#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 /* 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 /* 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 page 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 pagesize) { vr->num = num; vr->desc = p; vr->avail = p + num*sizeof(struct vring_desc); vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + pagesize-1) & ~(pagesize - 1)); } static inline unsigned vring_size(unsigned int num, unsigned long pagesize) { return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (2 + num) + pagesize - 1) & ~(pagesize - 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, struct virtio_device *vdev, void *pages, void (*notify)(struct virtqueue *vq), void (*callback)(struct virtqueue *vq)); void vring_del_virtqueue(struct virtqueue *vq); irqreturn_t vring_interrupt(int irq, void *_vq); #endif /* __KERNEL__ */ #endif /* _LINUX_VIRTIO_RING_H */