[PATCH kvmtool 3/3] virtio/pci: Register a single eventfd for vhost

[Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx>]

Vhost supports a single eventfd as the kick mechanism. Registering a
second one will override the first. To ensure vhost works with our
virtio-pci, only register the kick eventfd that is used by the guest.

Fixes: a508ea95f954 ("virtio/pci: Use port I/O for configuration registers by default")
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx>
---
 virtio/pci.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/virtio/pci.c b/virtio/pci.c
index 9a199013ac49..5a5fc6e12f35 100644
--- a/virtio/pci.c
+++ b/virtio/pci.c
@@ -25,8 +25,8 @@ static int virtio_pci__init_ioeventfd(struct kvm *kvm, struct virtio_device *vde
 {
 	struct ioevent ioevent;
 	struct virtio_pci *vpci = vdev->virtio;
-	int i, r, flags = 0;
-	int fds[2];
+	int r, flags = 0;
+	int fd;
 
 	vpci->ioeventfds[vq] = (struct virtio_pci_ioevent_param) {
 		.vdev		= vdev,
@@ -50,7 +50,7 @@ static int virtio_pci__init_ioeventfd(struct kvm *kvm, struct virtio_device *vde
 	/* ioport */
 	ioevent.io_addr	= vpci->port_addr + VIRTIO_PCI_QUEUE_NOTIFY;
 	ioevent.io_len	= sizeof(u16);
-	ioevent.fd	= fds[0] = eventfd(0, 0);
+	ioevent.fd	= fd = eventfd(0, 0);
 	r = ioeventfd__add_event(&ioevent, flags | IOEVENTFD_FLAG_PIO);
 	if (r)
 		return r;
@@ -58,15 +58,13 @@ static int virtio_pci__init_ioeventfd(struct kvm *kvm, struct virtio_device *vde
 	/* mmio */
 	ioevent.io_addr	= vpci->mmio_addr + VIRTIO_PCI_QUEUE_NOTIFY;
 	ioevent.io_len	= sizeof(u16);
-	ioevent.fd	= fds[1] = eventfd(0, 0);
+	ioevent.fd	= eventfd(0, 0);
 	r = ioeventfd__add_event(&ioevent, flags);
 	if (r)
 		goto free_ioport_evt;
 
 	if (vdev->ops->notify_vq_eventfd)
-		for (i = 0; i < 2; ++i)
-			vdev->ops->notify_vq_eventfd(kvm, vpci->dev, vq,
-						     fds[i]);
+		vdev->ops->notify_vq_eventfd(kvm, vpci->dev, vq, fd);
 	return 0;
 
 free_ioport_evt:
-- 
2.16.2