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 32/*********************************** 33 * GRANT TABLE REPRESENTATION 34 */ 35 36/* Some rough guidelines on accessing and updating grant-table entries 37 * in a concurrency-safe manner. For more information, Linux contains a 38 * reference implementation for guest OSes (arch/xen/kernel/grant_table.c). 39 * 40 * NB. WMB is a no-op on current-generation x86 processors. However, a 41 * compiler barrier will still be required. 42 * 43 * Introducing a valid entry into the grant table: 44 * 1. Write ent->domid. 45 * 2. Write ent->frame: 46 * GTF_permit_access: Frame to which access is permitted. 47 * GTF_accept_transfer: Pseudo-phys frame slot being filled by new 48 * frame, or zero if none. 49 * 3. Write memory barrier (WMB). 50 * 4. Write ent->flags, inc. valid type. 51 * 52 * Invalidating an unused GTF_permit_access entry: 53 * 1. flags = ent->flags. 54 * 2. Observe that !(flags & (GTF_reading|GTF_writing)). 55 * 3. Check result of SMP-safe CMPXCHG(&ent->flags, flags, 0). 56 * NB. No need for WMB as reuse of entry is control-dependent on success of 57 * step 3, and all architectures guarantee ordering of ctrl-dep writes. 58 * 59 * Invalidating an in-use GTF_permit_access entry: 60 * This cannot be done directly. Request assistance from the domain controller 61 * which can set a timeout on the use of a grant entry and take necessary 62 * action. (NB. This is not yet implemented!). 63 * 64 * Invalidating an unused GTF_accept_transfer entry: 65 * 1. flags = ent->flags. 66 * 2. Observe that !(flags & GTF_transfer_committed). [*] 67 * 3. Check result of SMP-safe CMPXCHG(&ent->flags, flags, 0). 68 * NB. No need for WMB as reuse of entry is control-dependent on success of 69 * step 3, and all architectures guarantee ordering of ctrl-dep writes. 70 * [*] If GTF_transfer_committed is set then the grant entry is 'committed'. 71 * The guest must /not/ modify the grant entry until the address of the 72 * transferred frame is written. It is safe for the guest to spin waiting 73 * for this to occur (detect by observing GTF_transfer_completed in 74 * ent->flags). 75 * 76 * Invalidating a committed GTF_accept_transfer entry: 77 * 1. Wait for (ent->flags & GTF_transfer_completed). 78 * 79 * Changing a GTF_permit_access from writable to read-only: 80 * Use SMP-safe CMPXCHG to set GTF_readonly, while checking !GTF_writing. 81 * 82 * Changing a GTF_permit_access from read-only to writable: 83 * Use SMP-safe bit-setting instruction. 84 */ 85 86/* 87 * A grant table comprises a packed array of grant entries in one or more 88 * page frames shared between Xen and a guest. 89 * [XEN]: This field is written by Xen and read by the sharing guest. 90 * [GST]: This field is written by the guest and read by Xen. 91 */ 92struct grant_entry { 93 /* GTF_xxx: various type and flag information. [XEN,GST] */ 94 uint16_t flags; 95 /* The domain being granted foreign privileges. [GST] */ 96 domid_t domid; 97 /* 98 * GTF_permit_access: Frame that @domid is allowed to map and access. [GST] 99 * GTF_accept_transfer: Frame whose ownership transferred by @domid. [XEN] 100 */ 101 uint32_t frame; 102}; 103typedef struct grant_entry grant_entry_t; 104 105/* 106 * Type of grant entry. 107 * GTF_invalid: This grant entry grants no privileges. 108 * GTF_permit_access: Allow @domid to map/access @frame. 109 * GTF_accept_transfer: Allow @domid to transfer ownership of one page frame 110 * to this guest. Xen writes the page number to @frame. 111 */ 112#define GTF_invalid (0U<<0) 113#define GTF_permit_access (1U<<0) 114#define GTF_accept_transfer (2U<<0) 115#define GTF_type_mask (3U<<0) 116 117/* 118 * Subflags for GTF_permit_access. 119 * GTF_readonly: Restrict @domid to read-only mappings and accesses. [GST] 120 * GTF_reading: Grant entry is currently mapped for reading by @domid. [XEN] 121 * GTF_writing: Grant entry is currently mapped for writing by @domid. [XEN] 122 * GTF_PAT, GTF_PWT, GTF_PCD: (x86) cache attribute flags for the grant [GST] 123 */ 124#define _GTF_readonly (2) 125#define GTF_readonly (1U<<_GTF_readonly) 126#define _GTF_reading (3) 127#define GTF_reading (1U<<_GTF_reading) 128#define _GTF_writing (4) 129#define GTF_writing (1U<<_GTF_writing) 130#define _GTF_PWT (5) 131#define GTF_PWT (1U<<_GTF_PWT) 132#define _GTF_PCD (6) 133#define GTF_PCD (1U<<_GTF_PCD) 134#define _GTF_PAT (7) 135#define GTF_PAT (1U<<_GTF_PAT) 136 137/* 138 * Subflags for GTF_accept_transfer: 139 * GTF_transfer_committed: Xen sets this flag to indicate that it is committed 140 * to transferring ownership of a page frame. When a guest sees this flag 141 * it must /not/ modify the grant entry until GTF_transfer_completed is 142 * set by Xen. 143 * GTF_transfer_completed: It is safe for the guest to spin-wait on this flag 144 * after reading GTF_transfer_committed. Xen will always write the frame 145 * address, followed by ORing this flag, in a timely manner. 146 */ 147#define _GTF_transfer_committed (2) 148#define GTF_transfer_committed (1U<<_GTF_transfer_committed) 149#define _GTF_transfer_completed (3) 150#define GTF_transfer_completed (1U<<_GTF_transfer_completed) 151 152 153/*********************************** 154 * GRANT TABLE QUERIES AND USES 155 */ 156 157/* 158 * Reference to a grant entry in a specified domain's grant table. 159 */ 160typedef uint32_t grant_ref_t; 161 162#define GRANT_REF_INVALID 0xffffffff 163 164/* 165 * Handle to track a mapping created via a grant reference. 166 */ 167typedef uint32_t grant_handle_t; 168 169/* 170 * GNTTABOP_map_grant_ref: Map the grant entry (<dom>,<ref>) for access 171 * by devices and/or host CPUs. If successful, <handle> is a tracking number 172 * that must be presented later to destroy the mapping(s). On error, <handle> 173 * is a negative status code. 174 * NOTES: 175 * 1. If GNTMAP_device_map is specified then <dev_bus_addr> is the address 176 * via which I/O devices may access the granted frame. 177 * 2. If GNTMAP_host_map is specified then a mapping will be added at 178 * either a host virtual address in the current address space, or at 179 * a PTE at the specified machine address. The type of mapping to 180 * perform is selected through the GNTMAP_contains_pte flag, and the 181 * address is specified in <host_addr>. 182 * 3. Mappings should only be destroyed via GNTTABOP_unmap_grant_ref. If a 183 * host mapping is destroyed by other means then it is *NOT* guaranteed 184 * to be accounted to the correct grant reference! 185 */ 186#define GNTTABOP_map_grant_ref 0 187struct gnttab_map_grant_ref { 188 /* IN parameters. */ 189 uint64_t host_addr; 190 uint32_t flags; /* GNTMAP_* */ 191 grant_ref_t ref; 192 domid_t dom; 193 /* OUT parameters. */ 194 int16_t status; /* GNTST_* */ 195 grant_handle_t handle; 196 uint64_t dev_bus_addr; 197}; 198typedef struct gnttab_map_grant_ref gnttab_map_grant_ref_t; 199DEFINE_XEN_GUEST_HANDLE(gnttab_map_grant_ref_t); 200 201/* 202 * GNTTABOP_unmap_grant_ref: Destroy one or more grant-reference mappings 203 * tracked by <handle>. If <host_addr> or <dev_bus_addr> is zero, that 204 * field is ignored. If non-zero, they must refer to a device/host mapping 205 * that is tracked by <handle> 206 * NOTES: 207 * 1. The call may fail in an undefined manner if either mapping is not 208 * tracked by <handle>. 209 * 3. After executing a batch of unmaps, it is guaranteed that no stale 210 * mappings will remain in the device or host TLBs. 211 */ 212#define GNTTABOP_unmap_grant_ref 1 213struct gnttab_unmap_grant_ref { 214 /* IN parameters. */ 215 uint64_t host_addr; 216 uint64_t dev_bus_addr; 217 grant_handle_t handle; 218 /* OUT parameters. */ 219 int16_t status; /* GNTST_* */ 220}; 221typedef struct gnttab_unmap_grant_ref gnttab_unmap_grant_ref_t; 222DEFINE_XEN_GUEST_HANDLE(gnttab_unmap_grant_ref_t); 223 224/* 225 * GNTTABOP_setup_table: Set up a grant table for <dom> comprising at least 226 * <nr_frames> pages. The frame addresses are written to the <frame_list>. 227 * Only <nr_frames> addresses are written, even if the table is larger. 228 * NOTES: 229 * 1. <dom> may be specified as DOMID_SELF. 230 * 2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF. 231 * 3. Xen may not support more than a single grant-table page per domain. 232 */ 233#define GNTTABOP_setup_table 2 234struct gnttab_setup_table { 235 /* IN parameters. */ 236 domid_t dom; 237 uint32_t nr_frames; 238 /* OUT parameters. */ 239 int16_t status; /* GNTST_* */ 240 XEN_GUEST_HANDLE(ulong) frame_list; 241}; 242typedef struct gnttab_setup_table gnttab_setup_table_t; 243DEFINE_XEN_GUEST_HANDLE(gnttab_setup_table_t); 244 245/* 246 * GNTTABOP_dump_table: Dump the contents of the grant table to the 247 * xen console. Debugging use only. 248 */ 249#define GNTTABOP_dump_table 3 250struct gnttab_dump_table { 251 /* IN parameters. */ 252 domid_t dom; 253 /* OUT parameters. */ 254 int16_t status; /* GNTST_* */ 255}; 256typedef struct gnttab_dump_table gnttab_dump_table_t; 257DEFINE_XEN_GUEST_HANDLE(gnttab_dump_table_t); 258 259/* 260 * GNTTABOP_transfer_grant_ref: Transfer <frame> to a foreign domain. The 261 * foreign domain has previously registered its interest in the transfer via 262 * <domid, ref>. 263 * 264 * Note that, even if the transfer fails, the specified page no longer belongs 265 * to the calling domain *unless* the error is GNTST_bad_page. 266 */ 267#define GNTTABOP_transfer 4 268struct gnttab_transfer { 269 /* IN parameters. */ 270 xen_pfn_t mfn; 271 domid_t domid; 272 grant_ref_t ref; 273 /* OUT parameters. */ 274 int16_t status; 275}; 276typedef struct gnttab_transfer gnttab_transfer_t; 277DEFINE_XEN_GUEST_HANDLE(gnttab_transfer_t); 278 279 280/* 281 * GNTTABOP_copy: Hypervisor based copy 282 * source and destinations can be eithers MFNs or, for foreign domains, 283 * grant references. the foreign domain has to grant read/write access 284 * in its grant table. 285 * 286 * The flags specify what type source and destinations are (either MFN 287 * or grant reference). 288 * 289 * Note that this can also be used to copy data between two domains 290 * via a third party if the source and destination domains had previously 291 * grant appropriate access to their pages to the third party. 292 * 293 * source_offset specifies an offset in the source frame, dest_offset 294 * the offset in the target frame and len specifies the number of 295 * bytes to be copied. 296 */ 297 298#define _GNTCOPY_source_gref (0) 299#define GNTCOPY_source_gref (1<<_GNTCOPY_source_gref) 300#define _GNTCOPY_dest_gref (1) 301#define GNTCOPY_dest_gref (1<<_GNTCOPY_dest_gref) 302 303#define GNTTABOP_copy 5 304typedef struct gnttab_copy { 305 /* IN parameters. */ 306 struct { 307 union { 308 grant_ref_t ref; 309 xen_pfn_t gmfn; 310 } u; 311 domid_t domid; 312 uint16_t offset; 313 } source, dest; 314 uint16_t len; 315 uint16_t flags; /* GNTCOPY_* */ 316 /* OUT parameters. */ 317 int16_t status; 318} gnttab_copy_t; 319DEFINE_XEN_GUEST_HANDLE(gnttab_copy_t); 320 321/* 322 * GNTTABOP_query_size: Query the current and maximum sizes of the shared 323 * grant table. 324 * NOTES: 325 * 1. <dom> may be specified as DOMID_SELF. 326 * 2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF. 327 */ 328#define GNTTABOP_query_size 6 329struct gnttab_query_size { 330 /* IN parameters. */ 331 domid_t dom; 332 /* OUT parameters. */ 333 uint32_t nr_frames; 334 uint32_t max_nr_frames; 335 int16_t status; /* GNTST_* */ 336}; 337typedef struct gnttab_query_size gnttab_query_size_t; 338DEFINE_XEN_GUEST_HANDLE(gnttab_query_size_t); 339 340/* 341 * GNTTABOP_unmap_and_replace: Destroy one or more grant-reference mappings 342 * tracked by <handle> but atomically replace the page table entry with one 343 * pointing to the machine address under <new_addr>. <new_addr> will be 344 * redirected to the null entry. 345 * NOTES: 346 * 1. The call may fail in an undefined manner if either mapping is not 347 * tracked by <handle>. 348 * 2. After executing a batch of unmaps, it is guaranteed that no stale 349 * mappings will remain in the device or host TLBs. 350 */ 351#define GNTTABOP_unmap_and_replace 7 352struct gnttab_unmap_and_replace { 353 /* IN parameters. */ 354 uint64_t host_addr; 355 uint64_t new_addr; 356 grant_handle_t handle; 357 /* OUT parameters. */ 358 int16_t status; /* GNTST_* */ 359}; 360typedef struct gnttab_unmap_and_replace gnttab_unmap_and_replace_t; 361DEFINE_XEN_GUEST_HANDLE(gnttab_unmap_and_replace_t); 362 363 364/* 365 * Bitfield values for update_pin_status.flags. 366 */ 367 /* Map the grant entry for access by I/O devices. */ 368#define _GNTMAP_device_map (0) 369#define GNTMAP_device_map (1<<_GNTMAP_device_map) 370 /* Map the grant entry for access by host CPUs. */ 371#define _GNTMAP_host_map (1) 372#define GNTMAP_host_map (1<<_GNTMAP_host_map) 373 /* Accesses to the granted frame will be restricted to read-only access. */ 374#define _GNTMAP_readonly (2) 375#define GNTMAP_readonly (1<<_GNTMAP_readonly) 376 /* 377 * GNTMAP_host_map subflag: 378 * 0 => The host mapping is usable only by the guest OS. 379 * 1 => The host mapping is usable by guest OS + current application. 380 */ 381#define _GNTMAP_application_map (3) 382#define GNTMAP_application_map (1<<_GNTMAP_application_map) 383 384 /* 385 * GNTMAP_contains_pte subflag: 386 * 0 => This map request contains a host virtual address. 387 * 1 => This map request contains the machine addess of the PTE to update. 388 */ 389#define _GNTMAP_contains_pte (4) 390#define GNTMAP_contains_pte (1<<_GNTMAP_contains_pte) 391 392/* 393 * Values for error status returns. All errors are -ve. 394 */ 395#define GNTST_okay (0) /* Normal return. */ 396#define GNTST_general_error (-1) /* General undefined error. */ 397#define GNTST_bad_domain (-2) /* Unrecognsed domain id. */ 398#define GNTST_bad_gntref (-3) /* Unrecognised or inappropriate gntref. */ 399#define GNTST_bad_handle (-4) /* Unrecognised or inappropriate handle. */ 400#define GNTST_bad_virt_addr (-5) /* Inappropriate virtual address to map. */ 401#define GNTST_bad_dev_addr (-6) /* Inappropriate device address to unmap.*/ 402#define GNTST_no_device_space (-7) /* Out of space in I/O MMU. */ 403#define GNTST_permission_denied (-8) /* Not enough privilege for operation. */ 404#define GNTST_bad_page (-9) /* Specified page was invalid for op. */ 405#define GNTST_bad_copy_arg (-10) /* copy arguments cross page boundary. */ 406#define GNTST_address_too_big (-11) /* transfer page address too large. */ 407 408#define GNTTABOP_error_msgs { \ 409 "okay", \ 410 "undefined error", \ 411 "unrecognised domain id", \ 412 "invalid grant reference", \ 413 "invalid mapping handle", \ 414 "invalid virtual address", \ 415 "invalid device address", \ 416 "no spare translation slot in the I/O MMU", \ 417 "permission denied", \ 418 "bad page", \ 419 "copy arguments cross page boundary", \ 420 "page address size too large" \ 421} 422 423#endif /* __XEN_PUBLIC_GRANT_TABLE_H__ */ 424 425/* 426 * Local variables: 427 * mode: C 428 * c-set-style: "BSD" 429 * c-basic-offset: 4 430 * tab-width: 4 431 * indent-tabs-mode: nil 432 * End: 433 */ 434