grant_table.h revision 181624
1248484Sneel/****************************************************************************** 2248484Sneel * grant_table.h 3248484Sneel * 4248484Sneel * Interface for granting foreign access to page frames, and receiving 5248484Sneel * page-ownership transfers. 6248484Sneel * 7248484Sneel * Permission is hereby granted, free of charge, to any person obtaining a copy 8248484Sneel * of this software and associated documentation files (the "Software"), to 9248484Sneel * deal in the Software without restriction, including without limitation the 10248484Sneel * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or 11248484Sneel * sell copies of the Software, and to permit persons to whom the Software is 12248484Sneel * furnished to do so, subject to the following conditions: 13248484Sneel * 14248484Sneel * The above copyright notice and this permission notice shall be included in 15248484Sneel * all copies or substantial portions of the Software. 16248484Sneel * 17248484Sneel * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 18248484Sneel * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 19248484Sneel * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 20248484Sneel * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 21248484Sneel * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 22248484Sneel * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 23248484Sneel * DEALINGS IN THE SOFTWARE. 24248484Sneel * 25248484Sneel * Copyright (c) 2004, K A Fraser 26248484Sneel */ 27248484Sneel 28248484Sneel#ifndef __XEN_PUBLIC_GRANT_TABLE_H__ 29248484Sneel#define __XEN_PUBLIC_GRANT_TABLE_H__ 30248484Sneel 31248484Sneel 32248484Sneel/*********************************** 33248484Sneel * GRANT TABLE REPRESENTATION 34256176Sneel */ 35248484Sneel 36248484Sneel/* Some rough guidelines on accessing and updating grant-table entries 37248484Sneel * in a concurrency-safe manner. For more information, Linux contains a 38248484Sneel * reference implementation for guest OSes (arch/xen/kernel/grant_table.c). 39248484Sneel * 40248484Sneel * NB. WMB is a no-op on current-generation x86 processors. However, a 41248484Sneel * compiler barrier will still be required. 42256657Sneel * 43248484Sneel * Introducing a valid entry into the grant table: 44248484Sneel * 1. Write ent->domid. 45248484Sneel * 2. Write ent->frame: 46248484Sneel * GTF_permit_access: Frame to which access is permitted. 47256657Sneel * GTF_accept_transfer: Pseudo-phys frame slot being filled by new 48248840Sneel * frame, or zero if none. 49248484Sneel * 3. Write memory barrier (WMB). 50248484Sneel * 4. Write ent->flags, inc. valid type. 51256176Sneel * 52248484Sneel * Invalidating an unused GTF_permit_access entry: 53248484Sneel * 1. flags = ent->flags. 54248484Sneel * 2. Observe that !(flags & (GTF_reading|GTF_writing)). 55248484Sneel * 3. Check result of SMP-safe CMPXCHG(&ent->flags, flags, 0). 56248484Sneel * NB. No need for WMB as reuse of entry is control-dependent on success of 57248484Sneel * step 3, and all architectures guarantee ordering of ctrl-dep writes. 58248484Sneel * 59248484Sneel * Invalidating an in-use GTF_permit_access entry: 60248484Sneel * This cannot be done directly. Request assistance from the domain controller 61248484Sneel * which can set a timeout on the use of a grant entry and take necessary 62248484Sneel * action. (NB. This is not yet implemented!). 63248484Sneel * 64248484Sneel * Invalidating an unused GTF_accept_transfer entry: 65248484Sneel * 1. flags = ent->flags. 66248484Sneel * 2. Observe that !(flags & GTF_transfer_committed). [*] 67248484Sneel * 3. Check result of SMP-safe CMPXCHG(&ent->flags, flags, 0). 68248484Sneel * NB. No need for WMB as reuse of entry is control-dependent on success of 69248484Sneel * step 3, and all architectures guarantee ordering of ctrl-dep writes. 70248484Sneel * [*] If GTF_transfer_committed is set then the grant entry is 'committed'. 71248484Sneel * The guest must /not/ modify the grant entry until the address of the 72248484Sneel * transferred frame is written. It is safe for the guest to spin waiting 73248484Sneel * for this to occur (detect by observing GTF_transfer_completed in 74248484Sneel * ent->flags). 75248484Sneel * 76248840Sneel * Invalidating a committed GTF_accept_transfer entry: 77256657Sneel * 1. Wait for (ent->flags & GTF_transfer_completed). 78248484Sneel * 79256657Sneel * Changing a GTF_permit_access from writable to read-only: 80248484Sneel * Use SMP-safe CMPXCHG to set GTF_readonly, while checking !GTF_writing. 81248484Sneel * 82248484Sneel * Changing a GTF_permit_access from read-only to writable: 83248484Sneel * Use SMP-safe bit-setting instruction. 84248484Sneel */ 85248484Sneel 86248484Sneel/* 87248484Sneel * A grant table comprises a packed array of grant entries in one or more 88248484Sneel * page frames shared between Xen and a guest. 89248484Sneel * [XEN]: This field is written by Xen and read by the sharing guest. 90256657Sneel * [GST]: This field is written by the guest and read by Xen. 91256657Sneel */ 92256657Sneelstruct grant_entry { 93248840Sneel /* GTF_xxx: various type and flag information. [XEN,GST] */ 94248840Sneel uint16_t flags; 95248484Sneel /* The domain being granted foreign privileges. [GST] */ 96248484Sneel domid_t domid; 97248484Sneel /* 98248484Sneel * GTF_permit_access: Frame that @domid is allowed to map and access. [GST] 99248484Sneel * GTF_accept_transfer: Frame whose ownership transferred by @domid. [XEN] 100248484Sneel */ 101248484Sneel uint32_t frame; 102248484Sneel}; 103248484Sneeltypedef struct grant_entry grant_entry_t; 104248484Sneel 105248484Sneel/* 106248484Sneel * Type of grant entry. 107248484Sneel * GTF_invalid: This grant entry grants no privileges. 108248484Sneel * GTF_permit_access: Allow @domid to map/access @frame. 109248484Sneel * GTF_accept_transfer: Allow @domid to transfer ownership of one page frame 110248484Sneel * to this guest. Xen writes the page number to @frame. 111248484Sneel */ 112248484Sneel#define GTF_invalid (0U<<0) 113248484Sneel#define GTF_permit_access (1U<<0) 114248484Sneel#define GTF_accept_transfer (2U<<0) 115248484Sneel#define GTF_type_mask (3U<<0) 116248484Sneel 117248484Sneel/* 118248484Sneel * Subflags for GTF_permit_access. 119248484Sneel * GTF_readonly: Restrict @domid to read-only mappings and accesses. [GST] 120248484Sneel * GTF_reading: Grant entry is currently mapped for reading by @domid. [XEN] 121248484Sneel * GTF_writing: Grant entry is currently mapped for writing by @domid. [XEN] 122248484Sneel */ 123248484Sneel#define _GTF_readonly (2) 124248484Sneel#define GTF_readonly (1U<<_GTF_readonly) 125248484Sneel#define _GTF_reading (3) 126248484Sneel#define GTF_reading (1U<<_GTF_reading) 127248484Sneel#define _GTF_writing (4) 128248484Sneel#define GTF_writing (1U<<_GTF_writing) 129248484Sneel 130248484Sneel/* 131248484Sneel * Subflags for GTF_accept_transfer: 132248484Sneel * GTF_transfer_committed: Xen sets this flag to indicate that it is committed 133248484Sneel * to transferring ownership of a page frame. When a guest sees this flag 134248484Sneel * it must /not/ modify the grant entry until GTF_transfer_completed is 135248484Sneel * set by Xen. 136248484Sneel * GTF_transfer_completed: It is safe for the guest to spin-wait on this flag 137248484Sneel * after reading GTF_transfer_committed. Xen will always write the frame 138248484Sneel * address, followed by ORing this flag, in a timely manner. 139248484Sneel */ 140248484Sneel#define _GTF_transfer_committed (2) 141248484Sneel#define GTF_transfer_committed (1U<<_GTF_transfer_committed) 142248484Sneel#define _GTF_transfer_completed (3) 143248484Sneel#define GTF_transfer_completed (1U<<_GTF_transfer_completed) 144248484Sneel 145248484Sneel 146248484Sneel/*********************************** 147248484Sneel * GRANT TABLE QUERIES AND USES 148248484Sneel */ 149248484Sneel 150248484Sneel/* 151248484Sneel * Reference to a grant entry in a specified domain's grant table. 152248484Sneel */ 153248484Sneeltypedef uint32_t grant_ref_t; 154248484Sneel 155248484Sneel/* 156248484Sneel * Handle to track a mapping created via a grant reference. 157248484Sneel */ 158248484Sneeltypedef uint32_t grant_handle_t; 159248484Sneel 160248484Sneel/* 161248484Sneel * GNTTABOP_map_grant_ref: Map the grant entry (<dom>,<ref>) for access 162248484Sneel * by devices and/or host CPUs. If successful, <handle> is a tracking number 163248484Sneel * that must be presented later to destroy the mapping(s). On error, <handle> 164248484Sneel * is a negative status code. 165248484Sneel * NOTES: 166248484Sneel * 1. If GNTMAP_device_map is specified then <dev_bus_addr> is the address 167248484Sneel * via which I/O devices may access the granted frame. 168248484Sneel * 2. If GNTMAP_host_map is specified then a mapping will be added at 169248484Sneel * either a host virtual address in the current address space, or at 170248484Sneel * a PTE at the specified machine address. The type of mapping to 171256657Sneel * perform is selected through the GNTMAP_contains_pte flag, and the 172248484Sneel * address is specified in <host_addr>. 173248484Sneel * 3. Mappings should only be destroyed via GNTTABOP_unmap_grant_ref. If a 174248484Sneel * host mapping is destroyed by other means then it is *NOT* guaranteed 175248484Sneel * to be accounted to the correct grant reference! 176248840Sneel */ 177248840Sneel#define GNTTABOP_map_grant_ref 0 178248484Sneelstruct gnttab_map_grant_ref { 179248484Sneel /* IN parameters. */ 180248484Sneel uint64_t host_addr; 181248484Sneel uint32_t flags; /* GNTMAP_* */ 182248484Sneel grant_ref_t ref; 183248484Sneel domid_t dom; 184248484Sneel /* OUT parameters. */ 185248484Sneel int16_t status; /* GNTST_* */ 186248484Sneel grant_handle_t handle; 187248484Sneel uint64_t dev_bus_addr; 188248484Sneel}; 189248484Sneeltypedef struct gnttab_map_grant_ref gnttab_map_grant_ref_t; 190DEFINE_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 204struct 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}; 212typedef struct gnttab_unmap_grant_ref gnttab_unmap_grant_ref_t; 213DEFINE_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 225struct 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}; 233typedef struct gnttab_setup_table gnttab_setup_table_t; 234DEFINE_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 241struct gnttab_dump_table { 242 /* IN parameters. */ 243 domid_t dom; 244 /* OUT parameters. */ 245 int16_t status; /* GNTST_* */ 246}; 247typedef struct gnttab_dump_table gnttab_dump_table_t; 248DEFINE_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 259struct 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}; 267typedef struct gnttab_transfer gnttab_transfer_t; 268DEFINE_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 295typedef 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; 310DEFINE_XEN_GUEST_HANDLE(gnttab_copy_t); 311 312/* 313 * GNTTABOP_query_size: Query the current and maximum sizes of the shared 314 * grant table. 315 * NOTES: 316 * 1. <dom> may be specified as DOMID_SELF. 317 * 2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF. 318 */ 319#define GNTTABOP_query_size 6 320struct gnttab_query_size { 321 /* IN parameters. */ 322 domid_t dom; 323 /* OUT parameters. */ 324 uint32_t nr_frames; 325 uint32_t max_nr_frames; 326 int16_t status; /* GNTST_* */ 327}; 328typedef struct gnttab_query_size gnttab_query_size_t; 329DEFINE_XEN_GUEST_HANDLE(gnttab_query_size_t); 330 331 332/* 333 * Bitfield values for update_pin_status.flags. 334 */ 335 /* Map the grant entry for access by I/O devices. */ 336#define _GNTMAP_device_map (0) 337#define GNTMAP_device_map (1<<_GNTMAP_device_map) 338 /* Map the grant entry for access by host CPUs. */ 339#define _GNTMAP_host_map (1) 340#define GNTMAP_host_map (1<<_GNTMAP_host_map) 341 /* Accesses to the granted frame will be restricted to read-only access. */ 342#define _GNTMAP_readonly (2) 343#define GNTMAP_readonly (1<<_GNTMAP_readonly) 344 /* 345 * GNTMAP_host_map subflag: 346 * 0 => The host mapping is usable only by the guest OS. 347 * 1 => The host mapping is usable by guest OS + current application. 348 */ 349#define _GNTMAP_application_map (3) 350#define GNTMAP_application_map (1<<_GNTMAP_application_map) 351 352 /* 353 * GNTMAP_contains_pte subflag: 354 * 0 => This map request contains a host virtual address. 355 * 1 => This map request contains the machine addess of the PTE to update. 356 */ 357#define _GNTMAP_contains_pte (4) 358#define GNTMAP_contains_pte (1<<_GNTMAP_contains_pte) 359 360/* 361 * Values for error status returns. All errors are -ve. 362 */ 363#define GNTST_okay (0) /* Normal return. */ 364#define GNTST_general_error (-1) /* General undefined error. */ 365#define GNTST_bad_domain (-2) /* Unrecognsed domain id. */ 366#define GNTST_bad_gntref (-3) /* Unrecognised or inappropriate gntref. */ 367#define GNTST_bad_handle (-4) /* Unrecognised or inappropriate handle. */ 368#define GNTST_bad_virt_addr (-5) /* Inappropriate virtual address to map. */ 369#define GNTST_bad_dev_addr (-6) /* Inappropriate device address to unmap.*/ 370#define GNTST_no_device_space (-7) /* Out of space in I/O MMU. */ 371#define GNTST_permission_denied (-8) /* Not enough privilege for operation. */ 372#define GNTST_bad_page (-9) /* Specified page was invalid for op. */ 373#define GNTST_bad_copy_arg (-10) /* copy arguments cross page boundary. */ 374#define GNTST_address_too_big (-11) /* transfer page address too large. */ 375 376#define GNTTABOP_error_msgs { \ 377 "okay", \ 378 "undefined error", \ 379 "unrecognised domain id", \ 380 "invalid grant reference", \ 381 "invalid mapping handle", \ 382 "invalid virtual address", \ 383 "invalid device address", \ 384 "no spare translation slot in the I/O MMU", \ 385 "permission denied", \ 386 "bad page", \ 387 "copy arguments cross page boundary", \ 388 "page address size too large" \ 389} 390 391#endif /* __XEN_PUBLIC_GRANT_TABLE_H__ */ 392 393/* 394 * Local variables: 395 * mode: C 396 * c-set-style: "BSD" 397 * c-basic-offset: 4 398 * tab-width: 4 399 * indent-tabs-mode: nil 400 * End: 401 */ 402