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/*
* vhost shadow virtqueue
*
* SPDX-FileCopyrightText: Red Hat, Inc. 2021
* SPDX-FileContributor: Author: Eugenio Pérez <eperezma@redhat.com>
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#ifndef VHOST_SHADOW_VIRTQUEUE_H
#define VHOST_SHADOW_VIRTQUEUE_H
#include "qemu/event_notifier.h"
#include "hw/virtio/virtio.h"
#include "standard-headers/linux/vhost_types.h"
#include "hw/virtio/vhost-iova-tree.h"
typedef struct SVQDescState {
VirtQueueElement *elem;
/*
* Number of descriptors exposed to the device. May or may not match
* guest's
*/
unsigned int ndescs;
} SVQDescState;
typedef struct VhostShadowVirtqueue VhostShadowVirtqueue;
/**
* Callback to handle an avail buffer.
*
* @svq: Shadow virtqueue
* @elem: Element placed in the queue by the guest
* @vq_callback_opaque: Opaque
*
* Returns 0 if the vq is running as expected.
*
* Note that ownership of elem is transferred to the callback.
*/
typedef int (*VirtQueueAvailCallback)(VhostShadowVirtqueue *svq,
VirtQueueElement *elem,
void *vq_callback_opaque);
typedef struct VhostShadowVirtqueueOps {
VirtQueueAvailCallback avail_handler;
} VhostShadowVirtqueueOps;
/* Shadow virtqueue to relay notifications */
typedef struct VhostShadowVirtqueue {
/* Shadow vring */
struct vring vring;
/* Shadow kick notifier, sent to vhost */
EventNotifier hdev_kick;
/* Shadow call notifier, sent to vhost */
EventNotifier hdev_call;
/*
* Borrowed virtqueue's guest to host notifier. To borrow it in this event
* notifier allows to recover the VhostShadowVirtqueue from the event loop
* easily. If we use the VirtQueue's one, we don't have an easy way to
* retrieve VhostShadowVirtqueue.
*
* So shadow virtqueue must not clean it, or we would lose VirtQueue one.
*/
EventNotifier svq_kick;
/* Guest's call notifier, where the SVQ calls guest. */
EventNotifier svq_call;
/* Virtio queue shadowing */
VirtQueue *vq;
/* Virtio device */
VirtIODevice *vdev;
/* IOVA mapping */
VhostIOVATree *iova_tree;
/* SVQ vring descriptors state */
SVQDescState *desc_state;
/* Next VirtQueue element that guest made available */
VirtQueueElement *next_guest_avail_elem;
/*
* Backup next field for each descriptor so we can recover securely, not
* needing to trust the device access.
*/
uint16_t *desc_next;
/* Caller callbacks */
const VhostShadowVirtqueueOps *ops;
/* Caller callbacks opaque */
void *ops_opaque;
/* Next head to expose to the device */
uint16_t shadow_avail_idx;
/* Next free descriptor */
uint16_t free_head;
/* Last seen used idx */
uint16_t shadow_used_idx;
/* Next head to consume from the device */
uint16_t last_used_idx;
/* Size of SVQ vring free descriptors */
uint16_t num_free;
} VhostShadowVirtqueue;
bool vhost_svq_valid_features(uint64_t features, Error **errp);
uint16_t vhost_svq_available_slots(const VhostShadowVirtqueue *svq);
void vhost_svq_push_elem(VhostShadowVirtqueue *svq,
const VirtQueueElement *elem, uint32_t len);
int vhost_svq_add(VhostShadowVirtqueue *svq, const struct iovec *out_sg,
size_t out_num, const struct iovec *in_sg, size_t in_num,
VirtQueueElement *elem);
size_t vhost_svq_poll(VhostShadowVirtqueue *svq, size_t num);
void vhost_svq_set_svq_kick_fd(VhostShadowVirtqueue *svq, int svq_kick_fd);
void vhost_svq_set_svq_call_fd(VhostShadowVirtqueue *svq, int call_fd);
void vhost_svq_get_vring_addr(const VhostShadowVirtqueue *svq,
struct vhost_vring_addr *addr);
size_t vhost_svq_driver_area_size(const VhostShadowVirtqueue *svq);
size_t vhost_svq_device_area_size(const VhostShadowVirtqueue *svq);
void vhost_svq_start(VhostShadowVirtqueue *svq, VirtIODevice *vdev,
VirtQueue *vq, VhostIOVATree *iova_tree);
void vhost_svq_stop(VhostShadowVirtqueue *svq);
VhostShadowVirtqueue *vhost_svq_new(const VhostShadowVirtqueueOps *ops,
void *ops_opaque);
void vhost_svq_free(gpointer vq);
G_DEFINE_AUTOPTR_CLEANUP_FUNC(VhostShadowVirtqueue, vhost_svq_free);
#endif
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