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Subject[PATCH 06/54] x86/kvm: replace bitmap_weight with bitmap_empty where appropriate
Date
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>
---
arch/x86/kvm/hyperv.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 6e38a7d22e97..2c3400dea4b3 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);
--
2.30.2
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