xref: /illumos-kvm-cmd/dma-helpers.c (revision 68396ea9)
1 /*
2  * DMA helper functions
3  *
4  * Copyright (c) 2009 Red Hat
5  *
6  * This work is licensed under the terms of the GNU General Public License
7  * (GNU GPL), version 2 or later.
8  */
9 
10 #include "dma.h"
11 #include "block_int.h"
12 
qemu_sglist_init(QEMUSGList * qsg,int alloc_hint)13 void qemu_sglist_init(QEMUSGList *qsg, int alloc_hint)
14 {
15     qsg->sg = qemu_malloc(alloc_hint * sizeof(ScatterGatherEntry));
16     qsg->nsg = 0;
17     qsg->nalloc = alloc_hint;
18     qsg->size = 0;
19 }
20 
qemu_sglist_add(QEMUSGList * qsg,target_phys_addr_t base,target_phys_addr_t len)21 void qemu_sglist_add(QEMUSGList *qsg, target_phys_addr_t base,
22                      target_phys_addr_t len)
23 {
24     if (qsg->nsg == qsg->nalloc) {
25         qsg->nalloc = 2 * qsg->nalloc + 1;
26         qsg->sg = qemu_realloc(qsg->sg, qsg->nalloc * sizeof(ScatterGatherEntry));
27     }
28     qsg->sg[qsg->nsg].base = base;
29     qsg->sg[qsg->nsg].len = len;
30     qsg->size += len;
31     ++qsg->nsg;
32 }
33 
qemu_sglist_destroy(QEMUSGList * qsg)34 void qemu_sglist_destroy(QEMUSGList *qsg)
35 {
36     qemu_free(qsg->sg);
37 }
38 
39 typedef struct {
40     BlockDriverAIOCB common;
41     BlockDriverState *bs;
42     BlockDriverAIOCB *acb;
43     QEMUSGList *sg;
44     uint64_t sector_num;
45     int is_write;
46     int sg_cur_index;
47     target_phys_addr_t sg_cur_byte;
48     QEMUIOVector iov;
49     QEMUBH *bh;
50 } DMAAIOCB;
51 
52 static void dma_bdrv_cb(void *opaque, int ret);
53 
reschedule_dma(void * opaque)54 static void reschedule_dma(void *opaque)
55 {
56     DMAAIOCB *dbs = (DMAAIOCB *)opaque;
57 
58     qemu_bh_delete(dbs->bh);
59     dbs->bh = NULL;
60     dma_bdrv_cb(opaque, 0);
61 }
62 
continue_after_map_failure(void * opaque)63 static void continue_after_map_failure(void *opaque)
64 {
65     DMAAIOCB *dbs = (DMAAIOCB *)opaque;
66 
67     dbs->bh = qemu_bh_new(reschedule_dma, dbs);
68     qemu_bh_schedule(dbs->bh);
69 }
70 
dma_bdrv_unmap(DMAAIOCB * dbs)71 static void dma_bdrv_unmap(DMAAIOCB *dbs)
72 {
73     int i;
74 
75     for (i = 0; i < dbs->iov.niov; ++i) {
76         cpu_physical_memory_unmap(dbs->iov.iov[i].iov_base,
77                                   dbs->iov.iov[i].iov_len, !dbs->is_write,
78                                   dbs->iov.iov[i].iov_len);
79     }
80 }
81 
dma_bdrv_cb(void * opaque,int ret)82 static void dma_bdrv_cb(void *opaque, int ret)
83 {
84     DMAAIOCB *dbs = (DMAAIOCB *)opaque;
85     target_phys_addr_t cur_addr, cur_len;
86     void *mem;
87 
88     dbs->acb = NULL;
89     dbs->sector_num += dbs->iov.size / 512;
90     dma_bdrv_unmap(dbs);
91     qemu_iovec_reset(&dbs->iov);
92 
93     if (dbs->sg_cur_index == dbs->sg->nsg || ret < 0) {
94         dbs->common.cb(dbs->common.opaque, ret);
95         qemu_iovec_destroy(&dbs->iov);
96         qemu_aio_release(dbs);
97         return;
98     }
99 
100     while (dbs->sg_cur_index < dbs->sg->nsg) {
101         cur_addr = dbs->sg->sg[dbs->sg_cur_index].base + dbs->sg_cur_byte;
102         cur_len = dbs->sg->sg[dbs->sg_cur_index].len - dbs->sg_cur_byte;
103         mem = cpu_physical_memory_map(cur_addr, &cur_len, !dbs->is_write);
104         if (!mem)
105             break;
106         qemu_iovec_add(&dbs->iov, mem, cur_len);
107         dbs->sg_cur_byte += cur_len;
108         if (dbs->sg_cur_byte == dbs->sg->sg[dbs->sg_cur_index].len) {
109             dbs->sg_cur_byte = 0;
110             ++dbs->sg_cur_index;
111         }
112     }
113 
114     if (dbs->iov.size == 0) {
115         cpu_register_map_client(dbs, continue_after_map_failure);
116         return;
117     }
118 
119     if (dbs->is_write) {
120         dbs->acb = bdrv_aio_writev(dbs->bs, dbs->sector_num, &dbs->iov,
121                                    dbs->iov.size / 512, dma_bdrv_cb, dbs);
122     } else {
123         dbs->acb = bdrv_aio_readv(dbs->bs, dbs->sector_num, &dbs->iov,
124                                   dbs->iov.size / 512, dma_bdrv_cb, dbs);
125     }
126     if (!dbs->acb) {
127         dma_bdrv_unmap(dbs);
128         qemu_iovec_destroy(&dbs->iov);
129         return;
130     }
131 }
132 
dma_aio_cancel(BlockDriverAIOCB * acb)133 static void dma_aio_cancel(BlockDriverAIOCB *acb)
134 {
135     DMAAIOCB *dbs = container_of(acb, DMAAIOCB, common);
136 
137     if (dbs->acb) {
138         bdrv_aio_cancel(dbs->acb);
139     }
140 }
141 
142 static AIOPool dma_aio_pool = {
143     .aiocb_size         = sizeof(DMAAIOCB),
144     .cancel             = dma_aio_cancel,
145 };
146 
dma_bdrv_io(BlockDriverState * bs,QEMUSGList * sg,uint64_t sector_num,BlockDriverCompletionFunc * cb,void * opaque,int is_write)147 static BlockDriverAIOCB *dma_bdrv_io(
148     BlockDriverState *bs, QEMUSGList *sg, uint64_t sector_num,
149     BlockDriverCompletionFunc *cb, void *opaque,
150     int is_write)
151 {
152     DMAAIOCB *dbs =  qemu_aio_get(&dma_aio_pool, bs, cb, opaque);
153 
154     dbs->acb = NULL;
155     dbs->bs = bs;
156     dbs->sg = sg;
157     dbs->sector_num = sector_num;
158     dbs->sg_cur_index = 0;
159     dbs->sg_cur_byte = 0;
160     dbs->is_write = is_write;
161     dbs->bh = NULL;
162     qemu_iovec_init(&dbs->iov, sg->nsg);
163     /*
164      * DMA flushing is handled in dma_bdrv_cb() calling dma_bdrv_unmap()
165      * so we don't need to do that here.
166      */
167     dma_bdrv_cb(dbs, 0);
168     if (!dbs->acb) {
169         qemu_aio_release(dbs);
170         return NULL;
171     }
172     return &dbs->common;
173 }
174 
175 
dma_bdrv_read(BlockDriverState * bs,QEMUSGList * sg,uint64_t sector,void (* cb)(void * opaque,int ret),void * opaque)176 BlockDriverAIOCB *dma_bdrv_read(BlockDriverState *bs,
177                                 QEMUSGList *sg, uint64_t sector,
178                                 void (*cb)(void *opaque, int ret), void *opaque)
179 {
180     return dma_bdrv_io(bs, sg, sector, cb, opaque, 0);
181 }
182 
dma_bdrv_write(BlockDriverState * bs,QEMUSGList * sg,uint64_t sector,void (* cb)(void * opaque,int ret),void * opaque)183 BlockDriverAIOCB *dma_bdrv_write(BlockDriverState *bs,
184                                  QEMUSGList *sg, uint64_t sector,
185                                  void (*cb)(void *opaque, int ret), void *opaque)
186 {
187     return dma_bdrv_io(bs, sg, sector, cb, opaque, 1);
188 }
189