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 }; 188 189 /* 190 * GNTTABOP_unmap_grant_ref: Destroy one or more grant-reference mappings 191 * tracked by <handle>. If <host_addr> or <dev_bus_addr> is zero, that 192 * field is ignored. If non-zero, they must refer to a device/host mapping 193 * that is tracked by <handle> 194 * NOTES: 195 * 1. The call may fail in an undefined manner if either mapping is not 196 * tracked by <handle>. 197 * 3. After executing a batch of unmaps, it is guaranteed that no stale 198 * mappings will remain in the device or host TLBs. 199 */ 200 #define GNTTABOP_unmap_grant_ref 1 201 struct gnttab_unmap_grant_ref { 202 /* IN parameters. */ 203 uint64_t host_addr; 204 uint64_t dev_bus_addr; 205 grant_handle_t handle; 206 /* OUT parameters. */ 207 int16_t status; /* GNTST_* */ 208 }; 209 210 /* 211 * GNTTABOP_setup_table: Set up a grant table for <dom> comprising at least 212 * <nr_frames> pages. The frame addresses are written to the <frame_list>. 213 * Only <nr_frames> addresses are written, even if the table is larger. 214 * NOTES: 215 * 1. <dom> may be specified as DOMID_SELF. 216 * 2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF. 217 * 3. Xen may not support more than a single grant-table page per domain. 218 */ 219 #define GNTTABOP_setup_table 2 220 struct gnttab_setup_table { 221 /* IN parameters. */ 222 domid_t dom; 223 uint32_t nr_frames; 224 /* OUT parameters. */ 225 int16_t status; /* GNTST_* */ 226 ulong *frame_list; 227 }; 228 229 /* 230 * GNTTABOP_dump_table: Dump the contents of the grant table to the 231 * xen console. Debugging use only. 232 */ 233 #define GNTTABOP_dump_table 3 234 struct gnttab_dump_table { 235 /* IN parameters. */ 236 domid_t dom; 237 /* OUT parameters. */ 238 int16_t status; /* GNTST_* */ 239 }; 240 241 /* 242 * GNTTABOP_transfer_grant_ref: Transfer <frame> to a foreign domain. The 243 * foreign domain has previously registered its interest in the transfer via 244 * <domid, ref>. 245 * 246 * Note that, even if the transfer fails, the specified page no longer belongs 247 * to the calling domain *unless* the error is GNTST_bad_page. 248 */ 249 #define GNTTABOP_transfer 4 250 struct gnttab_transfer { 251 /* IN parameters. */ 252 unsigned long mfn; 253 domid_t domid; 254 grant_ref_t ref; 255 /* OUT parameters. */ 256 int16_t status; 257 }; 258 259 260 /* 261 * GNTTABOP_copy: Hypervisor based copy 262 * source and destinations can be eithers MFNs or, for foreign domains, 263 * grant references. the foreign domain has to grant read/write access 264 * in its grant table. 265 * 266 * The flags specify what type source and destinations are (either MFN 267 * or grant reference). 268 * 269 * Note that this can also be used to copy data between two domains 270 * via a third party if the source and destination domains had previously 271 * grant appropriate access to their pages to the third party. 272 * 273 * source_offset specifies an offset in the source frame, dest_offset 274 * the offset in the target frame and len specifies the number of 275 * bytes to be copied. 276 */ 277 278 #define _GNTCOPY_source_gref (0) 279 #define GNTCOPY_source_gref (1<<_GNTCOPY_source_gref) 280 #define _GNTCOPY_dest_gref (1) 281 #define GNTCOPY_dest_gref (1<<_GNTCOPY_dest_gref) 282 283 #define GNTTABOP_copy 5 284 struct gnttab_copy { 285 /* IN parameters. */ 286 struct { 287 union { 288 grant_ref_t ref; 289 unsigned long gmfn; 290 } u; 291 domid_t domid; 292 uint16_t offset; 293 } source, dest; 294 uint16_t len; 295 uint16_t flags; /* GNTCOPY_* */ 296 /* OUT parameters. */ 297 int16_t status; 298 }; 299 300 /* 301 * GNTTABOP_query_size: Query the current and maximum sizes of the shared 302 * grant table. 303 * NOTES: 304 * 1. <dom> may be specified as DOMID_SELF. 305 * 2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF. 306 */ 307 #define GNTTABOP_query_size 6 308 struct gnttab_query_size { 309 /* IN parameters. */ 310 domid_t dom; 311 /* OUT parameters. */ 312 uint32_t nr_frames; 313 uint32_t max_nr_frames; 314 int16_t status; /* GNTST_* */ 315 }; 316 317 318 /* 319 * Bitfield values for update_pin_status.flags. 320 */ 321 /* Map the grant entry for access by I/O devices. */ 322 #define _GNTMAP_device_map (0) 323 #define GNTMAP_device_map (1<<_GNTMAP_device_map) 324 /* Map the grant entry for access by host CPUs. */ 325 #define _GNTMAP_host_map (1) 326 #define GNTMAP_host_map (1<<_GNTMAP_host_map) 327 /* Accesses to the granted frame will be restricted to read-only access. */ 328 #define _GNTMAP_readonly (2) 329 #define GNTMAP_readonly (1<<_GNTMAP_readonly) 330 /* 331 * GNTMAP_host_map subflag: 332 * 0 => The host mapping is usable only by the guest OS. 333 * 1 => The host mapping is usable by guest OS + current application. 334 */ 335 #define _GNTMAP_application_map (3) 336 #define GNTMAP_application_map (1<<_GNTMAP_application_map) 337 338 /* 339 * GNTMAP_contains_pte subflag: 340 * 0 => This map request contains a host virtual address. 341 * 1 => This map request contains the machine addess of the PTE to update. 342 */ 343 #define _GNTMAP_contains_pte (4) 344 #define GNTMAP_contains_pte (1<<_GNTMAP_contains_pte) 345 346 /* 347 * Values for error status returns. All errors are -ve. 348 */ 349 #define GNTST_okay (0) /* Normal return. */ 350 #define GNTST_general_error (-1) /* General undefined error. */ 351 #define GNTST_bad_domain (-2) /* Unrecognsed domain id. */ 352 #define GNTST_bad_gntref (-3) /* Unrecognised or inappropriate gntref. */ 353 #define GNTST_bad_handle (-4) /* Unrecognised or inappropriate handle. */ 354 #define GNTST_bad_virt_addr (-5) /* Inappropriate virtual address to map. */ 355 #define GNTST_bad_dev_addr (-6) /* Inappropriate device address to unmap.*/ 356 #define GNTST_no_device_space (-7) /* Out of space in I/O MMU. */ 357 #define GNTST_permission_denied (-8) /* Not enough privilege for operation. */ 358 #define GNTST_bad_page (-9) /* Specified page was invalid for op. */ 359 #define GNTST_bad_copy_arg (-10) /* copy arguments cross page boundary */ 360 361 #define GNTTABOP_error_msgs { \ 362 "okay", \ 363 "undefined error", \ 364 "unrecognised domain id", \ 365 "invalid grant reference", \ 366 "invalid mapping handle", \ 367 "invalid virtual address", \ 368 "invalid device address", \ 369 "no spare translation slot in the I/O MMU", \ 370 "permission denied", \ 371 "bad page", \ 372 "copy arguments cross page boundary" \ 373 } 374 375 #endif /* __XEN_PUBLIC_GRANT_TABLE_H__ */ 376