1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
|
/* 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 and allocates the descriptor ring with per
* virtqueue DMA device.
*/
struct virtqueue *vring_create_virtqueue_dma(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,
struct device *dma_dev);
/*
* 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 */
|
