diff mbox series

[07/49] KVM: x86: replace bitmap_weight with bitmap_empty where appropriate

Message ID 20220210224933.379149-8-yury.norov@gmail.com (mailing list archive)
State New, archived
Headers show
Series None | expand

Commit Message

Yury Norov Feb. 10, 2022, 10:48 p.m. UTC 
In some places kvm/hyperv.c code calls bitmap_weight() to check if any bit
of a given bitmap is set. It's better to use bitmap_empty() in that case
because bitmap_empty() stops traversing the bitmap as soon as it finds
first set bit, while bitmap_weight() counts all bits unconditionally.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 arch/x86/kvm/hyperv.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Comments

Sean Christopherson Feb. 11, 2022, 4:34 p.m. UTC | #1 
On Thu, Feb 10, 2022, Yury Norov wrote:
> In some places kvm/hyperv.c code calls bitmap_weight() to check if any bit
> of a given bitmap is set. It's better to use bitmap_empty() in that case
> because bitmap_empty() stops traversing the bitmap as soon as it finds
> first set bit, while bitmap_weight() counts all bits unconditionally.
> 
> Signed-off-by: Yury Norov <yury.norov@gmail.com>
> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> ---

Reviewed-by: Sean Christopherson <seanjc@google.com>
diff mbox series

Patch

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 6e38a7d22e97..06c2a5603123 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -90,7 +90,7 @@  static void synic_update_vector(struct kvm_vcpu_hv_synic *synic,
 {
 	struct kvm_vcpu *vcpu = hv_synic_to_vcpu(synic);
 	struct kvm_hv *hv = to_kvm_hv(vcpu->kvm);
-	int auto_eoi_old, auto_eoi_new;
+	bool auto_eoi_old, auto_eoi_new;
 
 	if (vector < HV_SYNIC_FIRST_VALID_VECTOR)
 		return;
@@ -100,16 +100,16 @@  static void synic_update_vector(struct kvm_vcpu_hv_synic *synic,
 	else
 		__clear_bit(vector, synic->vec_bitmap);
 
-	auto_eoi_old = bitmap_weight(synic->auto_eoi_bitmap, 256);
+	auto_eoi_old = !bitmap_empty(synic->auto_eoi_bitmap, 256);
 
 	if (synic_has_vector_auto_eoi(synic, vector))
 		__set_bit(vector, synic->auto_eoi_bitmap);
 	else
 		__clear_bit(vector, synic->auto_eoi_bitmap);
 
-	auto_eoi_new = bitmap_weight(synic->auto_eoi_bitmap, 256);
+	auto_eoi_new = !bitmap_empty(synic->auto_eoi_bitmap, 256);
 
-	if (!!auto_eoi_old == !!auto_eoi_new)
+	if (auto_eoi_old == auto_eoi_new)
 		return;
 
 	down_write(&vcpu->kvm->arch.apicv_update_lock);