src/drivers/bus/virtio-ring.c

   1 /* virtio-pci.c - virtio ring management
   2  *
   3  * (c) Copyright 2008 Bull S.A.S.
   4  *
   5  *  Author: Laurent Vivier <Laurent.Vivier@bull.net>
   6  *
   7  *  some parts from Linux Virtio Ring
   8  *
   9  *  Copyright Rusty Russell IBM Corporation 2007
  10  *
  11  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  12  * See the COPYING file in the top-level directory.
  13  *
  14  *
  15  */
  16
  17 FILE_LICENCE ( GPL2_OR_LATER );
  18
  19 #include "etherboot.h"
  20 #include "ipxe/io.h"
  21 #include "ipxe/virtio-ring.h"
  22 #include "ipxe/virtio-pci.h"
  23
  24 #define BUG() do { \
  25    printf("BUG: failure at %s:%d/%s()!\n", \
  26           __FILE__, __LINE__, __FUNCTION__); \
  27    while(1); \
  28 } while (0)
  29 #define BUG_ON(condition) do { if (condition) BUG(); } while (0)
  30
  31 /*
  32  * vring_free
  33  *
  34  * put at the begin of the free list the current desc[head]
  35  */
  36
  37 void vring_detach(struct vring_virtqueue *vq, unsigned int head)
  38 {
  39    struct vring *vr = &vq->vring;
  40    unsigned int i;
  41
  42    /* find end of given descriptor */
  43
  44    i = head;
  45    while (vr->desc[i].flags & VRING_DESC_F_NEXT)
  46            i = vr->desc[i].next;
  47
  48    /* link it with free list and point to it */
  49
  50    vr->desc[i].next = vq->free_head;
  51    wmb();
  52    vq->free_head = head;
  53 }
  54
  55 /*
  56  * vring_get_buf
  57  *
  58  * get a buffer from the used list
  59  *
  60  */
  61
  62 void *vring_get_buf(struct vring_virtqueue *vq, unsigned int *len)
  63 {
  64    struct vring *vr = &vq->vring;
  65    struct vring_used_elem *elem;
  66    u32 id;
  67    void *opaque;
  68
  69    BUG_ON(!vring_more_used(vq));
  70
  71    elem = &vr->used->ring[vq->last_used_idx % vr->num];
  72    wmb();
  73    id = elem->id;
  74    if (len != NULL)
  75            *len = elem->len;
  76
  77    opaque = vq->vdata[id];
  78
  79    vring_detach(vq, id);
  80
  81    vq->last_used_idx++;
  82
  83    return opaque;
  84 }
  85
  86 void vring_add_buf(struct vring_virtqueue *vq,
  87                    struct vring_list list[],
  88                    unsigned int out, unsigned int in,
  89                    void *opaque, int num_added)
  90 {
  91    struct vring *vr = &vq->vring;
  92    int i, avail, head, prev;
  93
  94    BUG_ON(out + in == 0);
  95
  96    prev = 0;
  97    head = vq->free_head;
  98    for (i = head; out; i = vr->desc[i].next, out--) {
  99
 100            vr->desc[i].flags = VRING_DESC_F_NEXT;
 101            vr->desc[i].addr = (u64)virt_to_phys(list->addr);
 102            vr->desc[i].len = list->length;
 103            prev = i;
 104            list++;
 105    }
 106    for ( ; in; i = vr->desc[i].next, in--) {
 107
 108            vr->desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE;
 109            vr->desc[i].addr = (u64)virt_to_phys(list->addr);
 110            vr->desc[i].len = list->length;
 111            prev = i;
 112            list++;
 113    }
 114    vr->desc[prev].flags &= ~VRING_DESC_F_NEXT;
 115
 116    vq->free_head = i;
 117
 118    vq->vdata[head] = opaque;
 119
 120    avail = (vr->avail->idx + num_added) % vr->num;
 121    vr->avail->ring[avail] = head;
 122    wmb();
 123 }
 124
 125 void vring_kick(unsigned int ioaddr, struct vring_virtqueue *vq, int num_added)
 126 {
 127    struct vring *vr = &vq->vring;
 128
 129    wmb();
 130    vr->avail->idx += num_added;
 131
 132    mb();
 133    if (!(vr->used->flags & VRING_USED_F_NO_NOTIFY))
 134            vp_notify(ioaddr, vq->queue_index);
 135 }
 136