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 |
| 17 | |
Rusty Russell | 426e3e0 | 2008-02-04 23:49:59 -0500 | [diff] [blame] | 18 | /* The Host uses this in used->flags to advise the Guest: don't kick me when |
| 19 | * you add a buffer. It's unreliable, so it's simply an optimization. Guest |
| 20 | * will still kick if it's out of buffers. */ |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 21 | #define VRING_USED_F_NO_NOTIFY 1 |
Rusty Russell | 426e3e0 | 2008-02-04 23:49:59 -0500 | [diff] [blame] | 22 | /* The Guest uses this in avail->flags to advise the Host: don't interrupt me |
| 23 | * when you consume a buffer. It's unreliable, so it's simply an |
| 24 | * optimization. */ |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 25 | #define VRING_AVAIL_F_NO_INTERRUPT 1 |
| 26 | |
| 27 | /* Virtio ring descriptors: 16 bytes. These can chain together via "next". */ |
| 28 | struct vring_desc |
| 29 | { |
| 30 | /* Address (guest-physical). */ |
| 31 | __u64 addr; |
| 32 | /* Length. */ |
| 33 | __u32 len; |
| 34 | /* The flags as indicated above. */ |
| 35 | __u16 flags; |
| 36 | /* We chain unused descriptors via this, too */ |
| 37 | __u16 next; |
| 38 | }; |
| 39 | |
| 40 | struct vring_avail |
| 41 | { |
| 42 | __u16 flags; |
| 43 | __u16 idx; |
| 44 | __u16 ring[]; |
| 45 | }; |
| 46 | |
| 47 | /* u32 is used here for ids for padding reasons. */ |
| 48 | struct vring_used_elem |
| 49 | { |
| 50 | /* Index of start of used descriptor chain. */ |
| 51 | __u32 id; |
| 52 | /* Total length of the descriptor chain which was used (written to) */ |
| 53 | __u32 len; |
| 54 | }; |
| 55 | |
| 56 | struct vring_used |
| 57 | { |
| 58 | __u16 flags; |
| 59 | __u16 idx; |
| 60 | struct vring_used_elem ring[]; |
| 61 | }; |
| 62 | |
| 63 | struct vring { |
| 64 | unsigned int num; |
| 65 | |
| 66 | struct vring_desc *desc; |
| 67 | |
| 68 | struct vring_avail *avail; |
| 69 | |
| 70 | struct vring_used *used; |
| 71 | }; |
| 72 | |
| 73 | /* 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] | 74 | * like this. We assume num is a power of 2. |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 75 | * |
| 76 | * struct vring |
| 77 | * { |
| 78 | * // The actual descriptors (16 bytes each) |
| 79 | * struct vring_desc desc[num]; |
| 80 | * |
| 81 | * // A ring of available descriptor heads with free-running index. |
| 82 | * __u16 avail_flags; |
| 83 | * __u16 avail_idx; |
| 84 | * __u16 available[num]; |
| 85 | * |
Rusty Russell | 5f0d1d7 | 2008-12-30 09:25:57 -0600 | [diff] [blame^] | 86 | * // Padding to the next align boundary. |
Rusty Russell | 42b36cc | 2007-11-12 13:39:18 +1100 | [diff] [blame] | 87 | * char pad[]; |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 88 | * |
| 89 | * // A ring of used descriptor heads with free-running index. |
| 90 | * __u16 used_flags; |
| 91 | * __u16 used_idx; |
| 92 | * struct vring_used_elem used[num]; |
| 93 | * }; |
| 94 | */ |
Rusty Russell | 42b36cc | 2007-11-12 13:39:18 +1100 | [diff] [blame] | 95 | 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^] | 96 | unsigned long align) |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 97 | { |
| 98 | vr->num = num; |
| 99 | vr->desc = p; |
Anthony Liguori | 44332f7 | 2007-11-07 16:31:52 +1100 | [diff] [blame] | 100 | vr->avail = p + num*sizeof(struct vring_desc); |
Rusty Russell | 5f0d1d7 | 2008-12-30 09:25:57 -0600 | [diff] [blame^] | 101 | vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + align-1) |
| 102 | & ~(align - 1)); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 103 | } |
| 104 | |
Rusty Russell | 5f0d1d7 | 2008-12-30 09:25:57 -0600 | [diff] [blame^] | 105 | static inline unsigned vring_size(unsigned int num, unsigned long align) |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 106 | { |
Rusty Russell | 42b36cc | 2007-11-12 13:39:18 +1100 | [diff] [blame] | 107 | return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (2 + num) |
Rusty Russell | 5f0d1d7 | 2008-12-30 09:25:57 -0600 | [diff] [blame^] | 108 | + align - 1) & ~(align - 1)) |
Rusty Russell | 42b36cc | 2007-11-12 13:39:18 +1100 | [diff] [blame] | 109 | + sizeof(__u16) * 2 + sizeof(struct vring_used_elem) * num; |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 110 | } |
| 111 | |
| 112 | #ifdef __KERNEL__ |
| 113 | #include <linux/irqreturn.h> |
| 114 | struct virtio_device; |
| 115 | struct virtqueue; |
| 116 | |
| 117 | struct virtqueue *vring_new_virtqueue(unsigned int num, |
| 118 | struct virtio_device *vdev, |
| 119 | void *pages, |
| 120 | void (*notify)(struct virtqueue *vq), |
Rusty Russell | 18445c4 | 2008-02-04 23:49:57 -0500 | [diff] [blame] | 121 | void (*callback)(struct virtqueue *vq)); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 122 | void vring_del_virtqueue(struct virtqueue *vq); |
Rusty Russell | e34f872 | 2008-07-25 12:06:13 -0500 | [diff] [blame] | 123 | /* Filter out transport-specific feature bits. */ |
| 124 | void vring_transport_features(struct virtio_device *vdev); |
Rusty Russell | 0a8a69d | 2007-10-22 11:03:40 +1000 | [diff] [blame] | 125 | |
| 126 | irqreturn_t vring_interrupt(int irq, void *_vq); |
| 127 | #endif /* __KERNEL__ */ |
| 128 | #endif /* _LINUX_VIRTIO_RING_H */ |