virtio: Add get_shm_region method

Virtio defines 'shared memory regions' that provide a continuously
shared region between the host and guest.

Provide a method to find a particular region on a device.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Cc: kvm@vger.kernel.org
Cc: virtualization@lists.linux-foundation.org
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index 8fe857e27ef32a2aab464fb437e93f3e320a8726..4b8e38c5c4d8c2fd4202d172ca14baef30ec760c 100644 (file)
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -11,6 +11,11 @@
 
 struct irq_affinity;
 
+struct virtio_shm_region {
+       u64 addr;
+       u64 len;
+};
+
 /**
  * virtio_config_ops - operations for configuring a virtio device
  * Note: Do not assume that a transport implements all of the operations
@@ -66,6 +71,7 @@ struct irq_affinity;
  *      the caller can then copy.
  * @set_vq_affinity: set the affinity for a virtqueue (optional).
  * @get_vq_affinity: get the affinity for a virtqueue (optional).
+ * @get_shm_region: get a shared memory region based on the index.
  */
 typedef void vq_callback_t(struct virtqueue *);
 struct virtio_config_ops {
@@ -89,6 +95,8 @@ struct virtio_config_ops {
                               const struct cpumask *cpu_mask);
        const struct cpumask *(*get_vq_affinity)(struct virtio_device *vdev,
                        int index);
+       bool (*get_shm_region)(struct virtio_device *vdev,
+                              struct virtio_shm_region *region, u8 id);
 };
 
 /* If driver didn't advertise the feature, it will never appear. */
@@ -251,6 +259,15 @@ int virtqueue_set_affinity(struct virtqueue *vq, const struct cpumask *cpu_mask)
        return 0;
 }
 
+static inline
+bool virtio_get_shm_region(struct virtio_device *vdev,
+                          struct virtio_shm_region *region, u8 id)
+{
+       if (!vdev->config->get_shm_region)
+               return false;
+       return vdev->config->get_shm_region(vdev, region, id);
+}
+
 static inline bool virtio_is_little_endian(struct virtio_device *vdev)
 {
        return virtio_has_feature(vdev, VIRTIO_F_VERSION_1) ||