From 91ab933f7514fc0fb42b77dc6d128c450baeae0b Mon Sep 17 00:00:00 2001
From: Li RongQing <lirongqing@baidu.com>
Date: Wed, 6 Apr 2022 19:25:02 +0800
Subject: [PATCH] KVM: VMX: clean up pi_wakeup_handler
Passing per_cpu() to list_for_each_entry() causes the macro to be
evaluated N+1 times for N sleeping vCPUs. This is a very small
inefficiency, and the code is cleaner if the address of the per-CPU
variable is loaded earlier. Do this for both the list and the spinlock.
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Message-Id: <1649244302-6777-1-git-send-email-lirongqing@baidu.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/vmx/posted_intr.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c
index 37d0bfff269d..07e5fcf5a5aa 100644
--- a/arch/x86/kvm/vmx/posted_intr.c
+++ b/arch/x86/kvm/vmx/posted_intr.c
@@ -202,16 +202,17 @@ void vmx_vcpu_pi_put(struct kvm_vcpu *vcpu)
void pi_wakeup_handler(void)
{
int cpu = smp_processor_id();
+ struct list_head *wakeup_list = &per_cpu(wakeup_vcpus_on_cpu, cpu);
+ raw_spinlock_t *spinlock = &per_cpu(wakeup_vcpus_on_cpu_lock, cpu);
struct vcpu_vmx *vmx;
- raw_spin_lock(&per_cpu(wakeup_vcpus_on_cpu_lock, cpu));
- list_for_each_entry(vmx, &per_cpu(wakeup_vcpus_on_cpu, cpu),
- pi_wakeup_list) {
+ raw_spin_lock(spinlock);
+ list_for_each_entry(vmx, wakeup_list, pi_wakeup_list) {
if (pi_test_on(&vmx->pi_desc))
kvm_vcpu_wake_up(&vmx->vcpu);
}
- raw_spin_unlock(&per_cpu(wakeup_vcpus_on_cpu_lock, cpu));
+ raw_spin_unlock(spinlock);
}
void __init pi_init_cpu(int cpu)