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 * Adopted for Seabios: Gleb Natapov <gleb@redhat.com>
12 *
13 * This work is licensed under the terms of the GNU LGPLv3
14 * See the COPYING file in the top-level directory.
15 *
16 *
17 */
18
19 #include "output.h" // panic
20 #include "virtio-ring.h"
21 #include "virtio-pci.h"
22
23 #define BUG() do { \
24 panic("BUG: failure at %d/%s()!\n", __LINE__, __func__); \
25 } while (0)
26 #define BUG_ON(condition) do { if (condition) BUG(); } while (0)
27
28 /*
29 * vring_more_used
30 *
31 * is there some used buffers ?
32 *
33 */
34
vring_more_used(struct vring_virtqueue * vq)35 int vring_more_used(struct vring_virtqueue *vq)
36 {
37 struct vring_used *used = vq->vring.used;
38 int more = vq->last_used_idx != used->idx;
39 /* Make sure ring reads are done after idx read above. */
40 smp_rmb();
41 return more;
42 }
43
44 /*
45 * vring_free
46 *
47 * put at the begin of the free list the current desc[head]
48 */
49
vring_detach(struct vring_virtqueue * vq,unsigned int head)50 void vring_detach(struct vring_virtqueue *vq, unsigned int head)
51 {
52 struct vring *vr = &vq->vring;
53 struct vring_desc *desc = GET_LOWFLAT(vr->desc);
54 unsigned int i;
55
56 /* find end of given descriptor */
57
58 i = head;
59 while (desc[i].flags & VRING_DESC_F_NEXT)
60 i = desc[i].next;
61
62 /* link it with free list and point to it */
63
64 desc[i].next = vq->free_head;
65 vq->free_head = head;
66 }
67
68 /*
69 * vring_get_buf
70 *
71 * get a buffer from the used list
72 *
73 */
74
vring_get_buf(struct vring_virtqueue * vq,unsigned int * len)75 int vring_get_buf(struct vring_virtqueue *vq, unsigned int *len)
76 {
77 struct vring *vr = &vq->vring;
78 struct vring_used_elem *elem;
79 struct vring_used *used = vq->vring.used;
80 u32 id;
81 int ret;
82
83 // BUG_ON(!vring_more_used(vq));
84
85 elem = &used->ring[vq->last_used_idx % vr->num];
86 id = elem->id;
87 if (len != NULL)
88 *len = elem->len;
89
90 ret = vq->vdata[id];
91
92 vring_detach(vq, id);
93
94 vq->last_used_idx = vq->last_used_idx + 1;
95
96 return ret;
97 }
98
vring_add_buf(struct vring_virtqueue * vq,struct vring_list list[],unsigned int out,unsigned int in,int index,int num_added)99 void vring_add_buf(struct vring_virtqueue *vq,
100 struct vring_list list[],
101 unsigned int out, unsigned int in,
102 int index, int num_added)
103 {
104 struct vring *vr = &vq->vring;
105 int i, av, head, prev;
106 struct vring_desc *desc = vr->desc;
107 struct vring_avail *avail = vr->avail;
108
109 BUG_ON(out + in == 0);
110
111 prev = 0;
112 head = vq->free_head;
113 for (i = head; out; i = desc[i].next, out--) {
114 desc[i].flags = VRING_DESC_F_NEXT;
115 desc[i].addr = (u64)virt_to_phys(list->addr);
116 desc[i].len = list->length;
117 prev = i;
118 list++;
119 }
120 for ( ; in; i = desc[i].next, in--) {
121 desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE;
122 desc[i].addr = (u64)virt_to_phys(list->addr);
123 desc[i].len = list->length;
124 prev = i;
125 list++;
126 }
127 desc[prev].flags = desc[prev].flags & ~VRING_DESC_F_NEXT;
128
129 vq->free_head = i;
130
131 vq->vdata[head] = index;
132
133 av = (avail->idx + num_added) % vr->num;
134 avail->ring[av] = head;
135 }
136
vring_kick(struct vp_device * vp,struct vring_virtqueue * vq,int num_added)137 void vring_kick(struct vp_device *vp, struct vring_virtqueue *vq, int num_added)
138 {
139 struct vring *vr = &vq->vring;
140 struct vring_avail *avail = vr->avail;
141
142 /* Make sure idx update is done after ring write. */
143 smp_wmb();
144 avail->idx = avail->idx + num_added;
145
146 vp_notify(vp, vq);
147 }
148