From: Reiji Watanabe <reijiw@xxxxxxxxxx>
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, assign a
default PMU to the guest just before doing the reset.
Signed-off-by: Reiji Watanabe <reijiw@xxxxxxxxxx>
Signed-off-by: Raghavendra Rao Ananta <rananta@xxxxxxxxxx>
---
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 c6cad400490f9..08c2f76983b9d 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1319,6 +1319,21 @@ static bool kvm_vcpu_init_changed(struct kvm_vcpu *vcpu,
KVM_VCPU_MAX_FEATURES);
}
+static int kvm_setup_vcpu(struct kvm_vcpu *vcpu)
+{
+ struct kvm *kvm = vcpu->kvm;
+
+ /*
+ * 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 &&
+ kvm_arm_set_default_pmu(kvm))
+ return -EINVAL;
+
+ return 0;
+}
+
static int __kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
const struct kvm_vcpu_init *init)
{
@@ -1334,6 +1349,10 @@ static int __kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
bitmap_copy(kvm->arch.vcpu_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. */
kvm_reset_vcpu(vcpu);
diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index eb5dcb12dafe9..66c244021ff08 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -717,10 +717,9 @@ 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 just before the vcpu reset. 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
@@ -893,7 +892,7 @@ 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();
@@ -946,13 +945,6 @@ 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 3546ebc469ad7..858ed9ce828a6 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -101,6 +101,7 @@ void kvm_vcpu_pmu_resync_el0(void);
})
u8 kvm_arm_pmu_get_pmuver_limit(void);
+int kvm_arm_set_default_pmu(struct kvm *kvm);
#else
struct kvm_pmu {
@@ -174,6 +175,11 @@ static inline u8 kvm_arm_pmu_get_pmuver_limit(void)
}
static inline void kvm_vcpu_pmu_resync_el0(void) {}
+static inline int kvm_arm_set_default_pmu(struct kvm *kvm)
+{
+ return -ENODEV;
+}
+
#endif
#endif
--
2.42.0.655.g421f12c284-goog
