hw/virtio/vhost.h

4 #include "hw/virtio/vhost-backend.h"
13 /* Generic structures common for any vhost based device. */
66     /* Vhost device config space changed callback
74  * struct vhost_dev - common vhost_dev structure
89     /* the first virtqueue which would be used by this vhost dev */
91     /* one past the last vq index for the virtio device (not vhost) */
93     /* if non-zero, minimum required value for max_queues */
96      * vhost feature handling requires matching the feature set
101      * @acked_features: final negotiated features with front-end driver
114      * @protocol_features: is the vhost-user only feature set by
123     /* @started: is the vhost device started? */
150  * vhost_dev_init() - initialise the vhost interface
152  * @opaque: opaque ptr passed to backend (vhost/vhost-user/vdpa)
157  * The initialisation of the vhost device will trigger the
162  * Return: 0 on success, non-zero on error while setting errp.
169  * vhost_dev_cleanup() - tear down and cleanup vhost interface
179  * vhost_dev_enable_notifiers() - enable event notifiers
183  * Enable notifications directly to the vhost device rather than being
185  * the vhost device is started via @vhost_dev_start.
192  * vhost_dev_disable_notifiers - disable event notifications
196  * Disable direct notifications to vhost device.
203  * vhost_dev_is_started() - report status of vhost device
206  * Return the started status of the vhost device
210     return hdev->started;  in vhost_dev_is_started()
214  * vhost_dev_start() - start the vhost device
219  * Starts the vhost device. From this point VirtIO feature negotiation
227  * vhost_dev_stop() - stop the vhost device
232  * Stop the vhost device. After the device is stopped the notifiers
241  * DOC: vhost device configuration handling
246  * change the configuration over time the vhost handler should
254  * vhost_dev_get_config() - fetch device configuration
265  * vhost_dev_set_config() - set device configuration
276  * Return: 0 on success, non-zero on error
282  * vhost_dev_set_config_notifier() - register VhostDevConfigOps
304  * vhost_get_features() - return a sanitised set of feature bits
310  * is supported by the vhost backend (hdev->features), the supported
317  * vhost_ack_features() - set vhost acked_features
322  * This sets the internal hdev->acked_features to the intersection of
355     return -ENOSYS;  in vhost_reset_device()
360  * vhost_supports_device_state(): Checks whether the back-end supports
365  * @dev: The vhost device
381  * the back-end for the purpose of migration.  Data is to be transferred
385  * must take this as the end-of-transfer signal and close its FD, too.
387  * @fd is the back-end's end of the pipe: The write FD for SAVE, and the
389  * back-end, i.e. closes it in the front-end.
391  * The back-end may optionally reply with an FD of its own, if this
393  * stored in *reply_fd.  The back-end will discard the FD sent to it,
394  * and the front-end must use *reply_fd for transferring state to/from
395  * the back-end.
397  * @dev: The vhost device
400  *             from the back-end and stored by the front-end in the
403  *             by the front-end from the migration stream and sent to
404  *             the back-end to restore the saved state.
408  * @fd: Back-end's end of the pipe through which to transfer state; note
409  *      that ownership is transferred to the back-end, so this function
410  *      closes @fd in the front-end.
411  * @reply_fd: If the back-end wishes to use a different pipe for state
412  *            transfer, this will contain an FD for the front-end to
413  *            use.  Otherwise, -1 is stored here.
416  * Returns 0 on success, and -errno on failure.
427  * back-end via vhost_set_device_state_fd(), i.e. once the sending end
428  * has closed the pipe, inquire the back-end to report any potential
431  * - During outgoing migration, when the source side had already started
433  * - During incoming migration, when the received state is somehow
434  *   invalid and cannot be processed by the back-end
436  * @dev: The vhost device
439  * Returns 0 when the back-end reports successful state transfer and
440  * processing, and -errno when an error occurred somewhere.
445  * vhost_save_backend_state(): High-level function to receive a vhost
446  * back-end's state, and save it in @f.  Uses
447  * `vhost_set_device_state_fd()` to get the data from the back-end, and
449  * respective length (be32).  The end is marked by a 0-length chunk.
454  * @dev: The vhost device from which to save the state
458  * Returns 0 on success, and -errno otherwise.
466     return -ENOSYS;  in vhost_save_backend_state()
471  * vhost_load_backend_state(): High-level function to load a vhost
472  * back-end's state from @f, and send it over to the back-end.  Reads
474  * `vhost_set_device_state_fd()` to transfer it to the back-end.
479  * @dev: The vhost device to which to send the state
483  * Returns 0 on success, and -errno otherwise.
491     return -ENOSYS;  in vhost_load_backend_state()