diff options
| author | Oliver Upton <oliver.upton@linux.dev> | 2025-02-26 21:31:21 +0300 |
|---|---|---|
| committer | Oliver Upton <oliver.upton@linux.dev> | 2025-02-27 00:22:48 +0300 |
| commit | a0d7e2fc61ab54f1be817c9300231a1b48432628 (patch) | |
| tree | b5b1d63be9d570312b76d1b66713316de71a9ec9 | |
| parent | 0ad2507d5d93f39619fc42372c347d6006b64319 (diff) | |
| download | linux-a0d7e2fc61ab54f1be817c9300231a1b48432628.tar.xz | |
KVM: arm64: vgic-v4: Only attempt vLPI mapping for actual MSIs
Some 'creative' VMMs out there may assign a VFIO MSI eventfd to an SPI
routing entry.
And yes, I can already hear you shouting about possibly driving a level
interrupt with an edge-sensitive one. You know who you are.
This works for the most part, and interrupt injection winds up taking
the software path. However, when running on GICv4-enabled hardware, KVM
erroneously attempts to setup LPI forwarding, even though the KVM
routing isn't an MSI.
Thanks to misuse of a union, the MSI destination is unlikely to match any
ITS in the VM and kvm_vgic_v4_set_forwarding() bails early. Later on when
the VM is being torn down, this half-configured state triggers the
WARN_ON() in kvm_vgic_v4_unset_forwarding() due to the fact that no HW
IRQ was ever assigned.
Avoid the whole mess by preventing SPI routing entries from getting into
the LPI forwarding helpers.
Reported-by: Sudheer Dantuluri <dantuluris@google.com>
Tested-by: Sudheer Dantuluri <dantuluris@google.com>
Fixes: 196b136498b3 ("KVM: arm/arm64: GICv4: Wire mapping/unmapping of VLPIs in VFIO irq bypass")
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20250226183124.82094-2-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
| -rw-r--r-- | arch/arm64/kvm/arm.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index b8e55a441282..36d8dd80b431 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -2717,6 +2717,14 @@ int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *cons, { struct kvm_kernel_irqfd *irqfd = container_of(cons, struct kvm_kernel_irqfd, consumer); + struct kvm_kernel_irq_routing_entry *irq_entry = &irqfd->irq_entry; + + /* + * The only thing we have a chance of directly-injecting is LPIs. Maybe + * one day... + */ + if (irq_entry->type != KVM_IRQ_ROUTING_MSI) + return 0; return kvm_vgic_v4_set_forwarding(irqfd->kvm, prod->irq, &irqfd->irq_entry); @@ -2726,6 +2734,10 @@ void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons, { struct kvm_kernel_irqfd *irqfd = container_of(cons, struct kvm_kernel_irqfd, consumer); + struct kvm_kernel_irq_routing_entry *irq_entry = &irqfd->irq_entry; + + if (irq_entry->type != KVM_IRQ_ROUTING_MSI) + return; kvm_vgic_v4_unset_forwarding(irqfd->kvm, prod->irq, &irqfd->irq_entry); |