Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 1 | #ifndef _LINUX_VIRTIO_RING_H |
| 2 | #define _LINUX_VIRTIO_RING_H |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 3 | |
Michael S. Tsirkin | c5610a5d | 2013-07-08 11:31:06 +0930 | [diff] [blame] | 4 | #include <asm/barrier.h> |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 5 | #include <linux/irqreturn.h> |
David Howells | 607ca46 | 2012-10-13 10:46:48 +0100 | [diff] [blame] | 6 | #include <uapi/linux/virtio_ring.h> |
| 7 | |
Rusty Russell | a9a0fef | 2013-03-18 13:22:19 +1030 | [diff] [blame] | 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 |
Michael S. Tsirkin | a659612 | 2015-12-27 17:55:35 +0200 | [diff] [blame] | 15 | * accesses through relaxed memory I/O windows, so virt_mb() et al are |
Rusty Russell | a9a0fef | 2013-03-18 13:22:19 +1030 | [diff] [blame] | 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 | |
Rusty Russell | a9a0fef | 2013-03-18 13:22:19 +1030 | [diff] [blame] | 24 | static inline void virtio_mb(bool weak_barriers) |
| 25 | { |
| 26 | if (weak_barriers) |
Michael S. Tsirkin | a659612 | 2015-12-27 17:55:35 +0200 | [diff] [blame] | 27 | virt_mb(); |
Rusty Russell | a9a0fef | 2013-03-18 13:22:19 +1030 | [diff] [blame] | 28 | else |
| 29 | mb(); |
| 30 | } |
| 31 | |
| 32 | static inline void virtio_rmb(bool weak_barriers) |
| 33 | { |
| 34 | if (weak_barriers) |
Michael S. Tsirkin | a659612 | 2015-12-27 17:55:35 +0200 | [diff] [blame] | 35 | virt_rmb(); |
Rusty Russell | a9a0fef | 2013-03-18 13:22:19 +1030 | [diff] [blame] | 36 | else |
| 37 | rmb(); |
| 38 | } |
| 39 | |
| 40 | static inline void virtio_wmb(bool weak_barriers) |
| 41 | { |
| 42 | if (weak_barriers) |
Michael S. Tsirkin | a659612 | 2015-12-27 17:55:35 +0200 | [diff] [blame] | 43 | virt_wmb(); |
Rusty Russell | a9a0fef | 2013-03-18 13:22:19 +1030 | [diff] [blame] | 44 | else |
| 45 | wmb(); |
| 46 | } |
Rusty Russell | a9a0fef | 2013-03-18 13:22:19 +1030 | [diff] [blame] | 47 | |
Michael S. Tsirkin | 788e5b3 | 2015-12-17 12:20:39 +0200 | [diff] [blame] | 48 | static inline void virtio_store_mb(bool weak_barriers, |
| 49 | __virtio16 *p, __virtio16 v) |
| 50 | { |
| 51 | if (weak_barriers) { |
| 52 | virt_store_mb(*p, v); |
| 53 | } else { |
| 54 | WRITE_ONCE(*p, v); |
| 55 | mb(); |
| 56 | } |
| 57 | } |
| 58 | |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 59 | struct virtio_device; |
| 60 | struct virtqueue; |
| 61 | |
Andy Lutomirski | 2a2d138 | 2016-02-02 21:46:37 -0800 | [diff] [blame] | 62 | /* |
| 63 | * Creates a virtqueue and allocates the descriptor ring. If |
| 64 | * may_reduce_num is set, then this may allocate a smaller ring than |
| 65 | * expected. The caller should query virtqueue_get_ring_size to learn |
| 66 | * the actual size of the ring. |
| 67 | */ |
| 68 | struct virtqueue *vring_create_virtqueue(unsigned int index, |
| 69 | unsigned int num, |
| 70 | unsigned int vring_align, |
| 71 | struct virtio_device *vdev, |
| 72 | bool weak_barriers, |
| 73 | bool may_reduce_num, |
Michael S. Tsirkin | f94682d | 2017-03-06 18:32:29 +0200 | [diff] [blame^] | 74 | bool ctx, |
Andy Lutomirski | 2a2d138 | 2016-02-02 21:46:37 -0800 | [diff] [blame] | 75 | bool (*notify)(struct virtqueue *vq), |
| 76 | void (*callback)(struct virtqueue *vq), |
| 77 | const char *name); |
| 78 | |
| 79 | /* Creates a virtqueue with a custom layout. */ |
| 80 | struct virtqueue *__vring_new_virtqueue(unsigned int index, |
| 81 | struct vring vring, |
| 82 | struct virtio_device *vdev, |
| 83 | bool weak_barriers, |
Michael S. Tsirkin | f94682d | 2017-03-06 18:32:29 +0200 | [diff] [blame^] | 84 | bool ctx, |
Andy Lutomirski | 2a2d138 | 2016-02-02 21:46:37 -0800 | [diff] [blame] | 85 | bool (*notify)(struct virtqueue *), |
| 86 | void (*callback)(struct virtqueue *), |
| 87 | const char *name); |
| 88 | |
| 89 | /* |
| 90 | * Creates a virtqueue with a standard layout but a caller-allocated |
| 91 | * ring. |
| 92 | */ |
Jason Wang | 17bb6d4 | 2012-08-28 13:54:13 +0200 | [diff] [blame] | 93 | struct virtqueue *vring_new_virtqueue(unsigned int index, |
| 94 | unsigned int num, |
Rusty Russell | 87c7d57 | 2008-12-30 09:26:03 -0600 | [diff] [blame] | 95 | unsigned int vring_align, |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 96 | struct virtio_device *vdev, |
Rusty Russell | 7b21e34 | 2012-01-12 15:44:42 +1030 | [diff] [blame] | 97 | bool weak_barriers, |
Michael S. Tsirkin | f94682d | 2017-03-06 18:32:29 +0200 | [diff] [blame^] | 98 | bool ctx, |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 99 | void *pages, |
Heinz Graalfs | 46f9c2b | 2013-10-29 09:38:50 +1030 | [diff] [blame] | 100 | bool (*notify)(struct virtqueue *vq), |
Rusty Russell | 9499f5e | 2009-06-12 22:16:35 -0600 | [diff] [blame] | 101 | void (*callback)(struct virtqueue *vq), |
| 102 | const char *name); |
Andy Lutomirski | 2a2d138 | 2016-02-02 21:46:37 -0800 | [diff] [blame] | 103 | |
| 104 | /* |
| 105 | * Destroys a virtqueue. If created with vring_create_virtqueue, this |
| 106 | * also frees the ring. |
| 107 | */ |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 108 | void vring_del_virtqueue(struct virtqueue *vq); |
Andy Lutomirski | 2a2d138 | 2016-02-02 21:46:37 -0800 | [diff] [blame] | 109 | |
Rusty Russell | e34f872 | 2008-07-25 12:06:13 -0500 | [diff] [blame] | 110 | /* Filter out transport-specific feature bits. */ |
| 111 | void vring_transport_features(struct virtio_device *vdev); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 112 | |
| 113 | irqreturn_t vring_interrupt(int irq, void *_vq); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 114 | #endif /* _LINUX_VIRTIO_RING_H */ |