/* 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. */ #ifndef VIRTQUEUE_H #define VIRTQUEUE_H typedef uint16_t le16; typedef uint32_t le32; typedef uint64_t le64; /* 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 #define VIRTQ_OFF_DESC(q) 0 #define VIRTQ_OFF_AVAIL(q) ((q) * sizeof(struct virtq_desc)) #define VIRTQ_OFF_AVAIL_RING(q) (VIRTQ_OFF_AVAIL(q) \ + sizeof(struct virtq_avail)) #define VIRTQ_OFF_PADDING(q) (VIRTQ_OFF_AVAIL_RING(q) \ + (sizeof(le16) * (q))) #define VIRTQ_OFF_USED(q) ((VIRTQ_OFF_PADDING(q) + PAGE_SIZE - 1) & PAGE_MASK) #define VIRTQ_OFF_USED_RING(q) (VIRTQ_OFF_USED(q) + sizeof(struct virtq_used)) #define VIRTQ_SIZE(q) (VIRTQ_OFF_USED_RING(q) \ + (sizeof(struct virtq_used_elem) * (q))) /* 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; volatile le16 idx; struct virtq_used_elem ring[]; /* Only if VIRTIO_F_EVENT_IDX: le16 avail_event; */ }; /* This is the max buffer length per descriptor. */ #define MAX_BUFFER_LEN 1526 /* * Each one of these io_buffer's map to a descriptor. An array of io_buffer's * of size virtq.num (same as virtq.desc) is allocated during init. */ struct io_buffer { uint8_t data[MAX_BUFFER_LEN]; /* Data length in Bytes. It is written by the driver on a tx/write, or * by the device on a rx/read on interrupt handling (do not remove the * volatile). */ volatile uint32_t len; /* Extra flags to be added to the corresponding descriptor. */ uint16_t extra_flags; }; struct virtq { unsigned int num; struct virtq_desc *desc; struct virtq_avail *avail; struct virtq_used *used; struct io_buffer *bufs; /* Keep track of available (free) descriptors */ uint16_t num_avail; /* Indexes in the descriptors array */ uint16_t last_used; uint16_t next_avail; }; 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]; } /* * Create a descriptor chain starting at index head, using vq->bufs also * starting at index head. Num is the number of descriptors (and number of bufs). * * Returns 0 on success. */ int virtq_add_descriptor_chain(struct virtq *vq, uint16_t head, uint16_t num); void virtq_init_rings(uint16_t pci_base, struct virtq *vq, int selector); #endif /* VIRTQUEUE_H */