvm->arch.arm_pmu = kvm_pmu_probe_armpmu();
> - if (!kvm->arch.arm_pmu)
> - return -ENODEV;
> + int ret = kvm_arm_set_default_pmu(kvm);
> +
> + if (ret)
> + return ret;
> }
>
> switch (attr->attr) {
