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Diffstat (limited to 'drivers/net/virtio/virtio_ring.h')
| -rw-r--r-- | drivers/net/virtio/virtio_ring.h | 163 |
1 files changed, 163 insertions, 0 deletions
diff --git a/drivers/net/virtio/virtio_ring.h b/drivers/net/virtio/virtio_ring.h new file mode 100644 index 00000000..447760a8 --- /dev/null +++ b/drivers/net/virtio/virtio_ring.h @@ -0,0 +1,163 @@ +/*- + * BSD LICENSE + * + * Copyright(c) 2010-2014 Intel Corporation. All rights reserved. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * 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. + * * Neither the name of Intel Corporation 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 THE COPYRIGHT + * OWNER 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 _VIRTIO_RING_H_ +#define _VIRTIO_RING_H_ + +#include <stdint.h> + +#include <rte_common.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 + +/* VirtIO ring descriptors: 16 bytes. + * These can chain together via "next". */ +struct vring_desc { + uint64_t addr; /* Address (guest-physical). */ + uint32_t len; /* Length. */ + uint16_t flags; /* The flags as indicated above. */ + uint16_t next; /* We chain unused descriptors via this. */ +}; + +struct vring_avail { + uint16_t flags; + uint16_t idx; + uint16_t ring[0]; +}; + +/* id is a 16bit index. uint32_t 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; +}; + +struct vring_used { + uint16_t flags; + uint16_t idx; + struct vring_used_elem ring[0]; +}; + +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]; + * __u16 used_event_idx; + * + * // 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]; + * __u16 avail_event_idx; + * }; + * + * NOTE: for VirtIO PCI, align is 4096. + */ + +/* + * We publish the used event index at the end of the available ring, and vice + * versa. They are at the end for backwards compatibility. + */ +#define vring_used_event(vr) ((vr)->avail->ring[(vr)->num]) +#define vring_avail_event(vr) (*(uint16_t *)&(vr)->used->ring[(vr)->num]) + +static inline size_t +vring_size(unsigned int num, unsigned long align) +{ + size_t size; + + size = num * sizeof(struct vring_desc); + size += sizeof(struct vring_avail) + (num * sizeof(uint16_t)); + size = RTE_ALIGN_CEIL(size, align); + size += sizeof(struct vring_used) + + (num * sizeof(struct vring_used_elem)); + return size; +} + +static inline void +vring_init(struct vring *vr, unsigned int num, uint8_t *p, + unsigned long align) +{ + vr->num = num; + vr->desc = (struct vring_desc *) p; + vr->avail = (struct vring_avail *) (p + + num * sizeof(struct vring_desc)); + vr->used = (void *) + RTE_ALIGN_CEIL((uintptr_t)(&vr->avail->ring[num]), align); +} + +/* + * The following is used with VIRTIO_RING_F_EVENT_IDX. + * Assuming a given event_idx value from the other size, if we have + * just incremented index from old to new_idx, should we trigger an + * event? + */ +static inline int +vring_need_event(uint16_t event_idx, uint16_t new_idx, uint16_t old) +{ + return (uint16_t)(new_idx - event_idx - 1) < (uint16_t)(new_idx - old); +} + +#endif /* _VIRTIO_RING_H_ */ |