virtio: find_vqs/del_vqs virtio operations

This replaces find_vq/del_vq with find_vqs/del_vqs virtio operations,
and updates all drivers. This is needed for MSI support, because MSI
needs to know the total number of vectors upfront.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (+ lguest/9p compile fixes)

1 files changed, 36 insertions, 11 deletions

diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index 9fae274751e0..4cd290c06a88 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -29,6 +29,7 @@
 #define VIRTIO_F_NOTIFY_ON_EMPTY        24
 
 #ifdef __KERNEL__
+#include <linux/err.h>
 #include <linux/virtio.h>
 
 /**
@@ -49,16 +50,26 @@
  * @set_status: write the status byte
  *      vdev: the virtio_device
  *      status: the new status byte
+ * @request_vqs: request the specified number of virtqueues
+ *      vdev: the virtio_device
+ *      max_vqs: the max number of virtqueues we want
+ *      If supplied, must call before any virtqueues are instantiated.
+ *      To modify the max number of virtqueues after request_vqs has been
+ *      called, call free_vqs and then request_vqs with a new value.
+ * @free_vqs: cleanup resources allocated by request_vqs
+ *      vdev: the virtio_device
+ *      If supplied, must call after all virtqueues have been deleted.
  * @reset: reset the device
  *      vdev: the virtio device
  *      After this, status and feature negotiation must be done again
- * @find_vq: find a virtqueue and instantiate it.
+ * @find_vqs: find virtqueues and instantiate them.
  *      vdev: the virtio_device
- *      index: the 0-based virtqueue number in case there's more than one.
- *      callback: the virtqueue callback
- *      name: the virtqueue name (mainly for debugging)
- *      Returns the new virtqueue or ERR_PTR() (eg. -ENOENT).
- * @del_vq: free a virtqueue found by find_vq().
+ *      nvqs: the number of virtqueues to find
+ *      vqs: on success, includes new virtqueues
+ *      callbacks: array of callbacks, for each virtqueue
+ *      names: array of virtqueue names (mainly for debugging)
+ *      Returns 0 on success or error status
+ * @del_vqs: free virtqueues found by find_vqs().
  * @get_features: get the array of feature bits for this device.
  *      vdev: the virtio_device
  *      Returns the first 32 feature bits (all we currently need).
@@ -67,6 +78,7 @@
  *      This gives the final feature bits for the device: it can change
  *      the dev->feature bits if it wants.
  */
+typedef void vq_callback_t(struct virtqueue *);
 struct virtio_config_ops
 {
         void (*get)(struct virtio_device *vdev, unsigned offset,
@@ -76,11 +88,11 @@ struct virtio_config_ops
         u8 (*get_status)(struct virtio_device *vdev);
         void (*set_status)(struct virtio_device *vdev, u8 status);
         void (*reset)(struct virtio_device *vdev);
-        struct virtqueue *(*find_vq)(struct virtio_device *vdev,
-                                     unsigned index,
-                                     void (*callback)(struct virtqueue *),
-                                     const char *name);
-        void (*del_vq)(struct virtqueue *vq);
+        int (*find_vqs)(struct virtio_device *, unsigned nvqs,
+                        struct virtqueue *vqs[],
+                        vq_callback_t *callbacks[],
+                        const char *names[]);
+        void (*del_vqs)(struct virtio_device *);
         u32 (*get_features)(struct virtio_device *vdev);
         void (*finalize_features)(struct virtio_device *vdev);
 };
@@ -128,5 +140,18 @@ static inline int virtio_config_buf(struct virtio_device *vdev,
         vdev->config->get(vdev, offset, buf, len);
         return 0;
 }
+
+static inline
+struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev,
+                                        vq_callback_t *c, const char *n)
+{
+        vq_callback_t *callbacks[] = { c };
+        const char *names[] = { n };
+        struct virtqueue *vq;
+        int err = vdev->config->find_vqs(vdev, 1, &vq, callbacks, names);
+        if (err < 0)
+                return ERR_PTR(err);
+        return vq;
+}
 #endif /* __KERNEL__ */
 #endif /* _LINUX_VIRTIO_CONFIG_H */