From: Reiji Watanabe <reijiw@google.com> mainline inclusion from mainline-v6.7-rc1 commit 427733579744ef22ee6d0da9907560d79d937458 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/IBN3WI Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h... ---------------------------------------------------------------------- Future changes to KVM's sysreg emulation will rely on having a valid PMU instance to determine the number of implemented counters (PMCR_EL0.N). This is earlier than when userspace is expected to modify the vPMU device attributes, where the default is selected today. Select the default PMU when handling KVM_ARM_VCPU_INIT such that it is available in time for sysreg emulation. Reviewed-by: Sebastian Ott <sebott@redhat.com> Co-developed-by: Marc Zyngier <maz@kernel.org> Signed-off-by: Marc Zyngier <maz@kernel.org> Signed-off-by: Reiji Watanabe <reijiw@google.com> Signed-off-by: Raghavendra Rao Ananta <rananta@google.com> Link: https://lore.kernel.org/r/20231020214053.2144305-3-rananta@google.com [Oliver: rewrite changelog] Signed-off-by: Oliver Upton <oliver.upton@linux.dev> --- arch/arm64/kvm/arm.c | 19 +++++++++++++++++++ arch/arm64/kvm/pmu-emul.c | 16 ++++------------ include/kvm/arm_pmu.h | 6 ++++++ 3 files changed, 29 insertions(+), 12 deletions(-) diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 57888cd1093b..3b168b1a28ce 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -1602,6 +1602,21 @@ static bool kvm_vcpu_init_changed(struct kvm_vcpu *vcpu, return !bitmap_equal(vcpu->arch.features, &features, KVM_VCPU_MAX_FEATURES); } +static int kvm_setup_vcpu(struct kvm_vcpu *vcpu) +{ + struct kvm *kvm = vcpu->kvm; + int ret = 0; + + /* + * When the vCPU has a PMU, but no PMU is set for the guest + * yet, set the default one. + */ + if (kvm_vcpu_has_pmu(vcpu) && !kvm->arch.arm_pmu) + ret = kvm_arm_set_default_pmu(kvm); + + return ret; +} + static int __kvm_vcpu_set_target(struct kvm_vcpu *vcpu, const struct kvm_vcpu_init *init) { @@ -1617,6 +1632,10 @@ static int __kvm_vcpu_set_target(struct kvm_vcpu *vcpu, bitmap_copy(vcpu->arch.features, &features, KVM_VCPU_MAX_FEATURES); + ret = kvm_setup_vcpu(vcpu); + if (ret) + goto out_unlock; + /* Now we know what it is, we can reset it. */ ret = kvm_reset_vcpu(vcpu); if (ret) { diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c index 1fb272b649d4..ebfbb3879522 100644 --- a/arch/arm64/kvm/pmu-emul.c +++ b/arch/arm64/kvm/pmu-emul.c @@ -742,10 +742,9 @@ static struct arm_pmu *kvm_pmu_probe_armpmu(void) * It is still necessary to get a valid cpu, though, to probe for the * default PMU instance as userspace is not required to specify a PMU * type. In order to uphold the preexisting behavior KVM selects the - * PMU instance for the core where the first call to the - * KVM_ARM_VCPU_PMU_V3_CTRL attribute group occurs. A dependent use case - * would be a user with disdain of all things big.LITTLE that affines - * the VMM to a particular cluster of cores. + * PMU instance for the core during vcpu init. A dependent use + * case would be a user with disdain of all things big.LITTLE that + * affines the VMM to a particular cluster of cores. * * In any case, userspace should just do the sane thing and use the UAPI * to select a PMU type directly. But, be wary of the baggage being @@ -919,7 +918,7 @@ static void kvm_arm_set_pmu(struct kvm *kvm, struct arm_pmu *arm_pmu) * 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) +int kvm_arm_set_default_pmu(struct kvm *kvm) { struct arm_pmu *arm_pmu = kvm_pmu_probe_armpmu(); @@ -990,13 +989,6 @@ int kvm_arm_pmu_v3_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr) if (vcpu->arch.pmu.created) return -EBUSY; - if (!kvm->arch.arm_pmu) { - int ret = kvm_arm_set_default_pmu(kvm); - - if (ret) - return ret; - } - switch (attr->attr) { case KVM_ARM_VCPU_PMU_V3_IRQ: { int __user *uaddr = (int __user *)(long)attr->addr; diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h index 295c726d11cd..6a518173e015 100644 --- a/include/kvm/arm_pmu.h +++ b/include/kvm/arm_pmu.h @@ -103,6 +103,7 @@ void kvm_vcpu_pmu_resync_el0(void); }) u8 kvm_arm_pmu_get_pmuver_limit(void); +int kvm_arm_set_default_pmu(struct kvm *kvm); u8 kvm_arm_pmu_get_max_counters(struct kvm *kvm); u64 kvm_pmu_evtyper_mask(struct kvm *kvm); @@ -185,6 +186,11 @@ static inline u64 kvm_pmu_evtyper_mask(struct kvm *kvm) } static inline void kvm_vcpu_pmu_resync_el0(void) {} +static inline int kvm_arm_set_default_pmu(struct kvm *kvm) +{ + return -ENODEV; +} + static inline u8 kvm_arm_pmu_get_max_counters(struct kvm *kvm) { return 0; -- 2.33.0