From: Sean Christopherson Date: Thu, 12 Jun 2025 23:51:47 +0000 (-0700) Subject: KVM: arm64: WARN if unmapping a vLPI fails in any path X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cd4178d19420359554e3da6fd77ecfd0f58067ce;p=thirdparty%2Fkernel%2Fstable.git KVM: arm64: WARN if unmapping a vLPI fails in any path When unmapping a vLPI, WARN if nullifying vCPU affinity fails, not just if failure occurs when freeing an ITE. If undoing vCPU affinity fails, then odds are very good that vLPI state tracking has has gotten out of whack, i.e. that KVM and the GIC disagree on the state of an IRQ/vLPI. At best, inconsistent state means there is a lurking bug/flaw somewhere. At worst, the inconsistency could eventually be fatal to the host, e.g. if an ITS command fails because KVM's view of things doesn't match reality/hardware. Note, only the call from kvm_arch_irq_bypass_del_producer() by way of kvm_vgic_v4_unset_forwarding() doesn't already WARN. Common KVM's kvm_irq_routing_update() WARNs if kvm_arch_update_irqfd_routing() fails. For that path, if its_unmap_vlpi() fails in kvm_vgic_v4_unset_forwarding(), the only possible causes are that the GIC doesn't have a v4 ITS (from its_irq_set_vcpu_affinity()): /* Need a v4 ITS */ if (!is_v4(its_dev->its)) return -EINVAL; guard(raw_spinlock)(&its_dev->event_map.vlpi_lock); /* Unmap request? */ if (!info) return its_vlpi_unmap(d); or that KVM has gotten out of sync with the GIC/ITS (from its_vlpi_unmap()): if (!its_dev->event_map.vm || !irqd_is_forwarded_to_vcpu(d)) return -EINVAL; All of the above failure scenarios are warnable offences, as they should never occur absent a kernel/KVM bug. Acked-by: Oliver Upton Link: https://lore.kernel.org/all/aFWY2LTVIxz5rfhh@google.com Signed-off-by: Sean Christopherson --- diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c index 534049c7c94b2..98630dae910d2 100644 --- a/arch/arm64/kvm/vgic/vgic-its.c +++ b/arch/arm64/kvm/vgic/vgic-its.c @@ -758,7 +758,7 @@ static void its_free_ite(struct kvm *kvm, struct its_ite *ite) if (irq) { scoped_guard(raw_spinlock_irqsave, &irq->irq_lock) { if (irq->hw) - WARN_ON(its_unmap_vlpi(ite->irq->host_irq)); + its_unmap_vlpi(ite->irq->host_irq); irq->hw = false; } diff --git a/arch/arm64/kvm/vgic/vgic-v4.c b/arch/arm64/kvm/vgic/vgic-v4.c index 1939461081923..911170d4a9c85 100644 --- a/arch/arm64/kvm/vgic/vgic-v4.c +++ b/arch/arm64/kvm/vgic/vgic-v4.c @@ -545,10 +545,10 @@ int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int host_irq) if (irq->hw) { atomic_dec(&irq->target_vcpu->arch.vgic_cpu.vgic_v3.its_vpe.vlpi_count); irq->hw = false; - ret = its_unmap_vlpi(host_irq); + its_unmap_vlpi(host_irq); } raw_spin_unlock_irqrestore(&irq->irq_lock, flags); vgic_put_irq(kvm, irq); - return ret; + return 0; } diff --git a/drivers/irqchip/irq-gic-v4.c b/drivers/irqchip/irq-gic-v4.c index 58c28895f8c42..8455b4a5fbb0d 100644 --- a/drivers/irqchip/irq-gic-v4.c +++ b/drivers/irqchip/irq-gic-v4.c @@ -342,10 +342,10 @@ int its_get_vlpi(int irq, struct its_vlpi_map *map) return irq_set_vcpu_affinity(irq, &info); } -int its_unmap_vlpi(int irq) +void its_unmap_vlpi(int irq) { irq_clear_status_flags(irq, IRQ_DISABLE_UNLAZY); - return irq_set_vcpu_affinity(irq, NULL); + WARN_ON_ONCE(irq_set_vcpu_affinity(irq, NULL)); } int its_prop_update_vlpi(int irq, u8 config, bool inv) diff --git a/include/linux/irqchip/arm-gic-v4.h b/include/linux/irqchip/arm-gic-v4.h index 7f1f11a5e4e44..0b0887099fd7a 100644 --- a/include/linux/irqchip/arm-gic-v4.h +++ b/include/linux/irqchip/arm-gic-v4.h @@ -146,7 +146,7 @@ int its_commit_vpe(struct its_vpe *vpe); int its_invall_vpe(struct its_vpe *vpe); int its_map_vlpi(int irq, struct its_vlpi_map *map); int its_get_vlpi(int irq, struct its_vlpi_map *map); -int its_unmap_vlpi(int irq); +void its_unmap_vlpi(int irq); int its_prop_update_vlpi(int irq, u8 config, bool inv); int its_prop_update_vsgi(int irq, u8 priority, bool group);