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    SubjectRe: [PATCH v2 23/43] KVM: VMX: Use boolean returns for Posted Interrupt "test" helpers
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    On Fri, 2021-10-08 at 19:12 -0700, Sean Christopherson wrote:
    > Return bools instead of ints for the posted interrupt "test" helpers.
    > The bit position of the flag being test does not matter to the callers,
    > and is in fact lost by virtue of test_bit() itself returning a bool.
    >
    > Returning ints is potentially dangerous, e.g. "pi_test_on(pi_desc) == 1"
    > is safe-ish because ON is bit 0 and thus any sane implementation of
    > pi_test_on() will work, but for SN (bit 1), checking "== 1" would rely on
    > pi_test_on() to return 0 or 1, a.k.a. bools, as opposed to 0 or 2 (the
    > positive bit position).
    >
    > Signed-off-by: Sean Christopherson <seanjc@google.com>
    > ---
    > arch/x86/kvm/vmx/posted_intr.c | 4 ++--
    > arch/x86/kvm/vmx/posted_intr.h | 6 +++---
    > 2 files changed, 5 insertions(+), 5 deletions(-)
    >
    > diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c
    > index 6c2110d91b06..1688f8dc535a 100644
    > --- a/arch/x86/kvm/vmx/posted_intr.c
    > +++ b/arch/x86/kvm/vmx/posted_intr.c
    > @@ -185,7 +185,7 @@ int pi_pre_block(struct kvm_vcpu *vcpu)
    > new.control) != old.control);
    >
    > /* We should not block the vCPU if an interrupt is posted for it. */
    > - if (pi_test_on(pi_desc) == 1)
    > + if (pi_test_on(pi_desc))
    > __pi_post_block(vcpu);
    >
    > local_irq_enable();
    > @@ -216,7 +216,7 @@ void pi_wakeup_handler(void)
    > blocked_vcpu_list) {
    > struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
    >
    > - if (pi_test_on(pi_desc) == 1)
    > + if (pi_test_on(pi_desc))
    > kvm_vcpu_kick(vcpu);
    > }
    > spin_unlock(&per_cpu(blocked_vcpu_on_cpu_lock, cpu));
    > diff --git a/arch/x86/kvm/vmx/posted_intr.h b/arch/x86/kvm/vmx/posted_intr.h
    > index 7f7b2326caf5..36ae035f14aa 100644
    > --- a/arch/x86/kvm/vmx/posted_intr.h
    > +++ b/arch/x86/kvm/vmx/posted_intr.h
    > @@ -40,7 +40,7 @@ static inline bool pi_test_and_clear_on(struct pi_desc *pi_desc)
    > (unsigned long *)&pi_desc->control);
    > }
    >
    > -static inline int pi_test_and_set_pir(int vector, struct pi_desc *pi_desc)
    > +static inline bool pi_test_and_set_pir(int vector, struct pi_desc *pi_desc)
    > {
    > return test_and_set_bit(vector, (unsigned long *)pi_desc->pir);
    > }
    > @@ -74,13 +74,13 @@ static inline void pi_clear_sn(struct pi_desc *pi_desc)
    > (unsigned long *)&pi_desc->control);
    > }
    >
    > -static inline int pi_test_on(struct pi_desc *pi_desc)
    > +static inline bool pi_test_on(struct pi_desc *pi_desc)
    > {
    > return test_bit(POSTED_INTR_ON,
    > (unsigned long *)&pi_desc->control);
    > }
    >
    > -static inline int pi_test_sn(struct pi_desc *pi_desc)
    > +static inline bool pi_test_sn(struct pi_desc *pi_desc)
    > {
    > return test_bit(POSTED_INTR_SN,
    > (unsigned long *)&pi_desc->control);
    Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>

    Best regards,
    Maxim Levitsky

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