hw/9pfs/xen-9p-backend.c

   1 /*
   2  * Xen 9p backend
   3  *
   4  * Copyright Aporeto 2017
   5  *
   6  * Authors:
   7  *  Stefano Stabellini <stefano@aporeto.com>
   8  *
   9  */
  10
  11 #include "qemu/osdep.h"
  12
  13 #include "hw/9pfs/9p.h"
  14 #include "hw/xen/xen-legacy-backend.h"
  15 #include "hw/9pfs/xen-9pfs.h"
  16 #include "qapi/error.h"
  17 #include "qemu/config-file.h"
  18 #include "qemu/main-loop.h"
  19 #include "qemu/option.h"
  20 #include "fsdev/qemu-fsdev.h"
  21
  22 #define VERSIONS "1"
  23 #define MAX_RINGS 8
  24 #define MAX_RING_ORDER 8
  25
  26 typedef struct Xen9pfsRing {
  27     struct Xen9pfsDev *priv;
  28
  29     int ref;
  30     xenevtchn_handle   *evtchndev;
  31     int evtchn;
  32     int local_port;
  33     int ring_order;
  34     struct xen_9pfs_data_intf *intf;
  35     unsigned char *data;
  36     struct xen_9pfs_data ring;
  37
  38     struct iovec *sg;
  39     QEMUBH *bh;
  40
  41     /* local copies, so that we can read/write PDU data directly from
  42      * the ring */
  43     RING_IDX out_cons, out_size, in_cons;
  44     bool inprogress;
  45 } Xen9pfsRing;
  46
  47 typedef struct Xen9pfsDev {
  48     struct XenLegacyDevice xendev;  /* must be first */
  49     V9fsState state;
  50     char *path;
  51     char *security_model;
  52     char *tag;
  53     char *id;
  54
  55     int num_rings;
  56     Xen9pfsRing *rings;
  57 } Xen9pfsDev;
  58
  59 static void xen_9pfs_disconnect(struct XenLegacyDevice *xendev);
  60
  61 static void xen_9pfs_in_sg(Xen9pfsRing *ring,
  62                            struct iovec *in_sg,
  63                            int *num,
  64                            uint32_t idx,
  65                            uint32_t size)
  66 {
  67     RING_IDX cons, prod, masked_prod, masked_cons;
  68
  69     cons = ring->intf->in_cons;
  70     prod = ring->intf->in_prod;
  71     xen_rmb();
  72     masked_prod = xen_9pfs_mask(prod, XEN_FLEX_RING_SIZE(ring->ring_order));
  73     masked_cons = xen_9pfs_mask(cons, XEN_FLEX_RING_SIZE(ring->ring_order));
  74
  75     if (masked_prod < masked_cons) {
  76         in_sg[0].iov_base = ring->ring.in + masked_prod;
  77         in_sg[0].iov_len = masked_cons - masked_prod;
  78         *num = 1;
  79     } else {
  80         in_sg[0].iov_base = ring->ring.in + masked_prod;
  81         in_sg[0].iov_len = XEN_FLEX_RING_SIZE(ring->ring_order) - masked_prod;
  82         in_sg[1].iov_base = ring->ring.in;
  83         in_sg[1].iov_len = masked_cons;
  84         *num = 2;
  85     }
  86 }
  87
  88 static void xen_9pfs_out_sg(Xen9pfsRing *ring,
  89                             struct iovec *out_sg,
  90                             int *num,
  91                             uint32_t idx)
  92 {
  93     RING_IDX cons, prod, masked_prod, masked_cons;
  94
  95     cons = ring->intf->out_cons;
  96     prod = ring->intf->out_prod;
  97     xen_rmb();
  98     masked_prod = xen_9pfs_mask(prod, XEN_FLEX_RING_SIZE(ring->ring_order));
  99     masked_cons = xen_9pfs_mask(cons, XEN_FLEX_RING_SIZE(ring->ring_order));
 100
 101     if (masked_cons < masked_prod) {
 102         out_sg[0].iov_base = ring->ring.out + masked_cons;
 103         out_sg[0].iov_len = ring->out_size;
 104         *num = 1;
 105     } else {
 106         if (ring->out_size >
 107             (XEN_FLEX_RING_SIZE(ring->ring_order) - masked_cons)) {
 108             out_sg[0].iov_base = ring->ring.out + masked_cons;
 109             out_sg[0].iov_len = XEN_FLEX_RING_SIZE(ring->ring_order) -
 110                                 masked_cons;
 111             out_sg[1].iov_base = ring->ring.out;
 112             out_sg[1].iov_len = ring->out_size -
 113                                 (XEN_FLEX_RING_SIZE(ring->ring_order) -
 114                                  masked_cons);
 115             *num = 2;
 116         } else {
 117             out_sg[0].iov_base = ring->ring.out + masked_cons;
 118             out_sg[0].iov_len = ring->out_size;
 119             *num = 1;
 120         }
 121     }
 122 }
 123
 124 static ssize_t xen_9pfs_pdu_vmarshal(V9fsPDU *pdu,
 125                                      size_t offset,
 126                                      const char *fmt,
 127                                      va_list ap)
 128 {
 129     Xen9pfsDev *xen_9pfs = container_of(pdu->s, Xen9pfsDev, state);
 130     struct iovec in_sg[2];
 131     int num;
 132     ssize_t ret;
 133
 134     xen_9pfs_in_sg(&xen_9pfs->rings[pdu->tag % xen_9pfs->num_rings],
 135                    in_sg, &num, pdu->idx, ROUND_UP(offset + 128, 512));
 136
 137     ret = v9fs_iov_vmarshal(in_sg, num, offset, 0, fmt, ap);
 138     if (ret < 0) {
 139         xen_pv_printf(&xen_9pfs->xendev, 0,
 140                       "Failed to encode VirtFS request type %d\n", pdu->id + 1);
 141         xen_be_set_state(&xen_9pfs->xendev, XenbusStateClosing);
 142         xen_9pfs_disconnect(&xen_9pfs->xendev);
 143     }
 144     return ret;
 145 }
 146
 147 static ssize_t xen_9pfs_pdu_vunmarshal(V9fsPDU *pdu,
 148                                        size_t offset,
 149                                        const char *fmt,
 150                                        va_list ap)
 151 {
 152     Xen9pfsDev *xen_9pfs = container_of(pdu->s, Xen9pfsDev, state);
 153     struct iovec out_sg[2];
 154     int num;
 155     ssize_t ret;
 156
 157     xen_9pfs_out_sg(&xen_9pfs->rings[pdu->tag % xen_9pfs->num_rings],
 158                     out_sg, &num, pdu->idx);
 159
 160     ret = v9fs_iov_vunmarshal(out_sg, num, offset, 0, fmt, ap);
 161     if (ret < 0) {
 162         xen_pv_printf(&xen_9pfs->xendev, 0,
 163                       "Failed to decode VirtFS request type %d\n", pdu->id);
 164         xen_be_set_state(&xen_9pfs->xendev, XenbusStateClosing);
 165         xen_9pfs_disconnect(&xen_9pfs->xendev);
 166     }
 167     return ret;
 168 }
 169
 170 static void xen_9pfs_init_out_iov_from_pdu(V9fsPDU *pdu,
 171                                            struct iovec **piov,
 172                                            unsigned int *pniov,
 173                                            size_t size)
 174 {
 175     Xen9pfsDev *xen_9pfs = container_of(pdu->s, Xen9pfsDev, state);
 176     Xen9pfsRing *ring = &xen_9pfs->rings[pdu->tag % xen_9pfs->num_rings];
 177     int num;
 178
 179     g_free(ring->sg);
 180
 181     ring->sg = g_new0(struct iovec, 2);
 182     xen_9pfs_out_sg(ring, ring->sg, &num, pdu->idx);
 183     *piov = ring->sg;
 184     *pniov = num;
 185 }
 186
 187 static void xen_9pfs_init_in_iov_from_pdu(V9fsPDU *pdu,
 188                                           struct iovec **piov,
 189                                           unsigned int *pniov,
 190                                           size_t size)
 191 {
 192     Xen9pfsDev *xen_9pfs = container_of(pdu->s, Xen9pfsDev, state);
 193     Xen9pfsRing *ring = &xen_9pfs->rings[pdu->tag % xen_9pfs->num_rings];
 194     int num;
 195     size_t buf_size;
 196
 197     g_free(ring->sg);
 198
 199     ring->sg = g_new0(struct iovec, 2);
 200     xen_9pfs_in_sg(ring, ring->sg, &num, pdu->idx, size);
 201
 202     buf_size = iov_size(ring->sg, num);
 203     if (buf_size  < size) {
 204         xen_pv_printf(&xen_9pfs->xendev, 0, "Xen 9pfs request type %d"
 205                 "needs %zu bytes, buffer has %zu\n", pdu->id, size,
 206                 buf_size);
 207         xen_be_set_state(&xen_9pfs->xendev, XenbusStateClosing);
 208         xen_9pfs_disconnect(&xen_9pfs->xendev);
 209     }
 210
 211     *piov = ring->sg;
 212     *pniov = num;
 213 }
 214
 215 static void xen_9pfs_push_and_notify(V9fsPDU *pdu)
 216 {
 217     RING_IDX prod;
 218     Xen9pfsDev *priv = container_of(pdu->s, Xen9pfsDev, state);
 219     Xen9pfsRing *ring = &priv->rings[pdu->tag % priv->num_rings];
 220
 221     g_free(ring->sg);
 222     ring->sg = NULL;
 223
 224     ring->intf->out_cons = ring->out_cons;
 225     xen_wmb();
 226
 227     prod = ring->intf->in_prod;
 228     xen_rmb();
 229     ring->intf->in_prod = prod + pdu->size;
 230     xen_wmb();
 231
 232     ring->inprogress = false;
 233     xenevtchn_notify(ring->evtchndev, ring->local_port);
 234
 235     qemu_bh_schedule(ring->bh);
 236 }
 237
 238 static const V9fsTransport xen_9p_transport = {
 239     .pdu_vmarshal = xen_9pfs_pdu_vmarshal,
 240     .pdu_vunmarshal = xen_9pfs_pdu_vunmarshal,
 241     .init_in_iov_from_pdu = xen_9pfs_init_in_iov_from_pdu,
 242     .init_out_iov_from_pdu = xen_9pfs_init_out_iov_from_pdu,
 243     .push_and_notify = xen_9pfs_push_and_notify,
 244 };
 245
 246 static int xen_9pfs_init(struct XenLegacyDevice *xendev)
 247 {
 248     return 0;
 249 }
 250
 251 static int xen_9pfs_receive(Xen9pfsRing *ring)
 252 {
 253     P9MsgHeader h;
 254     RING_IDX cons, prod, masked_prod, masked_cons, queued;
 255     V9fsPDU *pdu;
 256
 257     if (ring->inprogress) {
 258         return 0;
 259     }
 260
 261     cons = ring->intf->out_cons;
 262     prod = ring->intf->out_prod;
 263     xen_rmb();
 264
 265     queued = xen_9pfs_queued(prod, cons, XEN_FLEX_RING_SIZE(ring->ring_order));
 266     if (queued < sizeof(h)) {
 267         return 0;
 268     }
 269     ring->inprogress = true;
 270
 271     masked_prod = xen_9pfs_mask(prod, XEN_FLEX_RING_SIZE(ring->ring_order));
 272     masked_cons = xen_9pfs_mask(cons, XEN_FLEX_RING_SIZE(ring->ring_order));
 273
 274     xen_9pfs_read_packet((uint8_t *) &h, ring->ring.out, sizeof(h),
 275                          masked_prod, &masked_cons,
 276                          XEN_FLEX_RING_SIZE(ring->ring_order));
 277     if (queued < le32_to_cpu(h.size_le)) {
 278         return 0;
 279     }
 280
 281     /* cannot fail, because we only handle one request per ring at a time */
 282     pdu = pdu_alloc(&ring->priv->state);
 283     ring->out_size = le32_to_cpu(h.size_le);
 284     ring->out_cons = cons + le32_to_cpu(h.size_le);
 285
 286     pdu_submit(pdu, &h);
 287
 288     return 0;
 289 }
 290
 291 static void xen_9pfs_bh(void *opaque)
 292 {
 293     Xen9pfsRing *ring = opaque;
 294     xen_9pfs_receive(ring);
 295 }
 296
 297 static void xen_9pfs_evtchn_event(void *opaque)
 298 {
 299     Xen9pfsRing *ring = opaque;
 300     evtchn_port_t port;
 301
 302     port = xenevtchn_pending(ring->evtchndev);
 303     xenevtchn_unmask(ring->evtchndev, port);
 304
 305     qemu_bh_schedule(ring->bh);
 306 }
 307
 308 static void xen_9pfs_disconnect(struct XenLegacyDevice *xendev)
 309 {
 310     Xen9pfsDev *xen_9pdev = container_of(xendev, Xen9pfsDev, xendev);
 311     int i;
 312
 313     for (i = 0; i < xen_9pdev->num_rings; i++) {
 314         if (xen_9pdev->rings[i].evtchndev != NULL) {
 315             qemu_set_fd_handler(xenevtchn_fd(xen_9pdev->rings[i].evtchndev),
 316                     NULL, NULL, NULL);
 317             xenevtchn_unbind(xen_9pdev->rings[i].evtchndev,
 318                              xen_9pdev->rings[i].local_port);
 319             xen_9pdev->rings[i].evtchndev = NULL;
 320         }
 321     }
 322 }
 323
 324 static int xen_9pfs_free(struct XenLegacyDevice *xendev)
 325 {
 326     Xen9pfsDev *xen_9pdev = container_of(xendev, Xen9pfsDev, xendev);
 327     int i;
 328
 329     if (xen_9pdev->rings[0].evtchndev != NULL) {
 330         xen_9pfs_disconnect(xendev);
 331     }
 332
 333     for (i = 0; i < xen_9pdev->num_rings; i++) {
 334         if (xen_9pdev->rings[i].data != NULL) {
 335             xen_be_unmap_grant_refs(&xen_9pdev->xendev,
 336                                     xen_9pdev->rings[i].data,
 337                                     (1 << xen_9pdev->rings[i].ring_order));
 338         }
 339         if (xen_9pdev->rings[i].intf != NULL) {
 340             xen_be_unmap_grant_refs(&xen_9pdev->xendev,
 341                                     xen_9pdev->rings[i].intf,
 342                                     1);
 343         }
 344         if (xen_9pdev->rings[i].bh != NULL) {
 345             qemu_bh_delete(xen_9pdev->rings[i].bh);
 346         }
 347     }
 348
 349     g_free(xen_9pdev->id);
 350     g_free(xen_9pdev->tag);
 351     g_free(xen_9pdev->path);
 352     g_free(xen_9pdev->security_model);
 353     g_free(xen_9pdev->rings);
 354     return 0;
 355 }
 356
 357 static int xen_9pfs_connect(struct XenLegacyDevice *xendev)
 358 {
 359     Error *err = NULL;
 360     int i;
 361     Xen9pfsDev *xen_9pdev = container_of(xendev, Xen9pfsDev, xendev);
 362     V9fsState *s = &xen_9pdev->state;
 363     QemuOpts *fsdev;
 364
 365     if (xenstore_read_fe_int(&xen_9pdev->xendev, "num-rings",
 366                              &xen_9pdev->num_rings) == -1 ||
 367         xen_9pdev->num_rings > MAX_RINGS || xen_9pdev->num_rings < 1) {
 368         return -1;
 369     }
 370
 371     xen_9pdev->rings = g_new0(Xen9pfsRing, xen_9pdev->num_rings);
 372     for (i = 0; i < xen_9pdev->num_rings; i++) {
 373         char *str;
 374         int ring_order;
 375
 376         xen_9pdev->rings[i].priv = xen_9pdev;
 377         xen_9pdev->rings[i].evtchn = -1;
 378         xen_9pdev->rings[i].local_port = -1;
 379
 380         str = g_strdup_printf("ring-ref%u", i);
 381         if (xenstore_read_fe_int(&xen_9pdev->xendev, str,
 382                                  &xen_9pdev->rings[i].ref) == -1) {
 383             g_free(str);
 384             goto out;
 385         }
 386         g_free(str);
 387         str = g_strdup_printf("event-channel-%u", i);
 388         if (xenstore_read_fe_int(&xen_9pdev->xendev, str,
 389                                  &xen_9pdev->rings[i].evtchn) == -1) {
 390             g_free(str);
 391             goto out;
 392         }
 393         g_free(str);
 394
 395         xen_9pdev->rings[i].intf =
 396             xen_be_map_grant_ref(&xen_9pdev->xendev,
 397                                  xen_9pdev->rings[i].ref,
 398                                  PROT_READ | PROT_WRITE);
 399         if (!xen_9pdev->rings[i].intf) {
 400             goto out;
 401         }
 402         ring_order = xen_9pdev->rings[i].intf->ring_order;
 403         if (ring_order > MAX_RING_ORDER) {
 404             goto out;
 405         }
 406         xen_9pdev->rings[i].ring_order = ring_order;
 407         xen_9pdev->rings[i].data =
 408             xen_be_map_grant_refs(&xen_9pdev->xendev,
 409                                   xen_9pdev->rings[i].intf->ref,
 410                                   (1 << ring_order),
 411                                   PROT_READ | PROT_WRITE);
 412         if (!xen_9pdev->rings[i].data) {
 413             goto out;
 414         }
 415         xen_9pdev->rings[i].ring.in = xen_9pdev->rings[i].data;
 416         xen_9pdev->rings[i].ring.out = xen_9pdev->rings[i].data +
 417                                        XEN_FLEX_RING_SIZE(ring_order);
 418
 419         xen_9pdev->rings[i].bh = qemu_bh_new(xen_9pfs_bh, &xen_9pdev->rings[i]);
 420         xen_9pdev->rings[i].out_cons = 0;
 421         xen_9pdev->rings[i].out_size = 0;
 422         xen_9pdev->rings[i].inprogress = false;
 423
 424
 425         xen_9pdev->rings[i].evtchndev = xenevtchn_open(NULL, 0);
 426         if (xen_9pdev->rings[i].evtchndev == NULL) {
 427             goto out;
 428         }
 429         qemu_set_cloexec(xenevtchn_fd(xen_9pdev->rings[i].evtchndev));
 430         xen_9pdev->rings[i].local_port = xenevtchn_bind_interdomain
 431                                             (xen_9pdev->rings[i].evtchndev,
 432                                              xendev->dom,
 433                                              xen_9pdev->rings[i].evtchn);
 434         if (xen_9pdev->rings[i].local_port == -1) {
 435             xen_pv_printf(xendev, 0,
 436                           "xenevtchn_bind_interdomain failed port=%d\n",
 437                           xen_9pdev->rings[i].evtchn);
 438             goto out;
 439         }
 440         xen_pv_printf(xendev, 2, "bind evtchn port %d\n", xendev->local_port);
 441         qemu_set_fd_handler(xenevtchn_fd(xen_9pdev->rings[i].evtchndev),
 442                 xen_9pfs_evtchn_event, NULL, &xen_9pdev->rings[i]);
 443     }
 444
 445     xen_9pdev->security_model = xenstore_read_be_str(xendev, "security_model");
 446     xen_9pdev->path = xenstore_read_be_str(xendev, "path");
 447     xen_9pdev->id = s->fsconf.fsdev_id =
 448         g_strdup_printf("xen9p%d", xendev->dev);
 449     xen_9pdev->tag = s->fsconf.tag = xenstore_read_fe_str(xendev, "tag");
 450     fsdev = qemu_opts_create(qemu_find_opts("fsdev"),
 451             s->fsconf.tag,
 452             1, NULL);
 453     qemu_opt_set(fsdev, "fsdriver", "local", NULL);
 454     qemu_opt_set(fsdev, "path", xen_9pdev->path, NULL);
 455     qemu_opt_set(fsdev, "security_model", xen_9pdev->security_model, NULL);
 456     qemu_opts_set_id(fsdev, s->fsconf.fsdev_id);
 457     qemu_fsdev_add(fsdev, &err);
 458     if (err) {
 459         error_report_err(err);
 460     }
 461     v9fs_device_realize_common(s, &xen_9p_transport, NULL);
 462
 463     return 0;
 464
 465 out:
 466     xen_9pfs_free(xendev);
 467     return -1;
 468 }
 469
 470 static void xen_9pfs_alloc(struct XenLegacyDevice *xendev)
 471 {
 472     xenstore_write_be_str(xendev, "versions", VERSIONS);
 473     xenstore_write_be_int(xendev, "max-rings", MAX_RINGS);
 474     xenstore_write_be_int(xendev, "max-ring-page-order", MAX_RING_ORDER);
 475 }
 476
 477 struct XenDevOps xen_9pfs_ops = {
 478     .size       = sizeof(Xen9pfsDev),
 479     .flags      = DEVOPS_FLAG_NEED_GNTDEV,
 480     .alloc      = xen_9pfs_alloc,
 481     .init       = xen_9pfs_init,
 482     .initialise = xen_9pfs_connect,
 483     .disconnect = xen_9pfs_disconnect,
 484     .free       = xen_9pfs_free,
 485 };