Convert the list of PMUs to a RCU-protected list that has primitives to avoid read-side contention.
Signed-off-by: Akihiko Odaki <[email protected]> --- arch/arm64/kvm/pmu-emul.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c index 59ec96e09321..ef5140bbfe28 100644 --- a/arch/arm64/kvm/pmu-emul.c +++ b/arch/arm64/kvm/pmu-emul.c @@ -7,9 +7,9 @@ #include <linux/cpu.h> #include <linux/kvm.h> #include <linux/kvm_host.h> -#include <linux/list.h> #include <linux/perf_event.h> #include <linux/perf/arm_pmu.h> +#include <linux/rculist.h> #include <linux/uaccess.h> #include <asm/kvm_emulate.h> #include <kvm/arm_pmu.h> @@ -26,7 +26,6 @@ static bool kvm_pmu_counter_is_enabled(struct kvm_pmc *pmc); bool kvm_supports_guest_pmuv3(void) { - guard(mutex)(&arm_pmus_lock); return !list_empty(&arm_pmus); } @@ -808,7 +807,7 @@ void kvm_host_pmu_init(struct arm_pmu *pmu) return; entry->arm_pmu = pmu; - list_add_tail(&entry->entry, &arm_pmus); + list_add_tail_rcu(&entry->entry, &arm_pmus); } static struct arm_pmu *kvm_pmu_probe_armpmu(void) @@ -817,7 +816,7 @@ static struct arm_pmu *kvm_pmu_probe_armpmu(void) struct arm_pmu *pmu; int cpu; - guard(mutex)(&arm_pmus_lock); + guard(rcu)(); /* * It is safe to use a stale cpu to iterate the list of PMUs so long as @@ -837,7 +836,7 @@ static struct arm_pmu *kvm_pmu_probe_armpmu(void) * carried here. */ cpu = raw_smp_processor_id(); - list_for_each_entry(entry, &arm_pmus, entry) { + list_for_each_entry_rcu(entry, &arm_pmus, entry) { pmu = entry->arm_pmu; if (cpumask_test_cpu(cpu, &pmu->supported_cpus)) @@ -1088,9 +1087,9 @@ static int kvm_arm_pmu_v3_set_pmu(struct kvm_vcpu *vcpu, int pmu_id) int ret = -ENXIO; lockdep_assert_held(&kvm->arch.config_lock); - mutex_lock(&arm_pmus_lock); + guard(rcu)(); - list_for_each_entry(entry, &arm_pmus, entry) { + list_for_each_entry_rcu(entry, &arm_pmus, entry) { arm_pmu = entry->arm_pmu; if (arm_pmu->pmu.type == pmu_id) { if (kvm_vm_has_ran_once(kvm) || @@ -1106,7 +1105,6 @@ static int kvm_arm_pmu_v3_set_pmu(struct kvm_vcpu *vcpu, int pmu_id) } } - mutex_unlock(&arm_pmus_lock); return ret; } -- 2.53.0
