mirrors/qemu
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

include/hw: start documenting the vhost API

Browse Source 
While trying to get my head around the nest of interactions for vhost
devices I though I could start by documenting the key API functions.
This patch documents the main API hooks for creating and starting a
vhost device as well as how the configuration changes are handled.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20220321153037.3622127-11-alex.bennee@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Alex Bennée 2022-03-21 15:30:34 +00:00 committed by Michael S. Tsirkin
parent bcf317f859
commit 27351992bf
1 changed files with 122 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

132
include/hw/virtio/vhost.h
View File

@ -61,6 +61,12 @@ typedef struct VhostDevConfigOps {
} VhostDevConfigOps;
struct vhost_memory;
/**
* struct vhost_dev - common vhost_dev structure
* @vhost_ops: backend specific ops
* @config_ops: ops for config changes (see @vhost_dev_set_config_notifier)
*/
struct vhost_dev {
VirtIODevice *vdev;
MemoryListener memory_listener;
@ -108,15 +114,129 @@ struct vhost_net {
NetClientState *nc;
};
/**
* vhost_dev_init() - initialise the vhost interface
* @hdev: the common vhost_dev structure
* @opaque: opaque ptr passed to backend (vhost/vhost-user/vdpa)
* @backend_type: type of backend
* @busyloop_timeout: timeout for polling virtqueue
* @errp: error handle
*
* The initialisation of the vhost device will trigger the
* initialisation of the backend and potentially capability
* negotiation of backend interface. Configuration of the VirtIO
* itself won't happen until the interface is started.
*
* Return: 0 on success, non-zero on error while setting errp.
*/
int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
VhostBackendType backend_type,
uint32_t busyloop_timeout, Error **errp);
/**
* vhost_dev_cleanup() - tear down and cleanup vhost interface
* @hdev: the common vhost_dev structure
*/
void vhost_dev_cleanup(struct vhost_dev *hdev);
int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev);
void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev);
/**
* vhost_dev_enable_notifiers() - enable event notifiers
* @hdev: common vhost_dev structure
* @vdev: the VirtIODevice structure
*
* Enable notifications directly to the vhost device rather than being
* triggered by QEMU itself. Notifications should be enabled before
* the vhost device is started via @vhost_dev_start.
*
* Return: 0 on success, < 0 on error.
*/
int vhost_dev_enable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev);
/**
* vhost_dev_disable_notifiers - disable event notifications
* @hdev: common vhost_dev structure
* @vdev: the VirtIODevice structure
*
* Disable direct notifications to vhost device.
*/
void vhost_dev_disable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev);
/**
* vhost_dev_start() - start the vhost device
* @hdev: common vhost_dev structure
* @vdev: the VirtIODevice structure
*
* Starts the vhost device. From this point VirtIO feature negotiation
* can start and the device can start processing VirtIO transactions.
*
* Return: 0 on success, < 0 on error.
*/
int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev);
/**
* vhost_dev_stop() - stop the vhost device
* @hdev: common vhost_dev structure
* @vdev: the VirtIODevice structure
*
* Stop the vhost device. After the device is stopped the notifiers
* can be disabled (@vhost_dev_disable_notifiers) and the device can
* be torn down (@vhost_dev_cleanup).
*/
void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev);
/**
* DOC: vhost device configuration handling
*
* The VirtIO device configuration space is used for rarely changing
* or initialisation time parameters. The configuration can be updated
* by either the guest driver or the device itself. If the device can
* change the configuration over time the vhost handler should
* register a @VhostDevConfigOps structure with
* @vhost_dev_set_config_notifier so the guest can be notified. Some
* devices register a handler anyway and will signal an error if an
* unexpected config change happens.
*/
/**
* vhost_dev_get_config() - fetch device configuration
* @hdev: common vhost_dev_structure
* @config: pointer to device appropriate config structure
* @config_len: size of device appropriate config structure
*
* Return: 0 on success, < 0 on error while setting errp
*/
int vhost_dev_get_config(struct vhost_dev *hdev, uint8_t *config,
uint32_t config_len, Error **errp);
/**
* vhost_dev_set_config() - set device configuration
* @hdev: common vhost_dev_structure
* @data: pointer to data to set
* @offset: offset into configuration space
* @size: length of set
* @flags: @VhostSetConfigType flags
*
* By use of @offset/@size a subset of the configuration space can be
* written to. The @flags are used to indicate if it is a normal
* transaction or related to migration.
*
* Return: 0 on success, non-zero on error
*/
int vhost_dev_set_config(struct vhost_dev *dev, const uint8_t *data,
uint32_t offset, uint32_t size, uint32_t flags);
/**
* vhost_dev_set_config_notifier() - register VhostDevConfigOps
* @hdev: common vhost_dev_structure
* @ops: notifier ops
*
* If the device is expected to change configuration a notifier can be
* setup to handle the case.
*/
void vhost_dev_set_config_notifier(struct vhost_dev *dev,
const VhostDevConfigOps *ops);
/* Test and clear masked event pending status.
* Should be called after unmask to avoid losing events.
*/
@ -136,14 +256,6 @@ int vhost_net_set_backend(struct vhost_dev *hdev,
struct vhost_vring_file *file);
int vhost_device_iotlb_miss(struct vhost_dev *dev, uint64_t iova, int write);
int vhost_dev_get_config(struct vhost_dev *hdev, uint8_t *config,
uint32_t config_len, Error **errp);
int vhost_dev_set_config(struct vhost_dev *dev, const uint8_t *data,
uint32_t offset, uint32_t size, uint32_t flags);
/* notifier callback in case vhost device config space changed
*/
void vhost_dev_set_config_notifier(struct vhost_dev *dev,
const VhostDevConfigOps *ops);
void vhost_dev_reset_inflight(struct vhost_inflight *inflight);
void vhost_dev_free_inflight(struct vhost_inflight *inflight);