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