[PATCH 1/5] KVM: arm64: Divorce the perf code from oprofile helpers

Marc Zyngier
2021-04-14T13:44:25Z

KVM/arm64 is the sole user of perf_num_counters(), and really
could do without it. Stop using the obsolete API by relying on
the existing probing code.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/kvm/perf.c | 7 +------
arch/arm64/kvm/pmu-emul.c | 2 +-
include/kvm/arm_pmu.h | 4 ++++
3 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/kvm/perf.c b/arch/arm64/kvm/perf.c
index 739164324afe..b8b398670ef2 100644
--- a/arch/arm64/kvm/perf.c
+++ b/arch/arm64/kvm/perf.c
@@ -50,12 +50,7 @@ static struct perf_guest_info_callbacks kvm_guest_cbs = {

int kvm_perf_init(void)
{
- /*
- * Check if HW_PERF_EVENTS are supported by checking the number of
- * hardware performance counters. This could ensure the presence of
- * a physical PMU and CONFIG_PERF_EVENT is selected.
- */
- if (IS_ENABLED(CONFIG_ARM_PMU) && perf_num_counters() > 0)
+ if (kvm_pmu_probe_pmuver() != 0xf)
static_branch_enable(&kvm_arm_pmu_available);

return perf_register_guest_info_callbacks(&kvm_guest_cbs);
diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index e32c6e139a09..fd167d4f4215 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -739,7 +739,7 @@ void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, u64 data,
kvm_pmu_create_perf_event(vcpu, select_idx);
}

-static int kvm_pmu_probe_pmuver(void)
+int kvm_pmu_probe_pmuver(void)
{
struct perf_event_attr attr = { };
struct perf_event *event;
diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index 6fd3cda608e4..864b9997efb2 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -61,6 +61,7 @@ int kvm_arm_pmu_v3_get_attr(struct kvm_vcpu *vcpu,
int kvm_arm_pmu_v3_has_attr(struct kvm_vcpu *vcpu,
struct kvm_device_attr *attr);
int kvm_arm_pmu_v3_enable(struct kvm_vcpu *vcpu);
+int kvm_pmu_probe_pmuver(void);
#else
struct kvm_pmu {
};
@@ -116,6 +117,9 @@ static inline u64 kvm_pmu_get_pmceid(struct kvm_vcpu *vcpu, bool pmceid1)
{
return 0;
}
+
+static inline int kvm_pmu_probe_pmuver(void) { return 0xf; }
+
#endif

#endif
--
2.29.2