xen/interface/grant_table.h

5  * page-ownership transfers.
37 /* Some rough guidelines on accessing and updating grant-table entries
38  * in a concurrency-safe manner. For more information, Linux contains a
41  * NB. WMB is a no-op on current-generation x86 processors. However, a
45  *  1. Write ent->domid.
46  *  2. Write ent->frame:
48  *      GTF_accept_transfer: Pseudo-phys frame slot being filled by new
51  *  4. Write ent->flags, inc. valid type.
54  *  1. flags = ent->flags.
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.
60  * Invalidating an in-use GTF_permit_access entry:
66  *  1. flags = ent->flags.
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.
75  *      ent->flags).
78  *  1. Wait for (ent->flags & GTF_transfer_completed).
80  * Changing a GTF_permit_access from writable to read-only:
81  *  Use SMP-safe CMPXCHG to set GTF_readonly, while checking !GTF_writing.
83  * Changing a GTF_permit_access from read-only to writable:
84  *  Use SMP-safe bit-setting instruction.
132  *  GTF_readonly: Restrict @domid to read-only mappings and accesses. [GST]
154  *  GTF_transfer_completed: It is safe for the guest to spin-wait on this flag
169  * The interface by which domains use grant references does not depend
191      * This member is used for V1-style full page grants, where either:
193      * -- hdr.type is GTF_accept_transfer, or
194      * -- hdr.type is GTF_permit_access and GTF_sub_page is not set.
230     uint32_t __spacer[4]; /* Pad to a power of two */
276  * GNTTABOP_unmap_grant_ref: Destroy one or more grant-reference mappings
278  * field is ignored. If non-zero, they must refer to a device/host mapping
303  *  2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF.
304  *  3. Xen may not support more than a single grant-table page per domain.
351  * source and destinations can be eithers MFNs or, for foreign domains,
358  * Note that this can also be used to copy data between two domains
359  * via a third party if the source and destination domains had previously
395  *  2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF.
409  * GNTTABOP_unmap_and_replace: Destroy one or more grant-reference mappings
454  *  2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF.
490  /* Accesses to the granted frame will be restricted to read-only access. */
510  * Values for error status returns. All errors are -ve.
513 #define GNTST_general_error    (-1) /* General undefined error.              */
514 #define GNTST_bad_domain       (-2) /* Unrecognsed domain id.                */
515 #define GNTST_bad_gntref       (-3) /* Unrecognised or inappropriate gntref. */
516 #define GNTST_bad_handle       (-4) /* Unrecognised or inappropriate handle. */
517 #define GNTST_bad_virt_addr    (-5) /* Inappropriate virtual address to map. */
518 #define GNTST_bad_dev_addr     (-6) /* Inappropriate device address to unmap.*/
519 #define GNTST_no_device_space  (-7) /* Out of space in I/O MMU.              */
520 #define GNTST_permission_denied (-8) /* Not enough privilege for operation.  */
521 #define GNTST_bad_page         (-9) /* Specified page was invalid for op.    */
522 #define GNTST_bad_copy_arg    (-10) /* copy arguments cross page boundary */