[PATCH v2 13/35] KVM: x86: hyper-v: optimize and cleanup kvm_hv_process_stimers()

Yury Norov
2023-12-03T19:34:04Z

The function traverses stimer_pending_bitmap in a for-loop bit by bit.
We can do it faster by using atomic find_and_set_bit().

While here, refactor the logic by decreasing indentation level.

CC: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
arch/x86/kvm/hyperv.c | 39 +++++++++++++++++++--------------------
1 file changed, 19 insertions(+), 20 deletions(-)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 238afd7335e4..a0e45d20d451 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -870,27 +870,26 @@ void kvm_hv_process_stimers(struct kvm_vcpu *vcpu)
if (!hv_vcpu)
return;

- for (i = 0; i < ARRAY_SIZE(hv_vcpu->stimer); i++)
- if (test_and_clear_bit(i, hv_vcpu->stimer_pending_bitmap)) {
- stimer = &hv_vcpu->stimer[i];
- if (stimer->config.enable) {
- exp_time = stimer->exp_time;
-
- if (exp_time) {
- time_now =
- get_time_ref_counter(vcpu->kvm);
- if (time_now >= exp_time)
- stimer_expiration(stimer);
- }
-
- if ((stimer->config.enable) &&
- stimer->count) {
- if (!stimer->msg_pending)
- stimer_start(stimer);
- } else
- stimer_cleanup(stimer);
- }
+ for_each_test_and_clear_bit(i, hv_vcpu->stimer_pending_bitmap,
+ ARRAY_SIZE(hv_vcpu->stimer)) {
+ stimer = &hv_vcpu->stimer[i];
+ if (!stimer->config.enable)
+ continue;
+
+ exp_time = stimer->exp_time;
+
+ if (exp_time) {
+ time_now = get_time_ref_counter(vcpu->kvm);
+ if (time_now >= exp_time)
+ stimer_expiration(stimer);
}
+
+ if (stimer->config.enable && stimer->count) {
+ if (!stimer->msg_pending)
+ stimer_start(stimer);
+ } else
+ stimer_cleanup(stimer);
+ }
}

void kvm_hv_vcpu_uninit(struct kvm_vcpu *vcpu)
--
2.40.1