From: Jim Mattson jmattson@google.com
[ Upstream commit 7ff775aca48adc854436b92c060e5eebfffb6a4a ]
The PMU event filter may contain up to 300 events. Replace the linear search in reprogram_gp_counter() with a binary search.
Signed-off-by: Jim Mattson jmattson@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Message-Id: 20220115052431.447232-2-jmattson@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/kvm/pmu.c | 30 +++++++++++++++++++----------- 1 file changed, 19 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c index 2f83b5d948b3..350e7cdaad02 100644 --- a/arch/x86/kvm/pmu.c +++ b/arch/x86/kvm/pmu.c @@ -13,6 +13,8 @@ #include <linux/types.h> #include <linux/kvm_host.h> #include <linux/perf_event.h> +#include <linux/bsearch.h> +#include <linux/sort.h> #include <asm/perf_event.h> #include "x86.h" #include "cpuid.h" @@ -168,13 +170,17 @@ static bool pmc_resume_counter(struct kvm_pmc *pmc) return true; }
+static int cmp_u64(const void *a, const void *b) +{ + return *(__u64 *)a - *(__u64 *)b; +} + void reprogram_gp_counter(struct kvm_pmc *pmc, u64 eventsel) { u64 config; u32 type = PERF_TYPE_RAW; struct kvm *kvm = pmc->vcpu->kvm; struct kvm_pmu_event_filter *filter; - int i; bool allow_event = true;
if (eventsel & ARCH_PERFMON_EVENTSEL_PIN_CONTROL) @@ -189,16 +195,13 @@ void reprogram_gp_counter(struct kvm_pmc *pmc, u64 eventsel)
filter = srcu_dereference(kvm->arch.pmu_event_filter, &kvm->srcu); if (filter) { - for (i = 0; i < filter->nevents; i++) - if (filter->events[i] == - (eventsel & AMD64_RAW_EVENT_MASK_NB)) - break; - if (filter->action == KVM_PMU_EVENT_ALLOW && - i == filter->nevents) - allow_event = false; - if (filter->action == KVM_PMU_EVENT_DENY && - i < filter->nevents) - allow_event = false; + __u64 key = eventsel & AMD64_RAW_EVENT_MASK_NB; + + if (bsearch(&key, filter->events, filter->nevents, + sizeof(__u64), cmp_u64)) + allow_event = filter->action == KVM_PMU_EVENT_ALLOW; + else + allow_event = filter->action == KVM_PMU_EVENT_DENY; } if (!allow_event) return; @@ -507,6 +510,11 @@ int kvm_vm_ioctl_set_pmu_event_filter(struct kvm *kvm, void __user *argp) /* Ensure nevents can't be changed between the user copies. */ *filter = tmp;
+ /* + * Sort the in-kernel list so that we can search it with bsearch. + */ + sort(&filter->events, filter->nevents, sizeof(__u64), cmp_u64, NULL); + mutex_lock(&kvm->lock); filter = rcu_replace_pointer(kvm->arch.pmu_event_filter, filter, mutex_is_locked(&kvm->lock));