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Diffstat (limited to 'include/linux/virtio_ring.h')
| -rw-r--r-- | include/linux/virtio_ring.h | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h new file mode 100644 index 00000000000..e4d144b132b --- /dev/null +++ b/include/linux/virtio_ring.h @@ -0,0 +1,131 @@ +#ifndef _LINUX_VIRTIO_RING_H +#define _LINUX_VIRTIO_RING_H +/* An interface for efficient virtio implementation, currently for use by KVM + * and lguest, but hopefully others soon. Do NOT change this since it will + * break existing servers and clients. + * + * This header is BSD licensed so anyone can use the definitions to implement + * compatible drivers/servers. + * + * Copyright Rusty Russell IBM Corporation 2007. */ +#include <linux/types.h> + +/* This marks a buffer as continuing via the next field. */ +#define VRING_DESC_F_NEXT 1 +/* This marks a buffer as write-only (otherwise read-only). */ +#define VRING_DESC_F_WRITE 2 +/* This means the buffer contains a list of buffer descriptors. */ +#define VRING_DESC_F_INDIRECT 4 + +/* The Host uses this in used->flags to advise the Guest: don't kick me when + * you add a buffer. It's unreliable, so it's simply an optimization. Guest + * will still kick if it's out of buffers. */ +#define VRING_USED_F_NO_NOTIFY 1 +/* The Guest uses this in avail->flags to advise the Host: don't interrupt me + * when you consume a buffer. It's unreliable, so it's simply an + * optimization. */ +#define VRING_AVAIL_F_NO_INTERRUPT 1 + +/* We support indirect buffer descriptors */ +#define VIRTIO_RING_F_INDIRECT_DESC 28 + +/* Virtio ring descriptors: 16 bytes. These can chain together via "next". */ +struct vring_desc { + /* Address (guest-physical). */ + __u64 addr; + /* Length. */ + __u32 len; + /* The flags as indicated above. */ + __u16 flags; + /* We chain unused descriptors via this, too */ + __u16 next; +}; + +struct vring_avail { + __u16 flags; + __u16 idx; + __u16 ring[]; +}; + +/* u32 is used here for ids for padding reasons. */ +struct vring_used_elem { + /* Index of start of used descriptor chain. */ + __u32 id; + /* Total length of the descriptor chain which was used (written to) */ + __u32 len; +}; + +struct vring_used { + __u16 flags; + __u16 idx; + struct vring_used_elem ring[]; +}; + +struct vring { + unsigned int num; + + struct vring_desc *desc; + + struct vring_avail *avail; + + struct vring_used *used; +}; + +/* The standard layout for the ring is a continuous chunk of memory which looks + * like this. We assume num is a power of 2. + * + * struct vring + * { + * // The actual descriptors (16 bytes each) + * struct vring_desc desc[num]; + * + * // A ring of available descriptor heads with free-running index. + * __u16 avail_flags; + * __u16 avail_idx; + * __u16 available[num]; + * + * // Padding to the next align boundary. + * char pad[]; + * + * // A ring of used descriptor heads with free-running index. + * __u16 used_flags; + * __u16 used_idx; + * struct vring_used_elem used[num]; + * }; + */ +static inline void vring_init(struct vring *vr, unsigned int num, void *p, + unsigned long align) +{ + vr->num = num; + vr->desc = p; + vr->avail = p + num*sizeof(struct vring_desc); + vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + align-1) + & ~(align - 1)); +} + +static inline unsigned vring_size(unsigned int num, unsigned long align) +{ + return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (2 + num) + + align - 1) & ~(align - 1)) + + sizeof(__u16) * 2 + sizeof(struct vring_used_elem) * num; +} + +#ifdef __KERNEL__ +#include <linux/irqreturn.h> +struct virtio_device; +struct virtqueue; + +struct virtqueue *vring_new_virtqueue(unsigned int num, + unsigned int vring_align, + struct virtio_device *vdev, + void *pages, + void (*notify)(struct virtqueue *vq), + void (*callback)(struct virtqueue *vq), + const char *name); +void vring_del_virtqueue(struct virtqueue *vq); +/* Filter out transport-specific feature bits. */ +void vring_transport_features(struct virtio_device *vdev); + +irqreturn_t vring_interrupt(int irq, void *_vq); +#endif /* __KERNEL__ */ +#endif /* _LINUX_VIRTIO_RING_H */ |