linux-kernel - [PATCH v2 23/43] KVM: VMX: Use boolean returns for Posted Interrupt "test" helpers

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Message-Id: <20211009021236.4122790-24-seanjc@google.com>
Date:   Fri,  8 Oct 2021 19:12:16 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Marc Zyngier <maz@...nel.org>, Huacai Chen <chenhuacai@...nel.org>,
        Aleksandar Markovic <aleksandar.qemu.devel@...il.com>,
        Paul Mackerras <paulus@...abs.org>,
        Anup Patel <anup.patel@....com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Atish Patra <atish.patra@....com>,
        David Hildenbrand <david@...hat.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-mips@...r.kernel.org, kvm@...r.kernel.org,
        kvm-ppc@...r.kernel.org, kvm-riscv@...ts.infradead.org,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        David Matlack <dmatlack@...gle.com>,
        Oliver Upton <oupton@...gle.com>,
        Jing Zhang <jingzhangos@...gle.com>
Subject: [PATCH v2 23/43] KVM: VMX: Use boolean returns for Posted Interrupt
 "test" helpers

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@...gle.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);
-- 
2.33.0.882.g93a45727a2-goog