virtio: add context flag to find vqs

Allows maintaining extra context per vq.  For ease of use, passing in
NULL is legal and disables the feature for all vqs.

Includes fixes by Christian for s390, acked by Cornelia.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/s390/virtio/kvm_virtio.c

@@ -189,7 +189,7 @@ static bool kvm_notify(struct virtqueue *vq)
 static struct virtqueue *kvm_find_vq(struct virtio_device *vdev,
 				     unsigned index,
 				     void (*callback)(struct virtqueue *vq),
-				     const char *name)
+				     const char *name, bool ctx)
 {
 	struct kvm_device *kdev = to_kvmdev(vdev);
 	struct kvm_vqconfig *config;
@@ -211,7 +211,7 @@ static struct virtqueue *kvm_find_vq(struct virtio_device *vdev,
 		goto out;
 
 	vq = vring_new_virtqueue(index, config->num, KVM_S390_VIRTIO_RING_ALIGN,
-				 vdev, true, (void *) config->address,
+				 vdev, true, ctx, (void *) config->address,
 				 kvm_notify, callback, name);
 	if (!vq) {
 		err = -ENOMEM;
@@ -256,6 +256,7 @@ static int kvm_find_vqs(struct virtio_device *vdev, unsigned nvqs,
 			struct virtqueue *vqs[],
 			vq_callback_t *callbacks[],
 			const char * const names[],
+			const bool *ctx,
 			struct irq_affinity *desc)
 {
 	struct kvm_device *kdev = to_kvmdev(vdev);
@@ -266,7 +267,8 @@ static int kvm_find_vqs(struct virtio_device *vdev, unsigned nvqs,
 		return -ENOENT;
 
 	for (i = 0; i < nvqs; ++i) {
-		vqs[i] = kvm_find_vq(vdev, i, callbacks[i], names[i]);
+		vqs[i] = kvm_find_vq(vdev, i, callbacks[i], names[i],
+				     ctx ? ctx[i] : false);
 		if (IS_ERR(vqs[i]))
 			goto error;
 	}

drivers/s390/virtio/virtio_ccw.c

@@ -484,7 +484,7 @@ static void virtio_ccw_del_vqs(struct virtio_device *vdev)
 
 static struct virtqueue *virtio_ccw_setup_vq(struct virtio_device *vdev,
 					     int i, vq_callback_t *callback,
-					     const char *name,
+					     const char *name, bool ctx,
 					     struct ccw1 *ccw)
 {
 	struct virtio_ccw_device *vcdev = to_vc_device(vdev);
@@ -522,7 +522,7 @@ static struct virtqueue *virtio_ccw_setup_vq(struct virtio_device *vdev,
 	}
 
 	vq = vring_new_virtqueue(i, info->num, KVM_VIRTIO_CCW_RING_ALIGN, vdev,
-				 true, info->queue, virtio_ccw_kvm_notify,
+				 true, ctx, info->queue, virtio_ccw_kvm_notify,
 				 callback, name);
 	if (!vq) {
 		/* For now, we fail if we can't get the requested size. */
@@ -629,6 +629,7 @@ static int virtio_ccw_find_vqs(struct virtio_device *vdev, unsigned nvqs,
 			       struct virtqueue *vqs[],
 			       vq_callback_t *callbacks[],
 			       const char * const names[],
+			       const bool *ctx,
 			       struct irq_affinity *desc)
 {
 	struct virtio_ccw_device *vcdev = to_vc_device(vdev);
@@ -642,7 +643,7 @@ static int virtio_ccw_find_vqs(struct virtio_device *vdev, unsigned nvqs,
 
 	for (i = 0; i < nvqs; ++i) {
 		vqs[i] = virtio_ccw_setup_vq(vdev, i, callbacks[i], names[i],
-					     ccw);
+					     ctx ? ctx[i] : false, ccw);
 		if (IS_ERR(vqs[i])) {
 			ret = PTR_ERR(vqs[i]);
 			vqs[i] = NULL;