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1/* SPDX-License-Identifier: MIT */
2/******************************************************************************
3 * grant_table.h
4 *
5 * Interface for granting foreign access to page frames, and receiving
6 * page-ownership transfers.
7 *
8 * Copyright (c) 2004, K A Fraser
9 */
10
11#ifndef __XEN_PUBLIC_GRANT_TABLE_H__
12#define __XEN_PUBLIC_GRANT_TABLE_H__
13
14#include <xen/interface/xen.h>
15
16/***********************************
17 * GRANT TABLE REPRESENTATION
18 */
19
20/* Some rough guidelines on accessing and updating grant-table entries
21 * in a concurrency-safe manner. For more information, Linux contains a
22 * reference implementation for guest OSes (arch/xen/kernel/grant_table.c).
23 *
24 * NB. WMB is a no-op on current-generation x86 processors. However, a
25 * compiler barrier will still be required.
26 *
27 * Introducing a valid entry into the grant table:
28 * 1. Write ent->domid.
29 * 2. Write ent->frame:
30 * GTF_permit_access: Frame to which access is permitted.
31 * GTF_accept_transfer: Pseudo-phys frame slot being filled by new
32 * frame, or zero if none.
33 * 3. Write memory barrier (WMB).
34 * 4. Write ent->flags, inc. valid type.
35 *
36 * Invalidating an unused GTF_permit_access entry:
37 * 1. flags = ent->flags.
38 * 2. Observe that !(flags & (GTF_reading|GTF_writing)).
39 * 3. Check result of SMP-safe CMPXCHG(&ent->flags, flags, 0).
40 * NB. No need for WMB as reuse of entry is control-dependent on success of
41 * step 3, and all architectures guarantee ordering of ctrl-dep writes.
42 *
43 * Invalidating an in-use GTF_permit_access entry:
44 * This cannot be done directly. Request assistance from the domain controller
45 * which can set a timeout on the use of a grant entry and take necessary
46 * action. (NB. This is not yet implemented!).
47 *
48 * Invalidating an unused GTF_accept_transfer entry:
49 * 1. flags = ent->flags.
50 * 2. Observe that !(flags & GTF_transfer_committed). [*]
51 * 3. Check result of SMP-safe CMPXCHG(&ent->flags, flags, 0).
52 * NB. No need for WMB as reuse of entry is control-dependent on success of
53 * step 3, and all architectures guarantee ordering of ctrl-dep writes.
54 * [*] If GTF_transfer_committed is set then the grant entry is 'committed'.
55 * The guest must /not/ modify the grant entry until the address of the
56 * transferred frame is written. It is safe for the guest to spin waiting
57 * for this to occur (detect by observing GTF_transfer_completed in
58 * ent->flags).
59 *
60 * Invalidating a committed GTF_accept_transfer entry:
61 * 1. Wait for (ent->flags & GTF_transfer_completed).
62 *
63 * Changing a GTF_permit_access from writable to read-only:
64 * Use SMP-safe CMPXCHG to set GTF_readonly, while checking !GTF_writing.
65 *
66 * Changing a GTF_permit_access from read-only to writable:
67 * Use SMP-safe bit-setting instruction.
68 */
69
70/*
71 * Reference to a grant entry in a specified domain's grant table.
72 */
73typedef uint32_t grant_ref_t;
74
75/*
76 * A grant table comprises a packed array of grant entries in one or more
77 * page frames shared between Xen and a guest.
78 * [XEN]: This field is written by Xen and read by the sharing guest.
79 * [GST]: This field is written by the guest and read by Xen.
80 */
81
82/*
83 * Version 1 of the grant table entry structure is maintained purely
84 * for backwards compatibility. New guests should use version 2.
85 */
86struct grant_entry_v1 {
87 /* GTF_xxx: various type and flag information. [XEN,GST] */
88 uint16_t flags;
89 /* The domain being granted foreign privileges. [GST] */
90 domid_t domid;
91 /*
92 * GTF_permit_access: Frame that @domid is allowed to map and access. [GST]
93 * GTF_accept_transfer: Frame whose ownership transferred by @domid. [XEN]
94 */
95 uint32_t frame;
96};
97
98/*
99 * Type of grant entry.
100 * GTF_invalid: This grant entry grants no privileges.
101 * GTF_permit_access: Allow @domid to map/access @frame.
102 * GTF_accept_transfer: Allow @domid to transfer ownership of one page frame
103 * to this guest. Xen writes the page number to @frame.
104 * GTF_transitive: Allow @domid to transitively access a subrange of
105 * @trans_grant in @trans_domid. No mappings are allowed.
106 */
107#define GTF_invalid (0U<<0)
108#define GTF_permit_access (1U<<0)
109#define GTF_accept_transfer (2U<<0)
110#define GTF_transitive (3U<<0)
111#define GTF_type_mask (3U<<0)
112
113/*
114 * Subflags for GTF_permit_access.
115 * GTF_readonly: Restrict @domid to read-only mappings and accesses. [GST]
116 * GTF_reading: Grant entry is currently mapped for reading by @domid. [XEN]
117 * GTF_writing: Grant entry is currently mapped for writing by @domid. [XEN]
118 * GTF_sub_page: Grant access to only a subrange of the page. @domid
119 * will only be allowed to copy from the grant, and not
120 * map it. [GST]
121 */
122#define _GTF_readonly (2)
123#define GTF_readonly (1U<<_GTF_readonly)
124#define _GTF_reading (3)
125#define GTF_reading (1U<<_GTF_reading)
126#define _GTF_writing (4)
127#define GTF_writing (1U<<_GTF_writing)
128#define _GTF_sub_page (8)
129#define GTF_sub_page (1U<<_GTF_sub_page)
130
131/*
132 * Subflags for GTF_accept_transfer:
133 * GTF_transfer_committed: Xen sets this flag to indicate that it is committed
134 * to transferring ownership of a page frame. When a guest sees this flag
135 * it must /not/ modify the grant entry until GTF_transfer_completed is
136 * set by Xen.
137 * GTF_transfer_completed: It is safe for the guest to spin-wait on this flag
138 * after reading GTF_transfer_committed. Xen will always write the frame
139 * address, followed by ORing this flag, in a timely manner.
140 */
141#define _GTF_transfer_committed (2)
142#define GTF_transfer_committed (1U<<_GTF_transfer_committed)
143#define _GTF_transfer_completed (3)
144#define GTF_transfer_completed (1U<<_GTF_transfer_completed)
145
146/*
147 * Version 2 grant table entries. These fulfil the same role as
148 * version 1 entries, but can represent more complicated operations.
149 * Any given domain will have either a version 1 or a version 2 table,
150 * and every entry in the table will be the same version.
151 *
152 * The interface by which domains use grant references does not depend
153 * on the grant table version in use by the other domain.
154 */
155
156/*
157 * Version 1 and version 2 grant entries share a common prefix. The
158 * fields of the prefix are documented as part of struct
159 * grant_entry_v1.
160 */
161struct grant_entry_header {
162 uint16_t flags;
163 domid_t domid;
164};
165
166/*
167 * Version 2 of the grant entry structure, here is a union because three
168 * different types are suppotted: full_page, sub_page and transitive.
169 */
170union grant_entry_v2 {
171 struct grant_entry_header hdr;
172
173 /*
174 * This member is used for V1-style full page grants, where either:
175 *
176 * -- hdr.type is GTF_accept_transfer, or
177 * -- hdr.type is GTF_permit_access and GTF_sub_page is not set.
178 *
179 * In that case, the frame field has the same semantics as the
180 * field of the same name in the V1 entry structure.
181 */
182 struct {
183 struct grant_entry_header hdr;
184 uint32_t pad0;
185 uint64_t frame;
186 } full_page;
187
188 /*
189 * If the grant type is GTF_grant_access and GTF_sub_page is set,
190 * @domid is allowed to access bytes [@page_off,@page_off+@length)
191 * in frame @frame.
192 */
193 struct {
194 struct grant_entry_header hdr;
195 uint16_t page_off;
196 uint16_t length;
197 uint64_t frame;
198 } sub_page;
199
200 /*
201 * If the grant is GTF_transitive, @domid is allowed to use the
202 * grant @gref in domain @trans_domid, as if it was the local
203 * domain. Obviously, the transitive access must be compatible
204 * with the original grant.
205 */
206 struct {
207 struct grant_entry_header hdr;
208 domid_t trans_domid;
209 uint16_t pad0;
210 grant_ref_t gref;
211 } transitive;
212
213 uint32_t __spacer[4]; /* Pad to a power of two */
214};
215
216typedef uint16_t grant_status_t;
217
218/***********************************
219 * GRANT TABLE QUERIES AND USES
220 */
221
222/*
223 * Handle to track a mapping created via a grant reference.
224 */
225typedef uint32_t grant_handle_t;
226
227/*
228 * GNTTABOP_map_grant_ref: Map the grant entry (<dom>,<ref>) for access
229 * by devices and/or host CPUs. If successful, <handle> is a tracking number
230 * that must be presented later to destroy the mapping(s). On error, <handle>
231 * is a negative status code.
232 * NOTES:
233 * 1. If GNTMAP_device_map is specified then <dev_bus_addr> is the address
234 * via which I/O devices may access the granted frame.
235 * 2. If GNTMAP_host_map is specified then a mapping will be added at
236 * either a host virtual address in the current address space, or at
237 * a PTE at the specified machine address. The type of mapping to
238 * perform is selected through the GNTMAP_contains_pte flag, and the
239 * address is specified in <host_addr>.
240 * 3. Mappings should only be destroyed via GNTTABOP_unmap_grant_ref. If a
241 * host mapping is destroyed by other means then it is *NOT* guaranteed
242 * to be accounted to the correct grant reference!
243 */
244#define GNTTABOP_map_grant_ref 0
245struct gnttab_map_grant_ref {
246 /* IN parameters. */
247 uint64_t host_addr;
248 uint32_t flags; /* GNTMAP_* */
249 grant_ref_t ref;
250 domid_t dom;
251 /* OUT parameters. */
252 int16_t status; /* GNTST_* */
253 grant_handle_t handle;
254 uint64_t dev_bus_addr;
255};
256DEFINE_GUEST_HANDLE_STRUCT(gnttab_map_grant_ref);
257
258/*
259 * GNTTABOP_unmap_grant_ref: Destroy one or more grant-reference mappings
260 * tracked by <handle>. If <host_addr> or <dev_bus_addr> is zero, that
261 * field is ignored. If non-zero, they must refer to a device/host mapping
262 * that is tracked by <handle>
263 * NOTES:
264 * 1. The call may fail in an undefined manner if either mapping is not
265 * tracked by <handle>.
266 * 3. After executing a batch of unmaps, it is guaranteed that no stale
267 * mappings will remain in the device or host TLBs.
268 */
269#define GNTTABOP_unmap_grant_ref 1
270struct gnttab_unmap_grant_ref {
271 /* IN parameters. */
272 uint64_t host_addr;
273 uint64_t dev_bus_addr;
274 grant_handle_t handle;
275 /* OUT parameters. */
276 int16_t status; /* GNTST_* */
277};
278DEFINE_GUEST_HANDLE_STRUCT(gnttab_unmap_grant_ref);
279
280/*
281 * GNTTABOP_setup_table: Set up a grant table for <dom> comprising at least
282 * <nr_frames> pages. The frame addresses are written to the <frame_list>.
283 * Only <nr_frames> addresses are written, even if the table is larger.
284 * NOTES:
285 * 1. <dom> may be specified as DOMID_SELF.
286 * 2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF.
287 * 3. Xen may not support more than a single grant-table page per domain.
288 */
289#define GNTTABOP_setup_table 2
290struct gnttab_setup_table {
291 /* IN parameters. */
292 domid_t dom;
293 uint32_t nr_frames;
294 /* OUT parameters. */
295 int16_t status; /* GNTST_* */
296 GUEST_HANDLE(xen_pfn_t) frame_list;
297};
298DEFINE_GUEST_HANDLE_STRUCT(gnttab_setup_table);
299
300/*
301 * GNTTABOP_dump_table: Dump the contents of the grant table to the
302 * xen console. Debugging use only.
303 */
304#define GNTTABOP_dump_table 3
305struct gnttab_dump_table {
306 /* IN parameters. */
307 domid_t dom;
308 /* OUT parameters. */
309 int16_t status; /* GNTST_* */
310};
311DEFINE_GUEST_HANDLE_STRUCT(gnttab_dump_table);
312
313/*
314 * GNTTABOP_transfer_grant_ref: Transfer <frame> to a foreign domain. The
315 * foreign domain has previously registered its interest in the transfer via
316 * <domid, ref>.
317 *
318 * Note that, even if the transfer fails, the specified page no longer belongs
319 * to the calling domain *unless* the error is GNTST_bad_page.
320 */
321#define GNTTABOP_transfer 4
322struct gnttab_transfer {
323 /* IN parameters. */
324 xen_pfn_t mfn;
325 domid_t domid;
326 grant_ref_t ref;
327 /* OUT parameters. */
328 int16_t status;
329};
330DEFINE_GUEST_HANDLE_STRUCT(gnttab_transfer);
331
332/*
333 * GNTTABOP_copy: Hypervisor based copy
334 * source and destinations can be eithers MFNs or, for foreign domains,
335 * grant references. the foreign domain has to grant read/write access
336 * in its grant table.
337 *
338 * The flags specify what type source and destinations are (either MFN
339 * or grant reference).
340 *
341 * Note that this can also be used to copy data between two domains
342 * via a third party if the source and destination domains had previously
343 * grant appropriate access to their pages to the third party.
344 *
345 * source_offset specifies an offset in the source frame, dest_offset
346 * the offset in the target frame and len specifies the number of
347 * bytes to be copied.
348 */
349
350#define _GNTCOPY_source_gref (0)
351#define GNTCOPY_source_gref (1<<_GNTCOPY_source_gref)
352#define _GNTCOPY_dest_gref (1)
353#define GNTCOPY_dest_gref (1<<_GNTCOPY_dest_gref)
354
355#define GNTTABOP_copy 5
356struct gnttab_copy {
357 /* IN parameters. */
358 struct {
359 union {
360 grant_ref_t ref;
361 xen_pfn_t gmfn;
362 } u;
363 domid_t domid;
364 uint16_t offset;
365 } source, dest;
366 uint16_t len;
367 uint16_t flags; /* GNTCOPY_* */
368 /* OUT parameters. */
369 int16_t status;
370};
371DEFINE_GUEST_HANDLE_STRUCT(gnttab_copy);
372
373/*
374 * GNTTABOP_query_size: Query the current and maximum sizes of the shared
375 * grant table.
376 * NOTES:
377 * 1. <dom> may be specified as DOMID_SELF.
378 * 2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF.
379 */
380#define GNTTABOP_query_size 6
381struct gnttab_query_size {
382 /* IN parameters. */
383 domid_t dom;
384 /* OUT parameters. */
385 uint32_t nr_frames;
386 uint32_t max_nr_frames;
387 int16_t status; /* GNTST_* */
388};
389DEFINE_GUEST_HANDLE_STRUCT(gnttab_query_size);
390
391/*
392 * GNTTABOP_unmap_and_replace: Destroy one or more grant-reference mappings
393 * tracked by <handle> but atomically replace the page table entry with one
394 * pointing to the machine address under <new_addr>. <new_addr> will be
395 * redirected to the null entry.
396 * NOTES:
397 * 1. The call may fail in an undefined manner if either mapping is not
398 * tracked by <handle>.
399 * 2. After executing a batch of unmaps, it is guaranteed that no stale
400 * mappings will remain in the device or host TLBs.
401 */
402#define GNTTABOP_unmap_and_replace 7
403struct gnttab_unmap_and_replace {
404 /* IN parameters. */
405 uint64_t host_addr;
406 uint64_t new_addr;
407 grant_handle_t handle;
408 /* OUT parameters. */
409 int16_t status; /* GNTST_* */
410};
411DEFINE_GUEST_HANDLE_STRUCT(gnttab_unmap_and_replace);
412
413/*
414 * GNTTABOP_set_version: Request a particular version of the grant
415 * table shared table structure. This operation can only be performed
416 * once in any given domain. It must be performed before any grants
417 * are activated; otherwise, the domain will be stuck with version 1.
418 * The only defined versions are 1 and 2.
419 */
420#define GNTTABOP_set_version 8
421struct gnttab_set_version {
422 /* IN parameters */
423 uint32_t version;
424};
425DEFINE_GUEST_HANDLE_STRUCT(gnttab_set_version);
426
427/*
428 * GNTTABOP_get_status_frames: Get the list of frames used to store grant
429 * status for <dom>. In grant format version 2, the status is separated
430 * from the other shared grant fields to allow more efficient synchronization
431 * using barriers instead of atomic cmpexch operations.
432 * <nr_frames> specify the size of vector <frame_list>.
433 * The frame addresses are returned in the <frame_list>.
434 * Only <nr_frames> addresses are returned, even if the table is larger.
435 * NOTES:
436 * 1. <dom> may be specified as DOMID_SELF.
437 * 2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF.
438 */
439#define GNTTABOP_get_status_frames 9
440struct gnttab_get_status_frames {
441 /* IN parameters. */
442 uint32_t nr_frames;
443 domid_t dom;
444 /* OUT parameters. */
445 int16_t status; /* GNTST_* */
446 GUEST_HANDLE(uint64_t) frame_list;
447};
448DEFINE_GUEST_HANDLE_STRUCT(gnttab_get_status_frames);
449
450/*
451 * GNTTABOP_get_version: Get the grant table version which is in
452 * effect for domain <dom>.
453 */
454#define GNTTABOP_get_version 10
455struct gnttab_get_version {
456 /* IN parameters */
457 domid_t dom;
458 uint16_t pad;
459 /* OUT parameters */
460 uint32_t version;
461};
462DEFINE_GUEST_HANDLE_STRUCT(gnttab_get_version);
463
464/*
465 * Issue one or more cache maintenance operations on a portion of a
466 * page granted to the calling domain by a foreign domain.
467 */
468#define GNTTABOP_cache_flush 12
469struct gnttab_cache_flush {
470 union {
471 uint64_t dev_bus_addr;
472 grant_ref_t ref;
473 } a;
474 uint16_t offset; /* offset from start of grant */
475 uint16_t length; /* size within the grant */
476#define GNTTAB_CACHE_CLEAN (1<<0)
477#define GNTTAB_CACHE_INVAL (1<<1)
478#define GNTTAB_CACHE_SOURCE_GREF (1<<31)
479 uint32_t op;
480};
481DEFINE_GUEST_HANDLE_STRUCT(gnttab_cache_flush);
482
483/*
484 * Bitfield values for update_pin_status.flags.
485 */
486 /* Map the grant entry for access by I/O devices. */
487#define _GNTMAP_device_map (0)
488#define GNTMAP_device_map (1<<_GNTMAP_device_map)
489 /* Map the grant entry for access by host CPUs. */
490#define _GNTMAP_host_map (1)
491#define GNTMAP_host_map (1<<_GNTMAP_host_map)
492 /* Accesses to the granted frame will be restricted to read-only access. */
493#define _GNTMAP_readonly (2)
494#define GNTMAP_readonly (1<<_GNTMAP_readonly)
495 /*
496 * GNTMAP_host_map subflag:
497 * 0 => The host mapping is usable only by the guest OS.
498 * 1 => The host mapping is usable by guest OS + current application.
499 */
500#define _GNTMAP_application_map (3)
501#define GNTMAP_application_map (1<<_GNTMAP_application_map)
502
503 /*
504 * GNTMAP_contains_pte subflag:
505 * 0 => This map request contains a host virtual address.
506 * 1 => This map request contains the machine addess of the PTE to update.
507 */
508#define _GNTMAP_contains_pte (4)
509#define GNTMAP_contains_pte (1<<_GNTMAP_contains_pte)
510
511/*
512 * Bits to be placed in guest kernel available PTE bits (architecture
513 * dependent; only supported when XENFEAT_gnttab_map_avail_bits is set).
514 */
515#define _GNTMAP_guest_avail0 (16)
516#define GNTMAP_guest_avail_mask ((uint32_t)~0 << _GNTMAP_guest_avail0)
517
518/*
519 * Values for error status returns. All errors are -ve.
520 */
521#define GNTST_okay (0) /* Normal return. */
522#define GNTST_general_error (-1) /* General undefined error. */
523#define GNTST_bad_domain (-2) /* Unrecognsed domain id. */
524#define GNTST_bad_gntref (-3) /* Unrecognised or inappropriate gntref. */
525#define GNTST_bad_handle (-4) /* Unrecognised or inappropriate handle. */
526#define GNTST_bad_virt_addr (-5) /* Inappropriate virtual address to map. */
527#define GNTST_bad_dev_addr (-6) /* Inappropriate device address to unmap.*/
528#define GNTST_no_device_space (-7) /* Out of space in I/O MMU. */
529#define GNTST_permission_denied (-8) /* Not enough privilege for operation. */
530#define GNTST_bad_page (-9) /* Specified page was invalid for op. */
531#define GNTST_bad_copy_arg (-10) /* copy arguments cross page boundary. */
532#define GNTST_address_too_big (-11) /* transfer page address too large. */
533#define GNTST_eagain (-12) /* Operation not done; try again. */
534
535#define GNTTABOP_error_msgs { \
536 "okay", \
537 "undefined error", \
538 "unrecognised domain id", \
539 "invalid grant reference", \
540 "invalid mapping handle", \
541 "invalid virtual address", \
542 "invalid device address", \
543 "no spare translation slot in the I/O MMU", \
544 "permission denied", \
545 "bad page", \
546 "copy arguments cross page boundary", \
547 "page address size too large", \
548 "operation not done; try again" \
549}
550
551#endif /* __XEN_PUBLIC_GRANT_TABLE_H__ */