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 typedef 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 */ 123 #define _GTF_readonly (2) 124 #define GTF_readonly (1U<<_GTF_readonly) 125 #define _GTF_reading (3) 126 #define GTF_reading (1U<<_GTF_reading) 127 #define _GTF_writing (4) 128 #define GTF_writing (1U<<_GTF_writing) 129 130 /* 131 * Subflags for GTF_accept_transfer: 132 * GTF_transfer_committed: Xen sets this flag to indicate that it is committed 133 * to transferring ownership of a page frame. When a guest sees this flag 134 * it must /not/ modify the grant entry until GTF_transfer_completed is 135 * set by Xen. 136 * GTF_transfer_completed: It is safe for the guest to spin-wait on this flag 137 * after reading GTF_transfer_committed. Xen will always write the frame 138 * address, followed by ORing this flag, in a timely manner. 139 */ 140 #define _GTF_transfer_committed (2) 141 #define GTF_transfer_committed (1U<<_GTF_transfer_committed) 142 #define _GTF_transfer_completed (3) 143 #define GTF_transfer_completed (1U<<_GTF_transfer_completed) 144 145 146 /*********************************** 147 * GRANT TABLE QUERIES AND USES 148 */ 149 150 /* 151 * Reference to a grant entry in a specified domain's grant table. 152 */ 153 typedef uint32_t grant_ref_t; 154 155 /* 156 * Handle to track a mapping created via a grant reference. 157 */ 158 typedef uint32_t grant_handle_t; 159 160 /* 161 * GNTTABOP_map_grant_ref: Map the grant entry (<dom>,<ref>) for access 162 * by devices and/or host CPUs. If successful, <handle> is a tracking number 163 * that must be presented later to destroy the mapping(s). On error, <handle> 164 * is a negative status code. 165 * NOTES: 166 * 1. If GNTMAP_device_map is specified then <dev_bus_addr> is the address 167 * via which I/O devices may access the granted frame. 168 * 2. If GNTMAP_host_map is specified then a mapping will be added at 169 * either a host virtual address in the current address space, or at 170 * a PTE at the specified machine address. The type of mapping to 171 * perform is selected through the GNTMAP_contains_pte flag, and the 172 * address is specified in <host_addr>. 173 * 3. Mappings should only be destroyed via GNTTABOP_unmap_grant_ref. If a 174 * host mapping is destroyed by other means then it is *NOT* guaranteed 175 * to be accounted to the correct grant reference! 176 */ 177 #define GNTTABOP_map_grant_ref 0 178 struct gnttab_map_grant_ref { 179 /* IN parameters. */ 180 uint64_t host_addr; 181 uint32_t flags; /* GNTMAP_* */ 182 grant_ref_t ref; 183 domid_t dom; 184 /* OUT parameters. */ 185 int16_t status; /* GNTST_* */ 186 grant_handle_t handle; 187 uint64_t dev_bus_addr; 188 }; 189 typedef struct gnttab_map_grant_ref gnttab_map_grant_ref_t; 190 DEFINE_XEN_GUEST_HANDLE(gnttab_map_grant_ref_t); 191 192 /* 193 * GNTTABOP_unmap_grant_ref: Destroy one or more grant-reference mappings 194 * tracked by <handle>. If <host_addr> or <dev_bus_addr> is zero, that 195 * field is ignored. If non-zero, they must refer to a device/host mapping 196 * that is tracked by <handle> 197 * NOTES: 198 * 1. The call may fail in an undefined manner if either mapping is not 199 * tracked by <handle>. 200 * 3. After executing a batch of unmaps, it is guaranteed that no stale 201 * mappings will remain in the device or host TLBs. 202 */ 203 #define GNTTABOP_unmap_grant_ref 1 204 struct gnttab_unmap_grant_ref { 205 /* IN parameters. */ 206 uint64_t host_addr; 207 uint64_t dev_bus_addr; 208 grant_handle_t handle; 209 /* OUT parameters. */ 210 int16_t status; /* GNTST_* */ 211 }; 212 typedef struct gnttab_unmap_grant_ref gnttab_unmap_grant_ref_t; 213 DEFINE_XEN_GUEST_HANDLE(gnttab_unmap_grant_ref_t); 214 215 /* 216 * GNTTABOP_setup_table: Set up a grant table for <dom> comprising at least 217 * <nr_frames> pages. The frame addresses are written to the <frame_list>. 218 * Only <nr_frames> addresses are written, even if the table is larger. 219 * NOTES: 220 * 1. <dom> may be specified as DOMID_SELF. 221 * 2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF. 222 * 3. Xen may not support more than a single grant-table page per domain. 223 */ 224 #define GNTTABOP_setup_table 2 225 struct gnttab_setup_table { 226 /* IN parameters. */ 227 domid_t dom; 228 uint32_t nr_frames; 229 /* OUT parameters. */ 230 int16_t status; /* GNTST_* */ 231 XEN_GUEST_HANDLE(ulong) frame_list; 232 }; 233 typedef struct gnttab_setup_table gnttab_setup_table_t; 234 DEFINE_XEN_GUEST_HANDLE(gnttab_setup_table_t); 235 236 /* 237 * GNTTABOP_dump_table: Dump the contents of the grant table to the 238 * xen console. Debugging use only. 239 */ 240 #define GNTTABOP_dump_table 3 241 struct gnttab_dump_table { 242 /* IN parameters. */ 243 domid_t dom; 244 /* OUT parameters. */ 245 int16_t status; /* GNTST_* */ 246 }; 247 typedef struct gnttab_dump_table gnttab_dump_table_t; 248 DEFINE_XEN_GUEST_HANDLE(gnttab_dump_table_t); 249 250 /* 251 * GNTTABOP_transfer_grant_ref: Transfer <frame> to a foreign domain. The 252 * foreign domain has previously registered its interest in the transfer via 253 * <domid, ref>. 254 * 255 * Note that, even if the transfer fails, the specified page no longer belongs 256 * to the calling domain *unless* the error is GNTST_bad_page. 257 */ 258 #define GNTTABOP_transfer 4 259 struct gnttab_transfer { 260 /* IN parameters. */ 261 xen_pfn_t mfn; 262 domid_t domid; 263 grant_ref_t ref; 264 /* OUT parameters. */ 265 int16_t status; 266 }; 267 typedef struct gnttab_transfer gnttab_transfer_t; 268 DEFINE_XEN_GUEST_HANDLE(gnttab_transfer_t); 269 270 271 /* 272 * GNTTABOP_copy: Hypervisor based copy 273 * source and destinations can be eithers MFNs or, for foreign domains, 274 * grant references. the foreign domain has to grant read/write access 275 * in its grant table. 276 * 277 * The flags specify what type source and destinations are (either MFN 278 * or grant reference). 279 * 280 * Note that this can also be used to copy data between two domains 281 * via a third party if the source and destination domains had previously 282 * grant appropriate access to their pages to the third party. 283 * 284 * source_offset specifies an offset in the source frame, dest_offset 285 * the offset in the target frame and len specifies the number of 286 * bytes to be copied. 287 */ 288 289 #define _GNTCOPY_source_gref (0) 290 #define GNTCOPY_source_gref (1<<_GNTCOPY_source_gref) 291 #define _GNTCOPY_dest_gref (1) 292 #define GNTCOPY_dest_gref (1<<_GNTCOPY_dest_gref) 293 294 #define GNTTABOP_copy 5 295 typedef struct gnttab_copy { 296 /* IN parameters. */ 297 struct { 298 union { 299 grant_ref_t ref; 300 xen_pfn_t gmfn; 301 } u; 302 domid_t domid; 303 uint16_t offset; 304 } source, dest; 305 uint16_t len; 306 uint16_t flags; /* GNTCOPY_* */ 307 /* OUT parameters. */ 308 int16_t status; 309 } gnttab_copy_t; 310 DEFINE_XEN_GUEST_HANDLE(gnttab_copy_t); 311 312 313 /* 314 * Bitfield values for update_pin_status.flags. 315 */ 316 /* Map the grant entry for access by I/O devices. */ 317 #define _GNTMAP_device_map (0) 318 #define GNTMAP_device_map (1<<_GNTMAP_device_map) 319 /* Map the grant entry for access by host CPUs. */ 320 #define _GNTMAP_host_map (1) 321 #define GNTMAP_host_map (1<<_GNTMAP_host_map) 322 /* Accesses to the granted frame will be restricted to read-only access. */ 323 #define _GNTMAP_readonly (2) 324 #define GNTMAP_readonly (1<<_GNTMAP_readonly) 325 /* 326 * GNTMAP_host_map subflag: 327 * 0 => The host mapping is usable only by the guest OS. 328 * 1 => The host mapping is usable by guest OS + current application. 329 */ 330 #define _GNTMAP_application_map (3) 331 #define GNTMAP_application_map (1<<_GNTMAP_application_map) 332 333 /* 334 * GNTMAP_contains_pte subflag: 335 * 0 => This map request contains a host virtual address. 336 * 1 => This map request contains the machine addess of the PTE to update. 337 */ 338 #define _GNTMAP_contains_pte (4) 339 #define GNTMAP_contains_pte (1<<_GNTMAP_contains_pte) 340 341 /* 342 * Values for error status returns. All errors are -ve. 343 */ 344 #define GNTST_okay (0) /* Normal return. */ 345 #define GNTST_general_error (-1) /* General undefined error. */ 346 #define GNTST_bad_domain (-2) /* Unrecognsed domain id. */ 347 #define GNTST_bad_gntref (-3) /* Unrecognised or inappropriate gntref. */ 348 #define GNTST_bad_handle (-4) /* Unrecognised or inappropriate handle. */ 349 #define GNTST_bad_virt_addr (-5) /* Inappropriate virtual address to map. */ 350 #define GNTST_bad_dev_addr (-6) /* Inappropriate device address to unmap.*/ 351 #define GNTST_no_device_space (-7) /* Out of space in I/O MMU. */ 352 #define GNTST_permission_denied (-8) /* Not enough privilege for operation. */ 353 #define GNTST_bad_page (-9) /* Specified page was invalid for op. */ 354 #define GNTST_bad_copy_arg (-10) /* copy arguments cross page boundary */ 355 356 #define GNTTABOP_error_msgs { \ 357 "okay", \ 358 "undefined error", \ 359 "unrecognised domain id", \ 360 "invalid grant reference", \ 361 "invalid mapping handle", \ 362 "invalid virtual address", \ 363 "invalid device address", \ 364 "no spare translation slot in the I/O MMU", \ 365 "permission denied", \ 366 "bad page", \ 367 "copy arguments cross page boundary" \ 368 } 369 370 #endif /* __XEN_PUBLIC_GRANT_TABLE_H__ */ 371 372 /* 373 * Local variables: 374 * mode: C 375 * c-set-style: "BSD" 376 * c-basic-offset: 4 377 * tab-width: 4 378 * indent-tabs-mode: nil 379 * End: 380 */ 381