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
virtio_mb(bool weak_barriers)24 static inline void virtio_mb(bool weak_barriers)
25 {
26 #ifdef CONFIG_SMP
27 if (weak_barriers)
28 smp_mb();
29 else
30 #endif
31 mb();
32 }
33
virtio_rmb(bool weak_barriers)34 static inline void virtio_rmb(bool weak_barriers)
35 {
36 if (weak_barriers)
37 dma_rmb();
38 else
39 rmb();
40 }
41
virtio_wmb(bool weak_barriers)42 static inline void virtio_wmb(bool weak_barriers)
43 {
44 if (weak_barriers)
45 dma_wmb();
46 else
47 wmb();
48 }
49
50 struct virtio_device;
51 struct virtqueue;
52
53 struct virtqueue *vring_new_virtqueue(unsigned int index,
54 unsigned int num,
55 unsigned int vring_align,
56 struct virtio_device *vdev,
57 bool weak_barriers,
58 void *pages,
59 bool (*notify)(struct virtqueue *vq),
60 void (*callback)(struct virtqueue *vq),
61 const char *name);
62 void vring_del_virtqueue(struct virtqueue *vq);
63 /* Filter out transport-specific feature bits. */
64 void vring_transport_features(struct virtio_device *vdev);
65
66 irqreturn_t vring_interrupt(int irq, void *_vq);
67 #endif /* _LINUX_VIRTIO_RING_H */
68