/*
* Copyright (c) 2010 Minoura Makoto.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Part of the file derived from `Virtio PCI Card Specification v0.8.6 DRAFT'
* Appendix A.
*/
/* An interface for efficient virtio implementation.
*
* This header is BSD licensed so anyone can use the definitions
* to implement compatible drivers/servers.
*
* Copyright 2007, 2009, IBM Corporation
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of IBM nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/* marks a buffer as continuing via the next field. */
#define VRING_DESC_F_NEXT 1
/* marks a buffer as write-only (otherwise read-only). */
#define VRING_DESC_F_WRITE 2
/* 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
/* Virtio ring descriptors: 16 bytes.
* These can chain together via "next". */
struct vring_desc {
/* Address (guest-physical). */
uint64_t addr;
/* Length. */
uint32_t len;
/* The flags as indicated above. */
uint16_t flags;
/* We chain unused descriptors via this, too */
uint16_t next;
} __packed;
struct vring_avail {
uint16_t flags;
uint16_t idx;
uint16_t ring[];
/* trailed by uint16_t used_event when VIRTIO_F_RING_EVENT_IDX */
} __packed;
/* u32 is used here for ids for padding reasons. */
struct vring_used_elem {
/* Index of start of used descriptor chain. */
uint32_t id;
/* Total length of the descriptor chain which was written to. */
uint32_t len;
} __packed;
struct vring_used {
uint16_t flags;
uint16_t idx;
struct vring_used_elem ring[];
/* trailed by uint16_t avail_event when VIRTIO_F_RING_EVENT_IDX */
} __packed;
/* 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];
* };
* Note: for virtio PCI, align is 4096.
*/
