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