27351992bf
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>
270 lines
8.3 KiB
C
270 lines
8.3 KiB
C
#ifndef VHOST_H
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#define VHOST_H
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#include "hw/virtio/vhost-backend.h"
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#include "hw/virtio/virtio.h"
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#include "exec/memory.h"
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/* Generic structures common for any vhost based device. */
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struct vhost_inflight {
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int fd;
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void *addr;
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uint64_t size;
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uint64_t offset;
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uint16_t queue_size;
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};
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struct vhost_virtqueue {
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int kick;
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int call;
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void *desc;
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void *avail;
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void *used;
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int num;
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unsigned long long desc_phys;
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unsigned desc_size;
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unsigned long long avail_phys;
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unsigned avail_size;
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unsigned long long used_phys;
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unsigned used_size;
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EventNotifier masked_notifier;
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struct vhost_dev *dev;
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};
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typedef unsigned long vhost_log_chunk_t;
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#define VHOST_LOG_PAGE 0x1000
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#define VHOST_LOG_BITS (8 * sizeof(vhost_log_chunk_t))
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#define VHOST_LOG_CHUNK (VHOST_LOG_PAGE * VHOST_LOG_BITS)
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#define VHOST_INVALID_FEATURE_BIT (0xff)
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struct vhost_log {
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unsigned long long size;
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int refcnt;
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int fd;
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vhost_log_chunk_t *log;
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};
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struct vhost_dev;
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struct vhost_iommu {
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struct vhost_dev *hdev;
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MemoryRegion *mr;
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hwaddr iommu_offset;
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IOMMUNotifier n;
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QLIST_ENTRY(vhost_iommu) iommu_next;
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};
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typedef struct VhostDevConfigOps {
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/* Vhost device config space changed callback
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*/
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int (*vhost_dev_config_notifier)(struct vhost_dev *dev);
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} VhostDevConfigOps;
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struct vhost_memory;
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/**
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* struct vhost_dev - common vhost_dev structure
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* @vhost_ops: backend specific ops
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* @config_ops: ops for config changes (see @vhost_dev_set_config_notifier)
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*/
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struct vhost_dev {
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VirtIODevice *vdev;
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MemoryListener memory_listener;
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MemoryListener iommu_listener;
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struct vhost_memory *mem;
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int n_mem_sections;
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MemoryRegionSection *mem_sections;
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int n_tmp_sections;
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MemoryRegionSection *tmp_sections;
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struct vhost_virtqueue *vqs;
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unsigned int nvqs;
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/* the first virtqueue which would be used by this vhost dev */
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int vq_index;
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/* one past the last vq index for the virtio device (not vhost) */
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int vq_index_end;
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/* if non-zero, minimum required value for max_queues */
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int num_queues;
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uint64_t features;
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uint64_t acked_features;
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uint64_t backend_features;
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uint64_t protocol_features;
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uint64_t max_queues;
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uint64_t backend_cap;
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bool started;
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bool log_enabled;
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uint64_t log_size;
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Error *migration_blocker;
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const VhostOps *vhost_ops;
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void *opaque;
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struct vhost_log *log;
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QLIST_ENTRY(vhost_dev) entry;
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QLIST_HEAD(, vhost_iommu) iommu_list;
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IOMMUNotifier n;
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const VhostDevConfigOps *config_ops;
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};
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extern const VhostOps kernel_ops;
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extern const VhostOps user_ops;
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extern const VhostOps vdpa_ops;
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struct vhost_net {
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struct vhost_dev dev;
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struct vhost_virtqueue vqs[2];
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int backend;
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NetClientState *nc;
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};
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/**
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* vhost_dev_init() - initialise the vhost interface
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* @hdev: the common vhost_dev structure
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* @opaque: opaque ptr passed to backend (vhost/vhost-user/vdpa)
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* @backend_type: type of backend
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* @busyloop_timeout: timeout for polling virtqueue
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* @errp: error handle
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*
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* The initialisation of the vhost device will trigger the
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* initialisation of the backend and potentially capability
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* negotiation of backend interface. Configuration of the VirtIO
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* itself won't happen until the interface is started.
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*
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* Return: 0 on success, non-zero on error while setting errp.
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*/
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int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
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VhostBackendType backend_type,
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uint32_t busyloop_timeout, Error **errp);
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/**
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* vhost_dev_cleanup() - tear down and cleanup vhost interface
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* @hdev: the common vhost_dev structure
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*/
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void vhost_dev_cleanup(struct vhost_dev *hdev);
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/**
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* vhost_dev_enable_notifiers() - enable event notifiers
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* @hdev: common vhost_dev structure
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* @vdev: the VirtIODevice structure
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*
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* Enable notifications directly to the vhost device rather than being
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* triggered by QEMU itself. Notifications should be enabled before
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* the vhost device is started via @vhost_dev_start.
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*
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* Return: 0 on success, < 0 on error.
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*/
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int vhost_dev_enable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev);
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/**
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* vhost_dev_disable_notifiers - disable event notifications
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* @hdev: common vhost_dev structure
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* @vdev: the VirtIODevice structure
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*
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* Disable direct notifications to vhost device.
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*/
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void vhost_dev_disable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev);
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/**
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* vhost_dev_start() - start the vhost device
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* @hdev: common vhost_dev structure
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* @vdev: the VirtIODevice structure
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*
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* Starts the vhost device. From this point VirtIO feature negotiation
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* can start and the device can start processing VirtIO transactions.
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*
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* Return: 0 on success, < 0 on error.
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*/
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int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev);
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/**
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* vhost_dev_stop() - stop the vhost device
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* @hdev: common vhost_dev structure
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* @vdev: the VirtIODevice structure
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*
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* Stop the vhost device. After the device is stopped the notifiers
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* can be disabled (@vhost_dev_disable_notifiers) and the device can
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* be torn down (@vhost_dev_cleanup).
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*/
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void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev);
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/**
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* DOC: vhost device configuration handling
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*
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* The VirtIO device configuration space is used for rarely changing
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* or initialisation time parameters. The configuration can be updated
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* by either the guest driver or the device itself. If the device can
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* change the configuration over time the vhost handler should
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* register a @VhostDevConfigOps structure with
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* @vhost_dev_set_config_notifier so the guest can be notified. Some
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* devices register a handler anyway and will signal an error if an
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* unexpected config change happens.
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*/
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/**
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* vhost_dev_get_config() - fetch device configuration
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* @hdev: common vhost_dev_structure
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* @config: pointer to device appropriate config structure
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* @config_len: size of device appropriate config structure
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*
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* Return: 0 on success, < 0 on error while setting errp
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*/
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int vhost_dev_get_config(struct vhost_dev *hdev, uint8_t *config,
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uint32_t config_len, Error **errp);
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/**
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* vhost_dev_set_config() - set device configuration
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* @hdev: common vhost_dev_structure
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* @data: pointer to data to set
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* @offset: offset into configuration space
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* @size: length of set
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* @flags: @VhostSetConfigType flags
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*
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* By use of @offset/@size a subset of the configuration space can be
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* written to. The @flags are used to indicate if it is a normal
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* transaction or related to migration.
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*
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* Return: 0 on success, non-zero on error
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*/
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int vhost_dev_set_config(struct vhost_dev *dev, const uint8_t *data,
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uint32_t offset, uint32_t size, uint32_t flags);
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/**
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* vhost_dev_set_config_notifier() - register VhostDevConfigOps
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* @hdev: common vhost_dev_structure
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* @ops: notifier ops
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*
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* If the device is expected to change configuration a notifier can be
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* setup to handle the case.
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*/
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void vhost_dev_set_config_notifier(struct vhost_dev *dev,
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const VhostDevConfigOps *ops);
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/* Test and clear masked event pending status.
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* Should be called after unmask to avoid losing events.
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*/
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bool vhost_virtqueue_pending(struct vhost_dev *hdev, int n);
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/* Mask/unmask events from this vq.
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*/
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void vhost_virtqueue_mask(struct vhost_dev *hdev, VirtIODevice *vdev, int n,
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bool mask);
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uint64_t vhost_get_features(struct vhost_dev *hdev, const int *feature_bits,
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uint64_t features);
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void vhost_ack_features(struct vhost_dev *hdev, const int *feature_bits,
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uint64_t features);
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bool vhost_has_free_slot(void);
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int vhost_net_set_backend(struct vhost_dev *hdev,
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struct vhost_vring_file *file);
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int vhost_device_iotlb_miss(struct vhost_dev *dev, uint64_t iova, int write);
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void vhost_dev_reset_inflight(struct vhost_inflight *inflight);
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void vhost_dev_free_inflight(struct vhost_inflight *inflight);
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void vhost_dev_save_inflight(struct vhost_inflight *inflight, QEMUFile *f);
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int vhost_dev_load_inflight(struct vhost_inflight *inflight, QEMUFile *f);
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int vhost_dev_prepare_inflight(struct vhost_dev *hdev, VirtIODevice *vdev);
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int vhost_dev_set_inflight(struct vhost_dev *dev,
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struct vhost_inflight *inflight);
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int vhost_dev_get_inflight(struct vhost_dev *dev, uint16_t queue_size,
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struct vhost_inflight *inflight);
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#endif
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