10b59a9b4a
Tested on Qemu/KVM, VirtualBox, and BHyVe. Currently built as modules-only on i386/amd64. Man pages not yet hooked up, pending review. Submitted by: Bryan Venteicher bryanv at daemoninthecloset dot org Reviewed by: bz MFC after: 4 weeks or so
756 lines
18 KiB
C
756 lines
18 KiB
C
/*-
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* Copyright (c) 2011, Bryan Venteicher <bryanv@daemoninthecloset.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice unmodified, this list of conditions, and the following
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* disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* Implements the virtqueue interface as basically described
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* in the original VirtIO paper.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/malloc.h>
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#include <sys/sglist.h>
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#include <vm/vm.h>
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#include <vm/pmap.h>
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#include <machine/cpu.h>
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#include <machine/bus.h>
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#include <machine/atomic.h>
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#include <machine/resource.h>
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#include <sys/bus.h>
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#include <sys/rman.h>
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#include <dev/virtio/virtio.h>
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#include <dev/virtio/virtqueue.h>
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#include <dev/virtio/virtio_ring.h>
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#include "virtio_bus_if.h"
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struct virtqueue {
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device_t vq_dev;
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char vq_name[VIRTQUEUE_MAX_NAME_SZ];
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uint16_t vq_queue_index;
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uint16_t vq_nentries;
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uint32_t vq_flags;
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#define VIRTQUEUE_FLAG_INDIRECT 0x0001
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int vq_alignment;
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int vq_ring_size;
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void *vq_ring_mem;
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int vq_max_indirect_size;
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int vq_indirect_mem_size;
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virtqueue_intr_t *vq_intrhand;
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void *vq_intrhand_arg;
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struct vring vq_ring;
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uint16_t vq_free_cnt;
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uint16_t vq_queued_cnt;
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/*
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* Head of the free chain in the descriptor table. If
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* there are no free descriptors, this will be set to
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* VQ_RING_DESC_CHAIN_END.
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*/
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uint16_t vq_desc_head_idx;
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/*
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* Last consumed descriptor in the used table,
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* trails vq_ring.used->idx.
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*/
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uint16_t vq_used_cons_idx;
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struct vq_desc_extra {
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void *cookie;
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struct vring_desc *indirect;
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vm_paddr_t indirect_paddr;
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uint16_t ndescs;
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} vq_descx[0];
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};
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/*
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* The maximum virtqueue size is 2^15. Use that value as the end of
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* descriptor chain terminator since it will never be a valid index
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* in the descriptor table. This is used to verify we are correctly
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* handling vq_free_cnt.
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*/
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#define VQ_RING_DESC_CHAIN_END 32768
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#define VQASSERT(_vq, _exp, _msg, ...) \
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KASSERT((_exp),("%s: %s - "_msg, __func__, (_vq)->vq_name, \
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##__VA_ARGS__))
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#define VQ_RING_ASSERT_VALID_IDX(_vq, _idx) \
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VQASSERT((_vq), (_idx) < (_vq)->vq_nentries, \
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"invalid ring index: %d, max: %d", (_idx), \
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(_vq)->vq_nentries)
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#define VQ_RING_ASSERT_CHAIN_TERM(_vq) \
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VQASSERT((_vq), (_vq)->vq_desc_head_idx == \
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VQ_RING_DESC_CHAIN_END, "full ring terminated " \
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"incorrectly: head idx: %d", (_vq)->vq_desc_head_idx)
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static int virtqueue_init_indirect(struct virtqueue *vq, int);
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static void virtqueue_free_indirect(struct virtqueue *vq);
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static void virtqueue_init_indirect_list(struct virtqueue *,
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struct vring_desc *);
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static void vq_ring_init(struct virtqueue *);
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static void vq_ring_update_avail(struct virtqueue *, uint16_t);
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static uint16_t vq_ring_enqueue_segments(struct virtqueue *,
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struct vring_desc *, uint16_t, struct sglist *, int, int);
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static int vq_ring_use_indirect(struct virtqueue *, int);
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static void vq_ring_enqueue_indirect(struct virtqueue *, void *,
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struct sglist *, int, int);
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static void vq_ring_notify_host(struct virtqueue *, int);
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static void vq_ring_free_chain(struct virtqueue *, uint16_t);
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uint64_t
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virtqueue_filter_features(uint64_t features)
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{
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uint64_t mask;
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mask = (1 << VIRTIO_TRANSPORT_F_START) - 1;
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mask |= VIRTIO_RING_F_INDIRECT_DESC;
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return (features & mask);
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}
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int
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virtqueue_alloc(device_t dev, uint16_t queue, uint16_t size, int align,
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vm_paddr_t highaddr, struct vq_alloc_info *info, struct virtqueue **vqp)
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{
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struct virtqueue *vq;
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int error;
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*vqp = NULL;
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error = 0;
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if (size == 0) {
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device_printf(dev,
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"virtqueue %d (%s) does not exist (size is zero)\n",
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queue, info->vqai_name);
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return (ENODEV);
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} else if (!powerof2(size)) {
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device_printf(dev,
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"virtqueue %d (%s) size is not a power of 2: %d\n",
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queue, info->vqai_name, size);
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return (ENXIO);
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} else if (info->vqai_maxindirsz > VIRTIO_MAX_INDIRECT) {
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device_printf(dev, "virtqueue %d (%s) requested too many "
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"indirect descriptors: %d, max %d\n",
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queue, info->vqai_name, info->vqai_maxindirsz,
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VIRTIO_MAX_INDIRECT);
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return (EINVAL);
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}
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vq = malloc(sizeof(struct virtqueue) +
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size * sizeof(struct vq_desc_extra), M_DEVBUF, M_NOWAIT | M_ZERO);
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if (vq == NULL) {
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device_printf(dev, "cannot allocate virtqueue\n");
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return (ENOMEM);
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}
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vq->vq_dev = dev;
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strlcpy(vq->vq_name, info->vqai_name, sizeof(vq->vq_name));
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vq->vq_queue_index = queue;
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vq->vq_alignment = align;
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vq->vq_nentries = size;
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vq->vq_free_cnt = size;
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vq->vq_intrhand = info->vqai_intr;
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vq->vq_intrhand_arg = info->vqai_intr_arg;
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if (info->vqai_maxindirsz > 1) {
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error = virtqueue_init_indirect(vq, info->vqai_maxindirsz);
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if (error)
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goto fail;
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}
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vq->vq_ring_size = round_page(vring_size(size, align));
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vq->vq_ring_mem = contigmalloc(vq->vq_ring_size, M_DEVBUF,
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M_NOWAIT | M_ZERO, 0, highaddr, PAGE_SIZE, 0);
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if (vq->vq_ring_mem == NULL) {
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device_printf(dev,
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"cannot allocate memory for virtqueue ring\n");
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error = ENOMEM;
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goto fail;
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}
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vq_ring_init(vq);
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virtqueue_disable_intr(vq);
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*vqp = vq;
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fail:
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if (error)
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virtqueue_free(vq);
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return (error);
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}
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static int
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virtqueue_init_indirect(struct virtqueue *vq, int indirect_size)
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{
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device_t dev;
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struct vq_desc_extra *dxp;
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int i, size;
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dev = vq->vq_dev;
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if (VIRTIO_BUS_WITH_FEATURE(dev, VIRTIO_RING_F_INDIRECT_DESC) == 0) {
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/*
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* Indirect descriptors requested by the driver but not
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* negotiated. Return zero to keep the initialization
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* going: we'll run fine without.
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*/
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if (bootverbose)
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device_printf(dev, "virtqueue %d (%s) requested "
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"indirect descriptors but not negotiated\n",
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vq->vq_queue_index, vq->vq_name);
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return (0);
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}
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size = indirect_size * sizeof(struct vring_desc);
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vq->vq_max_indirect_size = indirect_size;
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vq->vq_indirect_mem_size = size;
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vq->vq_flags |= VIRTQUEUE_FLAG_INDIRECT;
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for (i = 0; i < vq->vq_nentries; i++) {
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dxp = &vq->vq_descx[i];
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dxp->indirect = malloc(size, M_DEVBUF, M_NOWAIT);
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if (dxp->indirect == NULL) {
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device_printf(dev, "cannot allocate indirect list\n");
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return (ENOMEM);
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}
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dxp->indirect_paddr = vtophys(dxp->indirect);
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virtqueue_init_indirect_list(vq, dxp->indirect);
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}
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return (0);
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}
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static void
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virtqueue_free_indirect(struct virtqueue *vq)
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{
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struct vq_desc_extra *dxp;
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int i;
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for (i = 0; i < vq->vq_nentries; i++) {
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dxp = &vq->vq_descx[i];
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if (dxp->indirect == NULL)
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break;
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free(dxp->indirect, M_DEVBUF);
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dxp->indirect = NULL;
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dxp->indirect_paddr = 0;
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}
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vq->vq_flags &= ~VIRTQUEUE_FLAG_INDIRECT;
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vq->vq_indirect_mem_size = 0;
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}
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static void
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virtqueue_init_indirect_list(struct virtqueue *vq,
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struct vring_desc *indirect)
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{
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int i;
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bzero(indirect, vq->vq_indirect_mem_size);
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for (i = 0; i < vq->vq_max_indirect_size - 1; i++)
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indirect[i].next = i + 1;
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indirect[i].next = VQ_RING_DESC_CHAIN_END;
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}
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int
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virtqueue_reinit(struct virtqueue *vq, uint16_t size)
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{
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struct vq_desc_extra *dxp;
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int i;
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if (vq->vq_nentries != size) {
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device_printf(vq->vq_dev,
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"%s: '%s' changed size; old=%hu, new=%hu\n",
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__func__, vq->vq_name, vq->vq_nentries, size);
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return (EINVAL);
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}
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/* Warn if the virtqueue was not properly cleaned up. */
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if (vq->vq_free_cnt != vq->vq_nentries) {
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device_printf(vq->vq_dev,
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"%s: warning, '%s' virtqueue not empty, "
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"leaking %d entries\n", __func__, vq->vq_name,
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vq->vq_nentries - vq->vq_free_cnt);
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}
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vq->vq_desc_head_idx = 0;
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vq->vq_used_cons_idx = 0;
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vq->vq_queued_cnt = 0;
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vq->vq_free_cnt = vq->vq_nentries;
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/* To be safe, reset all our allocated memory. */
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bzero(vq->vq_ring_mem, vq->vq_ring_size);
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for (i = 0; i < vq->vq_nentries; i++) {
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dxp = &vq->vq_descx[i];
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dxp->cookie = NULL;
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dxp->ndescs = 0;
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if (vq->vq_flags & VIRTQUEUE_FLAG_INDIRECT)
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virtqueue_init_indirect_list(vq, dxp->indirect);
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}
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vq_ring_init(vq);
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virtqueue_disable_intr(vq);
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return (0);
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}
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void
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virtqueue_free(struct virtqueue *vq)
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{
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if (vq->vq_free_cnt != vq->vq_nentries) {
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device_printf(vq->vq_dev, "%s: freeing non-empty virtqueue, "
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"leaking %d entries\n", vq->vq_name,
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vq->vq_nentries - vq->vq_free_cnt);
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}
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if (vq->vq_flags & VIRTQUEUE_FLAG_INDIRECT)
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virtqueue_free_indirect(vq);
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if (vq->vq_ring_mem != NULL) {
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contigfree(vq->vq_ring_mem, vq->vq_ring_size, M_DEVBUF);
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vq->vq_ring_size = 0;
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vq->vq_ring_mem = NULL;
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}
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free(vq, M_DEVBUF);
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}
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vm_paddr_t
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virtqueue_paddr(struct virtqueue *vq)
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{
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return (vtophys(vq->vq_ring_mem));
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}
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int
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virtqueue_size(struct virtqueue *vq)
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{
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return (vq->vq_nentries);
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}
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int
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virtqueue_empty(struct virtqueue *vq)
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{
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return (vq->vq_nentries == vq->vq_free_cnt);
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}
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int
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virtqueue_full(struct virtqueue *vq)
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{
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return (vq->vq_free_cnt == 0);
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}
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void
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virtqueue_notify(struct virtqueue *vq)
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{
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vq->vq_queued_cnt = 0;
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vq_ring_notify_host(vq, 0);
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}
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int
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virtqueue_nused(struct virtqueue *vq)
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{
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uint16_t used_idx, nused;
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used_idx = vq->vq_ring.used->idx;
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if (used_idx >= vq->vq_used_cons_idx)
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nused = used_idx - vq->vq_used_cons_idx;
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else
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nused = UINT16_MAX - vq->vq_used_cons_idx +
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used_idx + 1;
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VQASSERT(vq, nused <= vq->vq_nentries, "used more than available");
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return (nused);
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}
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int
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virtqueue_intr(struct virtqueue *vq)
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{
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if (vq->vq_intrhand == NULL ||
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vq->vq_used_cons_idx == vq->vq_ring.used->idx)
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return (0);
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vq->vq_intrhand(vq->vq_intrhand_arg);
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return (1);
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}
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int
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virtqueue_enable_intr(struct virtqueue *vq)
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{
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/*
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* Enable interrupts, making sure we get the latest
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* index of what's already been consumed.
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*/
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vq->vq_ring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT;
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mb();
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/*
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* Additional items may have been consumed in the time between
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* since we last checked and enabled interrupts above. Let our
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* caller know so it processes the new entries.
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*/
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if (vq->vq_used_cons_idx != vq->vq_ring.used->idx)
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return (1);
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return (0);
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}
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void
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virtqueue_disable_intr(struct virtqueue *vq)
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{
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/*
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* Note this is only considered a hint to the host.
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*/
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vq->vq_ring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT;
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}
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int
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virtqueue_enqueue(struct virtqueue *vq, void *cookie, struct sglist *sg,
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int readable, int writable)
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{
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struct vq_desc_extra *dxp;
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int needed;
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uint16_t head_idx, idx;
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needed = readable + writable;
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VQASSERT(vq, cookie != NULL, "enqueuing with no cookie");
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VQASSERT(vq, needed == sg->sg_nseg,
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"segment count mismatch, %d, %d", needed, sg->sg_nseg);
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VQASSERT(vq,
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needed <= vq->vq_nentries || needed <= vq->vq_max_indirect_size,
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"too many segments to enqueue: %d, %d/%d", needed,
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vq->vq_nentries, vq->vq_max_indirect_size);
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if (needed < 1)
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return (EINVAL);
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if (vq->vq_free_cnt == 0)
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return (ENOSPC);
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if (vq_ring_use_indirect(vq, needed)) {
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vq_ring_enqueue_indirect(vq, cookie, sg, readable, writable);
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return (0);
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} else if (vq->vq_free_cnt < needed)
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return (EMSGSIZE);
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head_idx = vq->vq_desc_head_idx;
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VQ_RING_ASSERT_VALID_IDX(vq, head_idx);
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dxp = &vq->vq_descx[head_idx];
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VQASSERT(vq, dxp->cookie == NULL,
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"cookie already exists for index %d", head_idx);
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dxp->cookie = cookie;
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dxp->ndescs = needed;
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idx = vq_ring_enqueue_segments(vq, vq->vq_ring.desc, head_idx,
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sg, readable, writable);
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vq->vq_desc_head_idx = idx;
|
|
vq->vq_free_cnt -= needed;
|
|
if (vq->vq_free_cnt == 0)
|
|
VQ_RING_ASSERT_CHAIN_TERM(vq);
|
|
else
|
|
VQ_RING_ASSERT_VALID_IDX(vq, idx);
|
|
|
|
vq_ring_update_avail(vq, head_idx);
|
|
|
|
return (0);
|
|
}
|
|
|
|
void *
|
|
virtqueue_dequeue(struct virtqueue *vq, uint32_t *len)
|
|
{
|
|
struct vring_used_elem *uep;
|
|
void *cookie;
|
|
uint16_t used_idx, desc_idx;
|
|
|
|
if (vq->vq_used_cons_idx == vq->vq_ring.used->idx)
|
|
return (NULL);
|
|
|
|
used_idx = vq->vq_used_cons_idx++ & (vq->vq_nentries - 1);
|
|
uep = &vq->vq_ring.used->ring[used_idx];
|
|
|
|
mb();
|
|
desc_idx = (uint16_t) uep->id;
|
|
if (len != NULL)
|
|
*len = uep->len;
|
|
|
|
vq_ring_free_chain(vq, desc_idx);
|
|
|
|
cookie = vq->vq_descx[desc_idx].cookie;
|
|
VQASSERT(vq, cookie != NULL, "no cookie for index %d", desc_idx);
|
|
vq->vq_descx[desc_idx].cookie = NULL;
|
|
|
|
return (cookie);
|
|
}
|
|
|
|
void *
|
|
virtqueue_poll(struct virtqueue *vq, uint32_t *len)
|
|
{
|
|
void *cookie;
|
|
|
|
while ((cookie = virtqueue_dequeue(vq, len)) == NULL)
|
|
cpu_spinwait();
|
|
|
|
return (cookie);
|
|
}
|
|
|
|
void *
|
|
virtqueue_drain(struct virtqueue *vq, int *last)
|
|
{
|
|
void *cookie;
|
|
int idx;
|
|
|
|
cookie = NULL;
|
|
idx = *last;
|
|
|
|
while (idx < vq->vq_nentries && cookie == NULL) {
|
|
if ((cookie = vq->vq_descx[idx].cookie) != NULL) {
|
|
vq->vq_descx[idx].cookie = NULL;
|
|
/* Free chain to keep free count consistent. */
|
|
vq_ring_free_chain(vq, idx);
|
|
}
|
|
idx++;
|
|
}
|
|
|
|
*last = idx;
|
|
|
|
return (cookie);
|
|
}
|
|
|
|
void
|
|
virtqueue_dump(struct virtqueue *vq)
|
|
{
|
|
|
|
if (vq == NULL)
|
|
return;
|
|
|
|
printf("VQ: %s - size=%d; free=%d; used=%d; queued=%d; "
|
|
"desc_head_idx=%d; avail.idx=%d; used_cons_idx=%d; "
|
|
"used.idx=%d; avail.flags=0x%x; used.flags=0x%x\n",
|
|
vq->vq_name, vq->vq_nentries, vq->vq_free_cnt,
|
|
virtqueue_nused(vq), vq->vq_queued_cnt, vq->vq_desc_head_idx,
|
|
vq->vq_ring.avail->idx, vq->vq_used_cons_idx,
|
|
vq->vq_ring.used->idx, vq->vq_ring.avail->flags,
|
|
vq->vq_ring.used->flags);
|
|
}
|
|
|
|
static void
|
|
vq_ring_init(struct virtqueue *vq)
|
|
{
|
|
struct vring *vr;
|
|
char *ring_mem;
|
|
int i, size;
|
|
|
|
ring_mem = vq->vq_ring_mem;
|
|
size = vq->vq_nentries;
|
|
vr = &vq->vq_ring;
|
|
|
|
vring_init(vr, size, ring_mem, vq->vq_alignment);
|
|
|
|
for (i = 0; i < size - 1; i++)
|
|
vr->desc[i].next = i + 1;
|
|
vr->desc[i].next = VQ_RING_DESC_CHAIN_END;
|
|
}
|
|
|
|
static void
|
|
vq_ring_update_avail(struct virtqueue *vq, uint16_t desc_idx)
|
|
{
|
|
uint16_t avail_idx;
|
|
|
|
/*
|
|
* Place the head of the descriptor chain into the next slot and make
|
|
* it usable to the host. The chain is made available now rather than
|
|
* deferring to virtqueue_notify() in the hopes that if the host is
|
|
* currently running on another CPU, we can keep it processing the new
|
|
* descriptor.
|
|
*/
|
|
avail_idx = vq->vq_ring.avail->idx & (vq->vq_nentries - 1);
|
|
vq->vq_ring.avail->ring[avail_idx] = desc_idx;
|
|
|
|
mb();
|
|
vq->vq_ring.avail->idx++;
|
|
|
|
/* Keep pending count until virtqueue_notify() for debugging. */
|
|
vq->vq_queued_cnt++;
|
|
}
|
|
|
|
static uint16_t
|
|
vq_ring_enqueue_segments(struct virtqueue *vq, struct vring_desc *desc,
|
|
uint16_t head_idx, struct sglist *sg, int readable, int writable)
|
|
{
|
|
struct sglist_seg *seg;
|
|
struct vring_desc *dp;
|
|
int i, needed;
|
|
uint16_t idx;
|
|
|
|
needed = readable + writable;
|
|
|
|
for (i = 0, idx = head_idx, seg = sg->sg_segs;
|
|
i < needed;
|
|
i++, idx = dp->next, seg++) {
|
|
VQASSERT(vq, idx != VQ_RING_DESC_CHAIN_END,
|
|
"premature end of free desc chain");
|
|
|
|
dp = &desc[idx];
|
|
dp->addr = seg->ss_paddr;
|
|
dp->len = seg->ss_len;
|
|
dp->flags = 0;
|
|
|
|
if (i < needed - 1)
|
|
dp->flags |= VRING_DESC_F_NEXT;
|
|
if (i >= readable)
|
|
dp->flags |= VRING_DESC_F_WRITE;
|
|
}
|
|
|
|
return (idx);
|
|
}
|
|
|
|
static int
|
|
vq_ring_use_indirect(struct virtqueue *vq, int needed)
|
|
{
|
|
|
|
if ((vq->vq_flags & VIRTQUEUE_FLAG_INDIRECT) == 0)
|
|
return (0);
|
|
|
|
if (vq->vq_max_indirect_size < needed)
|
|
return (0);
|
|
|
|
if (needed < 2)
|
|
return (0);
|
|
|
|
return (1);
|
|
}
|
|
|
|
static void
|
|
vq_ring_enqueue_indirect(struct virtqueue *vq, void *cookie,
|
|
struct sglist *sg, int readable, int writable)
|
|
{
|
|
struct vring_desc *dp;
|
|
struct vq_desc_extra *dxp;
|
|
int needed;
|
|
uint16_t head_idx;
|
|
|
|
needed = readable + writable;
|
|
VQASSERT(vq, needed <= vq->vq_max_indirect_size,
|
|
"enqueuing too many indirect descriptors");
|
|
|
|
head_idx = vq->vq_desc_head_idx;
|
|
VQ_RING_ASSERT_VALID_IDX(vq, head_idx);
|
|
dp = &vq->vq_ring.desc[head_idx];
|
|
dxp = &vq->vq_descx[head_idx];
|
|
|
|
VQASSERT(vq, dxp->cookie == NULL,
|
|
"cookie already exists for index %d", head_idx);
|
|
dxp->cookie = cookie;
|
|
dxp->ndescs = 1;
|
|
|
|
dp->addr = dxp->indirect_paddr;
|
|
dp->len = needed * sizeof(struct vring_desc);
|
|
dp->flags = VRING_DESC_F_INDIRECT;
|
|
|
|
vq_ring_enqueue_segments(vq, dxp->indirect, 0,
|
|
sg, readable, writable);
|
|
|
|
vq->vq_desc_head_idx = dp->next;
|
|
vq->vq_free_cnt--;
|
|
if (vq->vq_free_cnt == 0)
|
|
VQ_RING_ASSERT_CHAIN_TERM(vq);
|
|
else
|
|
VQ_RING_ASSERT_VALID_IDX(vq, vq->vq_desc_head_idx);
|
|
|
|
vq_ring_update_avail(vq, head_idx);
|
|
}
|
|
|
|
static void
|
|
vq_ring_notify_host(struct virtqueue *vq, int force)
|
|
{
|
|
|
|
mb();
|
|
|
|
if (force ||
|
|
(vq->vq_ring.used->flags & VRING_USED_F_NO_NOTIFY) == 0)
|
|
VIRTIO_BUS_NOTIFY_VQ(vq->vq_dev, vq->vq_queue_index);
|
|
}
|
|
|
|
static void
|
|
vq_ring_free_chain(struct virtqueue *vq, uint16_t desc_idx)
|
|
{
|
|
struct vring_desc *dp;
|
|
struct vq_desc_extra *dxp;
|
|
|
|
VQ_RING_ASSERT_VALID_IDX(vq, desc_idx);
|
|
dp = &vq->vq_ring.desc[desc_idx];
|
|
dxp = &vq->vq_descx[desc_idx];
|
|
|
|
if (vq->vq_free_cnt == 0)
|
|
VQ_RING_ASSERT_CHAIN_TERM(vq);
|
|
|
|
vq->vq_free_cnt += dxp->ndescs;
|
|
dxp->ndescs--;
|
|
|
|
if ((dp->flags & VRING_DESC_F_INDIRECT) == 0) {
|
|
while (dp->flags & VRING_DESC_F_NEXT) {
|
|
VQ_RING_ASSERT_VALID_IDX(vq, dp->next);
|
|
dp = &vq->vq_ring.desc[dp->next];
|
|
dxp->ndescs--;
|
|
}
|
|
}
|
|
VQASSERT(vq, dxp->ndescs == 0, "failed to free entire desc chain");
|
|
|
|
/*
|
|
* We must append the existing free chain, if any, to the end of
|
|
* newly freed chain. If the virtqueue was completely used, then
|
|
* head would be VQ_RING_DESC_CHAIN_END (ASSERTed above).
|
|
*/
|
|
dp->next = vq->vq_desc_head_idx;
|
|
vq->vq_desc_head_idx = desc_idx;
|
|
}
|