Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 1 | #ifndef _LINUX_VIRTIO_RING_H |
| 2 | #define _LINUX_VIRTIO_RING_H |
| 3 | /* An interface for efficient virtio implementation, currently for use by KVM |
| 4 | * and lguest, but hopefully others soon. Do NOT change this since it will |
| 5 | * break existing servers and clients. |
| 6 | * |
| 7 | * This header is BSD licensed so anyone can use the definitions to implement |
| 8 | * compatible drivers/servers. |
| 9 | * |
| 10 | * Copyright Rusty Russell IBM Corporation 2007. */ |
| 11 | #include <linux/types.h> |
| 12 | |
| 13 | /* This marks a buffer as continuing via the next field. */ |
| 14 | #define VRING_DESC_F_NEXT 1 |
| 15 | /* This marks a buffer as write-only (otherwise read-only). */ |
| 16 | #define VRING_DESC_F_WRITE 2 |
Mark McLoughlin | 9fa29b9d | 2009-05-11 18:11:45 +0100 | [diff] [blame^] | 17 | /* This means the buffer contains a list of buffer descriptors. */ |
| 18 | #define VRING_DESC_F_INDIRECT 4 |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 19 | |
Rusty Russell | 426e3e0 | 2008-02-04 23:49:59 -0500 | [diff] [blame] | 20 | /* The Host uses this in used->flags to advise the Guest: don't kick me when |
| 21 | * you add a buffer. It's unreliable, so it's simply an optimization. Guest |
| 22 | * will still kick if it's out of buffers. */ |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 23 | #define VRING_USED_F_NO_NOTIFY 1 |
Rusty Russell | 426e3e0 | 2008-02-04 23:49:59 -0500 | [diff] [blame] | 24 | /* The Guest uses this in avail->flags to advise the Host: don't interrupt me |
| 25 | * when you consume a buffer. It's unreliable, so it's simply an |
| 26 | * optimization. */ |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 27 | #define VRING_AVAIL_F_NO_INTERRUPT 1 |
| 28 | |
Mark McLoughlin | 9fa29b9d | 2009-05-11 18:11:45 +0100 | [diff] [blame^] | 29 | /* We support indirect buffer descriptors */ |
| 30 | #define VIRTIO_RING_F_INDIRECT_DESC 28 |
| 31 | |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 32 | /* Virtio ring descriptors: 16 bytes. These can chain together via "next". */ |
| 33 | struct vring_desc |
| 34 | { |
| 35 | /* Address (guest-physical). */ |
| 36 | __u64 addr; |
| 37 | /* Length. */ |
| 38 | __u32 len; |
| 39 | /* The flags as indicated above. */ |
| 40 | __u16 flags; |
| 41 | /* We chain unused descriptors via this, too */ |
| 42 | __u16 next; |
| 43 | }; |
| 44 | |
| 45 | struct vring_avail |
| 46 | { |
| 47 | __u16 flags; |
| 48 | __u16 idx; |
| 49 | __u16 ring[]; |
| 50 | }; |
| 51 | |
| 52 | /* u32 is used here for ids for padding reasons. */ |
| 53 | struct vring_used_elem |
| 54 | { |
| 55 | /* Index of start of used descriptor chain. */ |
| 56 | __u32 id; |
| 57 | /* Total length of the descriptor chain which was used (written to) */ |
| 58 | __u32 len; |
| 59 | }; |
| 60 | |
| 61 | struct vring_used |
| 62 | { |
| 63 | __u16 flags; |
| 64 | __u16 idx; |
| 65 | struct vring_used_elem ring[]; |
| 66 | }; |
| 67 | |
| 68 | struct vring { |
| 69 | unsigned int num; |
| 70 | |
| 71 | struct vring_desc *desc; |
| 72 | |
| 73 | struct vring_avail *avail; |
| 74 | |
| 75 | struct vring_used *used; |
| 76 | }; |
| 77 | |
| 78 | /* The standard layout for the ring is a continuous chunk of memory which looks |
Rusty Russell | 42b36cc | 2007-11-12 13:39:18 +1100 | [diff] [blame] | 79 | * like this. We assume num is a power of 2. |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 80 | * |
| 81 | * struct vring |
| 82 | * { |
| 83 | * // The actual descriptors (16 bytes each) |
| 84 | * struct vring_desc desc[num]; |
| 85 | * |
| 86 | * // A ring of available descriptor heads with free-running index. |
| 87 | * __u16 avail_flags; |
| 88 | * __u16 avail_idx; |
| 89 | * __u16 available[num]; |
| 90 | * |
Rusty Russell | 5f0d1d7 | 2008-12-30 09:25:57 -0600 | [diff] [blame] | 91 | * // Padding to the next align boundary. |
Rusty Russell | 42b36cc | 2007-11-12 13:39:18 +1100 | [diff] [blame] | 92 | * char pad[]; |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 93 | * |
| 94 | * // A ring of used descriptor heads with free-running index. |
| 95 | * __u16 used_flags; |
| 96 | * __u16 used_idx; |
| 97 | * struct vring_used_elem used[num]; |
| 98 | * }; |
| 99 | */ |
Rusty Russell | 42b36cc | 2007-11-12 13:39:18 +1100 | [diff] [blame] | 100 | static inline void vring_init(struct vring *vr, unsigned int num, void *p, |
Rusty Russell | 5f0d1d7 | 2008-12-30 09:25:57 -0600 | [diff] [blame] | 101 | unsigned long align) |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 102 | { |
| 103 | vr->num = num; |
| 104 | vr->desc = p; |
Anthony Liguori | 44332f7 | 2007-11-07 16:31:52 +1100 | [diff] [blame] | 105 | vr->avail = p + num*sizeof(struct vring_desc); |
Rusty Russell | 5f0d1d7 | 2008-12-30 09:25:57 -0600 | [diff] [blame] | 106 | vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + align-1) |
| 107 | & ~(align - 1)); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 108 | } |
| 109 | |
Rusty Russell | 5f0d1d7 | 2008-12-30 09:25:57 -0600 | [diff] [blame] | 110 | static inline unsigned vring_size(unsigned int num, unsigned long align) |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 111 | { |
Rusty Russell | 42b36cc | 2007-11-12 13:39:18 +1100 | [diff] [blame] | 112 | return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (2 + num) |
Rusty Russell | 5f0d1d7 | 2008-12-30 09:25:57 -0600 | [diff] [blame] | 113 | + align - 1) & ~(align - 1)) |
Rusty Russell | 42b36cc | 2007-11-12 13:39:18 +1100 | [diff] [blame] | 114 | + sizeof(__u16) * 2 + sizeof(struct vring_used_elem) * num; |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 115 | } |
| 116 | |
| 117 | #ifdef __KERNEL__ |
| 118 | #include <linux/irqreturn.h> |
| 119 | struct virtio_device; |
| 120 | struct virtqueue; |
| 121 | |
| 122 | struct virtqueue *vring_new_virtqueue(unsigned int num, |
Rusty Russell | 87c7d57 | 2008-12-30 09:26:03 -0600 | [diff] [blame] | 123 | unsigned int vring_align, |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 124 | struct virtio_device *vdev, |
| 125 | void *pages, |
| 126 | void (*notify)(struct virtqueue *vq), |
Rusty Russell | 9499f5e | 2009-06-12 22:16:35 -0600 | [diff] [blame] | 127 | void (*callback)(struct virtqueue *vq), |
| 128 | const char *name); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 129 | void vring_del_virtqueue(struct virtqueue *vq); |
Rusty Russell | e34f872 | 2008-07-25 12:06:13 -0500 | [diff] [blame] | 130 | /* Filter out transport-specific feature bits. */ |
| 131 | void vring_transport_features(struct virtio_device *vdev); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 132 | |
| 133 | irqreturn_t vring_interrupt(int irq, void *_vq); |
| 134 | #endif /* __KERNEL__ */ |
| 135 | #endif /* _LINUX_VIRTIO_RING_H */ |