On 4/2/22 06:01, Li RongQing wrote:
pi_wakeup_handler is used to wakeup the sleep vCPUs by posted irq
list_for_each_entry is used in it, and whose input is other function
per_cpu(), That cause that per_cpu() be invoked at least twice when
there is one sleep vCPU
so optimize pi_wakeup_handler it by reading once which is safe in
spinlock protection
and same to per CPU spinlock
What's the difference in the generated code?
Paolo
Signed-off-by: Li RongQing <lirongqing@xxxxxxxxx>
---
arch/x86/kvm/vmx/posted_intr.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c
index 5fdabf3..0dae431 100644
--- a/arch/x86/kvm/vmx/posted_intr.c
+++ b/arch/x86/kvm/vmx/posted_intr.c
@@ -214,17 +214,21 @@ void vmx_vcpu_pi_put(struct kvm_vcpu *vcpu)
*/
void pi_wakeup_handler(void)
{
+ struct list_head *wakeup_list;
int cpu = smp_processor_id();
+ raw_spinlock_t *spinlock;
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) {
+ spinlock = &per_cpu(wakeup_vcpus_on_cpu_lock, cpu);
+
+ raw_spin_lock(spinlock);
+ wakeup_list = &per_cpu(wakeup_vcpus_on_cpu, cpu);
+ 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)
