sys/arch/xen/include/xen3-public/grant_table.h

   1 /* $NetBSD: grant_table.h,v 1.7 2007/10/17 19:58:30 garbled Exp $ */
   2 /******************************************************************************
   3  * grant_table.h
   4  *
   5  * Interface for granting foreign access to page frames, and receiving
   6  * page-ownership transfers.
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a copy
   9  * of this software and associated documentation files (the "Software"), to
  10  * deal in the Software without restriction, including without limitation the
  11  * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
  12  * sell copies of the Software, and to permit persons to whom the Software is
  13  * furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be included in
  16  * all copies or substantial portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  21  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  22  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  23  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  24  * DEALINGS IN THE SOFTWARE.
  25  *
  26  * Copyright (c) 2004, K A Fraser
  27  */
  28
  29 #ifndef __XEN_PUBLIC_GRANT_TABLE_H__
  30 #define __XEN_PUBLIC_GRANT_TABLE_H__
  31
  32
  33 /***********************************
  34  * GRANT TABLE REPRESENTATION
  35  */
  36
  37 /* Some rough guidelines on accessing and updating grant-table entries
  38  * in a concurrency-safe manner. For more information, Linux contains a
  39  * reference implementation for guest OSes (arch/xen/kernel/grant_table.c).
  40  *
  41  * NB. WMB is a no-op on current-generation x86 processors. However, a
  42  *     compiler barrier will still be required.
  43  *
  44  * Introducing a valid entry into the grant table:
  45  *  1. Write ent->domid.
  46  *  2. Write ent->frame:
  47  *      GTF_permit_access:   Frame to which access is permitted.
  48  *      GTF_accept_transfer: Pseudo-phys frame slot being filled by new
  49  *                           frame, or zero if none.
  50  *  3. Write memory barrier (WMB).
  51  *  4. Write ent->flags, inc. valid type.
  52  *
  53  * Invalidating an unused GTF_permit_access entry:
  54  *  1. flags = ent->flags.
  55  *  2. Observe that !(flags & (GTF_reading|GTF_writing)).
  56  *  3. Check result of SMP-safe CMPXCHG(&ent->flags, flags, 0).
  57  *  NB. No need for WMB as reuse of entry is control-dependent on success of
  58  *      step 3, and all architectures guarantee ordering of ctrl-dep writes.
  59  *
  60  * Invalidating an in-use GTF_permit_access entry:
  61  *  This cannot be done directly. Request assistance from the domain controller
  62  *  which can set a timeout on the use of a grant entry and take necessary
  63  *  action. (NB. This is not yet implemented!).
  64  *
  65  * Invalidating an unused GTF_accept_transfer entry:
  66  *  1. flags = ent->flags.
  67  *  2. Observe that !(flags & GTF_transfer_committed). [*]
  68  *  3. Check result of SMP-safe CMPXCHG(&ent->flags, flags, 0).
  69  *  NB. No need for WMB as reuse of entry is control-dependent on success of
  70  *      step 3, and all architectures guarantee ordering of ctrl-dep writes.
  71  *  [*] If GTF_transfer_committed is set then the grant entry is 'committed'.
  72  *      The guest must /not/ modify the grant entry until the address of the
  73  *      transferred frame is written. It is safe for the guest to spin waiting
  74  *      for this to occur (detect by observing GTF_transfer_completed in
  75  *      ent->flags).
  76  *
  77  * Invalidating a committed GTF_accept_transfer entry:
  78  *  1. Wait for (ent->flags & GTF_transfer_completed).
  79  *
  80  * Changing a GTF_permit_access from writable to read-only:
  81  *  Use SMP-safe CMPXCHG to set GTF_readonly, while checking !GTF_writing.
  82  *
  83  * Changing a GTF_permit_access from read-only to writable:
  84  *  Use SMP-safe bit-setting instruction.
  85  */
  86
  87 /*
  88  * A grant table comprises a packed array of grant entries in one or more
  89  * page frames shared between Xen and a guest.
  90  * [XEN]: This field is written by Xen and read by the sharing guest.
  91  * [GST]: This field is written by the guest and read by Xen.
  92  */
  93 struct grant_entry {
  94     /* GTF_xxx: various type and flag information.  [XEN,GST] */
  95     uint16_t flags;
  96     /* The domain being granted foreign privileges. [GST] */
  97     domid_t  domid;
  98     /*
  99      * GTF_permit_access: Frame that @domid is allowed to map and access. [GST]
 100      * GTF_accept_transfer: Frame whose ownership transferred by @domid. [XEN]
 101      */
 102     uint32_t frame;
 103 };
 104 typedef struct grant_entry grant_entry_t;
 105
 106 /*
 107  * Type of grant entry.
 108  *  GTF_invalid: This grant entry grants no privileges.
 109  *  GTF_permit_access: Allow @domid to map/access @frame.
 110  *  GTF_accept_transfer: Allow @domid to transfer ownership of one page frame
 111  *                       to this guest. Xen writes the page number to @frame.
 112  */
 113 #define GTF_invalid         (0U<<0)
 114 #define GTF_permit_access   (1U<<0)
 115 #define GTF_accept_transfer (2U<<0)
 116 #define GTF_type_mask       (3U<<0)
 117
 118 /*
 119  * Subflags for GTF_permit_access.
 120  *  GTF_readonly: Restrict @domid to read-only mappings and accesses. [GST]
 121  *  GTF_reading: Grant entry is currently mapped for reading by @domid. [XEN]
 122  *  GTF_writing: Grant entry is currently mapped for writing by @domid. [XEN]
 123  *  GTF_PAT, GTF_PWT, GTF_PCD: (x86) cache attribute flags for the grant [GST]
 124  */
 125 #define _GTF_readonly       (2)
 126 #define GTF_readonly        (1U<<_GTF_readonly)
 127 #define _GTF_reading        (3)
 128 #define GTF_reading         (1U<<_GTF_reading)
 129 #define _GTF_writing        (4)
 130 #define GTF_writing         (1U<<_GTF_writing)
 131 #define _GTF_PWT            (5)
 132 #define GTF_PWT             (1U<<_GTF_PWT)
 133 #define _GTF_PCD            (6)
 134 #define GTF_PCD             (1U<<_GTF_PCD)
 135 #define _GTF_PAT            (7)
 136 #define GTF_PAT             (1U<<_GTF_PAT)
 137
 138 /*
 139  * Subflags for GTF_accept_transfer:
 140  *  GTF_transfer_committed: Xen sets this flag to indicate that it is committed
 141  *      to transferring ownership of a page frame. When a guest sees this flag
 142  *      it must /not/ modify the grant entry until GTF_transfer_completed is
 143  *      set by Xen.
 144  *  GTF_transfer_completed: It is safe for the guest to spin-wait on this flag
 145  *      after reading GTF_transfer_committed. Xen will always write the frame
 146  *      address, followed by ORing this flag, in a timely manner.
 147  */
 148 #define _GTF_transfer_committed (2)
 149 #define GTF_transfer_committed  (1U<<_GTF_transfer_committed)
 150 #define _GTF_transfer_completed (3)
 151 #define GTF_transfer_completed  (1U<<_GTF_transfer_completed)
 152
 153
 154 /***********************************
 155  * GRANT TABLE QUERIES AND USES
 156  */
 157
 158 /*
 159  * Reference to a grant entry in a specified domain's grant table.
 160  */
 161 typedef uint32_t grant_ref_t;
 162
 163 /*
 164  * Handle to track a mapping created via a grant reference.
 165  */
 166 typedef uint32_t grant_handle_t;
 167
 168 /*
 169  * GNTTABOP_map_grant_ref: Map the grant entry (<dom>,<ref>) for access
 170  * by devices and/or host CPUs. If successful, <handle> is a tracking number
 171  * that must be presented later to destroy the mapping(s). On error, <handle>
 172  * is a negative status code.
 173  * NOTES:
 174  *  1. If GNTMAP_device_map is specified then <dev_bus_addr> is the address
 175  *     via which I/O devices may access the granted frame.
 176  *  2. If GNTMAP_host_map is specified then a mapping will be added at
 177  *     either a host virtual address in the current address space, or at
 178  *     a PTE at the specified machine address.  The type of mapping to
 179  *     perform is selected through the GNTMAP_contains_pte flag, and the
 180  *     address is specified in <host_addr>.
 181  *  3. Mappings should only be destroyed via GNTTABOP_unmap_grant_ref. If a
 182  *     host mapping is destroyed by other means then it is *NOT* guaranteed
 183  *     to be accounted to the correct grant reference!
 184  */
 185 #define GNTTABOP_map_grant_ref        0
 186 struct gnttab_map_grant_ref {
 187     /* IN parameters. */
 188     uint64_t host_addr;
 189     uint32_t flags;               /* GNTMAP_* */
 190     grant_ref_t ref;
 191     domid_t  dom;
 192     /* OUT parameters. */
 193     int16_t  status;              /* GNTST_* */
 194     grant_handle_t handle;
 195     uint64_t dev_bus_addr;
 196 };
 197 typedef struct gnttab_map_grant_ref gnttab_map_grant_ref_t;
 198 DEFINE_XEN_GUEST_HANDLE(gnttab_map_grant_ref_t);
 199
 200 /*
 201  * GNTTABOP_unmap_grant_ref: Destroy one or more grant-reference mappings
 202  * tracked by <handle>. If <host_addr> or <dev_bus_addr> is zero, that
 203  * field is ignored. If non-zero, they must refer to a device/host mapping
 204  * that is tracked by <handle>
 205  * NOTES:
 206  *  1. The call may fail in an undefined manner if either mapping is not
 207  *     tracked by <handle>.
 208  *  3. After executing a batch of unmaps, it is guaranteed that no stale
 209  *     mappings will remain in the device or host TLBs.
 210  */
 211 #define GNTTABOP_unmap_grant_ref      1
 212 struct gnttab_unmap_grant_ref {
 213     /* IN parameters. */
 214     uint64_t host_addr;
 215     uint64_t dev_bus_addr;
 216     grant_handle_t handle;
 217     /* OUT parameters. */
 218     int16_t  status;              /* GNTST_* */
 219 };
 220 typedef struct gnttab_unmap_grant_ref gnttab_unmap_grant_ref_t;
 221 DEFINE_XEN_GUEST_HANDLE(gnttab_unmap_grant_ref_t);
 222
 223 /*
 224  * GNTTABOP_setup_table: Set up a grant table for <dom> comprising at least
 225  * <nr_frames> pages. The frame addresses are written to the <frame_list>.
 226  * Only <nr_frames> addresses are written, even if the table is larger.
 227  * NOTES:
 228  *  1. <dom> may be specified as DOMID_SELF.
 229  *  2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF.
 230  *  3. Xen may not support more than a single grant-table page per domain.
 231  */
 232 #define GNTTABOP_setup_table          2
 233 struct gnttab_setup_table {
 234     /* IN parameters. */
 235     domid_t  dom;
 236     uint32_t nr_frames;
 237     /* OUT parameters. */
 238     int16_t  status;              /* GNTST_* */
 239     XEN_GUEST_HANDLE(ulong) frame_list;
 240 };
 241 typedef struct gnttab_setup_table gnttab_setup_table_t;
 242 DEFINE_XEN_GUEST_HANDLE(gnttab_setup_table_t);
 243
 244 /*
 245  * GNTTABOP_dump_table: Dump the contents of the grant table to the
 246  * xen console. Debugging use only.
 247  */
 248 #define GNTTABOP_dump_table           3
 249 struct gnttab_dump_table {
 250     /* IN parameters. */
 251     domid_t dom;
 252     /* OUT parameters. */
 253     int16_t status;               /* GNTST_* */
 254 };
 255 typedef struct gnttab_dump_table gnttab_dump_table_t;
 256 DEFINE_XEN_GUEST_HANDLE(gnttab_dump_table_t);
 257
 258 /*
 259  * GNTTABOP_transfer_grant_ref: Transfer <frame> to a foreign domain. The
 260  * foreign domain has previously registered its interest in the transfer via
 261  * <domid, ref>.
 262  *
 263  * Note that, even if the transfer fails, the specified page no longer belongs
 264  * to the calling domain *unless* the error is GNTST_bad_page.
 265  */
 266 #define GNTTABOP_transfer                4
 267 struct gnttab_transfer {
 268     /* IN parameters. */
 269     xen_pfn_t     mfn;
 270     domid_t       domid;
 271     grant_ref_t   ref;
 272     /* OUT parameters. */
 273     int16_t       status;
 274 };
 275 typedef struct gnttab_transfer gnttab_transfer_t;
 276 DEFINE_XEN_GUEST_HANDLE(gnttab_transfer_t);
 277
 278
 279 /*
 280  * GNTTABOP_copy: Hypervisor based copy
 281  * source and destinations can be eithers MFNs or, for foreign domains,
 282  * grant references. the foreign domain has to grant read/write access
 283  * in its grant table.
 284  *
 285  * The flags specify what type source and destinations are (either MFN
 286  * or grant reference).
 287  *
 288  * Note that this can also be used to copy data between two domains
 289  * via a third party if the source and destination domains had previously
 290  * grant appropriate access to their pages to the third party.
 291  *
 292  * source_offset specifies an offset in the source frame, dest_offset
 293  * the offset in the target frame and  len specifies the number of
 294  * bytes to be copied.
 295  */
 296
 297 #define _GNTCOPY_source_gref      (0)
 298 #define GNTCOPY_source_gref       (1<<_GNTCOPY_source_gref)
 299 #define _GNTCOPY_dest_gref        (1)
 300 #define GNTCOPY_dest_gref         (1<<_GNTCOPY_dest_gref)
 301
 302 #define GNTTABOP_copy                 5
 303 typedef struct gnttab_copy {
 304     /* IN parameters. */
 305     struct {
 306         union {
 307             grant_ref_t ref;
 308             xen_pfn_t   gmfn;
 309         } u;
 310         domid_t  domid;
 311         uint16_t offset;
 312     } source, dest;
 313     uint16_t      len;
 314     uint16_t      flags;          /* GNTCOPY_* */
 315     /* OUT parameters. */
 316     int16_t       status;
 317 } gnttab_copy_t;
 318 DEFINE_XEN_GUEST_HANDLE(gnttab_copy_t);
 319
 320 /*
 321  * GNTTABOP_query_size: Query the current and maximum sizes of the shared
 322  * grant table.
 323  * NOTES:
 324  *  1. <dom> may be specified as DOMID_SELF.
 325  *  2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF.
 326  */
 327 #define GNTTABOP_query_size           6
 328 struct gnttab_query_size {
 329     /* IN parameters. */
 330     domid_t  dom;
 331     /* OUT parameters. */
 332     uint32_t nr_frames;
 333     uint32_t max_nr_frames;
 334     int16_t  status;              /* GNTST_* */
 335 };
 336 typedef struct gnttab_query_size gnttab_query_size_t;
 337 DEFINE_XEN_GUEST_HANDLE(gnttab_query_size_t);
 338
 339 /*
 340  * GNTTABOP_unmap_and_replace: Destroy one or more grant-reference mappings
 341  * tracked by <handle> but atomically replace the page table entry with one
 342  * pointing to the machine address under <new_addr>.  <new_addr> will be
 343  * redirected to the null entry.
 344  * NOTES:
 345  *  1. The call may fail in an undefined manner if either mapping is not
 346  *     tracked by <handle>.
 347  *  2. After executing a batch of unmaps, it is guaranteed that no stale
 348  *     mappings will remain in the device or host TLBs.
 349  */
 350 #define GNTTABOP_unmap_and_replace    7
 351 struct gnttab_unmap_and_replace {
 352     /* IN parameters. */
 353     uint64_t host_addr;
 354     uint64_t new_addr;
 355     grant_handle_t handle;
 356     /* OUT parameters. */
 357     int16_t  status;              /* GNTST_* */
 358 };
 359 typedef struct gnttab_unmap_and_replace gnttab_unmap_and_replace_t;
 360 DEFINE_XEN_GUEST_HANDLE(gnttab_unmap_and_replace_t);
 361
 362
 363 /*
 364  * Bitfield values for update_pin_status.flags.
 365  */
 366  /* Map the grant entry for access by I/O devices. */
 367 #define _GNTMAP_device_map      (0)
 368 #define GNTMAP_device_map       (1<<_GNTMAP_device_map)
 369  /* Map the grant entry for access by host CPUs. */
 370 #define _GNTMAP_host_map        (1)
 371 #define GNTMAP_host_map         (1<<_GNTMAP_host_map)
 372  /* Accesses to the granted frame will be restricted to read-only access. */
 373 #define _GNTMAP_readonly        (2)
 374 #define GNTMAP_readonly         (1<<_GNTMAP_readonly)
 375  /*
 376   * GNTMAP_host_map subflag:
 377   *  0 => The host mapping is usable only by the guest OS.
 378   *  1 => The host mapping is usable by guest OS + current application.
 379   */
 380 #define _GNTMAP_application_map (3)
 381 #define GNTMAP_application_map  (1<<_GNTMAP_application_map)
 382
 383  /*
 384   * GNTMAP_contains_pte subflag:
 385   *  0 => This map request contains a host virtual address.
 386   *  1 => This map request contains the machine addess of the PTE to update.
 387   */
 388 #define _GNTMAP_contains_pte    (4)
 389 #define GNTMAP_contains_pte     (1<<_GNTMAP_contains_pte)
 390
 391 /*
 392  * Values for error status returns. All errors are -ve.
 393  */
 394 #define GNTST_okay             (0)  /* Normal return.                        */
 395 #define GNTST_general_error    (-1) /* General undefined error.              */
 396 #define GNTST_bad_domain       (-2) /* Unrecognsed domain id.                */
 397 #define GNTST_bad_gntref       (-3) /* Unrecognised or inappropriate gntref. */
 398 #define GNTST_bad_handle       (-4) /* Unrecognised or inappropriate handle. */
 399 #define GNTST_bad_virt_addr    (-5) /* Inappropriate virtual address to map. */
 400 #define GNTST_bad_dev_addr     (-6) /* Inappropriate device address to unmap.*/
 401 #define GNTST_no_device_space  (-7) /* Out of space in I/O MMU.              */
 402 #define GNTST_permission_denied (-8) /* Not enough privilege for operation.  */
 403 #define GNTST_bad_page         (-9) /* Specified page was invalid for op.    */
 404 #define GNTST_bad_copy_arg    (-10) /* copy arguments cross page boundary.   */
 405 #define GNTST_address_too_big (-11) /* transfer page address too large.      */
 406
 407 #define GNTTABOP_error_msgs {                   \
 408     "okay",                                     \
 409     "undefined error",                          \
 410     "unrecognised domain id",                   \
 411     "invalid grant reference",                  \
 412     "invalid mapping handle",                   \
 413     "invalid virtual address",                  \
 414     "invalid device address",                   \
 415     "no spare translation slot in the I/O MMU", \
 416     "permission denied",                        \
 417     "bad page",                                 \
 418     "copy arguments cross page boundary",       \
 419     "page address size too large"               \
 420 }
 421
 422 #endif /* __XEN_PUBLIC_GRANT_TABLE_H__ */
 423
 424 /*
 425  * Local variables:
 426  * mode: C
 427  * c-set-style: "BSD"
 428  * c-basic-offset: 4
 429  * tab-width: 4
 430  * indent-tabs-mode: nil
 431  * End:
 432  */