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 #include "etherboot.h"
18 #include "gpxe/io.h"
19 #include "gpxe/virtio-ring.h"
20 #include "gpxe/virtio-pci.h"
21
22 #define BUG() do { \
23 printf("BUG: failure at %s:%d/%s()!\n", \
24 __FILE__, __LINE__, __FUNCTION__); \
25 while(1); \
26 } while (0)
27 #define BUG_ON(condition) do { if (condition) BUG(); } while (0)
28
29 /*
30 * vring_free
31 *
32 * put at the begin of the free list the current desc[head]
33 */
34
vring_detach(struct vring_virtqueue * vq,unsigned int head)35 void vring_detach(struct vring_virtqueue *vq, unsigned int head)
36 {
37 struct vring *vr = &vq->vring;
38 unsigned int i;
39
40 /* find end of given descriptor */
41
42 i = head;
43 while (vr->desc[i].flags & VRING_DESC_F_NEXT)
44 i = vr->desc[i].next;
45
46 /* link it with free list and point to it */
47
48 vr->desc[i].next = vq->free_head;
49 wmb();
50 vq->free_head = head;
51 }
52
53 /*
54 * vring_get_buf
55 *
56 * get a buffer from the used list
57 *
58 */
59
vring_get_buf(struct vring_virtqueue * vq,unsigned int * len)60 int vring_get_buf(struct vring_virtqueue *vq, unsigned int *len)
61 {
62 struct vring *vr = &vq->vring;
63 struct vring_used_elem *elem;
64 u32 id;
65 int ret;
66
67 BUG_ON(!vring_more_used(vq));
68
69 elem = &vr->used->ring[vq->last_used_idx % vr->num];
70 wmb();
71 id = elem->id;
72 if (len != NULL)
73 *len = elem->len;
74
75 ret = vq->vdata[id];
76
77 vring_detach(vq, id);
78
79 vq->last_used_idx++;
80
81 return ret;
82 }
83
vring_add_buf(struct vring_virtqueue * vq,struct vring_list list[],unsigned int out,unsigned int in,int index,int num_added)84 void vring_add_buf(struct vring_virtqueue *vq,
85 struct vring_list list[],
86 unsigned int out, unsigned int in,
87 int index, int num_added)
88 {
89 struct vring *vr = &vq->vring;
90 int i, avail, head, prev;
91
92 BUG_ON(out + in == 0);
93
94 prev = 0;
95 head = vq->free_head;
96 for (i = head; out; i = vr->desc[i].next, out--) {
97
98 vr->desc[i].flags = VRING_DESC_F_NEXT;
99 vr->desc[i].addr = (u64)virt_to_phys(list->addr);
100 vr->desc[i].len = list->length;
101 prev = i;
102 list++;
103 }
104 for ( ; in; i = vr->desc[i].next, in--) {
105
106 vr->desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE;
107 vr->desc[i].addr = (u64)virt_to_phys(list->addr);
108 vr->desc[i].len = list->length;
109 prev = i;
110 list++;
111 }
112 vr->desc[prev].flags &= ~VRING_DESC_F_NEXT;
113
114 vq->free_head = i;
115
116 vq->vdata[head] = index;
117
118 avail = (vr->avail->idx + num_added) % vr->num;
119 vr->avail->ring[avail] = head;
120 wmb();
121 }
122
vring_kick(unsigned int ioaddr,struct vring_virtqueue * vq,int num_added)123 void vring_kick(unsigned int ioaddr, struct vring_virtqueue *vq, int num_added)
124 {
125 struct vring *vr = &vq->vring;
126
127 wmb();
128 vr->avail->idx += num_added;
129
130 mb();
131 if (!(vr->used->flags & VRING_USED_F_NO_NOTIFY))
132 vp_notify(ioaddr, vq->queue_index);
133 }
134
135