From cd9140ad8312234ec296d566a9d9d0b2b437ee7c Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 11 Jun 2025 14:35:51 -0700 Subject: [PATCH] KVM: x86: Explicitly check for in-kernel PIC when getting ExtINT Explicitly check for an in-kernel PIC when checking for a pending ExtINT in the PIC. Effectively swapping the split vs. full irqchip logic will allow guarding the in-kernel I/O APIC (and PIC) emulation with a Kconfig, and also makes it more obvious that kvm_pic_read_irq() won't result in a NULL pointer dereference. Opportunistically add WARNs in the fallthrough path, mostly to document that the userspace ExtINT logic is only relevant to split IRQ chips. Acked-by: Kai Huang Link: https://lore.kernel.org/r/20250611213557.294358-13-seanjc@google.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/irq.c | 25 ++++++++++++++++--------- 1 file changed, 16 insertions(+), 9 deletions(-) diff --git a/arch/x86/kvm/irq.c b/arch/x86/kvm/irq.c index b696161ec0786..fb3bad0f49657 100644 --- a/arch/x86/kvm/irq.c +++ b/arch/x86/kvm/irq.c @@ -42,6 +42,14 @@ static int pending_userspace_extint(struct kvm_vcpu *v) return v->arch.pending_external_vector != -1; } +static int get_userspace_extint(struct kvm_vcpu *vcpu) +{ + int vector = vcpu->arch.pending_external_vector; + + vcpu->arch.pending_external_vector = -1; + return vector; +} + /* * check if there is pending interrupt from * non-APIC source without intack. @@ -68,10 +76,11 @@ int kvm_cpu_has_extint(struct kvm_vcpu *v) if (!kvm_apic_accept_pic_intr(v)) return 0; - if (irqchip_split(v->kvm)) - return pending_userspace_extint(v); - else + if (pic_in_kernel(v->kvm)) return v->kvm->arch.vpic->output; + + WARN_ON_ONCE(!irqchip_split(v->kvm)); + return pending_userspace_extint(v); } /* @@ -127,13 +136,11 @@ int kvm_cpu_get_extint(struct kvm_vcpu *v) return v->kvm->arch.xen.upcall_vector; #endif - if (irqchip_split(v->kvm)) { - int vector = v->arch.pending_external_vector; - - v->arch.pending_external_vector = -1; - return vector; - } else + if (pic_in_kernel(v->kvm)) return kvm_pic_read_irq(v->kvm); /* PIC */ + + WARN_ON_ONCE(!irqchip_split(v->kvm)); + return get_userspace_extint(v); } EXPORT_SYMBOL_GPL(kvm_cpu_get_extint); -- 2.47.2