xref: /illumos-kvm-cmd/hw/xen_disk.c (revision 68396ea9)
1 /*
2  *  xen paravirt block device backend
3  *
4  *  (c) Gerd Hoffmann <kraxel@redhat.com>
5  *
6  *  This program is free software; you can redistribute it and/or modify
7  *  it under the terms of the GNU General Public License as published by
8  *  the Free Software Foundation; under version 2 of the License.
9  *
10  *  This program is distributed in the hope that it will be useful,
11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13  *  GNU General Public License for more details.
14  *
15  *  You should have received a copy of the GNU General Public License along
16  *  with this program; if not, see <http://www.gnu.org/licenses/>.
17  */
18 
19 #include <stdio.h>
20 #include <stdlib.h>
21 #include <stdarg.h>
22 #include <string.h>
23 #include <unistd.h>
24 #include <signal.h>
25 #include <inttypes.h>
26 #include <time.h>
27 #include <fcntl.h>
28 #include <errno.h>
29 #include <sys/ioctl.h>
30 #include <sys/types.h>
31 #include <sys/stat.h>
32 #include <sys/mman.h>
33 #include <sys/uio.h>
34 
35 #include <xs.h>
36 #include <xenctrl.h>
37 #include <xen/io/xenbus.h>
38 
39 #include "hw.h"
40 #include "block_int.h"
41 #include "qemu-char.h"
42 #include "xen_blkif.h"
43 #include "xen_backend.h"
44 #include "blockdev.h"
45 
46 /* ------------------------------------------------------------- */
47 
48 static int syncwrite    = 0;
49 static int batch_maps   = 0;
50 
51 static int max_requests = 32;
52 static int use_aio      = 1;
53 
54 /* ------------------------------------------------------------- */
55 
56 #define BLOCK_SIZE  512
57 #define IOCB_COUNT  (BLKIF_MAX_SEGMENTS_PER_REQUEST + 2)
58 
59 struct ioreq {
60     blkif_request_t     req;
61     int16_t             status;
62 
63     /* parsed request */
64     off_t               start;
65     QEMUIOVector        v;
66     int                 presync;
67     int                 postsync;
68 
69     /* grant mapping */
70     uint32_t            domids[BLKIF_MAX_SEGMENTS_PER_REQUEST];
71     uint32_t            refs[BLKIF_MAX_SEGMENTS_PER_REQUEST];
72     int                 prot;
73     void                *page[BLKIF_MAX_SEGMENTS_PER_REQUEST];
74     void                *pages;
75 
76     /* aio status */
77     int                 aio_inflight;
78     int                 aio_errors;
79 
80     struct XenBlkDev    *blkdev;
81     QLIST_ENTRY(ioreq)   list;
82 };
83 
84 struct XenBlkDev {
85     struct XenDevice    xendev;  /* must be first */
86     char                *params;
87     char                *mode;
88     char                *type;
89     char                *dev;
90     char                *devtype;
91     const char          *fileproto;
92     const char          *filename;
93     int                 ring_ref;
94     void                *sring;
95     int64_t             file_blk;
96     int64_t             file_size;
97     int                 protocol;
98     blkif_back_rings_t  rings;
99     int                 more_work;
100     int                 cnt_map;
101 
102     /* request lists */
103     QLIST_HEAD(inflight_head, ioreq) inflight;
104     QLIST_HEAD(finished_head, ioreq) finished;
105     QLIST_HEAD(freelist_head, ioreq) freelist;
106     int                 requests_total;
107     int                 requests_inflight;
108     int                 requests_finished;
109 
110     /* qemu block driver */
111     DriveInfo           *dinfo;
112     BlockDriverState    *bs;
113     QEMUBH              *bh;
114 };
115 
116 /* ------------------------------------------------------------- */
117 
ioreq_start(struct XenBlkDev * blkdev)118 static struct ioreq *ioreq_start(struct XenBlkDev *blkdev)
119 {
120     struct ioreq *ioreq = NULL;
121 
122     if (QLIST_EMPTY(&blkdev->freelist)) {
123 	if (blkdev->requests_total >= max_requests)
124 	    goto out;
125 	/* allocate new struct */
126 	ioreq = qemu_mallocz(sizeof(*ioreq));
127 	ioreq->blkdev = blkdev;
128 	blkdev->requests_total++;
129         qemu_iovec_init(&ioreq->v, BLKIF_MAX_SEGMENTS_PER_REQUEST);
130     } else {
131 	/* get one from freelist */
132 	ioreq = QLIST_FIRST(&blkdev->freelist);
133 	QLIST_REMOVE(ioreq, list);
134         qemu_iovec_reset(&ioreq->v);
135     }
136     QLIST_INSERT_HEAD(&blkdev->inflight, ioreq, list);
137     blkdev->requests_inflight++;
138 
139 out:
140     return ioreq;
141 }
142 
ioreq_finish(struct ioreq * ioreq)143 static void ioreq_finish(struct ioreq *ioreq)
144 {
145     struct XenBlkDev *blkdev = ioreq->blkdev;
146 
147     QLIST_REMOVE(ioreq, list);
148     QLIST_INSERT_HEAD(&blkdev->finished, ioreq, list);
149     blkdev->requests_inflight--;
150     blkdev->requests_finished++;
151 }
152 
ioreq_release(struct ioreq * ioreq)153 static void ioreq_release(struct ioreq *ioreq)
154 {
155     struct XenBlkDev *blkdev = ioreq->blkdev;
156 
157     QLIST_REMOVE(ioreq, list);
158     memset(ioreq, 0, sizeof(*ioreq));
159     ioreq->blkdev = blkdev;
160     QLIST_INSERT_HEAD(&blkdev->freelist, ioreq, list);
161     blkdev->requests_finished--;
162 }
163 
164 /*
165  * translate request into iovec + start offset
166  * do sanity checks along the way
167  */
ioreq_parse(struct ioreq * ioreq)168 static int ioreq_parse(struct ioreq *ioreq)
169 {
170     struct XenBlkDev *blkdev = ioreq->blkdev;
171     uintptr_t mem;
172     size_t len;
173     int i;
174 
175     xen_be_printf(&blkdev->xendev, 3,
176 		  "op %d, nr %d, handle %d, id %" PRId64 ", sector %" PRId64 "\n",
177 		  ioreq->req.operation, ioreq->req.nr_segments,
178 		  ioreq->req.handle, ioreq->req.id, ioreq->req.sector_number);
179     switch (ioreq->req.operation) {
180     case BLKIF_OP_READ:
181 	ioreq->prot = PROT_WRITE; /* to memory */
182 	break;
183     case BLKIF_OP_WRITE_BARRIER:
184         if (!ioreq->req.nr_segments) {
185             ioreq->presync = 1;
186             return 0;
187         }
188 	if (!syncwrite)
189 	    ioreq->presync = ioreq->postsync = 1;
190 	/* fall through */
191     case BLKIF_OP_WRITE:
192 	ioreq->prot = PROT_READ; /* from memory */
193 	if (syncwrite)
194 	    ioreq->postsync = 1;
195 	break;
196     default:
197 	xen_be_printf(&blkdev->xendev, 0, "error: unknown operation (%d)\n",
198 		      ioreq->req.operation);
199 	goto err;
200     };
201 
202     if (ioreq->req.operation != BLKIF_OP_READ && blkdev->mode[0] != 'w') {
203         xen_be_printf(&blkdev->xendev, 0, "error: write req for ro device\n");
204         goto err;
205     }
206 
207     ioreq->start = ioreq->req.sector_number * blkdev->file_blk;
208     for (i = 0; i < ioreq->req.nr_segments; i++) {
209 	if (i == BLKIF_MAX_SEGMENTS_PER_REQUEST) {
210 	    xen_be_printf(&blkdev->xendev, 0, "error: nr_segments too big\n");
211 	    goto err;
212 	}
213 	if (ioreq->req.seg[i].first_sect > ioreq->req.seg[i].last_sect) {
214 	    xen_be_printf(&blkdev->xendev, 0, "error: first > last sector\n");
215 	    goto err;
216 	}
217 	if (ioreq->req.seg[i].last_sect * BLOCK_SIZE >= XC_PAGE_SIZE) {
218 	    xen_be_printf(&blkdev->xendev, 0, "error: page crossing\n");
219 	    goto err;
220 	}
221 
222 	ioreq->domids[i] = blkdev->xendev.dom;
223 	ioreq->refs[i]   = ioreq->req.seg[i].gref;
224 
225 	mem = ioreq->req.seg[i].first_sect * blkdev->file_blk;
226 	len = (ioreq->req.seg[i].last_sect - ioreq->req.seg[i].first_sect + 1) * blkdev->file_blk;
227         qemu_iovec_add(&ioreq->v, (void*)mem, len);
228     }
229     if (ioreq->start + ioreq->v.size > blkdev->file_size) {
230 	xen_be_printf(&blkdev->xendev, 0, "error: access beyond end of file\n");
231 	goto err;
232     }
233     return 0;
234 
235 err:
236     ioreq->status = BLKIF_RSP_ERROR;
237     return -1;
238 }
239 
ioreq_unmap(struct ioreq * ioreq)240 static void ioreq_unmap(struct ioreq *ioreq)
241 {
242     int gnt = ioreq->blkdev->xendev.gnttabdev;
243     int i;
244 
245     if (ioreq->v.niov == 0)
246         return;
247     if (batch_maps) {
248 	if (!ioreq->pages)
249 	    return;
250 	if (xc_gnttab_munmap(gnt, ioreq->pages, ioreq->v.niov) != 0)
251 	    xen_be_printf(&ioreq->blkdev->xendev, 0, "xc_gnttab_munmap failed: %s\n",
252 			  strerror(errno));
253 	ioreq->blkdev->cnt_map -= ioreq->v.niov;
254 	ioreq->pages = NULL;
255     } else {
256 	for (i = 0; i < ioreq->v.niov; i++) {
257 	    if (!ioreq->page[i])
258 		continue;
259 	    if (xc_gnttab_munmap(gnt, ioreq->page[i], 1) != 0)
260 		xen_be_printf(&ioreq->blkdev->xendev, 0, "xc_gnttab_munmap failed: %s\n",
261 			      strerror(errno));
262 	    ioreq->blkdev->cnt_map--;
263 	    ioreq->page[i] = NULL;
264 	}
265     }
266 }
267 
ioreq_map(struct ioreq * ioreq)268 static int ioreq_map(struct ioreq *ioreq)
269 {
270     int gnt = ioreq->blkdev->xendev.gnttabdev;
271     int i;
272 
273     if (ioreq->v.niov == 0)
274         return 0;
275     if (batch_maps) {
276 	ioreq->pages = xc_gnttab_map_grant_refs
277 	    (gnt, ioreq->v.niov, ioreq->domids, ioreq->refs, ioreq->prot);
278 	if (ioreq->pages == NULL) {
279 	    xen_be_printf(&ioreq->blkdev->xendev, 0,
280 			  "can't map %d grant refs (%s, %d maps)\n",
281 			  ioreq->v.niov, strerror(errno), ioreq->blkdev->cnt_map);
282 	    return -1;
283 	}
284 	for (i = 0; i < ioreq->v.niov; i++)
285 	    ioreq->v.iov[i].iov_base = ioreq->pages + i * XC_PAGE_SIZE +
286 		(uintptr_t)ioreq->v.iov[i].iov_base;
287 	ioreq->blkdev->cnt_map += ioreq->v.niov;
288     } else  {
289 	for (i = 0; i < ioreq->v.niov; i++) {
290 	    ioreq->page[i] = xc_gnttab_map_grant_ref
291 		(gnt, ioreq->domids[i], ioreq->refs[i], ioreq->prot);
292 	    if (ioreq->page[i] == NULL) {
293 		xen_be_printf(&ioreq->blkdev->xendev, 0,
294 			      "can't map grant ref %d (%s, %d maps)\n",
295 			      ioreq->refs[i], strerror(errno), ioreq->blkdev->cnt_map);
296 		ioreq_unmap(ioreq);
297 		return -1;
298 	    }
299 	    ioreq->v.iov[i].iov_base = ioreq->page[i] + (uintptr_t)ioreq->v.iov[i].iov_base;
300 	    ioreq->blkdev->cnt_map++;
301 	}
302     }
303     return 0;
304 }
305 
ioreq_runio_qemu_sync(struct ioreq * ioreq)306 static int ioreq_runio_qemu_sync(struct ioreq *ioreq)
307 {
308     struct XenBlkDev *blkdev = ioreq->blkdev;
309     int i, rc, len = 0;
310     off_t pos;
311 
312     if (ioreq->req.nr_segments && ioreq_map(ioreq) == -1)
313 	goto err;
314     if (ioreq->presync)
315 	bdrv_flush(blkdev->bs);
316 
317     switch (ioreq->req.operation) {
318     case BLKIF_OP_READ:
319 	pos = ioreq->start;
320 	for (i = 0; i < ioreq->v.niov; i++) {
321 	    rc = bdrv_read(blkdev->bs, pos / BLOCK_SIZE,
322 			   ioreq->v.iov[i].iov_base,
323 			   ioreq->v.iov[i].iov_len / BLOCK_SIZE);
324 	    if (rc != 0) {
325 		xen_be_printf(&blkdev->xendev, 0, "rd I/O error (%p, len %zd)\n",
326 			      ioreq->v.iov[i].iov_base,
327 			      ioreq->v.iov[i].iov_len);
328 		goto err;
329 	    }
330 	    len += ioreq->v.iov[i].iov_len;
331 	    pos += ioreq->v.iov[i].iov_len;
332 	}
333 	break;
334     case BLKIF_OP_WRITE:
335     case BLKIF_OP_WRITE_BARRIER:
336         if (!ioreq->req.nr_segments)
337             break;
338 	pos = ioreq->start;
339 	for (i = 0; i < ioreq->v.niov; i++) {
340 	    rc = bdrv_write(blkdev->bs, pos / BLOCK_SIZE,
341 			    ioreq->v.iov[i].iov_base,
342 			    ioreq->v.iov[i].iov_len / BLOCK_SIZE);
343 	    if (rc != 0) {
344 		xen_be_printf(&blkdev->xendev, 0, "wr I/O error (%p, len %zd)\n",
345 			      ioreq->v.iov[i].iov_base,
346 			      ioreq->v.iov[i].iov_len);
347 		goto err;
348 	    }
349 	    len += ioreq->v.iov[i].iov_len;
350 	    pos += ioreq->v.iov[i].iov_len;
351 	}
352 	break;
353     default:
354 	/* unknown operation (shouldn't happen -- parse catches this) */
355 	goto err;
356     }
357 
358     if (ioreq->postsync)
359 	bdrv_flush(blkdev->bs);
360     ioreq->status = BLKIF_RSP_OKAY;
361 
362     ioreq_unmap(ioreq);
363     ioreq_finish(ioreq);
364     return 0;
365 
366 err:
367     ioreq->status = BLKIF_RSP_ERROR;
368     return -1;
369 }
370 
qemu_aio_complete(void * opaque,int ret)371 static void qemu_aio_complete(void *opaque, int ret)
372 {
373     struct ioreq *ioreq = opaque;
374 
375     if (ret != 0) {
376         xen_be_printf(&ioreq->blkdev->xendev, 0, "%s I/O error\n",
377                       ioreq->req.operation == BLKIF_OP_READ ? "read" : "write");
378         ioreq->aio_errors++;
379     }
380 
381     ioreq->aio_inflight--;
382     if (ioreq->aio_inflight > 0)
383         return;
384 
385     ioreq->status = ioreq->aio_errors ? BLKIF_RSP_ERROR : BLKIF_RSP_OKAY;
386     ioreq_unmap(ioreq);
387     ioreq_finish(ioreq);
388     qemu_bh_schedule(ioreq->blkdev->bh);
389 }
390 
ioreq_runio_qemu_aio(struct ioreq * ioreq)391 static int ioreq_runio_qemu_aio(struct ioreq *ioreq)
392 {
393     struct XenBlkDev *blkdev = ioreq->blkdev;
394 
395     if (ioreq->req.nr_segments && ioreq_map(ioreq) == -1)
396 	goto err;
397 
398     ioreq->aio_inflight++;
399     if (ioreq->presync)
400 	bdrv_flush(blkdev->bs); /* FIXME: aio_flush() ??? */
401 
402     switch (ioreq->req.operation) {
403     case BLKIF_OP_READ:
404         ioreq->aio_inflight++;
405         bdrv_aio_readv(blkdev->bs, ioreq->start / BLOCK_SIZE,
406                        &ioreq->v, ioreq->v.size / BLOCK_SIZE,
407                        qemu_aio_complete, ioreq);
408 	break;
409     case BLKIF_OP_WRITE:
410     case BLKIF_OP_WRITE_BARRIER:
411         ioreq->aio_inflight++;
412         if (!ioreq->req.nr_segments)
413             break;
414         bdrv_aio_writev(blkdev->bs, ioreq->start / BLOCK_SIZE,
415                         &ioreq->v, ioreq->v.size / BLOCK_SIZE,
416                         qemu_aio_complete, ioreq);
417 	break;
418     default:
419 	/* unknown operation (shouldn't happen -- parse catches this) */
420 	goto err;
421     }
422 
423     if (ioreq->postsync)
424 	bdrv_flush(blkdev->bs); /* FIXME: aio_flush() ??? */
425     qemu_aio_complete(ioreq, 0);
426 
427     return 0;
428 
429 err:
430     ioreq->status = BLKIF_RSP_ERROR;
431     return -1;
432 }
433 
blk_send_response_one(struct ioreq * ioreq)434 static int blk_send_response_one(struct ioreq *ioreq)
435 {
436     struct XenBlkDev  *blkdev = ioreq->blkdev;
437     int               send_notify   = 0;
438     int               have_requests = 0;
439     blkif_response_t  resp;
440     void              *dst;
441 
442     resp.id        = ioreq->req.id;
443     resp.operation = ioreq->req.operation;
444     resp.status    = ioreq->status;
445 
446     /* Place on the response ring for the relevant domain. */
447     switch (blkdev->protocol) {
448     case BLKIF_PROTOCOL_NATIVE:
449 	dst = RING_GET_RESPONSE(&blkdev->rings.native, blkdev->rings.native.rsp_prod_pvt);
450 	break;
451     case BLKIF_PROTOCOL_X86_32:
452         dst = RING_GET_RESPONSE(&blkdev->rings.x86_32_part,
453                                 blkdev->rings.x86_32_part.rsp_prod_pvt);
454 	break;
455     case BLKIF_PROTOCOL_X86_64:
456         dst = RING_GET_RESPONSE(&blkdev->rings.x86_64_part,
457                                 blkdev->rings.x86_64_part.rsp_prod_pvt);
458 	break;
459     default:
460 	dst = NULL;
461     }
462     memcpy(dst, &resp, sizeof(resp));
463     blkdev->rings.common.rsp_prod_pvt++;
464 
465     RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blkdev->rings.common, send_notify);
466     if (blkdev->rings.common.rsp_prod_pvt == blkdev->rings.common.req_cons) {
467 	/*
468 	 * Tail check for pending requests. Allows frontend to avoid
469 	 * notifications if requests are already in flight (lower
470 	 * overheads and promotes batching).
471 	 */
472 	RING_FINAL_CHECK_FOR_REQUESTS(&blkdev->rings.common, have_requests);
473     } else if (RING_HAS_UNCONSUMED_REQUESTS(&blkdev->rings.common)) {
474 	have_requests = 1;
475     }
476 
477     if (have_requests)
478 	blkdev->more_work++;
479     return send_notify;
480 }
481 
482 /* walk finished list, send outstanding responses, free requests */
blk_send_response_all(struct XenBlkDev * blkdev)483 static void blk_send_response_all(struct XenBlkDev *blkdev)
484 {
485     struct ioreq *ioreq;
486     int send_notify = 0;
487 
488     while (!QLIST_EMPTY(&blkdev->finished)) {
489         ioreq = QLIST_FIRST(&blkdev->finished);
490 	send_notify += blk_send_response_one(ioreq);
491 	ioreq_release(ioreq);
492     }
493     if (send_notify)
494 	xen_be_send_notify(&blkdev->xendev);
495 }
496 
blk_get_request(struct XenBlkDev * blkdev,struct ioreq * ioreq,RING_IDX rc)497 static int blk_get_request(struct XenBlkDev *blkdev, struct ioreq *ioreq, RING_IDX rc)
498 {
499     switch (blkdev->protocol) {
500     case BLKIF_PROTOCOL_NATIVE:
501 	memcpy(&ioreq->req, RING_GET_REQUEST(&blkdev->rings.native, rc),
502 	       sizeof(ioreq->req));
503 	break;
504     case BLKIF_PROTOCOL_X86_32:
505         blkif_get_x86_32_req(&ioreq->req,
506                              RING_GET_REQUEST(&blkdev->rings.x86_32_part, rc));
507 	break;
508     case BLKIF_PROTOCOL_X86_64:
509         blkif_get_x86_64_req(&ioreq->req,
510                              RING_GET_REQUEST(&blkdev->rings.x86_64_part, rc));
511 	break;
512     }
513     return 0;
514 }
515 
blk_handle_requests(struct XenBlkDev * blkdev)516 static void blk_handle_requests(struct XenBlkDev *blkdev)
517 {
518     RING_IDX rc, rp;
519     struct ioreq *ioreq;
520 
521     blkdev->more_work = 0;
522 
523     rc = blkdev->rings.common.req_cons;
524     rp = blkdev->rings.common.sring->req_prod;
525     xen_rmb(); /* Ensure we see queued requests up to 'rp'. */
526 
527     if (use_aio)
528         blk_send_response_all(blkdev);
529     while (rc != rp) {
530         /* pull request from ring */
531         if (RING_REQUEST_CONS_OVERFLOW(&blkdev->rings.common, rc))
532             break;
533         ioreq = ioreq_start(blkdev);
534         if (ioreq == NULL) {
535             blkdev->more_work++;
536             break;
537         }
538         blk_get_request(blkdev, ioreq, rc);
539         blkdev->rings.common.req_cons = ++rc;
540 
541         /* parse them */
542         if (ioreq_parse(ioreq) != 0) {
543             if (blk_send_response_one(ioreq))
544                 xen_be_send_notify(&blkdev->xendev);
545             ioreq_release(ioreq);
546             continue;
547         }
548 
549         if (use_aio) {
550             /* run i/o in aio mode */
551             ioreq_runio_qemu_aio(ioreq);
552         } else {
553             /* run i/o in sync mode */
554             ioreq_runio_qemu_sync(ioreq);
555         }
556     }
557     if (!use_aio)
558         blk_send_response_all(blkdev);
559 
560     if (blkdev->more_work && blkdev->requests_inflight < max_requests)
561         qemu_bh_schedule(blkdev->bh);
562 }
563 
564 /* ------------------------------------------------------------- */
565 
blk_bh(void * opaque)566 static void blk_bh(void *opaque)
567 {
568     struct XenBlkDev *blkdev = opaque;
569     blk_handle_requests(blkdev);
570 }
571 
blk_alloc(struct XenDevice * xendev)572 static void blk_alloc(struct XenDevice *xendev)
573 {
574     struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
575 
576     QLIST_INIT(&blkdev->inflight);
577     QLIST_INIT(&blkdev->finished);
578     QLIST_INIT(&blkdev->freelist);
579     blkdev->bh = qemu_bh_new(blk_bh, blkdev);
580     if (xen_mode != XEN_EMULATE)
581         batch_maps = 1;
582 }
583 
blk_init(struct XenDevice * xendev)584 static int blk_init(struct XenDevice *xendev)
585 {
586     struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
587     int index, qflags, have_barriers, info = 0;
588     char *h;
589 
590     /* read xenstore entries */
591     if (blkdev->params == NULL) {
592 	blkdev->params = xenstore_read_be_str(&blkdev->xendev, "params");
593         h = strchr(blkdev->params, ':');
594 	if (h != NULL) {
595 	    blkdev->fileproto = blkdev->params;
596 	    blkdev->filename  = h+1;
597 	    *h = 0;
598 	} else {
599 	    blkdev->fileproto = "<unset>";
600 	    blkdev->filename  = blkdev->params;
601 	}
602     }
603     if (blkdev->mode == NULL)
604 	blkdev->mode = xenstore_read_be_str(&blkdev->xendev, "mode");
605     if (blkdev->type == NULL)
606 	blkdev->type = xenstore_read_be_str(&blkdev->xendev, "type");
607     if (blkdev->dev == NULL)
608 	blkdev->dev = xenstore_read_be_str(&blkdev->xendev, "dev");
609     if (blkdev->devtype == NULL)
610 	blkdev->devtype = xenstore_read_be_str(&blkdev->xendev, "device-type");
611 
612     /* do we have all we need? */
613     if (blkdev->params == NULL ||
614 	blkdev->mode == NULL   ||
615 	blkdev->type == NULL   ||
616 	blkdev->dev == NULL)
617 	return -1;
618 
619     /* read-only ? */
620     if (strcmp(blkdev->mode, "w") == 0) {
621 	qflags = BDRV_O_RDWR;
622     } else {
623 	qflags = 0;
624 	info  |= VDISK_READONLY;
625     }
626 
627     /* cdrom ? */
628     if (blkdev->devtype && !strcmp(blkdev->devtype, "cdrom"))
629 	info  |= VDISK_CDROM;
630 
631     /* init qemu block driver */
632     index = (blkdev->xendev.dev - 202 * 256) / 16;
633     blkdev->dinfo = drive_get(IF_XEN, 0, index);
634     if (!blkdev->dinfo) {
635         /* setup via xenbus -> create new block driver instance */
636         xen_be_printf(&blkdev->xendev, 2, "create new bdrv (xenbus setup)\n");
637         blkdev->bs = bdrv_new(blkdev->dev);
638         if (bdrv_open(blkdev->bs, blkdev->filename, qflags,
639                       bdrv_find_whitelisted_format(blkdev->fileproto)) != 0) {
640             bdrv_delete(blkdev->bs);
641             return -1;
642         }
643     } else {
644         /* setup via qemu cmdline -> already setup for us */
645         xen_be_printf(&blkdev->xendev, 2, "get configured bdrv (cmdline setup)\n");
646 	blkdev->bs = blkdev->dinfo->bdrv;
647     }
648     blkdev->file_blk  = BLOCK_SIZE;
649     blkdev->file_size = bdrv_getlength(blkdev->bs);
650     if (blkdev->file_size < 0) {
651         xen_be_printf(&blkdev->xendev, 1, "bdrv_getlength: %d (%s) | drv %s\n",
652                       (int)blkdev->file_size, strerror(-blkdev->file_size),
653                       blkdev->bs->drv ? blkdev->bs->drv->format_name : "-");
654 	blkdev->file_size = 0;
655     }
656     have_barriers = blkdev->bs->drv && blkdev->bs->drv->bdrv_flush ? 1 : 0;
657 
658     xen_be_printf(xendev, 1, "type \"%s\", fileproto \"%s\", filename \"%s\","
659 		  " size %" PRId64 " (%" PRId64 " MB)\n",
660 		  blkdev->type, blkdev->fileproto, blkdev->filename,
661 		  blkdev->file_size, blkdev->file_size >> 20);
662 
663     /* fill info */
664     xenstore_write_be_int(&blkdev->xendev, "feature-barrier", have_barriers);
665     xenstore_write_be_int(&blkdev->xendev, "info",            info);
666     xenstore_write_be_int(&blkdev->xendev, "sector-size",     blkdev->file_blk);
667     xenstore_write_be_int(&blkdev->xendev, "sectors",
668 			  blkdev->file_size / blkdev->file_blk);
669     return 0;
670 }
671 
blk_connect(struct XenDevice * xendev)672 static int blk_connect(struct XenDevice *xendev)
673 {
674     struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
675 
676     if (xenstore_read_fe_int(&blkdev->xendev, "ring-ref", &blkdev->ring_ref) == -1)
677 	return -1;
678     if (xenstore_read_fe_int(&blkdev->xendev, "event-channel",
679                              &blkdev->xendev.remote_port) == -1)
680 	return -1;
681 
682     blkdev->protocol = BLKIF_PROTOCOL_NATIVE;
683     if (blkdev->xendev.protocol) {
684         if (strcmp(blkdev->xendev.protocol, XEN_IO_PROTO_ABI_X86_32) == 0)
685             blkdev->protocol = BLKIF_PROTOCOL_X86_32;
686         if (strcmp(blkdev->xendev.protocol, XEN_IO_PROTO_ABI_X86_64) == 0)
687             blkdev->protocol = BLKIF_PROTOCOL_X86_64;
688     }
689 
690     blkdev->sring = xc_gnttab_map_grant_ref(blkdev->xendev.gnttabdev,
691 					    blkdev->xendev.dom,
692 					    blkdev->ring_ref,
693 					    PROT_READ | PROT_WRITE);
694     if (!blkdev->sring)
695 	return -1;
696     blkdev->cnt_map++;
697 
698     switch (blkdev->protocol) {
699     case BLKIF_PROTOCOL_NATIVE:
700     {
701 	blkif_sring_t *sring_native = blkdev->sring;
702 	BACK_RING_INIT(&blkdev->rings.native, sring_native, XC_PAGE_SIZE);
703 	break;
704     }
705     case BLKIF_PROTOCOL_X86_32:
706     {
707 	blkif_x86_32_sring_t *sring_x86_32 = blkdev->sring;
708 
709         BACK_RING_INIT(&blkdev->rings.x86_32_part, sring_x86_32, XC_PAGE_SIZE);
710 	break;
711     }
712     case BLKIF_PROTOCOL_X86_64:
713     {
714 	blkif_x86_64_sring_t *sring_x86_64 = blkdev->sring;
715 
716         BACK_RING_INIT(&blkdev->rings.x86_64_part, sring_x86_64, XC_PAGE_SIZE);
717 	break;
718     }
719     }
720 
721     xen_be_bind_evtchn(&blkdev->xendev);
722 
723     xen_be_printf(&blkdev->xendev, 1, "ok: proto %s, ring-ref %d, "
724 		  "remote port %d, local port %d\n",
725 		  blkdev->xendev.protocol, blkdev->ring_ref,
726 		  blkdev->xendev.remote_port, blkdev->xendev.local_port);
727     return 0;
728 }
729 
blk_disconnect(struct XenDevice * xendev)730 static void blk_disconnect(struct XenDevice *xendev)
731 {
732     struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
733 
734     if (blkdev->bs) {
735         if (!blkdev->dinfo) {
736             /* close/delete only if we created it ourself */
737             bdrv_close(blkdev->bs);
738             bdrv_delete(blkdev->bs);
739         }
740 	blkdev->bs = NULL;
741     }
742     xen_be_unbind_evtchn(&blkdev->xendev);
743 
744     if (blkdev->sring) {
745 	xc_gnttab_munmap(blkdev->xendev.gnttabdev, blkdev->sring, 1);
746 	blkdev->cnt_map--;
747 	blkdev->sring = NULL;
748     }
749 }
750 
blk_free(struct XenDevice * xendev)751 static int blk_free(struct XenDevice *xendev)
752 {
753     struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
754     struct ioreq *ioreq;
755 
756     while (!QLIST_EMPTY(&blkdev->freelist)) {
757 	ioreq = QLIST_FIRST(&blkdev->freelist);
758         QLIST_REMOVE(ioreq, list);
759         qemu_iovec_destroy(&ioreq->v);
760 	qemu_free(ioreq);
761     }
762 
763     qemu_free(blkdev->params);
764     qemu_free(blkdev->mode);
765     qemu_free(blkdev->type);
766     qemu_free(blkdev->dev);
767     qemu_free(blkdev->devtype);
768     qemu_bh_delete(blkdev->bh);
769     return 0;
770 }
771 
blk_event(struct XenDevice * xendev)772 static void blk_event(struct XenDevice *xendev)
773 {
774     struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
775 
776     qemu_bh_schedule(blkdev->bh);
777 }
778 
779 struct XenDevOps xen_blkdev_ops = {
780     .size       = sizeof(struct XenBlkDev),
781     .flags      = DEVOPS_FLAG_NEED_GNTDEV,
782     .alloc      = blk_alloc,
783     .init       = blk_init,
784     .connect    = blk_connect,
785     .disconnect = blk_disconnect,
786     .event      = blk_event,
787     .free       = blk_free,
788 };
789