Commit 928ab7ac authored by Andre Przywara's avatar Andre Przywara Committed by Will Deacon
Browse files

PCI: Only allocate IRQ routing entry when available



If we need to inject an MSI into the guest, we rely at the moment on a
working GSI MSI routing functionality. However we can get away without
IRQ routing, if the host supports MSI injection via the KVM_SIGNAL_MSI
ioctl.
So we try the GSI routing first, but if that fails due to a missing
IRQ routing functionality, we fall back to KVM_SIGNAL_MSI (if that is
supported).

Acked-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Andre Przywara's avatarAndre Przywara <andre.przywara@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent b960f243
......@@ -193,8 +193,20 @@ static bool virtio_pci__specific_io_out(struct kvm *kvm, struct virtio_device *v
gsi = irq__add_msix_route(kvm,
&vpci->msix_table[vec].msg);
if (gsi >= 0)
vpci->config_gsi = gsi;
/*
* We don't need IRQ routing if we can use
* MSI injection via the KVM_SIGNAL_MSI ioctl.
*/
if (gsi == -ENXIO &&
vpci->features & VIRTIO_PCI_F_SIGNAL_MSI)
break;
if (gsi < 0) {
die("failed to configure MSIs");
break;
}
vpci->config_gsi = gsi;
break;
case VIRTIO_MSI_QUEUE_VECTOR:
vec = ioport__read16(data);
......@@ -205,8 +217,19 @@ static bool virtio_pci__specific_io_out(struct kvm *kvm, struct virtio_device *v
gsi = irq__add_msix_route(kvm,
&vpci->msix_table[vec].msg);
if (gsi < 0)
/*
* We don't need IRQ routing if we can use
* MSI injection via the KVM_SIGNAL_MSI ioctl.
*/
if (gsi == -ENXIO &&
vpci->features & VIRTIO_PCI_F_SIGNAL_MSI)
break;
if (gsi < 0) {
die("failed to configure MSIs");
break;
}
vpci->gsis[vpci->queue_selector] = gsi;
if (vdev->ops->notify_vq_gsi)
vdev->ops->notify_vq_gsi(kvm, vpci->dev,
......
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