/* SPDX-License-Identifier: GPL-2.0 */
|
#ifndef _LINUX_VIRTIO_RING_H
|
#define _LINUX_VIRTIO_RING_H
|
|
#include <asm/barrier.h>
|
#include <linux/irqreturn.h>
|
#include <uapi/linux/virtio_ring.h>
|
|
/*
|
* Barriers in virtio are tricky. Non-SMP virtio guests can't assume
|
* they're not on an SMP host system, so they need to assume real
|
* barriers. Non-SMP virtio hosts could skip the barriers, but does
|
* anyone care?
|
*
|
* For virtio_pci on SMP, we don't need to order with respect to MMIO
|
* accesses through relaxed memory I/O windows, so virt_mb() et al are
|
* sufficient.
|
*
|
* For using virtio to talk to real devices (eg. other heterogeneous
|
* CPUs) we do need real barriers. In theory, we could be using both
|
* kinds of virtio, so it's a runtime decision, and the branch is
|
* actually quite cheap.
|
*/
|
|
static inline void virtio_mb(bool weak_barriers)
|
{
|
if (weak_barriers)
|
virt_mb();
|
else
|
mb();
|
}
|
|
static inline void virtio_rmb(bool weak_barriers)
|
{
|
if (weak_barriers)
|
virt_rmb();
|
else
|
dma_rmb();
|
}
|
|
static inline void virtio_wmb(bool weak_barriers)
|
{
|
if (weak_barriers)
|
virt_wmb();
|
else
|
dma_wmb();
|
}
|
|
#define virtio_store_mb(weak_barriers, p, v) \
|
do { \
|
if (weak_barriers) { \
|
virt_store_mb(*p, v); \
|
} else { \
|
WRITE_ONCE(*p, v); \
|
mb(); \
|
} \
|
} while (0) \
|
|
struct virtio_device;
|
struct virtqueue;
|
|
/*
|
* Creates a virtqueue and allocates the descriptor ring. If
|
* may_reduce_num is set, then this may allocate a smaller ring than
|
* expected. The caller should query virtqueue_get_vring_size to learn
|
* the actual size of the ring.
|
*/
|
struct virtqueue *vring_create_virtqueue(unsigned int index,
|
unsigned int num,
|
unsigned int vring_align,
|
struct virtio_device *vdev,
|
bool weak_barriers,
|
bool may_reduce_num,
|
bool ctx,
|
bool (*notify)(struct virtqueue *vq),
|
void (*callback)(struct virtqueue *vq),
|
const char *name);
|
|
/* Creates a virtqueue with a custom layout. */
|
struct virtqueue *__vring_new_virtqueue(unsigned int index,
|
struct vring vring,
|
struct virtio_device *vdev,
|
bool weak_barriers,
|
bool ctx,
|
bool (*notify)(struct virtqueue *),
|
void (*callback)(struct virtqueue *),
|
const char *name);
|
|
/*
|
* Creates a virtqueue with a standard layout but a caller-allocated
|
* ring.
|
*/
|
struct virtqueue *vring_new_virtqueue(unsigned int index,
|
unsigned int num,
|
unsigned int vring_align,
|
struct virtio_device *vdev,
|
bool weak_barriers,
|
bool ctx,
|
void *pages,
|
bool (*notify)(struct virtqueue *vq),
|
void (*callback)(struct virtqueue *vq),
|
const char *name);
|
|
/*
|
* Destroys a virtqueue. If created with vring_create_virtqueue, this
|
* also frees the ring.
|
*/
|
void vring_del_virtqueue(struct virtqueue *vq);
|
|
/* Filter out transport-specific feature bits. */
|
void vring_transport_features(struct virtio_device *vdev);
|
|
irqreturn_t vring_interrupt(int irq, void *_vq);
|
#endif /* _LINUX_VIRTIO_RING_H */
|
