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1.1 root 1: /* virtio-pci.c - virtio ring management
2: *
3: * (c) Copyright 2008 Bull S.A.S.
4: *
5: * Author: Laurent Vivier <[email protected]>
6: *
7: * some parts from Linux Virtio Ring
8: *
9: * Copyright Rusty Russell IBM Corporation 2007
10: *
11: * Adopted for Seabios: Gleb Natapov <[email protected]>
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 "virtio-ring.h"
20: #include "virtio-pci.h"
21: #include "biosvar.h" // GET_GLOBAL
22: #include "util.h" // dprintf
23:
24: #define BUG() do { \
25: dprintf(1, "BUG: failure at %s:%d/%s()!\n", \
26: __FILE__, __LINE__, __func__); \
27: while(1); \
28: } while (0)
29: #define BUG_ON(condition) do { if (condition) BUG(); } while (0)
30:
31: /*
32: * vring_more_used
33: *
34: * is there some used buffers ?
35: *
36: */
37:
38: int vring_more_used(struct vring_virtqueue *vq)
39: {
40: struct vring_used *used = GET_FLATPTR(vq->vring.used);
41: int more = GET_FLATPTR(vq->last_used_idx) != GET_FLATPTR(used->idx);
42: /* Make sure ring reads are done after idx read above. */
43: smp_rmb();
44: return more;
45: }
46:
47: /*
48: * vring_free
49: *
50: * put at the begin of the free list the current desc[head]
51: */
52:
53: void vring_detach(struct vring_virtqueue *vq, unsigned int head)
54: {
55: struct vring *vr = &vq->vring;
56: struct vring_desc *desc = GET_FLATPTR(vr->desc);
57: unsigned int i;
58:
59: /* find end of given descriptor */
60:
61: i = head;
62: while (GET_FLATPTR(desc[i].flags) & VRING_DESC_F_NEXT)
63: i = GET_FLATPTR(desc[i].next);
64:
65: /* link it with free list and point to it */
66:
67: SET_FLATPTR(desc[i].next, GET_FLATPTR(vq->free_head));
68: SET_FLATPTR(vq->free_head, head);
69: }
70:
71: /*
72: * vring_get_buf
73: *
74: * get a buffer from the used list
75: *
76: */
77:
78: int vring_get_buf(struct vring_virtqueue *vq, unsigned int *len)
79: {
80: struct vring *vr = &vq->vring;
81: struct vring_used_elem *elem;
82: struct vring_used *used = GET_FLATPTR(vq->vring.used);
83: u32 id;
84: int ret;
85:
86: // BUG_ON(!vring_more_used(vq));
87:
88: elem = &used->ring[GET_FLATPTR(vq->last_used_idx) % GET_FLATPTR(vr->num)];
89: id = GET_FLATPTR(elem->id);
90: if (len != NULL)
91: *len = GET_FLATPTR(elem->len);
92:
93: ret = GET_FLATPTR(vq->vdata[id]);
94:
95: vring_detach(vq, id);
96:
97: SET_FLATPTR(vq->last_used_idx, GET_FLATPTR(vq->last_used_idx) + 1);
98:
99: return ret;
100: }
101:
102: void vring_add_buf(struct vring_virtqueue *vq,
103: struct vring_list list[],
104: unsigned int out, unsigned int in,
105: int index, int num_added)
106: {
107: struct vring *vr = &vq->vring;
108: int i, av, head, prev;
109: struct vring_desc *desc = GET_FLATPTR(vr->desc);
110: struct vring_avail *avail = GET_FLATPTR(vr->avail);
111:
112: BUG_ON(out + in == 0);
113:
114: prev = 0;
115: head = GET_FLATPTR(vq->free_head);
116: for (i = head; out; i = GET_FLATPTR(desc[i].next), out--) {
117: SET_FLATPTR(desc[i].flags, VRING_DESC_F_NEXT);
118: SET_FLATPTR(desc[i].addr, (u64)virt_to_phys(list->addr));
119: SET_FLATPTR(desc[i].len, list->length);
120: prev = i;
121: list++;
122: }
123: for ( ; in; i = GET_FLATPTR(desc[i].next), in--) {
124: SET_FLATPTR(desc[i].flags, VRING_DESC_F_NEXT|VRING_DESC_F_WRITE);
125: SET_FLATPTR(desc[i].addr, (u64)virt_to_phys(list->addr));
126: SET_FLATPTR(desc[i].len, list->length);
127: prev = i;
128: list++;
129: }
130: SET_FLATPTR(desc[prev].flags,
131: GET_FLATPTR(desc[prev].flags) & ~VRING_DESC_F_NEXT);
132:
133: SET_FLATPTR(vq->free_head, i);
134:
135: SET_FLATPTR(vq->vdata[head], index);
136:
137: av = (GET_FLATPTR(avail->idx) + num_added) % GET_FLATPTR(vr->num);
138: SET_FLATPTR(avail->ring[av], head);
139: }
140:
141: void vring_kick(unsigned int ioaddr, struct vring_virtqueue *vq, int num_added)
142: {
143: struct vring *vr = &vq->vring;
144: struct vring_avail *avail = GET_FLATPTR(vr->avail);
145:
146: /* Make sure idx update is done after ring write. */
147: smp_wmb();
148: SET_FLATPTR(avail->idx, GET_FLATPTR(avail->idx) + num_added);
149:
150: vp_notify(ioaddr, GET_FLATPTR(vq->queue_index));
151: }
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