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0a8a69dd RR |
1 | #ifndef _LINUX_VIRTIO_RING_H |
2 | #define _LINUX_VIRTIO_RING_H | |
0a8a69dd | 3 | |
0a8a69dd | 4 | #include <linux/irqreturn.h> |
607ca46e DH |
5 | #include <uapi/linux/virtio_ring.h> |
6 | ||
a9a0fef7 RR |
7 | /* |
8 | * Barriers in virtio are tricky. Non-SMP virtio guests can't assume | |
9 | * they're not on an SMP host system, so they need to assume real | |
10 | * barriers. Non-SMP virtio hosts could skip the barriers, but does | |
11 | * anyone care? | |
12 | * | |
13 | * For virtio_pci on SMP, we don't need to order with respect to MMIO | |
14 | * accesses through relaxed memory I/O windows, so smp_mb() et al are | |
15 | * sufficient. | |
16 | * | |
17 | * For using virtio to talk to real devices (eg. other heterogeneous | |
18 | * CPUs) we do need real barriers. In theory, we could be using both | |
19 | * kinds of virtio, so it's a runtime decision, and the branch is | |
20 | * actually quite cheap. | |
21 | */ | |
22 | ||
23 | #ifdef CONFIG_SMP | |
24 | static inline void virtio_mb(bool weak_barriers) | |
25 | { | |
26 | if (weak_barriers) | |
27 | smp_mb(); | |
28 | else | |
29 | mb(); | |
30 | } | |
31 | ||
32 | static inline void virtio_rmb(bool weak_barriers) | |
33 | { | |
34 | if (weak_barriers) | |
35 | smp_rmb(); | |
36 | else | |
37 | rmb(); | |
38 | } | |
39 | ||
40 | static inline void virtio_wmb(bool weak_barriers) | |
41 | { | |
42 | if (weak_barriers) | |
43 | smp_wmb(); | |
44 | else | |
45 | wmb(); | |
46 | } | |
47 | #else | |
48 | static inline void virtio_mb(bool weak_barriers) | |
49 | { | |
50 | mb(); | |
51 | } | |
52 | ||
53 | static inline void virtio_rmb(bool weak_barriers) | |
54 | { | |
55 | rmb(); | |
56 | } | |
57 | ||
58 | static inline void virtio_wmb(bool weak_barriers) | |
59 | { | |
60 | wmb(); | |
61 | } | |
62 | #endif | |
63 | ||
0a8a69dd RR |
64 | struct virtio_device; |
65 | struct virtqueue; | |
66 | ||
17bb6d40 JW |
67 | struct virtqueue *vring_new_virtqueue(unsigned int index, |
68 | unsigned int num, | |
87c7d57c | 69 | unsigned int vring_align, |
0a8a69dd | 70 | struct virtio_device *vdev, |
7b21e34f | 71 | bool weak_barriers, |
0a8a69dd RR |
72 | void *pages, |
73 | void (*notify)(struct virtqueue *vq), | |
9499f5e7 RR |
74 | void (*callback)(struct virtqueue *vq), |
75 | const char *name); | |
0a8a69dd | 76 | void vring_del_virtqueue(struct virtqueue *vq); |
e34f8725 RR |
77 | /* Filter out transport-specific feature bits. */ |
78 | void vring_transport_features(struct virtio_device *vdev); | |
0a8a69dd RR |
79 | |
80 | irqreturn_t vring_interrupt(int irq, void *_vq); | |
0a8a69dd | 81 | #endif /* _LINUX_VIRTIO_RING_H */ |