linux-kernel - [PATCH v2 1/3] KVM: x86: Warn if KVM tries to deliver an #APF completion when APF is not enabled

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Message-ID: <20251015033258.50974-2-mlevitsk@redhat.com>
Date: Tue, 14 Oct 2025 23:32:56 -0400
From: Maxim Levitsky <mlevitsk@...hat.com>
To: kvm@...r.kernel.org
Cc: x86@...nel.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Ingo Molnar <mingo@...hat.com>,
	linux-kernel@...r.kernel.org,
	Sean Christopherson <seanjc@...gle.com>,
	Borislav Petkov <bp@...en8.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH v2 1/3] KVM: x86: Warn if KVM tries to deliver an #APF completion when APF is not enabled

KVM flushes the APF queue completely when the asynchronous pagefault is
disabled, therefore this case should not occur.

Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
---
 arch/x86/kvm/x86.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4b8138bd4857..22024de00cbd 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -13896,7 +13896,7 @@ void kvm_arch_async_page_present_queued(struct kvm_vcpu *vcpu)
 
 bool kvm_arch_can_dequeue_async_page_present(struct kvm_vcpu *vcpu)
 {
-	if (!kvm_pv_async_pf_enabled(vcpu))
+	if (WARN_ON_ONCE(!kvm_pv_async_pf_enabled(vcpu)))
 		return true;
 	else
 		return kvm_lapic_enabled(vcpu) && apf_pageready_slot_free(vcpu);
-- 
2.49.0