| Message ID | 20220123183925.1052919-7-yury.norov@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | None | expand |
Yury Norov <yury.norov@gmail.com> writes: > 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); I would've preferred this written as auto_eoi_old = !bitmap_empty(synic->auto_eoi_bitmap, 256); so the variable would indicate wether AutoEOI was previosly enabled, not disabled. > > 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); Same here, of course. "auto_eoi_new = true" sounds like "AutoEOI is now enabled". > > - if (!!auto_eoi_old == !!auto_eoi_new) > + if (auto_eoi_old == auto_eoi_new) > return; > > down_write(&vcpu->kvm->arch.apicv_update_lock); The change look good to me otherwise, feel free to add Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
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);
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(-)