diff options
| author | Oliver Upton <oliver.upton@linux.dev> | 2025-02-26 10:31:23 -0800 |
|---|---|---|
| committer | Oliver Upton <oliver.upton@linux.dev> | 2025-02-26 13:22:49 -0800 |
| commit | 5c57533eb8c1efeeab4e2e417fa983d65707b925 (patch) | |
| tree | 741e27b722c7e59b6aeb0ca2c1a692e4767c4234 | |
| parent | d0b79563fd60c063ee4ad2a76024e60338ed3881 (diff) | |
KVM: arm64: vgic-v4: Fall back to software irqbypass if LPI not found
Continuing with the theme of broken VMMs and guests, irqbypass
registration can fail if the virtual ITS lacks a translation for the
MSI. Either the guest hasn't mapped it or userspace may have forgotten
to restore the ITS.
Exit silently and allow irqbypass configuration to succeed. As a reward
for ingenuity, LPIs are demoted to software injection.
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/20250226183124.82094-4-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
| -rw-r--r-- | arch/arm64/kvm/vgic/vgic-v4.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/arch/arm64/kvm/vgic/vgic-v4.c b/arch/arm64/kvm/vgic/vgic-v4.c index 3e1de40720e0..9f51d58b5f8a 100644 --- a/arch/arm64/kvm/vgic/vgic-v4.c +++ b/arch/arm64/kvm/vgic/vgic-v4.c @@ -415,7 +415,7 @@ int kvm_vgic_v4_set_forwarding(struct kvm *kvm, int virq, struct vgic_irq *irq; struct its_vlpi_map map; unsigned long flags; - int ret; + int ret = 0; if (!vgic_supports_direct_msis(kvm)) return 0; @@ -430,10 +430,15 @@ int kvm_vgic_v4_set_forwarding(struct kvm *kvm, int virq, mutex_lock(&its->its_lock); - /* Perform the actual DevID/EventID -> LPI translation. */ - ret = vgic_its_resolve_lpi(kvm, its, irq_entry->msi.devid, - irq_entry->msi.data, &irq); - if (ret) + /* + * Perform the actual DevID/EventID -> LPI translation. + * + * Silently exit if translation fails as the guest (or userspace!) has + * managed to do something stupid. Emulated LPI injection will still + * work if the guest figures itself out at a later time. + */ + if (vgic_its_resolve_lpi(kvm, its, irq_entry->msi.devid, + irq_entry->msi.data, &irq)) goto out; /* Silently exit if the vLPI is already mapped */ |