summaryrefslogtreecommitdiffstats
path: root/include/xen/interface/grant_table.h
blob: bcce56439d644559c5a46569ef83d4c5160f12b4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
/******************************************************************************
 * grant_table.h
 *
 * Interface for granting foreign access to page frames, and receiving
 * page-ownership transfers.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 *
 * Copyright (c) 2004, K A Fraser
 */

#ifndef __XEN_PUBLIC_GRANT_TABLE_H__
#define __XEN_PUBLIC_GRANT_TABLE_H__

#include <xen/interface/xen.h>

/***********************************
 * GRANT TABLE REPRESENTATION
 */

/* Some rough guidelines on accessing and updating grant-table entries
 * in a concurrency-safe manner. For more information, Linux contains a
 * reference implementation for guest OSes (arch/xen/kernel/grant_table.c).
 *
 * NB. WMB is a no-op on current-generation x86 processors. However, a
 *     compiler barrier will still be required.
 *
 * Introducing a valid entry into the grant table:
 *  1. Write ent->domid.
 *  2. Write ent->frame:
 *      GTF_permit_access:   Frame to which access is permitted.
 *      GTF_accept_transfer: Pseudo-phys frame slot being filled by new
 *                           frame, or zero if none.
 *  3. Write memory barrier (WMB).
 *  4. Write ent->flags, inc. valid type.
 *
 * Invalidating an unused GTF_permit_access entry:
 *  1. flags = ent->flags.
 *  2. Observe that !(flags & (GTF_reading|GTF_writing)).
 *  3. Check result of SMP-safe CMPXCHG(&ent->flags, flags, 0).
 *  NB. No need for WMB as reuse of entry is control-dependent on success of
 *      step 3, and all architectures guarantee ordering of ctrl-dep writes.
 *
 * Invalidating an in-use GTF_permit_access entry:
 *  This cannot be done directly. Request assistance from the domain controller
 *  which can set a timeout on the use of a grant entry and take necessary
 *  action. (NB. This is not yet implemented!).
 *
 * Invalidating an unused GTF_accept_transfer entry:
 *  1. flags = ent->flags.
 *  2. Observe that !(flags & GTF_transfer_committed). [*]
 *  3. Check result of SMP-safe CMPXCHG(&ent->flags, flags, 0).
 *  NB. No need for WMB as reuse of entry is control-dependent on success of
 *      step 3, and all architectures guarantee ordering of ctrl-dep writes.
 *  [*] If GTF_transfer_committed is set then the grant entry is 'committed'.
 *      The guest must /not/ modify the grant entry until the address of the
 *      transferred frame is written. It is safe for the guest to spin waiting
 *      for this to occur (detect by observing GTF_transfer_completed in
 *      ent->flags).
 *
 * Invalidating a committed GTF_accept_transfer entry:
 *  1. Wait for (ent->flags & GTF_transfer_completed).
 *
 * Changing a GTF_permit_access from writable to read-only:
 *  Use SMP-safe CMPXCHG to set GTF_readonly, while checking !GTF_writing.
 *
 * Changing a GTF_permit_access from read-only to writable:
 *  Use SMP-safe bit-setting instruction.
 */

/*
 * Reference to a grant entry in a specified domain's grant table.
 */
typedef uint32_t grant_ref_t;

/*
 * A grant table comprises a packed array of grant entries in one or more
 * page frames shared between Xen and a guest.
 * [XEN]: This field is written by Xen and read by the sharing guest.
 * [GST]: This field is written by the guest and read by Xen.
 */

/*
 * Version 1 of the grant table entry structure is maintained purely
 * for backwards compatibility.  New guests should use version 2.
 */
struct grant_entry_v1 {
    /* GTF_xxx: various type and flag information.  [XEN,GST] */
    uint16_t flags;
    /* The domain being granted foreign privileges. [GST] */
    domid_t  domid;
    /*
     * GTF_permit_access: Frame that @domid is allowed to map and access. [GST]
     * GTF_accept_transfer: Frame whose ownership transferred by @domid. [XEN]
     */
    uint32_t frame;
};

/*
 * Type of grant entry.
 *  GTF_invalid: This grant entry grants no privileges.
 *  GTF_permit_access: Allow @domid to map/access @frame.
 *  GTF_accept_transfer: Allow @domid to transfer ownership of one page frame
 *                       to this guest. Xen writes the page number to @frame.
 *  GTF_transitive: Allow @domid to transitively access a subrange of
 *                  @trans_grant in @trans_domid.  No mappings are allowed.
 */
#define GTF_invalid         (0U<<0)
#define GTF_permit_access   (1U<<0)
#define GTF_accept_transfer (2U<<0)
#define GTF_transitive      (3U<<0)
#define GTF_type_mask       (3U<<0)

/*
 * Subflags for GTF_permit_access.
 *  GTF_readonly: Restrict @domid to read-only mappings and accesses. [GST]
 *  GTF_reading: Grant entry is currently mapped for reading by @domid. [XEN]
 *  GTF_writing: Grant entry is currently mapped for writing by @domid. [XEN]
 *  GTF_sub_page: Grant access to only a subrange of the page.  @domid
 *                will only be allowed to copy from the grant, and not
 *                map it. [GST]
 */
#define _GTF_readonly       (2)
#define GTF_readonly        (1U<<_GTF_readonly)
#define _GTF_reading        (3)
#define GTF_reading         (1U<<_GTF_reading)
#define _GTF_writing        (4)
#define GTF_writing         (1U<<_GTF_writing)
#define _GTF_sub_page       (8)
#define GTF_sub_page        (1U<<_GTF_sub_page)

/*
 * Subflags for GTF_accept_transfer:
 *  GTF_transfer_committed: Xen sets this flag to indicate that it is committed
 *      to transferring ownership of a page frame. When a guest sees this flag
 *      it must /not/ modify the grant entry until GTF_transfer_completed is
 *      set by Xen.
 *  GTF_transfer_completed: It is safe for the guest to spin-wait on this flag
 *      after reading GTF_transfer_committed. Xen will always write the frame
 *      address, followed by ORing this flag, in a timely manner.
 */
#define _GTF_transfer_committed (2)
#define GTF_transfer_committed  (1U<<_GTF_transfer_committed)
#define _GTF_transfer_completed (3)
#define GTF_transfer_completed  (1U<<_GTF_transfer_completed)

/*
 * Version 2 grant table entries.  These fulfil the same role as
 * version 1 entries, but can represent more complicated operations.
 * Any given domain will have either a version 1 or a version 2 table,
 * and every entry in the table will be the same version.
 *
 * The interface by which domains use grant references does not depend
 * on the grant table version in use by the other domain.
 */

/*
 * Version 1 and version 2 grant entries share a common prefix.  The
 * fields of the prefix are documented as part of struct
 * grant_entry_v1.
 */
struct grant_entry_header {
    uint16_t flags;
    domid_t  domid;
};

/*
 * Version 2 of the grant entry structure, here is an union because three
 * different types are suppotted: full_page, sub_page and transitive.
 */
union grant_entry_v2 {
    struct grant_entry_header hdr;

    /*
     * This member is used for V1-style full page grants, where either:
     *
     * -- hdr.type is GTF_accept_transfer, or
     * -- hdr.type is GTF_permit_access and GTF_sub_page is not set.
     *
     * In that case, the frame field has the same semantics as the
     * field of the same name in the V1 entry structure.
     */
    struct {
	struct grant_entry_header hdr;
	uint32_t pad0;
	uint64_t frame;
    } full_page;

    /*
     * If the grant type is GTF_grant_access and GTF_sub_page is set,
     * @domid is allowed to access bytes [@page_off,@page_off+@length)
     * in frame @frame.
     */
    struct {
	struct grant_entry_header hdr;
	uint16_t page_off;
	uint16_t length;
	uint64_t frame;
    } sub_page;

    /*
     * If the grant is GTF_transitive, @domid is allowed to use the
     * grant @gref in domain @trans_domid, as if it was the local
     * domain.  Obviously, the transitive access must be compatible
     * with the original grant.
     */
    struct {
	struct grant_entry_header hdr;
	domid_t trans_domid;
	uint16_t pad0;
	grant_ref_t gref;
    } transitive;

    uint32_t __spacer[4]; /* Pad to a power of two */
};

typedef uint16_t grant_status_t;

/***********************************
 * GRANT TABLE QUERIES AND USES
 */

/*
 * Handle to track a mapping created via a grant reference.
 */
typedef uint32_t grant_handle_t;

/*
 * GNTTABOP_map_grant_ref: Map the grant entry (<dom>,<ref>) for access
 * by devices and/or host CPUs. If successful, <handle> is a tracking number
 * that must be presented later to destroy the mapping(s). On error, <handle>
 * is a negative status code.
 * NOTES:
 *  1. If GNTMAP_device_map is specified then <dev_bus_addr> is the address
 *     via which I/O devices may access the granted frame.
 *  2. If GNTMAP_host_map is specified then a mapping will be added at
 *     either a host virtual address in the current address space, or at
 *     a PTE at the specified machine address.  The type of mapping to
 *     perform is selected through the GNTMAP_contains_pte flag, and the
 *     address is specified in <host_addr>.
 *  3. Mappings should only be destroyed via GNTTABOP_unmap_grant_ref. If a
 *     host mapping is destroyed by other means then it is *NOT* guaranteed
 *     to be accounted to the correct grant reference!
 */
#define GNTTABOP_map_grant_ref        0
struct gnttab_map_grant_ref {
    /* IN parameters. */
    uint64_t host_addr;
    uint32_t flags;               /* GNTMAP_* */
    grant_ref_t ref;
    domid_t  dom;
    /* OUT parameters. */
    int16_t  status;              /* GNTST_* */
    grant_handle_t handle;
    uint64_t dev_bus_addr;
};
DEFINE_GUEST_HANDLE_STRUCT(gnttab_map_grant_ref);

/*
 * GNTTABOP_unmap_grant_ref: Destroy one or more grant-reference mappings
 * tracked by <handle>. If <host_addr> or <dev_bus_addr> is zero, that
 * field is ignored. If non-zero, they must refer to a device/host mapping
 * that is tracked by <handle>
 * NOTES:
 *  1. The call may fail in an undefined manner if either mapping is not
 *     tracked by <handle>.
 *  3. After executing a batch of unmaps, it is guaranteed that no stale
 *     mappings will remain in the device or host TLBs.
 */
#define GNTTABOP_unmap_grant_ref      1
struct gnttab_unmap_grant_ref {
    /* IN parameters. */
    uint64_t host_addr;
    uint64_t dev_bus_addr;
    grant_handle_t handle;
    /* OUT parameters. */
    int16_t  status;              /* GNTST_* */
};
DEFINE_GUEST_HANDLE_STRUCT(gnttab_unmap_grant_ref);

/*
 * GNTTABOP_setup_table: Set up a grant table for <dom> comprising at least
 * <nr_frames> pages. The frame addresses are written to the <frame_list>.
 * Only <nr_frames> addresses are written, even if the table is larger.
 * NOTES:
 *  1. <dom> may be specified as DOMID_SELF.
 *  2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF.
 *  3. Xen may not support more than a single grant-table page per domain.
 */
#define GNTTABOP_setup_table          2
struct gnttab_setup_table {
    /* IN parameters. */
    domid_t  dom;
    uint32_t nr_frames;
    /* OUT parameters. */
    int16_t  status;              /* GNTST_* */
    GUEST_HANDLE(xen_pfn_t) frame_list;
};
DEFINE_GUEST_HANDLE_STRUCT(gnttab_setup_table);

/*
 * GNTTABOP_dump_table: Dump the contents of the grant table to the
 * xen console. Debugging use only.
 */
#define GNTTABOP_dump_table           3
struct gnttab_dump_table {
    /* IN parameters. */
    domid_t dom;
    /* OUT parameters. */
    int16_t status;               /* GNTST_* */
};
DEFINE_GUEST_HANDLE_STRUCT(gnttab_dump_table);

/*
 * GNTTABOP_transfer_grant_ref: Transfer <frame> to a foreign domain. The
 * foreign domain has previously registered its interest in the transfer via
 * <domid, ref>.
 *
 * Note that, even if the transfer fails, the specified page no longer belongs
 * to the calling domain *unless* the error is GNTST_bad_page.
 */
#define GNTTABOP_transfer                4
struct gnttab_transfer {
    /* IN parameters. */
    xen_pfn_t mfn;
    domid_t       domid;
    grant_ref_t   ref;
    /* OUT parameters. */
    int16_t       status;
};
DEFINE_GUEST_HANDLE_STRUCT(gnttab_transfer);

/*
 * GNTTABOP_copy: Hypervisor based copy
 * source and destinations can be eithers MFNs or, for foreign domains,
 * grant references. the foreign domain has to grant read/write access
 * in its grant table.
 *
 * The flags specify what type source and destinations are (either MFN
 * or grant reference).
 *
 * Note that this can also be used to copy data between two domains
 * via a third party if the source and destination domains had previously
 * grant appropriate access to their pages to the third party.
 *
 * source_offset specifies an offset in the source frame, dest_offset
 * the offset in the target frame and  len specifies the number of
 * bytes to be copied.
 */

#define _GNTCOPY_source_gref      (0)
#define GNTCOPY_source_gref       (1<<_GNTCOPY_source_gref)
#define _GNTCOPY_dest_gref        (1)
#define GNTCOPY_dest_gref         (1<<_GNTCOPY_dest_gref)

#define GNTTABOP_copy                 5
struct gnttab_copy {
	/* IN parameters. */
	struct {
		union {
			grant_ref_t ref;
			xen_pfn_t   gmfn;
		} u;
		domid_t  domid;
		uint16_t offset;
	} source, dest;
	uint16_t      len;
	uint16_t      flags;          /* GNTCOPY_* */
	/* OUT parameters. */
	int16_t       status;
};
DEFINE_GUEST_HANDLE_STRUCT(gnttab_copy);

/*
 * GNTTABOP_query_size: Query the current and maximum sizes of the shared
 * grant table.
 * NOTES:
 *  1. <dom> may be specified as DOMID_SELF.
 *  2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF.
 */
#define GNTTABOP_query_size           6
struct gnttab_query_size {
    /* IN parameters. */
    domid_t  dom;
    /* OUT parameters. */
    uint32_t nr_frames;
    uint32_t max_nr_frames;
    int16_t  status;              /* GNTST_* */
};
DEFINE_GUEST_HANDLE_STRUCT(gnttab_query_size);

/*
 * GNTTABOP_unmap_and_replace: Destroy one or more grant-reference mappings
 * tracked by <handle> but atomically replace the page table entry with one
 * pointing to the machine address under <new_addr>.  <new_addr> will be
 * redirected to the null entry.
 * NOTES:
 *  1. The call may fail in an undefined manner if either mapping is not
 *     tracked by <handle>.
 *  2. After executing a batch of unmaps, it is guaranteed that no stale
 *     mappings will remain in the device or host TLBs.
 */
#define GNTTABOP_unmap_and_replace    7
struct gnttab_unmap_and_replace {
    /* IN parameters. */
    uint64_t host_addr;
    uint64_t new_addr;
    grant_handle_t handle;
    /* OUT parameters. */
    int16_t  status;              /* GNTST_* */
};
DEFINE_GUEST_HANDLE_STRUCT(gnttab_unmap_and_replace);

/*
 * GNTTABOP_set_version: Request a particular version of the grant
 * table shared table structure.  This operation can only be performed
 * once in any given domain.  It must be performed before any grants
 * are activated; otherwise, the domain will be stuck with version 1.
 * The only defined versions are 1 and 2.
 */
#define GNTTABOP_set_version          8
struct gnttab_set_version {
    /* IN parameters */
    uint32_t version;
};
DEFINE_GUEST_HANDLE_STRUCT(gnttab_set_version);

/*
 * GNTTABOP_get_status_frames: Get the list of frames used to store grant
 * status for <dom>. In grant format version 2, the status is separated
 * from the other shared grant fields to allow more efficient synchronization
 * using barriers instead of atomic cmpexch operations.
 * <nr_frames> specify the size of vector <frame_list>.
 * The frame addresses are returned in the <frame_list>.
 * Only <nr_frames> addresses are returned, even if the table is larger.
 * NOTES:
 *  1. <dom> may be specified as DOMID_SELF.
 *  2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF.
 */
#define GNTTABOP_get_status_frames     9
struct gnttab_get_status_frames {
    /* IN parameters. */
    uint32_t nr_frames;
    domid_t  dom;
    /* OUT parameters. */
    int16_t  status;              /* GNTST_* */
    GUEST_HANDLE(uint64_t) frame_list;
};
DEFINE_GUEST_HANDLE_STRUCT(gnttab_get_status_frames);

/*
 * GNTTABOP_get_version: Get the grant table version which is in
 * effect for domain <dom>.
 */
#define GNTTABOP_get_version          10
struct gnttab_get_version {
    /* IN parameters */
    domid_t dom;
    uint16_t pad;
    /* OUT parameters */
    uint32_t version;
};
DEFINE_GUEST_HANDLE_STRUCT(gnttab_get_version);

/*
 * Issue one or more cache maintenance operations on a portion of a
 * page granted to the calling domain by a foreign domain.
 */
#define GNTTABOP_cache_flush          12
struct gnttab_cache_flush {
    union {
        uint64_t dev_bus_addr;
        grant_ref_t ref;
    } a;
    uint16_t offset;   /* offset from start of grant */
    uint16_t length;   /* size within the grant */
#define GNTTAB_CACHE_CLEAN          (1<<0)
#define GNTTAB_CACHE_INVAL          (1<<1)
#define GNTTAB_CACHE_SOURCE_GREF    (1<<31)
    uint32_t op;
};
DEFINE_GUEST_HANDLE_STRUCT(gnttab_cache_flush);

/*
 * Bitfield values for update_pin_status.flags.
 */
 /* Map the grant entry for access by I/O devices. */
#define _GNTMAP_device_map      (0)
#define GNTMAP_device_map       (1<<_GNTMAP_device_map)
 /* Map the grant entry for access by host CPUs. */
#define _GNTMAP_host_map        (1)
#define GNTMAP_host_map         (1<<_GNTMAP_host_map)
 /* Accesses to the granted frame will be restricted to read-only access. */
#define _GNTMAP_readonly        (2)
#define GNTMAP_readonly         (1<<_GNTMAP_readonly)
 /*
  * GNTMAP_host_map subflag:
  *  0 => The host mapping is usable only by the guest OS.
  *  1 => The host mapping is usable by guest OS + current application.
  */
#define _GNTMAP_application_map (3)
#define GNTMAP_application_map  (1<<_GNTMAP_application_map)

 /*
  * GNTMAP_contains_pte subflag:
  *  0 => This map request contains a host virtual address.
  *  1 => This map request contains the machine addess of the PTE to update.
  */
#define _GNTMAP_contains_pte    (4)
#define GNTMAP_contains_pte     (1<<_GNTMAP_contains_pte)

/*
 * Values for error status returns. All errors are -ve.
 */
#define GNTST_okay             (0)  /* Normal return.                        */
#define GNTST_general_error    (-1) /* General undefined error.              */
#define GNTST_bad_domain       (-2) /* Unrecognsed domain id.                */
#define GNTST_bad_gntref       (-3) /* Unrecognised or inappropriate gntref. */
#define GNTST_bad_handle       (-4) /* Unrecognised or inappropriate handle. */
#define GNTST_bad_virt_addr    (-5) /* Inappropriate virtual address to map. */
#define GNTST_bad_dev_addr     (-6) /* Inappropriate device address to unmap.*/
#define GNTST_no_device_space  (-7) /* Out of space in I/O MMU.              */
#define GNTST_permission_denied (-8) /* Not enough privilege for operation.  */
#define GNTST_bad_page         (-9) /* Specified page was invalid for op.    */
#define GNTST_bad_copy_arg    (-10) /* copy arguments cross page boundary.   */
#define GNTST_address_too_big (-11) /* transfer page address too large.      */
#define GNTST_eagain          (-12) /* Operation not done; try again.        */

#define GNTTABOP_error_msgs {                   \
    "okay",                                     \
    "undefined error",                          \
    "unrecognised domain id",                   \
    "invalid grant reference",                  \
    "invalid mapping handle",                   \
    "invalid virtual address",                  \
    "invalid device address",                   \
    "no spare translation slot in the I/O MMU", \
    "permission denied",                        \
    "bad page",                                 \
    "copy arguments cross page boundary",       \
    "page address size too large",              \
    "operation not done; try again"             \
}

#endif /* __XEN_PUBLIC_GRANT_TABLE_H__ */
OpenPOWER on IntegriCloud