[PATCH v5 02/12] KVM: arm64: PMU: Set the default PMU for the guest on vCPU reset

Raghavendra Rao Ananta
2023-08-17T00:31:30Z

From: Reiji Watanabe <reijiw@google.com>

The following patches will use the number of counters information
from the arm_pmu and use this to set the PMCR.N for the guest
during vCPU reset. However, since the guest is not associated
with any arm_pmu until userspace configures the vPMU device
attributes, and a reset can happen before this event, call
kvm_arm_support_pmu_v3() just before doing the reset.

No functional change intended.

Signed-off-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
---
arch/arm64/kvm/pmu-emul.c | 9 +--------
arch/arm64/kvm/reset.c | 18 +++++++++++++-----
include/kvm/arm_pmu.h | 6 ++++++
3 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index 0ffd1efa90c07..b87822024828a 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -865,7 +865,7 @@ static bool pmu_irq_is_valid(struct kvm *kvm, int irq)
return true;
}

-static int kvm_arm_set_vm_pmu(struct kvm *kvm, struct arm_pmu *arm_pmu)
+int kvm_arm_set_vm_pmu(struct kvm *kvm, struct arm_pmu *arm_pmu)
{
lockdep_assert_held(&kvm->arch.config_lock);

@@ -937,13 +937,6 @@ 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_vm_pmu(kvm, NULL);
-
- 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/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index bc8556b6f4590..4c20f1ccd0789 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -206,6 +206,7 @@ static int kvm_vcpu_enable_ptrauth(struct kvm_vcpu *vcpu)
*/
int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
{
+ struct kvm *kvm = vcpu->kvm;
struct vcpu_reset_state reset_state;
int ret;
bool loaded;
@@ -216,6 +217,18 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
vcpu->arch.reset_state.reset = false;
spin_unlock(&vcpu->arch.mp_state_lock);

+ /*
+ * 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) && unlikely(!kvm->arch.arm_pmu)) {
+ ret = -EINVAL;
+ if (kvm_arm_support_pmu_v3())
+ ret = kvm_arm_set_vm_pmu(kvm, NULL);
+ if (ret)
+ return ret;
+ }
+
/* Reset PMU outside of the non-preemptible section */
kvm_pmu_vcpu_reset(vcpu);

@@ -257,11 +270,6 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
} else {
pstate = VCPU_RESET_PSTATE_EL1;
}
-
- if (kvm_vcpu_has_pmu(vcpu) && !kvm_arm_support_pmu_v3()) {
- ret = -EINVAL;
- goto out;
- }
break;
}

diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index 847da6fc27139..66a2f8477641e 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -100,6 +100,7 @@ void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu);
})

u8 kvm_arm_pmu_get_pmuver_limit(void);
+int kvm_arm_set_vm_pmu(struct kvm *kvm, struct arm_pmu *arm_pmu);

#else
struct kvm_pmu {
@@ -172,6 +173,11 @@ static inline u8 kvm_arm_pmu_get_pmuver_limit(void)
return 0;
}

+static inline int kvm_arm_set_vm_pmu(struct kvm *kvm, struct arm_pmu *arm_pmu)
+{
+ return -ENODEV;
+}
+
#endif

#endif
--
2.41.0.694.ge786442a9b-goog