| #ifndef VIRTQUEUE_H |
| #define VIRTQUEUE_H |
| /* 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 |
| * Copyright 2011, Red Hat, Inc |
| * 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. |
| */ |
| #include <stdint.h> |
| |
| /* This marks a buffer as continuing via the next field. */ |
| #define VIRTQ_DESC_F_NEXT 1 |
| /* This marks a buffer as write-only (otherwise read-only). */ |
| #define VIRTQ_DESC_F_WRITE 2 |
| /* This means the buffer contains a list of buffer descriptors. */ |
| #define VIRTQ_DESC_F_INDIRECT 4 |
| |
| /* The device uses this in used->flags to advise the driver: don't kick me |
| * when you add a buffer. It's unreliable, so it's simply an |
| * optimization. */ |
| #define VIRTQ_USED_F_NO_NOTIFY 1 |
| /* The driver uses this in avail->flags to advise the device: don't |
| * interrupt me when you consume a buffer. It's unreliable, so it's |
| * simply an optimization. */ |
| #define VIRTQ_AVAIL_F_NO_INTERRUPT 1 |
| |
| /* Support for indirect descriptors */ |
| #define VIRTIO_F_INDIRECT_DESC 28 |
| |
| /* Support for avail_event and used_event fields */ |
| #define VIRTIO_F_EVENT_IDX 29 |
| |
| /* Arbitrary descriptor layouts. */ |
| #define VIRTIO_F_ANY_LAYOUT 27 |
| |
| /* Virtqueue descriptors: 16 bytes. |
| * These can chain together via "next". */ |
| struct virtq_desc { |
| /* Address (guest-physical). */ |
| le64 addr; |
| /* Length. */ |
| le32 len; |
| /* The flags as indicated above. */ |
| le16 flags; |
| /* We chain unused descriptors via this, too */ |
| le16 next; |
| }; |
| |
| struct virtq_avail { |
| le16 flags; |
| le16 idx; |
| le16 ring[]; |
| /* Only if VIRTIO_F_EVENT_IDX: le16 used_event; */ |
| }; |
| |
| /* le32 is used here for ids for padding reasons. */ |
| struct virtq_used_elem { |
| /* Index of start of used descriptor chain. */ |
| le32 id; |
| /* Total length of the descriptor chain which was written to. */ |
| le32 len; |
| }; |
| |
| struct virtq_used { |
| le16 flags; |
| le16 idx; |
| struct virtq_used_elem ring[]; |
| /* Only if VIRTIO_F_EVENT_IDX: le16 avail_event; */ |
| }; |
| |
| struct virtq { |
| unsigned int num; |
| |
| struct virtq_desc *desc; |
| struct virtq_avail *avail; |
| struct virtq_used *used; |
| }; |
| |
| static inline int virtq_need_event(uint16_t event_idx, uint16_t new_idx, uint16_t old_idx) |
| { |
| return (uint16_t)(new_idx - event_idx - 1) < (uint16_t)(new_idx - old_idx); |
| } |
| |
| /* Get location of event indices (only with VIRTIO_F_EVENT_IDX) */ |
| static inline le16 *virtq_used_event(struct virtq *vq) |
| { |
| /* For backwards compat, used event index is at *end* of avail ring. */ |
| return &vq->avail->ring[vq->num]; |
| } |
| |
| static inline le16 *virtq_avail_event(struct virtq *vq) |
| { |
| /* For backwards compat, avail event index is at *end* of used ring. */ |
| return (le16 *)&vq->used->ring[vq->num]; |
| } |
| #endif /* VIRTQUEUE_H */ |