qemu/hw/virtio-blk.c

   1 /*
   2  * Virtio Block Device
   3  *
   4  * Copyright IBM, Corp. 2007
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <aliguori@us.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 #include <qemu-common.h>
  15 #include <sysemu.h>
  16 #include "virtio-blk.h"
  17 #include "block_int.h"
  18
  19 typedef struct VirtIOBlock
  20 {
  21     VirtIODevice vdev;
  22     BlockDriverState *bs;
  23     VirtQueue *vq;
  24     void *rq;
  25 } VirtIOBlock;
  26
  27 static VirtIOBlock *to_virtio_blk(VirtIODevice *vdev)
  28 {
  29     return (VirtIOBlock *)vdev;
  30 }
  31
  32 typedef struct VirtIOBlockReq
  33 {
  34     VirtIOBlock *dev;
  35     VirtQueueElement elem;
  36     struct virtio_blk_inhdr *in;
  37     struct virtio_blk_outhdr *out;
  38     size_t size;
  39     uint8_t *buffer;
  40     struct VirtIOBlockReq *next;
  41 } VirtIOBlockReq;
  42
  43 static void virtio_blk_req_complete(VirtIOBlockReq *req, int status)
  44 {
  45     VirtIOBlock *s = req->dev;
  46
  47     req->in->status = status;
  48     virtqueue_push(s->vq, &req->elem, req->size + sizeof(*req->in));
  49     virtio_notify(&s->vdev, s->vq);
  50
  51     qemu_free(req->buffer);
  52     qemu_free(req);
  53 }
  54
  55 static int virtio_blk_handle_write_error(VirtIOBlockReq *req, int error)
  56 {
  57     BlockInterfaceErrorAction action = drive_get_onerror(req->dev->bs);
  58     VirtIOBlock *s = req->dev;
  59
  60     if (action == BLOCK_ERR_IGNORE)
  61         return 0;
  62
  63     if ((error == ENOSPC && action == BLOCK_ERR_STOP_ENOSPC)
  64             || action == BLOCK_ERR_STOP_ANY) {
  65         req->next = s->rq;
  66         s->rq = req;
  67         vm_stop(0);
  68     } else {
  69         virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
  70     }
  71
  72     return 1;
  73 }
  74
  75 static void virtio_blk_rw_complete(void *opaque, int ret)
  76 {
  77     VirtIOBlockReq *req = opaque;
  78
  79     /* Copy read data to the guest */
  80     if (!ret && !(req->out->type & VIRTIO_BLK_T_OUT)) {
  81         size_t offset = 0;
  82         int i;
  83
  84         for (i = 0; i < req->elem.in_num - 1; i++) {
  85             size_t len;
  86
  87             /* Be pretty defensive wrt malicious guests */
  88             len = MIN(req->elem.in_sg[i].iov_len,
  89                       req->size - offset);
  90
  91             memcpy(req->elem.in_sg[i].iov_base,
  92                    req->buffer + offset,
  93                    len);
  94             offset += len;
  95         }
  96     } else if (ret && (req->out->type & VIRTIO_BLK_T_OUT)) {
  97         if (virtio_blk_handle_write_error(req, -ret))
  98             return;
  99     }
 100
 101     virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
 102 }
 103
 104 static VirtIOBlockReq *virtio_blk_alloc_request(VirtIOBlock *s)
 105 {
 106     VirtIOBlockReq *req = qemu_mallocz(sizeof(*req));
 107     req->dev = s;
 108     return req;
 109 }
 110
 111 static VirtIOBlockReq *virtio_blk_get_request(VirtIOBlock *s)
 112 {
 113     VirtIOBlockReq *req = virtio_blk_alloc_request(s);
 114
 115     if (req != NULL) {
 116         if (!virtqueue_pop(s->vq, &req->elem)) {
 117             qemu_free(req);
 118             return NULL;
 119         }
 120     }
 121
 122     return req;
 123 }
 124
 125 static int virtio_blk_handle_write(VirtIOBlockReq *req)
 126 {
 127     if (!req->buffer) {
 128         size_t offset = 0;
 129         int i;
 130
 131         for (i = 1; i < req->elem.out_num; i++)
 132             req->size += req->elem.out_sg[i].iov_len;
 133
 134         req->buffer = qemu_memalign(512, req->size);
 135         if (req->buffer == NULL) {
 136             qemu_free(req);
 137             return -1;
 138         }
 139
 140         /* We copy the data from the SG list to avoid splitting up the request.
 141            This helps performance a lot until we can pass full sg lists as AIO
 142            operations */
 143         for (i = 1; i < req->elem.out_num; i++) {
 144             size_t len;
 145
 146             len = MIN(req->elem.out_sg[i].iov_len,
 147                     req->size - offset);
 148             memcpy(req->buffer + offset,
 149                     req->elem.out_sg[i].iov_base,
 150                     len);
 151             offset += len;
 152         }
 153     }
 154
 155     bdrv_aio_write(req->dev->bs, req->out->sector, req->buffer, req->size / 512,
 156             virtio_blk_rw_complete, req);
 157     return 0;
 158 }
 159
 160 static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
 161 {
 162     VirtIOBlock *s = to_virtio_blk(vdev);
 163     VirtIOBlockReq *req;
 164
 165     while ((req = virtio_blk_get_request(s))) {
 166         int i;
 167
 168         if (req->elem.out_num < 1 || req->elem.in_num < 1) {
 169             fprintf(stderr, "virtio-blk missing headers\n");
 170             exit(1);
 171         }
 172
 173         if (req->elem.out_sg[0].iov_len < sizeof(*req->out) ||
 174             req->elem.in_sg[req->elem.in_num - 1].iov_len < sizeof(*req->in)) {
 175             fprintf(stderr, "virtio-blk header not in correct element\n");
 176             exit(1);
 177         }
 178
 179         req->out = (void *)req->elem.out_sg[0].iov_base;
 180         req->in = (void *)req->elem.in_sg[req->elem.in_num - 1].iov_base;
 181
 182         if (req->out->type & VIRTIO_BLK_T_SCSI_CMD) {
 183             unsigned int len = sizeof(*req->in);
 184
 185             req->in->status = VIRTIO_BLK_S_UNSUPP;
 186             virtqueue_push(vq, &req->elem, len);
 187             virtio_notify(vdev, vq);
 188             qemu_free(req);
 189         } else if (req->out->type & VIRTIO_BLK_T_OUT) {
 190             if (virtio_blk_handle_write(req) < 0)
 191                 break;
 192         } else {
 193             for (i = 0; i < req->elem.in_num - 1; i++)
 194                 req->size += req->elem.in_sg[i].iov_len;
 195
 196             req->buffer = qemu_memalign(512, req->size);
 197             if (req->buffer == NULL) {
 198                 qemu_free(req);
 199                 break;
 200             }
 201
 202             bdrv_aio_read(s->bs, req->out->sector,
 203                           req->buffer,
 204                           req->size / 512,
 205                           virtio_blk_rw_complete,
 206                           req);
 207         }
 208     }
 209     /*
 210      * FIXME: Want to check for completions before returning to guest mode,
 211      * so cached reads and writes are reported as quickly as possible. But
 212      * that should be done in the generic block layer.
 213      */
 214 }
 215
 216 static void virtio_blk_dma_restart_cb(void *opaque, int running, int reason)
 217 {
 218     VirtIOBlock *s = opaque;
 219     VirtIOBlockReq *req = s->rq;
 220
 221     if (!running)
 222         return;
 223
 224     s->rq = NULL;
 225
 226     while (req) {
 227         virtio_blk_handle_write(req);
 228         req = req->next;
 229     }
 230 }
 231
 232 static void virtio_blk_reset(VirtIODevice *vdev)
 233 {
 234     /*
 235      * This should cancel pending requests, but can't do nicely until there
 236      * are per-device request lists.
 237      */
 238     qemu_aio_flush();
 239 }
 240
 241 static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config)
 242 {
 243     VirtIOBlock *s = to_virtio_blk(vdev);
 244     struct virtio_blk_config blkcfg;
 245     uint64_t capacity;
 246     int cylinders, heads, secs;
 247
 248     bdrv_get_geometry(s->bs, &capacity);
 249     bdrv_get_geometry_hint(s->bs, &cylinders, &heads, &secs);
 250     stq_raw(&blkcfg.capacity, capacity);
 251     stl_raw(&blkcfg.seg_max, 128 - 2);
 252     stw_raw(&blkcfg.cylinders, cylinders);
 253     blkcfg.heads = heads;
 254     blkcfg.sectors = secs;
 255     memcpy(config, &blkcfg, sizeof(blkcfg));
 256 }
 257
 258 static uint32_t virtio_blk_get_features(VirtIODevice *vdev)
 259 {
 260     return (1 << VIRTIO_BLK_F_SEG_MAX | 1 << VIRTIO_BLK_F_GEOMETRY);
 261 }
 262
 263 static void virtio_blk_save(QEMUFile *f, void *opaque)
 264 {
 265     VirtIOBlock *s = opaque;
 266     VirtIOBlockReq *req = s->rq;
 267
 268     virtio_save(&s->vdev, f);
 269
 270     while (req) {
 271         qemu_put_sbyte(f, 1);
 272         qemu_put_buffer(f, (unsigned char*)&req->elem, sizeof(req->elem));
 273         req = req->next;
 274     }
 275     qemu_put_sbyte(f, 0);
 276 }
 277
 278 static int virtio_blk_load(QEMUFile *f, void *opaque, int version_id)
 279 {
 280     VirtIOBlock *s = opaque;
 281
 282     if (version_id != 2)
 283         return -EINVAL;
 284
 285     virtio_load(&s->vdev, f);
 286     while (qemu_get_sbyte(f)) {
 287         VirtIOBlockReq *req = virtio_blk_alloc_request(s);
 288         qemu_get_buffer(f, (unsigned char*)&req->elem, sizeof(req->elem));
 289         req->next = s->rq;
 290         s->rq = req->next;
 291     }
 292
 293     return 0;
 294 }
 295
 296 void *virtio_blk_init(PCIBus *bus, BlockDriverState *bs)
 297 {
 298     VirtIOBlock *s;
 299     int cylinders, heads, secs;
 300     static int virtio_blk_id;
 301
 302     s = (VirtIOBlock *)virtio_init_pci(bus, "virtio-blk",
 303                                        PCI_VENDOR_ID_REDHAT_QUMRANET,
 304                                        PCI_DEVICE_ID_VIRTIO_BLOCK,
 305                                        PCI_VENDOR_ID_REDHAT_QUMRANET,
 306                                        VIRTIO_ID_BLOCK,
 307                                        PCI_CLASS_STORAGE_OTHER, 0x00,
 308                                        sizeof(struct virtio_blk_config), sizeof(VirtIOBlock));
 309     if (!s)
 310         return NULL;
 311
 312     s->vdev.get_config = virtio_blk_update_config;
 313     s->vdev.get_features = virtio_blk_get_features;
 314     s->vdev.reset = virtio_blk_reset;
 315     s->bs = bs;
 316     s->rq = NULL;
 317     bs->devfn = s->vdev.pci_dev.devfn;
 318     bdrv_guess_geometry(s->bs, &cylinders, &heads, &secs);
 319     bdrv_set_geometry_hint(s->bs, cylinders, heads, secs);
 320
 321     s->vq = virtio_add_queue(&s->vdev, 128, virtio_blk_handle_output);
 322
 323     qemu_add_vm_change_state_handler(virtio_blk_dma_restart_cb, s);
 324     register_savevm("virtio-blk", virtio_blk_id++, 2,
 325                     virtio_blk_save, virtio_blk_load, s);
 326
 327     return s;
 328 }