| Message ID | 20231009230858.3444834-2-rananta@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: arm64: PMU: Allow userspace to limit the number of PMCs on vCPU | expand |
Hi Reiji, On 10/10/23 01:08, Raghavendra Rao Ananta wrote: > From: Reiji Watanabe <reijiw@google.com> > > 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@google.com> > Signed-off-by: Raghavendra Rao Ananta <rananta@google.com> Reviewed-by: Eric Auger <eric.auger@redhat.com> 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) {
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) {