hw/virtio/vhost.h

4 #include "hw/virtio/vhost-backend.h"
74  * struct vhost_dev - common vhost_dev structure
93     /* if non-zero, minimum required value for max_queues */
101      * @acked_features: final negotiated features with front-end driver
114      * @protocol_features: is the vhost-user only feature set by
150  * vhost_dev_init() - initialise the vhost interface
152  * @opaque: opaque ptr passed to backend (vhost/vhost-user/vdpa)
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
192  * vhost_dev_disable_notifiers - disable event notifications
203  * vhost_dev_is_started() - report status of vhost device
210     return hdev->started;  in vhost_dev_is_started()
214  * vhost_dev_start() - start the vhost device
227  * vhost_dev_stop() - stop the vhost device
252  * vhost_dev_get_config() - fetch device configuration
263  * vhost_dev_set_config() - set device configuration
274  * Return: 0 on success, non-zero on error
280  * vhost_dev_set_config_notifier() - register VhostDevConfigOps
302  * vhost_get_features() - return a sanitised set of feature bits
308  * is supported by the vhost backend (hdev->features), the supported
315  * vhost_ack_features() - set vhost acked_features
320  * This sets the internal hdev->acked_features to the intersection of
353     return -ENOSYS;  in vhost_reset_device()
358  * vhost_supports_device_state(): Checks whether the back-end supports
372  * the back-end for the purpose of migration.  Data is to be transferred
373  * over a pipe according to @direction and @phase.  The sending end must
374  * only write to the pipe, and the receiving end must only read from it.
375  * Once the sending end is done, it closes its FD.  The receiving end
376  * must take this as the end-of-transfer signal and close its FD, too.
378  * @fd is the back-end's end of the pipe: The write FD for SAVE, and the
380  * back-end, i.e. closes it in the front-end.
382  * The back-end may optionally reply with an FD of its own, if this
383  * improves efficiency on its end.  In this case, the returned FD is
384  * stored in *reply_fd.  The back-end will discard the FD sent to it,
385  * and the front-end must use *reply_fd for transferring state to/from
386  * the back-end.
391  *             from the back-end and stored by the front-end in the
394  *             by the front-end from the migration stream and sent to
395  *             the back-end to restore the saved state.
399  * @fd: Back-end's end of the pipe through which to transfer state; note
400  *      that ownership is transferred to the back-end, so this function
401  *      closes @fd in the front-end.
402  * @reply_fd: If the back-end wishes to use a different pipe for state
403  *            transfer, this will contain an FD for the front-end to
404  *            use.  Otherwise, -1 is stored here.
407  * Returns 0 on success, and -errno on failure.
418  * back-end via vhost_set_device_state_fd(), i.e. once the sending end
419  * has closed the pipe, inquire the back-end to report any potential
422  * - During outgoing migration, when the source side had already started
424  * - During incoming migration, when the received state is somehow
425  *   invalid and cannot be processed by the back-end
430  * Returns 0 when the back-end reports successful state transfer and
431  * processing, and -errno when an error occurred somewhere.
436  * vhost_save_backend_state(): High-level function to receive a vhost
437  * back-end's state, and save it in @f.  Uses
438  * `vhost_set_device_state_fd()` to get the data from the back-end, and
440  * respective length (be32).  The end is marked by a 0-length chunk.
449  * Returns 0 on success, and -errno otherwise.
454  * vhost_load_backend_state(): High-level function to load a vhost
455  * back-end's state from @f, and send it over to the back-end.  Reads
457  * `vhost_set_device_state_fd()` to transfer it to the back-end.
466  * Returns 0 on success, and -errno otherwise.