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 | |
| 18 | /* This means don't notify other side when buffer added. */ |
| 19 | #define VRING_USED_F_NO_NOTIFY 1 |
| 20 | /* This means don't interrupt guest when buffer consumed. */ |
| 21 | #define VRING_AVAIL_F_NO_INTERRUPT 1 |
| 22 | |
| 23 | /* Virtio ring descriptors: 16 bytes. These can chain together via "next". */ |
| 24 | struct vring_desc |
| 25 | { |
| 26 | /* Address (guest-physical). */ |
| 27 | __u64 addr; |
| 28 | /* Length. */ |
| 29 | __u32 len; |
| 30 | /* The flags as indicated above. */ |
| 31 | __u16 flags; |
| 32 | /* We chain unused descriptors via this, too */ |
| 33 | __u16 next; |
| 34 | }; |
| 35 | |
| 36 | struct vring_avail |
| 37 | { |
| 38 | __u16 flags; |
| 39 | __u16 idx; |
| 40 | __u16 ring[]; |
| 41 | }; |
| 42 | |
| 43 | /* u32 is used here for ids for padding reasons. */ |
| 44 | struct vring_used_elem |
| 45 | { |
| 46 | /* Index of start of used descriptor chain. */ |
| 47 | __u32 id; |
| 48 | /* Total length of the descriptor chain which was used (written to) */ |
| 49 | __u32 len; |
| 50 | }; |
| 51 | |
| 52 | struct vring_used |
| 53 | { |
| 54 | __u16 flags; |
| 55 | __u16 idx; |
| 56 | struct vring_used_elem ring[]; |
| 57 | }; |
| 58 | |
| 59 | struct vring { |
| 60 | unsigned int num; |
| 61 | |
| 62 | struct vring_desc *desc; |
| 63 | |
| 64 | struct vring_avail *avail; |
| 65 | |
| 66 | struct vring_used *used; |
| 67 | }; |
| 68 | |
| 69 | /* The standard layout for the ring is a continuous chunk of memory which looks |
| 70 | * like this. The used fields will be aligned to a "num+1" boundary. |
| 71 | * |
| 72 | * struct vring |
| 73 | * { |
| 74 | * // The actual descriptors (16 bytes each) |
| 75 | * struct vring_desc desc[num]; |
| 76 | * |
| 77 | * // A ring of available descriptor heads with free-running index. |
| 78 | * __u16 avail_flags; |
| 79 | * __u16 avail_idx; |
| 80 | * __u16 available[num]; |
| 81 | * |
| 82 | * // Padding so a correctly-chosen num value will cache-align used_idx. |
| 83 | * char pad[sizeof(struct vring_desc) - sizeof(avail_flags)]; |
| 84 | * |
| 85 | * // A ring of used descriptor heads with free-running index. |
| 86 | * __u16 used_flags; |
| 87 | * __u16 used_idx; |
| 88 | * struct vring_used_elem used[num]; |
| 89 | * }; |
| 90 | */ |
| 91 | static inline void vring_init(struct vring *vr, unsigned int num, void *p) |
| 92 | { |
| 93 | vr->num = num; |
| 94 | vr->desc = p; |
| 95 | vr->avail = p + num*sizeof(struct vring); |
| 96 | vr->used = p + (num+1)*(sizeof(struct vring) + sizeof(__u16)); |
| 97 | } |
| 98 | |
| 99 | static inline unsigned vring_size(unsigned int num) |
| 100 | { |
| 101 | return (num + 1) * (sizeof(struct vring_desc) + sizeof(__u16)) |
| 102 | + sizeof(__u32) + num * sizeof(struct vring_used_elem); |
| 103 | } |
| 104 | |
| 105 | #ifdef __KERNEL__ |
| 106 | #include <linux/irqreturn.h> |
| 107 | struct virtio_device; |
| 108 | struct virtqueue; |
| 109 | |
| 110 | struct virtqueue *vring_new_virtqueue(unsigned int num, |
| 111 | struct virtio_device *vdev, |
| 112 | void *pages, |
| 113 | void (*notify)(struct virtqueue *vq), |
| 114 | bool (*callback)(struct virtqueue *vq)); |
| 115 | void vring_del_virtqueue(struct virtqueue *vq); |
| 116 | |
| 117 | irqreturn_t vring_interrupt(int irq, void *_vq); |
| 118 | #endif /* __KERNEL__ */ |
| 119 | #endif /* _LINUX_VIRTIO_RING_H */ |