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