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 */ 92 struct 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 }; 103 104 /* 105 * Type of grant entry. 106 * GTF_invalid: This grant entry grants no privileges. 107 * GTF_permit_access: Allow @domid to map/access @frame. 108 * GTF_accept_transfer: Allow @domid to transfer ownership of one page frame 109 * to this guest. Xen writes the page number to @frame. 110 */ 111 #define GTF_invalid (0U<<0) 112 #define GTF_permit_access (1U<<0) 113 #define GTF_accept_transfer (2U<<0) 114 #define GTF_type_mask (3U<<0) 115 116 /* 117 * Subflags for GTF_permit_access. 118 * GTF_readonly: Restrict @domid to read-only mappings and accesses. [GST] 119 * GTF_reading: Grant entry is currently mapped for reading by @domid. [XEN] 120 * GTF_writing: Grant entry is currently mapped for writing by @domid. [XEN] 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) 128 129 /* 130 * Subflags for GTF_accept_transfer: 131 * GTF_transfer_committed: Xen sets this flag to indicate that it is committed 132 * to transferring ownership of a page frame. When a guest sees this flag 133 * it must /not/ modify the grant entry until GTF_transfer_completed is 134 * set by Xen. 135 * GTF_transfer_completed: It is safe for the guest to spin-wait on this flag 136 * after reading GTF_transfer_committed. Xen will always write the frame 137 * address, followed by ORing this flag, in a timely manner. 138 */ 139 #define _GTF_transfer_committed (2) 140 #define GTF_transfer_committed (1U<<_GTF_transfer_committed) 141 #define _GTF_transfer_completed (3) 142 #define GTF_transfer_completed (1U<<_GTF_transfer_completed) 143 144 145 /*********************************** 146 * GRANT TABLE QUERIES AND USES 147 */ 148 149 /* 150 * Reference to a grant entry in a specified domain's grant table. 151 */ 152 typedef uint32_t grant_ref_t; 153 154 /* 155 * Handle to track a mapping created via a grant reference. 156 */ 157 typedef uint32_t grant_handle_t; 158 159 /* 160 * GNTTABOP_map_grant_ref: Map the grant entry (<dom>,<ref>) for access 161 * by devices and/or host CPUs. If successful, <handle> is a tracking number 162 * that must be presented later to destroy the mapping(s). On error, <handle> 163 * is a negative status code. 164 * NOTES: 165 * 1. If GNTMAP_device_map is specified then <dev_bus_addr> is the address 166 * via which I/O devices may access the granted frame. 167 * 2. If GNTMAP_host_map is specified then a mapping will be added at 168 * either a host virtual address in the current address space, or at 169 * a PTE at the specified machine address. The type of mapping to 170 * perform is selected through the GNTMAP_contains_pte flag, and the 171 * address is specified in <host_addr>. 172 * 3. Mappings should only be destroyed via GNTTABOP_unmap_grant_ref. If a 173 * host mapping is destroyed by other means then it is *NOT* guaranteed 174 * to be accounted to the correct grant reference! 175 */ 176 #define GNTTABOP_map_grant_ref 0 177 struct gnttab_map_grant_ref { 178 /* IN parameters. */ 179 uint64_t host_addr; 180 uint32_t flags; /* GNTMAP_* */ 181 grant_ref_t ref; 182 domid_t dom; 183 /* OUT parameters. */ 184 int16_t status; /* GNTST_* */ 185 grant_handle_t handle; 186 uint64_t dev_bus_addr; 187 }; 188 DEFINE_GUEST_HANDLE_STRUCT(gnttab_map_grant_ref); 189 190 /* 191 * GNTTABOP_unmap_grant_ref: Destroy one or more grant-reference mappings 192 * tracked by <handle>. If <host_addr> or <dev_bus_addr> is zero, that 193 * field is ignored. If non-zero, they must refer to a device/host mapping 194 * that is tracked by <handle> 195 * NOTES: 196 * 1. The call may fail in an undefined manner if either mapping is not 197 * tracked by <handle>. 198 * 3. After executing a batch of unmaps, it is guaranteed that no stale 199 * mappings will remain in the device or host TLBs. 200 */ 201 #define GNTTABOP_unmap_grant_ref 1 202 struct gnttab_unmap_grant_ref { 203 /* IN parameters. */ 204 uint64_t host_addr; 205 uint64_t dev_bus_addr; 206 grant_handle_t handle; 207 /* OUT parameters. */ 208 int16_t status; /* GNTST_* */ 209 }; 210 DEFINE_GUEST_HANDLE_STRUCT(gnttab_unmap_grant_ref); 211 212 /* 213 * GNTTABOP_setup_table: Set up a grant table for <dom> comprising at least 214 * <nr_frames> pages. The frame addresses are written to the <frame_list>. 215 * Only <nr_frames> addresses are written, even if the table is larger. 216 * NOTES: 217 * 1. <dom> may be specified as DOMID_SELF. 218 * 2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF. 219 * 3. Xen may not support more than a single grant-table page per domain. 220 */ 221 #define GNTTABOP_setup_table 2 222 struct gnttab_setup_table { 223 /* IN parameters. */ 224 domid_t dom; 225 uint32_t nr_frames; 226 /* OUT parameters. */ 227 int16_t status; /* GNTST_* */ 228 GUEST_HANDLE(ulong) frame_list; 229 }; 230 DEFINE_GUEST_HANDLE_STRUCT(gnttab_setup_table); 231 232 /* 233 * GNTTABOP_dump_table: Dump the contents of the grant table to the 234 * xen console. Debugging use only. 235 */ 236 #define GNTTABOP_dump_table 3 237 struct gnttab_dump_table { 238 /* IN parameters. */ 239 domid_t dom; 240 /* OUT parameters. */ 241 int16_t status; /* GNTST_* */ 242 }; 243 DEFINE_GUEST_HANDLE_STRUCT(gnttab_dump_table); 244 245 /* 246 * GNTTABOP_transfer_grant_ref: Transfer <frame> to a foreign domain. The 247 * foreign domain has previously registered its interest in the transfer via 248 * <domid, ref>. 249 * 250 * Note that, even if the transfer fails, the specified page no longer belongs 251 * to the calling domain *unless* the error is GNTST_bad_page. 252 */ 253 #define GNTTABOP_transfer 4 254 struct gnttab_transfer { 255 /* IN parameters. */ 256 unsigned long mfn; 257 domid_t domid; 258 grant_ref_t ref; 259 /* OUT parameters. */ 260 int16_t status; 261 }; 262 DEFINE_GUEST_HANDLE_STRUCT(gnttab_transfer); 263 264 /* 265 * GNTTABOP_copy: Hypervisor based copy 266 * source and destinations can be eithers MFNs or, for foreign domains, 267 * grant references. the foreign domain has to grant read/write access 268 * in its grant table. 269 * 270 * The flags specify what type source and destinations are (either MFN 271 * or grant reference). 272 * 273 * Note that this can also be used to copy data between two domains 274 * via a third party if the source and destination domains had previously 275 * grant appropriate access to their pages to the third party. 276 * 277 * source_offset specifies an offset in the source frame, dest_offset 278 * the offset in the target frame and len specifies the number of 279 * bytes to be copied. 280 */ 281 282 #define _GNTCOPY_source_gref (0) 283 #define GNTCOPY_source_gref (1<<_GNTCOPY_source_gref) 284 #define _GNTCOPY_dest_gref (1) 285 #define GNTCOPY_dest_gref (1<<_GNTCOPY_dest_gref) 286 287 #define GNTTABOP_copy 5 288 struct gnttab_copy { 289 /* IN parameters. */ 290 struct { 291 union { 292 grant_ref_t ref; 293 unsigned long gmfn; 294 } u; 295 domid_t domid; 296 uint16_t offset; 297 } source, dest; 298 uint16_t len; 299 uint16_t flags; /* GNTCOPY_* */ 300 /* OUT parameters. */ 301 int16_t status; 302 }; 303 DEFINE_GUEST_HANDLE_STRUCT(gnttab_copy); 304 305 /* 306 * GNTTABOP_query_size: Query the current and maximum sizes of the shared 307 * grant table. 308 * NOTES: 309 * 1. <dom> may be specified as DOMID_SELF. 310 * 2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF. 311 */ 312 #define GNTTABOP_query_size 6 313 struct gnttab_query_size { 314 /* IN parameters. */ 315 domid_t dom; 316 /* OUT parameters. */ 317 uint32_t nr_frames; 318 uint32_t max_nr_frames; 319 int16_t status; /* GNTST_* */ 320 }; 321 DEFINE_GUEST_HANDLE_STRUCT(gnttab_query_size); 322 323 /* 324 * Bitfield values for update_pin_status.flags. 325 */ 326 /* Map the grant entry for access by I/O devices. */ 327 #define _GNTMAP_device_map (0) 328 #define GNTMAP_device_map (1<<_GNTMAP_device_map) 329 /* Map the grant entry for access by host CPUs. */ 330 #define _GNTMAP_host_map (1) 331 #define GNTMAP_host_map (1<<_GNTMAP_host_map) 332 /* Accesses to the granted frame will be restricted to read-only access. */ 333 #define _GNTMAP_readonly (2) 334 #define GNTMAP_readonly (1<<_GNTMAP_readonly) 335 /* 336 * GNTMAP_host_map subflag: 337 * 0 => The host mapping is usable only by the guest OS. 338 * 1 => The host mapping is usable by guest OS + current application. 339 */ 340 #define _GNTMAP_application_map (3) 341 #define GNTMAP_application_map (1<<_GNTMAP_application_map) 342 343 /* 344 * GNTMAP_contains_pte subflag: 345 * 0 => This map request contains a host virtual address. 346 * 1 => This map request contains the machine addess of the PTE to update. 347 */ 348 #define _GNTMAP_contains_pte (4) 349 #define GNTMAP_contains_pte (1<<_GNTMAP_contains_pte) 350 351 /* 352 * Values for error status returns. All errors are -ve. 353 */ 354 #define GNTST_okay (0) /* Normal return. */ 355 #define GNTST_general_error (-1) /* General undefined error. */ 356 #define GNTST_bad_domain (-2) /* Unrecognsed domain id. */ 357 #define GNTST_bad_gntref (-3) /* Unrecognised or inappropriate gntref. */ 358 #define GNTST_bad_handle (-4) /* Unrecognised or inappropriate handle. */ 359 #define GNTST_bad_virt_addr (-5) /* Inappropriate virtual address to map. */ 360 #define GNTST_bad_dev_addr (-6) /* Inappropriate device address to unmap.*/ 361 #define GNTST_no_device_space (-7) /* Out of space in I/O MMU. */ 362 #define GNTST_permission_denied (-8) /* Not enough privilege for operation. */ 363 #define GNTST_bad_page (-9) /* Specified page was invalid for op. */ 364 #define GNTST_bad_copy_arg (-10) /* copy arguments cross page boundary */ 365 366 #define GNTTABOP_error_msgs { \ 367 "okay", \ 368 "undefined error", \ 369 "unrecognised domain id", \ 370 "invalid grant reference", \ 371 "invalid mapping handle", \ 372 "invalid virtual address", \ 373 "invalid device address", \ 374 "no spare translation slot in the I/O MMU", \ 375 "permission denied", \ 376 "bad page", \ 377 "copy arguments cross page boundary" \ 378 } 379 380 #endif /* __XEN_PUBLIC_GRANT_TABLE_H__ */ 381