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 * A grant table comprises a packed array of grant entries in one or more 89 * page frames shared between Xen and a guest. 90 * [XEN]: This field is written by Xen and read by the sharing guest. 91 * [GST]: This field is written by the guest and read by Xen. 92 */ 93struct grant_entry { 94 /* GTF_xxx: various type and flag information. [XEN,GST] */ 95 uint16_t flags; 96 /* The domain being granted foreign privileges. [GST] */ 97 domid_t domid; 98 /* 99 * GTF_permit_access: Frame that @domid is allowed to map and access. [GST] 100 * GTF_accept_transfer: Frame whose ownership transferred by @domid. [XEN] 101 */ 102 uint32_t frame; 103}; 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 */ 153typedef uint32_t grant_ref_t; 154 155/* 156 * Handle to track a mapping created via a grant reference. 157 */ 158typedef 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 178struct 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}; 189DEFINE_GUEST_HANDLE_STRUCT(gnttab_map_grant_ref); 190 191/* 192 * GNTTABOP_unmap_grant_ref: Destroy one or more grant-reference mappings 193 * tracked by <handle>. If <host_addr> or <dev_bus_addr> is zero, that 194 * field is ignored. If non-zero, they must refer to a device/host mapping 195 * that is tracked by <handle> 196 * NOTES: 197 * 1. The call may fail in an undefined manner if either mapping is not 198 * tracked by <handle>. 199 * 3. After executing a batch of unmaps, it is guaranteed that no stale 200 * mappings will remain in the device or host TLBs. 201 */ 202#define GNTTABOP_unmap_grant_ref 1 203struct gnttab_unmap_grant_ref { 204 /* IN parameters. */ 205 uint64_t host_addr; 206 uint64_t dev_bus_addr; 207 grant_handle_t handle; 208 /* OUT parameters. */ 209 int16_t status; /* GNTST_* */ 210}; 211DEFINE_GUEST_HANDLE_STRUCT(gnttab_unmap_grant_ref); 212 213/* 214 * GNTTABOP_setup_table: Set up a grant table for <dom> comprising at least 215 * <nr_frames> pages. The frame addresses are written to the <frame_list>. 216 * Only <nr_frames> addresses are written, even if the table is larger. 217 * NOTES: 218 * 1. <dom> may be specified as DOMID_SELF. 219 * 2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF. 220 * 3. Xen may not support more than a single grant-table page per domain. 221 */ 222#define GNTTABOP_setup_table 2 223struct gnttab_setup_table { 224 /* IN parameters. */ 225 domid_t dom; 226 uint32_t nr_frames; 227 /* OUT parameters. */ 228 int16_t status; /* GNTST_* */ 229 GUEST_HANDLE(ulong) frame_list; 230}; 231DEFINE_GUEST_HANDLE_STRUCT(gnttab_setup_table); 232 233/* 234 * GNTTABOP_dump_table: Dump the contents of the grant table to the 235 * xen console. Debugging use only. 236 */ 237#define GNTTABOP_dump_table 3 238struct gnttab_dump_table { 239 /* IN parameters. */ 240 domid_t dom; 241 /* OUT parameters. */ 242 int16_t status; /* GNTST_* */ 243}; 244DEFINE_GUEST_HANDLE_STRUCT(gnttab_dump_table); 245 246/* 247 * GNTTABOP_transfer_grant_ref: Transfer <frame> to a foreign domain. The 248 * foreign domain has previously registered its interest in the transfer via 249 * <domid, ref>. 250 * 251 * Note that, even if the transfer fails, the specified page no longer belongs 252 * to the calling domain *unless* the error is GNTST_bad_page. 253 */ 254#define GNTTABOP_transfer 4 255struct gnttab_transfer { 256 /* IN parameters. */ 257 unsigned long mfn; 258 domid_t domid; 259 grant_ref_t ref; 260 /* OUT parameters. */ 261 int16_t status; 262}; 263DEFINE_GUEST_HANDLE_STRUCT(gnttab_transfer); 264 265/* 266 * GNTTABOP_copy: Hypervisor based copy 267 * source and destinations can be eithers MFNs or, for foreign domains, 268 * grant references. the foreign domain has to grant read/write access 269 * in its grant table. 270 * 271 * The flags specify what type source and destinations are (either MFN 272 * or grant reference). 273 * 274 * Note that this can also be used to copy data between two domains 275 * via a third party if the source and destination domains had previously 276 * grant appropriate access to their pages to the third party. 277 * 278 * source_offset specifies an offset in the source frame, dest_offset 279 * the offset in the target frame and len specifies the number of 280 * bytes to be copied. 281 */ 282 283#define _GNTCOPY_source_gref (0) 284#define GNTCOPY_source_gref (1<<_GNTCOPY_source_gref) 285#define _GNTCOPY_dest_gref (1) 286#define GNTCOPY_dest_gref (1<<_GNTCOPY_dest_gref) 287 288#define GNTTABOP_copy 5 289struct gnttab_copy { 290 /* IN parameters. */ 291 struct { 292 union { 293 grant_ref_t ref; 294 unsigned long gmfn; 295 } u; 296 domid_t domid; 297 uint16_t offset; 298 } source, dest; 299 uint16_t len; 300 uint16_t flags; /* GNTCOPY_* */ 301 /* OUT parameters. */ 302 int16_t status; 303}; 304DEFINE_GUEST_HANDLE_STRUCT(gnttab_copy); 305 306/* 307 * GNTTABOP_query_size: Query the current and maximum sizes of the shared 308 * grant table. 309 * NOTES: 310 * 1. <dom> may be specified as DOMID_SELF. 311 * 2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF. 312 */ 313#define GNTTABOP_query_size 6 314struct gnttab_query_size { 315 /* IN parameters. */ 316 domid_t dom; 317 /* OUT parameters. */ 318 uint32_t nr_frames; 319 uint32_t max_nr_frames; 320 int16_t status; /* GNTST_* */ 321}; 322DEFINE_GUEST_HANDLE_STRUCT(gnttab_query_size); 323 324/* 325 * Bitfield values for update_pin_status.flags. 326 */ 327 /* Map the grant entry for access by I/O devices. */ 328#define _GNTMAP_device_map (0) 329#define GNTMAP_device_map (1<<_GNTMAP_device_map) 330 /* Map the grant entry for access by host CPUs. */ 331#define _GNTMAP_host_map (1) 332#define GNTMAP_host_map (1<<_GNTMAP_host_map) 333 /* Accesses to the granted frame will be restricted to read-only access. */ 334#define _GNTMAP_readonly (2) 335#define GNTMAP_readonly (1<<_GNTMAP_readonly) 336 /* 337 * GNTMAP_host_map subflag: 338 * 0 => The host mapping is usable only by the guest OS. 339 * 1 => The host mapping is usable by guest OS + current application. 340 */ 341#define _GNTMAP_application_map (3) 342#define GNTMAP_application_map (1<<_GNTMAP_application_map) 343 344 /* 345 * GNTMAP_contains_pte subflag: 346 * 0 => This map request contains a host virtual address. 347 * 1 => This map request contains the machine addess of the PTE to update. 348 */ 349#define _GNTMAP_contains_pte (4) 350#define GNTMAP_contains_pte (1<<_GNTMAP_contains_pte) 351 352/* 353 * Values for error status returns. All errors are -ve. 354 */ 355#define GNTST_okay (0) /* Normal return. */ 356#define GNTST_general_error (-1) /* General undefined error. */ 357#define GNTST_bad_domain (-2) /* Unrecognsed domain id. */ 358#define GNTST_bad_gntref (-3) /* Unrecognised or inappropriate gntref. */ 359#define GNTST_bad_handle (-4) /* Unrecognised or inappropriate handle. */ 360#define GNTST_bad_virt_addr (-5) /* Inappropriate virtual address to map. */ 361#define GNTST_bad_dev_addr (-6) /* Inappropriate device address to unmap.*/ 362#define GNTST_no_device_space (-7) /* Out of space in I/O MMU. */ 363#define GNTST_permission_denied (-8) /* Not enough privilege for operation. */ 364#define GNTST_bad_page (-9) /* Specified page was invalid for op. */ 365#define GNTST_bad_copy_arg (-10) /* copy arguments cross page boundary */ 366 367#define GNTTABOP_error_msgs { \ 368 "okay", \ 369 "undefined error", \ 370 "unrecognised domain id", \ 371 "invalid grant reference", \ 372 "invalid mapping handle", \ 373 "invalid virtual address", \ 374 "invalid device address", \ 375 "no spare translation slot in the I/O MMU", \ 376 "permission denied", \ 377 "bad page", \ 378 "copy arguments cross page boundary" \ 379} 380 381#endif /* __XEN_PUBLIC_GRANT_TABLE_H__ */ 382