KVM: async_pf: change kvm_setup_async_pf()/kvm_arch_setup_async_pf() return type to bool

Unlike normal 'int' functions returning '0' on success, kvm_setup_async_pf()/
kvm_arch_setup_async_pf() return '1' when a job to handle page fault
asynchronously was scheduled and '0' otherwise. To avoid the confusion
change return type to 'bool'.

No functional change intended.
Suggested-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200615121334.91300-1-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/s390/kvm/kvm-s390.c

@@ -3954,33 +3954,31 @@ bool kvm_arch_can_dequeue_async_page_present(struct kvm_vcpu *vcpu)
 	return true;
 }
 
-static int kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu)
+static bool kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu)
 {
 	hva_t hva;
 	struct kvm_arch_async_pf arch;
-	int rc;
 
 	if (vcpu->arch.pfault_token == KVM_S390_PFAULT_TOKEN_INVALID)
-		return 0;
+		return false;
 	if ((vcpu->arch.sie_block->gpsw.mask & vcpu->arch.pfault_select) !=
 	    vcpu->arch.pfault_compare)
-		return 0;
+		return false;
 	if (psw_extint_disabled(vcpu))
-		return 0;
+		return false;
 	if (kvm_s390_vcpu_has_irq(vcpu, 0))
-		return 0;
+		return false;
 	if (!(vcpu->arch.sie_block->gcr[0] & CR0_SERVICE_SIGNAL_SUBMASK))
-		return 0;
+		return false;
 	if (!vcpu->arch.gmap->pfault_enabled)
-		return 0;
+		return false;
 
 	hva = gfn_to_hva(vcpu->kvm, gpa_to_gfn(current->thread.gmap_addr));
 	hva += current->thread.gmap_addr & ~PAGE_MASK;
 	if (read_guest_real(vcpu, vcpu->arch.pfault_token, &arch.pfault_token, 8))
-		return 0;
+		return false;
 
-	rc = kvm_setup_async_pf(vcpu, current->thread.gmap_addr, hva, &arch);
-	return rc;
+	return kvm_setup_async_pf(vcpu, current->thread.gmap_addr, hva, &arch);
 }
 
 static int vcpu_pre_run(struct kvm_vcpu *vcpu)

arch/x86/kvm/mmu/mmu.c

@@ -4045,7 +4045,7 @@ static void shadow_page_table_clear_flood(struct kvm_vcpu *vcpu, gva_t addr)
 	walk_shadow_page_lockless_end(vcpu);
 }
 
-static int kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
+static bool kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 				    gfn_t gfn)
 {
 	struct kvm_arch_async_pf arch;

include/linux/kvm_host.h

@@ -211,7 +211,7 @@ struct kvm_async_pf {
 
 void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu);
 void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu);
-int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
+bool kvm_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 			unsigned long hva, struct kvm_arch_async_pf *arch);
 int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu);
 #endif

virt/kvm/async_pf.c

@@ -156,17 +156,21 @@ void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu)
 	}
 }
 
-int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
+/*
+ * Try to schedule a job to handle page fault asynchronously. Returns 'true' on
+ * success, 'false' on failure (page fault has to be handled synchronously).
+ */
+bool kvm_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 			unsigned long hva, struct kvm_arch_async_pf *arch)
 {
 	struct kvm_async_pf *work;
 
 	if (vcpu->async_pf.queued >= ASYNC_PF_PER_VCPU)
-		return 0;
+		return false;
 
 	/* Arch specific code should not do async PF in this case */
 	if (unlikely(kvm_is_error_hva(hva)))
-		return 0;
+		return false;
 
 	/*
 	 * do alloc nowait since if we are going to sleep anyway we
@@ -174,7 +178,7 @@ int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 	 */
 	work = kmem_cache_zalloc(async_pf_cache, GFP_NOWAIT | __GFP_NOWARN);
 	if (!work)
-		return 0;
+		return false;
 
 	work->wakeup_all = false;
 	work->vcpu = vcpu;
@@ -193,7 +197,7 @@ int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 
 	schedule_work(&work->work);
 
-	return 1;
+	return true;
 }
 
 int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu)