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

   1 /*
   2  * Xen 9p backend
   3  *
   4  * Copyright Aporeto 2017
   5  *
   6  * Authors:
   7  *  Stefano Stabellini <[email protected]>
   8  *
   9  */
  10
  11 #include "qemu/osdep.h"
  12
  13 #include "hw/hw.h"
  14 #include "hw/9pfs/9p.h"
  15 #include "hw/xen/xen_backend.h"
  16 #include "hw/9pfs/xen-9pfs.h"
  17 #include "qemu/config-file.h"
  18 #include "fsdev/qemu-fsdev.h"
  19
  20 #define VERSIONS "1"
  21 #define MAX_RINGS 8
  22 #define MAX_RING_ORDER 8
  23
  24 typedef struct Xen9pfsRing {
  25     struct Xen9pfsDev *priv;
  26
  27     int ref;
  28     xenevtchn_handle   *evtchndev;
  29     int evtchn;
  30     int local_port;
  31     int ring_order;
  32     struct xen_9pfs_data_intf *intf;
  33     unsigned char *data;
  34     struct xen_9pfs_data ring;
  35
  36     struct iovec *sg;
  37     QEMUBH *bh;
  38
  39     /* local copies, so that we can read/write PDU data directly from
  40      * the ring */
  41     RING_IDX out_cons, out_size, in_cons;
  42     bool inprogress;
  43 } Xen9pfsRing;
  44
  45 typedef struct Xen9pfsDev {
  46     struct XenDevice xendev;  /* must be first */
  47     V9fsState state;
  48     char *path;
  49     char *security_model;
  50     char *tag;
  51     char *id;
  52
  53     int num_rings;
  54     Xen9pfsRing *rings;
  55 } Xen9pfsDev;
  56
  57 static void xen_9pfs_disconnect(struct XenDevice *xendev);
  58
  59 static void xen_9pfs_in_sg(Xen9pfsRing *ring,
  60                            struct iovec *in_sg,
  61                            int *num,
  62                            uint32_t idx,
  63                            uint32_t size)
  64 {
  65     RING_IDX cons, prod, masked_prod, masked_cons;
  66
  67     cons = ring->intf->in_cons;
  68     prod = ring->intf->in_prod;
  69     xen_rmb();
  70     masked_prod = xen_9pfs_mask(prod, XEN_FLEX_RING_SIZE(ring->ring_order));
  71     masked_cons = xen_9pfs_mask(cons, XEN_FLEX_RING_SIZE(ring->ring_order));
  72
  73     if (masked_prod < masked_cons) {
  74         in_sg[0].iov_base = ring->ring.in + masked_prod;
  75         in_sg[0].iov_len = masked_cons - masked_prod;
  76         *num = 1;
  77     } else {
  78         in_sg[0].iov_base = ring->ring.in + masked_prod;
  79         in_sg[0].iov_len = XEN_FLEX_RING_SIZE(ring->ring_order) - masked_prod;
  80         in_sg[1].iov_base = ring->ring.in;
  81         in_sg[1].iov_len = masked_cons;
  82         *num = 2;
  83     }
  84 }
  85
  86 static void xen_9pfs_out_sg(Xen9pfsRing *ring,
  87                             struct iovec *out_sg,
  88                             int *num,
  89                             uint32_t idx)
  90 {
  91     RING_IDX cons, prod, masked_prod, masked_cons;
  92
  93     cons = ring->intf->out_cons;
  94     prod = ring->intf->out_prod;
  95     xen_rmb();
  96     masked_prod = xen_9pfs_mask(prod, XEN_FLEX_RING_SIZE(ring->ring_order));
  97     masked_cons = xen_9pfs_mask(cons, XEN_FLEX_RING_SIZE(ring->ring_order));
  98
  99     if (masked_cons < masked_prod) {
 100         out_sg[0].iov_base = ring->ring.out + masked_cons;
 101         out_sg[0].iov_len = ring->out_size;
 102         *num = 1;
 103     } else {
 104         if (ring->out_size >
 105             (XEN_FLEX_RING_SIZE(ring->ring_order) - masked_cons)) {
 106             out_sg[0].iov_base = ring->ring.out + masked_cons;
 107             out_sg[0].iov_len = XEN_FLEX_RING_SIZE(ring->ring_order) -
 108                                 masked_cons;
 109             out_sg[1].iov_base = ring->ring.out;
 110             out_sg[1].iov_len = ring->out_size -
 111                                 (XEN_FLEX_RING_SIZE(ring->ring_order) -
 112                                  masked_cons);
 113             *num = 2;
 114         } else {
 115             out_sg[0].iov_base = ring->ring.out + masked_cons;
 116             out_sg[0].iov_len = ring->out_size;
 117             *num = 1;
 118         }
 119     }
 120 }
 121
 122 static ssize_t xen_9pfs_pdu_vmarshal(V9fsPDU *pdu,
 123                                      size_t offset,
 124                                      const char *fmt,
 125                                      va_list ap)
 126 {
 127     Xen9pfsDev *xen_9pfs = container_of(pdu->s, Xen9pfsDev, state);
 128     struct iovec in_sg[2];
 129     int num;
 130     ssize_t ret;
 131
 132     xen_9pfs_in_sg(&xen_9pfs->rings[pdu->tag % xen_9pfs->num_rings],
 133                    in_sg, &num, pdu->idx, ROUND_UP(offset + 128, 512));
 134
 135     ret = v9fs_iov_vmarshal(in_sg, num, offset, 0, fmt, ap);
 136     if (ret < 0) {
 137         xen_pv_printf(&xen_9pfs->xendev, 0,
 138                       "Failed to encode VirtFS request type %d\n", pdu->id + 1);
 139         xen_be_set_state(&xen_9pfs->xendev, XenbusStateClosing);
 140         xen_9pfs_disconnect(&xen_9pfs->xendev);
 141     }
 142     return ret;
 143 }
 144
 145 static ssize_t xen_9pfs_pdu_vunmarshal(V9fsPDU *pdu,
 146                                        size_t offset,
 147                                        const char *fmt,
 148                                        va_list ap)
 149 {
 150     Xen9pfsDev *xen_9pfs = container_of(pdu->s, Xen9pfsDev, state);
 151     struct iovec out_sg[2];
 152     int num;
 153     ssize_t ret;
 154
 155     xen_9pfs_out_sg(&xen_9pfs->rings[pdu->tag % xen_9pfs->num_rings],
 156                     out_sg, &num, pdu->idx);
 157
 158     ret = v9fs_iov_vunmarshal(out_sg, num, offset, 0, fmt, ap);
 159     if (ret < 0) {
 160         xen_pv_printf(&xen_9pfs->xendev, 0,
 161                       "Failed to decode VirtFS request type %d\n", pdu->id);
 162         xen_be_set_state(&xen_9pfs->xendev, XenbusStateClosing);
 163         xen_9pfs_disconnect(&xen_9pfs->xendev);
 164     }
 165     return ret;
 166 }
 167
 168 static void xen_9pfs_init_out_iov_from_pdu(V9fsPDU *pdu,
 169                                            struct iovec **piov,
 170                                            unsigned int *pniov,
 171                                            size_t size)
 172 {
 173     Xen9pfsDev *xen_9pfs = container_of(pdu->s, Xen9pfsDev, state);
 174     Xen9pfsRing *ring = &xen_9pfs->rings[pdu->tag % xen_9pfs->num_rings];
 175     int num;
 176
 177     g_free(ring->sg);
 178
 179     ring->sg = g_malloc0(sizeof(*ring->sg) * 2);
 180     xen_9pfs_out_sg(ring, ring->sg, &num, pdu->idx);
 181     *piov = ring->sg;
 182     *pniov = num;
 183 }
 184
 185 static void xen_9pfs_init_in_iov_from_pdu(V9fsPDU *pdu,
 186                                           struct iovec **piov,
 187                                           unsigned int *pniov,
 188                                           size_t size)
 189 {
 190     Xen9pfsDev *xen_9pfs = container_of(pdu->s, Xen9pfsDev, state);
 191     Xen9pfsRing *ring = &xen_9pfs->rings[pdu->tag % xen_9pfs->num_rings];
 192     int num;
 193     size_t buf_size;
 194
 195     g_free(ring->sg);
 196
 197     ring->sg = g_malloc0(sizeof(*ring->sg) * 2);
 198     xen_9pfs_in_sg(ring, ring->sg, &num, pdu->idx, size);
 199
 200     buf_size = iov_size(ring->sg, num);
 201     if (buf_size  < size) {
 202         xen_pv_printf(&xen_9pfs->xendev, 0, "Xen 9pfs request type %d"
 203                 "needs %zu bytes, buffer has %zu\n", pdu->id, size,
 204                 buf_size);
 205         xen_be_set_state(&xen_9pfs->xendev, XenbusStateClosing);
 206         xen_9pfs_disconnect(&xen_9pfs->xendev);
 207     }
 208
 209     *piov = ring->sg;
 210     *pniov = num;
 211 }
 212
 213 static void xen_9pfs_push_and_notify(V9fsPDU *pdu)
 214 {
 215     RING_IDX prod;
 216     Xen9pfsDev *priv = container_of(pdu->s, Xen9pfsDev, state);
 217     Xen9pfsRing *ring = &priv->rings[pdu->tag % priv->num_rings];
 218
 219     g_free(ring->sg);
 220     ring->sg = NULL;
 221
 222     ring->intf->out_cons = ring->out_cons;
 223     xen_wmb();
 224
 225     prod = ring->intf->in_prod;
 226     xen_rmb();
 227     ring->intf->in_prod = prod + pdu->size;
 228     xen_wmb();
 229
 230     ring->inprogress = false;
 231     xenevtchn_notify(ring->evtchndev, ring->local_port);
 232
 233     qemu_bh_schedule(ring->bh);
 234 }
 235
 236 static const struct V9fsTransport xen_9p_transport = {
 237     .pdu_vmarshal = xen_9pfs_pdu_vmarshal,
 238     .pdu_vunmarshal = xen_9pfs_pdu_vunmarshal,
 239     .init_in_iov_from_pdu = xen_9pfs_init_in_iov_from_pdu,
 240     .init_out_iov_from_pdu = xen_9pfs_init_out_iov_from_pdu,
 241     .push_and_notify = xen_9pfs_push_and_notify,
 242 };
 243
 244 static int xen_9pfs_init(struct XenDevice *xendev)
 245 {
 246     return 0;
 247 }
 248
 249 static int xen_9pfs_receive(Xen9pfsRing *ring)
 250 {
 251     P9MsgHeader h;
 252     RING_IDX cons, prod, masked_prod, masked_cons, queued;
 253     V9fsPDU *pdu;
 254
 255     if (ring->inprogress) {
 256         return 0;
 257     }
 258
 259     cons = ring->intf->out_cons;
 260     prod = ring->intf->out_prod;
 261     xen_rmb();
 262
 263     queued = xen_9pfs_queued(prod, cons, XEN_FLEX_RING_SIZE(ring->ring_order));
 264     if (queued < sizeof(h)) {
 265         return 0;
 266     }
 267     ring->inprogress = true;
 268
 269     masked_prod = xen_9pfs_mask(prod, XEN_FLEX_RING_SIZE(ring->ring_order));
 270     masked_cons = xen_9pfs_mask(cons, XEN_FLEX_RING_SIZE(ring->ring_order));
 271
 272     xen_9pfs_read_packet((uint8_t *) &h, ring->ring.out, sizeof(h),
 273                          masked_prod, &masked_cons,
 274                          XEN_FLEX_RING_SIZE(ring->ring_order));
 275     if (queued < le32_to_cpu(h.size_le)) {
 276         return 0;
 277     }
 278
 279     /* cannot fail, because we only handle one request per ring at a time */
 280     pdu = pdu_alloc(&ring->priv->state);
 281     ring->out_size = le32_to_cpu(h.size_le);
 282     ring->out_cons = cons + le32_to_cpu(h.size_le);
 283
 284     pdu_submit(pdu, &h);
 285
 286     return 0;
 287 }
 288
 289 static void xen_9pfs_bh(void *opaque)
 290 {
 291     Xen9pfsRing *ring = opaque;
 292     xen_9pfs_receive(ring);
 293 }
 294
 295 static void xen_9pfs_evtchn_event(void *opaque)
 296 {
 297     Xen9pfsRing *ring = opaque;
 298     evtchn_port_t port;
 299
 300     port = xenevtchn_pending(ring->evtchndev);
 301     xenevtchn_unmask(ring->evtchndev, port);
 302
 303     qemu_bh_schedule(ring->bh);
 304 }
 305
 306 static void xen_9pfs_disconnect(struct XenDevice *xendev)
 307 {
 308     Xen9pfsDev *xen_9pdev = container_of(xendev, Xen9pfsDev, xendev);
 309     int i;
 310
 311     for (i = 0; i < xen_9pdev->num_rings; i++) {
 312         if (xen_9pdev->rings[i].evtchndev != NULL) {
 313             qemu_set_fd_handler(xenevtchn_fd(xen_9pdev->rings[i].evtchndev),
 314                     NULL, NULL, NULL);
 315             xenevtchn_unbind(xen_9pdev->rings[i].evtchndev,
 316                              xen_9pdev->rings[i].local_port);
 317             xen_9pdev->rings[i].evtchndev = NULL;
 318         }
 319     }
 320 }
 321
 322 static int xen_9pfs_free(struct XenDevice *xendev)
 323 {
 324     Xen9pfsDev *xen_9pdev = container_of(xendev, Xen9pfsDev, xendev);
 325     int i;
 326
 327     if (xen_9pdev->rings[0].evtchndev != NULL) {
 328         xen_9pfs_disconnect(xendev);
 329     }
 330
 331     for (i = 0; i < xen_9pdev->num_rings; i++) {
 332         if (xen_9pdev->rings[i].data != NULL) {
 333             xengnttab_unmap(xen_9pdev->xendev.gnttabdev,
 334                     xen_9pdev->rings[i].data,
 335                     (1 << xen_9pdev->rings[i].ring_order));
 336         }
 337         if (xen_9pdev->rings[i].intf != NULL) {
 338             xengnttab_unmap(xen_9pdev->xendev.gnttabdev,
 339                     xen_9pdev->rings[i].intf,
 340                     1);
 341         }
 342         if (xen_9pdev->rings[i].bh != NULL) {
 343             qemu_bh_delete(xen_9pdev->rings[i].bh);
 344         }
 345     }
 346
 347     g_free(xen_9pdev->id);
 348     g_free(xen_9pdev->tag);
 349     g_free(xen_9pdev->path);
 350     g_free(xen_9pdev->security_model);
 351     g_free(xen_9pdev->rings);
 352     return 0;
 353 }
 354
 355 static int xen_9pfs_connect(struct XenDevice *xendev)
 356 {
 357     int i;
 358     Xen9pfsDev *xen_9pdev = container_of(xendev, Xen9pfsDev, xendev);
 359     V9fsState *s = &xen_9pdev->state;
 360     QemuOpts *fsdev;
 361
 362     if (xenstore_read_fe_int(&xen_9pdev->xendev, "num-rings",
 363                              &xen_9pdev->num_rings) == -1 ||
 364         xen_9pdev->num_rings > MAX_RINGS || xen_9pdev->num_rings < 1) {
 365         return -1;
 366     }
 367
 368     xen_9pdev->rings = g_malloc0(xen_9pdev->num_rings * sizeof(Xen9pfsRing));
 369     for (i = 0; i < xen_9pdev->num_rings; i++) {
 370         char *str;
 371         int ring_order;
 372
 373         xen_9pdev->rings[i].priv = xen_9pdev;
 374         xen_9pdev->rings[i].evtchn = -1;
 375         xen_9pdev->rings[i].local_port = -1;
 376
 377         str = g_strdup_printf("ring-ref%u", i);
 378         if (xenstore_read_fe_int(&xen_9pdev->xendev, str,
 379                                  &xen_9pdev->rings[i].ref) == -1) {
 380             g_free(str);
 381             goto out;
 382         }
 383         g_free(str);
 384         str = g_strdup_printf("event-channel-%u", i);
 385         if (xenstore_read_fe_int(&xen_9pdev->xendev, str,
 386                                  &xen_9pdev->rings[i].evtchn) == -1) {
 387             g_free(str);
 388             goto out;
 389         }
 390         g_free(str);
 391
 392         xen_9pdev->rings[i].intf =  xengnttab_map_grant_ref(
 393                 xen_9pdev->xendev.gnttabdev,
 394                 xen_9pdev->xendev.dom,
 395                 xen_9pdev->rings[i].ref,
 396                 PROT_READ | PROT_WRITE);
 397         if (!xen_9pdev->rings[i].intf) {
 398             goto out;
 399         }
 400         ring_order = xen_9pdev->rings[i].intf->ring_order;
 401         if (ring_order > MAX_RING_ORDER) {
 402             goto out;
 403         }
 404         xen_9pdev->rings[i].ring_order = ring_order;
 405         xen_9pdev->rings[i].data = xengnttab_map_domain_grant_refs(
 406                 xen_9pdev->xendev.gnttabdev,
 407                 (1 << ring_order),
 408                 xen_9pdev->xendev.dom,
 409                 xen_9pdev->rings[i].intf->ref,
 410                 PROT_READ | PROT_WRITE);
 411         if (!xen_9pdev->rings[i].data) {
 412             goto out;
 413         }
 414         xen_9pdev->rings[i].ring.in = xen_9pdev->rings[i].data;
 415         xen_9pdev->rings[i].ring.out = xen_9pdev->rings[i].data +
 416                                        XEN_FLEX_RING_SIZE(ring_order);
 417
 418         xen_9pdev->rings[i].bh = qemu_bh_new(xen_9pfs_bh, &xen_9pdev->rings[i]);
 419         xen_9pdev->rings[i].out_cons = 0;
 420         xen_9pdev->rings[i].out_size = 0;
 421         xen_9pdev->rings[i].inprogress = false;
 422
 423
 424         xen_9pdev->rings[i].evtchndev = xenevtchn_open(NULL, 0);
 425         if (xen_9pdev->rings[i].evtchndev == NULL) {
 426             goto out;
 427         }
 428         qemu_set_cloexec(xenevtchn_fd(xen_9pdev->rings[i].evtchndev));
 429         xen_9pdev->rings[i].local_port = xenevtchn_bind_interdomain
 430                                             (xen_9pdev->rings[i].evtchndev,
 431                                              xendev->dom,
 432                                              xen_9pdev->rings[i].evtchn);
 433         if (xen_9pdev->rings[i].local_port == -1) {
 434             xen_pv_printf(xendev, 0,
 435                           "xenevtchn_bind_interdomain failed port=%d\n",
 436                           xen_9pdev->rings[i].evtchn);
 437             goto out;
 438         }
 439         xen_pv_printf(xendev, 2, "bind evtchn port %d\n", xendev->local_port);
 440         qemu_set_fd_handler(xenevtchn_fd(xen_9pdev->rings[i].evtchndev),
 441                 xen_9pfs_evtchn_event, NULL, &xen_9pdev->rings[i]);
 442     }
 443
 444     xen_9pdev->security_model = xenstore_read_be_str(xendev, "security_model");
 445     xen_9pdev->path = xenstore_read_be_str(xendev, "path");
 446     xen_9pdev->id = s->fsconf.fsdev_id =
 447         g_strdup_printf("xen9p%d", xendev->dev);
 448     xen_9pdev->tag = s->fsconf.tag = xenstore_read_fe_str(xendev, "tag");
 449     v9fs_register_transport(s, &xen_9p_transport);
 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);
 458     v9fs_device_realize_common(s, NULL);
 459
 460     return 0;
 461
 462 out:
 463     xen_9pfs_free(xendev);
 464     return -1;
 465 }
 466
 467 static void xen_9pfs_alloc(struct XenDevice *xendev)
 468 {
 469     xenstore_write_be_str(xendev, "versions", VERSIONS);
 470     xenstore_write_be_int(xendev, "max-rings", MAX_RINGS);
 471     xenstore_write_be_int(xendev, "max-ring-page-order", MAX_RING_ORDER);
 472 }
 473
 474 struct XenDevOps xen_9pfs_ops = {
 475     .size       = sizeof(Xen9pfsDev),
 476     .flags      = DEVOPS_FLAG_NEED_GNTDEV,
 477     .alloc      = xen_9pfs_alloc,
 478     .init       = xen_9pfs_init,
 479     .initialise = xen_9pfs_connect,
 480     .disconnect = xen_9pfs_disconnect,
 481     .free       = xen_9pfs_free,
 482 };