virtio_ring: change host notification API

Currently a host kick error is silently ignored and not reflected in
the virtqueue of a particular virtio device.

Changing the notify API for guest->host notification seems to be one
prerequisite in order to be able to handle such errors in the context
where the kick is triggered.

This patch changes the notify API. The notify function must return a
bool return value. It returns false if the host notification failed.

Signed-off-by: Heinz Graalfs <graalfs@linux.vnet.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

3 files changed, 6 insertions, 4 deletions

diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index 1ba0d6831015..e9fdeb861992 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -219,13 +219,14 @@ static void vm_reset(struct virtio_device *vdev)
 /* Transport interface */
 
 /* the notify function used when creating a virt queue */
-static void vm_notify(struct virtqueue *vq)
+static bool vm_notify(struct virtqueue *vq)
 {
         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
 
         /* We write the queue's selector into the notification register to
          * signal the other end */
         writel(vq->index, vm_dev->base + VIRTIO_MMIO_QUEUE_NOTIFY);
+        return true;
 }
 
 /* Notify all virtqueues on an interrupt. */
diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index 98917fc872a4..a37c69941d30 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -197,13 +197,14 @@ static void vp_reset(struct virtio_device *vdev)
 }
 
 /* the notify function used when creating a virt queue */
-static void vp_notify(struct virtqueue *vq)
+static bool vp_notify(struct virtqueue *vq)
 {
         struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
 
         /* we write the queue's selector into the notification register to
          * signal the other end */
         iowrite16(vq->index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_NOTIFY);
+        return true;
 }
 
 /* Handle a configuration change: Tell driver if it wants to know. */
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 6547d46171b3..97dd51619b55 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -81,7 +81,7 @@ struct vring_virtqueue
         u16 last_used_idx;
 
         /* How to notify other side. FIXME: commonalize hcalls! */
-        void (*notify)(struct virtqueue *vq);
+        bool (*notify)(struct virtqueue *vq);
 
 #ifdef DEBUG
         /* They're supposed to lock for us. */
@@ -744,7 +744,7 @@ struct virtqueue *vring_new_virtqueue(unsigned int index,
                                       struct virtio_device *vdev,
                                       bool weak_barriers,
                                       void *pages,
-                                      void (*notify)(struct virtqueue *),
+                                      bool (*notify)(struct virtqueue *),
                                       void (*callback)(struct virtqueue *),
                                       const char *name)
 {