include/xen/interface/grant_table.h - kernel/msm-4.9 - Gitiles

 /******************************************************************************
  * grant_table.h
  *
  * Interface for granting foreign access to page frames, and receiving
  * page-ownership transfers.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to
  * deal in the Software without restriction, including without limitation the
  * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
  * sell copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  * DEALINGS IN THE SOFTWARE.
  *
  * Copyright (c) 2004, K A Fraser
  */

 #ifndef __XEN_PUBLIC_GRANT_TABLE_H__
 #define __XEN_PUBLIC_GRANT_TABLE_H__

 #include <xen/interface/xen.h>

 /***********************************
  * GRANT TABLE REPRESENTATION
  */

 /* Some rough guidelines on accessing and updating grant-table entries
  * in a concurrency-safe manner. For more information, Linux contains a
  * reference implementation for guest OSes (arch/xen/kernel/grant_table.c).
  *
  * NB. WMB is a no-op on current-generation x86 processors. However, a
  *     compiler barrier will still be required.
  *
  * Introducing a valid entry into the grant table:
  *  1. Write ent->domid.
  *  2. Write ent->frame:
  *      GTF_permit_access:   Frame to which access is permitted.
  *      GTF_accept_transfer: Pseudo-phys frame slot being filled by new
  *                           frame, or zero if none.
  *  3. Write memory barrier (WMB).
  *  4. Write ent->flags, inc. valid type.
  *
  * Invalidating an unused GTF_permit_access entry:
  *  1. flags = ent->flags.
  *  2. Observe that !(flags & (GTF_reading|GTF_writing)).
  *  3. Check result of SMP-safe CMPXCHG(&ent->flags, flags, 0).
  *  NB. No need for WMB as reuse of entry is control-dependent on success of
  *      step 3, and all architectures guarantee ordering of ctrl-dep writes.
  *
  * Invalidating an in-use GTF_permit_access entry:
  *  This cannot be done directly. Request assistance from the domain controller
  *  which can set a timeout on the use of a grant entry and take necessary
  *  action. (NB. This is not yet implemented!).
  *
  * Invalidating an unused GTF_accept_transfer entry:
  *  1. flags = ent->flags.
  *  2. Observe that !(flags & GTF_transfer_committed). [*]
  *  3. Check result of SMP-safe CMPXCHG(&ent->flags, flags, 0).
  *  NB. No need for WMB as reuse of entry is control-dependent on success of
  *      step 3, and all architectures guarantee ordering of ctrl-dep writes.
  *  [*] If GTF_transfer_committed is set then the grant entry is 'committed'.
  *      The guest must /not/ modify the grant entry until the address of the
  *      transferred frame is written. It is safe for the guest to spin waiting
  *      for this to occur (detect by observing GTF_transfer_completed in
  *      ent->flags).
  *
  * Invalidating a committed GTF_accept_transfer entry:
  *  1. Wait for (ent->flags & GTF_transfer_completed).
  *
  * Changing a GTF_permit_access from writable to read-only:
  *  Use SMP-safe CMPXCHG to set GTF_readonly, while checking !GTF_writing.
  *
  * Changing a GTF_permit_access from read-only to writable:
  *  Use SMP-safe bit-setting instruction.
  */

 /*
  * A grant table comprises a packed array of grant entries in one or more
  * page frames shared between Xen and a guest.
  * [XEN]: This field is written by Xen and read by the sharing guest.
  * [GST]: This field is written by the guest and read by Xen.
  */
 struct grant_entry {
     /* GTF_xxx: various type and flag information.  [XEN,GST] */
     uint16_t flags;
     /* The domain being granted foreign privileges. [GST] */
     domid_t  domid;
     /*
      * GTF_permit_access: Frame that @domid is allowed to map and access. [GST]
      * GTF_accept_transfer: Frame whose ownership transferred by @domid. [XEN]
      */
     uint32_t frame;
 };

 /*
  * Type of grant entry.
  *  GTF_invalid: This grant entry grants no privileges.
  *  GTF_permit_access: Allow @domid to map/access @frame.
  *  GTF_accept_transfer: Allow @domid to transfer ownership of one page frame
  *                       to this guest. Xen writes the page number to @frame.
  */
 #define GTF_invalid         (0U<<0)
 #define GTF_permit_access   (1U<<0)
 #define GTF_accept_transfer (2U<<0)
 #define GTF_type_mask       (3U<<0)

 /*
  * Subflags for GTF_permit_access.
  *  GTF_readonly: Restrict @domid to read-only mappings and accesses. [GST]
  *  GTF_reading: Grant entry is currently mapped for reading by @domid. [XEN]
  *  GTF_writing: Grant entry is currently mapped for writing by @domid. [XEN]
  */
 #define _GTF_readonly       (2)
 #define GTF_readonly        (1U<<_GTF_readonly)
 #define _GTF_reading        (3)
 #define GTF_reading         (1U<<_GTF_reading)
 #define _GTF_writing        (4)
 #define GTF_writing         (1U<<_GTF_writing)

 /*
  * Subflags for GTF_accept_transfer:
  *  GTF_transfer_committed: Xen sets this flag to indicate that it is committed
  *      to transferring ownership of a page frame. When a guest sees this flag
  *      it must /not/ modify the grant entry until GTF_transfer_completed is
  *      set by Xen.
  *  GTF_transfer_completed: It is safe for the guest to spin-wait on this flag
  *      after reading GTF_transfer_committed. Xen will always write the frame
  *      address, followed by ORing this flag, in a timely manner.
  */
 #define _GTF_transfer_committed (2)
 #define GTF_transfer_committed  (1U<<_GTF_transfer_committed)
 #define _GTF_transfer_completed (3)
 #define GTF_transfer_completed  (1U<<_GTF_transfer_completed)


 /***********************************
  * GRANT TABLE QUERIES AND USES
  */

 /*
  * Reference to a grant entry in a specified domain's grant table.
  */
 typedef uint32_t grant_ref_t;

 /*
  * Handle to track a mapping created via a grant reference.
  */
 typedef uint32_t grant_handle_t;

 /*
  * GNTTABOP_map_grant_ref: Map the grant entry (<dom>,<ref>) for access
  * by devices and/or host CPUs. If successful, <handle> is a tracking number
  * that must be presented later to destroy the mapping(s). On error, <handle>
  * is a negative status code.
  * NOTES:
  *  1. If GNTMAP_device_map is specified then <dev_bus_addr> is the address
  *     via which I/O devices may access the granted frame.
  *  2. If GNTMAP_host_map is specified then a mapping will be added at
  *     either a host virtual address in the current address space, or at
  *     a PTE at the specified machine address.  The type of mapping to
  *     perform is selected through the GNTMAP_contains_pte flag, and the
  *     address is specified in <host_addr>.
  *  3. Mappings should only be destroyed via GNTTABOP_unmap_grant_ref. If a
  *     host mapping is destroyed by other means then it is *NOT* guaranteed
  *     to be accounted to the correct grant reference!
  */
 #define GNTTABOP_map_grant_ref        0
 struct gnttab_map_grant_ref {
     /* IN parameters. */
     uint64_t host_addr;
     uint32_t flags;               /* GNTMAP_* */
     grant_ref_t ref;
     domid_t  dom;
     /* OUT parameters. */
     int16_t  status;              /* GNTST_* */
     grant_handle_t handle;
     uint64_t dev_bus_addr;
 };
 DEFINE_GUEST_HANDLE_STRUCT(gnttab_map_grant_ref);

 /*
  * GNTTABOP_unmap_grant_ref: Destroy one or more grant-reference mappings
  * tracked by <handle>. If <host_addr> or <dev_bus_addr> is zero, that
  * field is ignored. If non-zero, they must refer to a device/host mapping
  * that is tracked by <handle>
  * NOTES:
  *  1. The call may fail in an undefined manner if either mapping is not
  *     tracked by <handle>.
  *  3. After executing a batch of unmaps, it is guaranteed that no stale
  *     mappings will remain in the device or host TLBs.
  */
 #define GNTTABOP_unmap_grant_ref      1
 struct gnttab_unmap_grant_ref {
     /* IN parameters. */
     uint64_t host_addr;
     uint64_t dev_bus_addr;
     grant_handle_t handle;
     /* OUT parameters. */
     int16_t  status;              /* GNTST_* */
 };
 DEFINE_GUEST_HANDLE_STRUCT(gnttab_unmap_grant_ref);

 /*
  * GNTTABOP_setup_table: Set up a grant table for <dom> comprising at least
  * <nr_frames> pages. The frame addresses are written to the <frame_list>.
  * Only <nr_frames> addresses are written, even if the table is larger.
  * NOTES:
  *  1. <dom> may be specified as DOMID_SELF.
  *  2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF.
  *  3. Xen may not support more than a single grant-table page per domain.
  */
 #define GNTTABOP_setup_table          2
 struct gnttab_setup_table {
     /* IN parameters. */
     domid_t  dom;
     uint32_t nr_frames;
     /* OUT parameters. */
     int16_t  status;              /* GNTST_* */
     GUEST_HANDLE(ulong) frame_list;
 };
 DEFINE_GUEST_HANDLE_STRUCT(gnttab_setup_table);

 /*
  * GNTTABOP_dump_table: Dump the contents of the grant table to the
  * xen console. Debugging use only.
  */
 #define GNTTABOP_dump_table           3
 struct gnttab_dump_table {
     /* IN parameters. */
     domid_t dom;
     /* OUT parameters. */
     int16_t status;               /* GNTST_* */
 };
 DEFINE_GUEST_HANDLE_STRUCT(gnttab_dump_table);

 /*
  * GNTTABOP_transfer_grant_ref: Transfer <frame> to a foreign domain. The
  * foreign domain has previously registered its interest in the transfer via
  * <domid, ref>.
  *
  * Note that, even if the transfer fails, the specified page no longer belongs
  * to the calling domain *unless* the error is GNTST_bad_page.
  */
 #define GNTTABOP_transfer                4
 struct gnttab_transfer {
     /* IN parameters. */
     unsigned long mfn;
     domid_t       domid;
     grant_ref_t   ref;
     /* OUT parameters. */
     int16_t       status;
 };
 DEFINE_GUEST_HANDLE_STRUCT(gnttab_transfer);

 /*
  * GNTTABOP_copy: Hypervisor based copy
  * source and destinations can be eithers MFNs or, for foreign domains,
  * grant references. the foreign domain has to grant read/write access
  * in its grant table.
  *
  * The flags specify what type source and destinations are (either MFN
  * or grant reference).
  *
  * Note that this can also be used to copy data between two domains
  * via a third party if the source and destination domains had previously
  * grant appropriate access to their pages to the third party.
  *
  * source_offset specifies an offset in the source frame, dest_offset
  * the offset in the target frame and  len specifies the number of
  * bytes to be copied.
  */

 #define _GNTCOPY_source_gref      (0)
 #define GNTCOPY_source_gref       (1<<_GNTCOPY_source_gref)
 #define _GNTCOPY_dest_gref        (1)
 #define GNTCOPY_dest_gref         (1<<_GNTCOPY_dest_gref)

 #define GNTTABOP_copy                 5
 struct gnttab_copy {
 	/* IN parameters. */
 	struct {
 		union {
 			grant_ref_t ref;
 			unsigned long   gmfn;
 		} u;
 		domid_t  domid;
 		uint16_t offset;
 	} source, dest;
 	uint16_t      len;
 	uint16_t      flags;          /* GNTCOPY_* */
 	/* OUT parameters. */
 	int16_t       status;
 };
 DEFINE_GUEST_HANDLE_STRUCT(gnttab_copy);

 /*
  * GNTTABOP_query_size: Query the current and maximum sizes of the shared
  * grant table.
  * NOTES:
  *  1. <dom> may be specified as DOMID_SELF.
  *  2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF.
  */
 #define GNTTABOP_query_size           6
 struct gnttab_query_size {
     /* IN parameters. */
     domid_t  dom;
     /* OUT parameters. */
     uint32_t nr_frames;
     uint32_t max_nr_frames;
     int16_t  status;              /* GNTST_* */
 };
 DEFINE_GUEST_HANDLE_STRUCT(gnttab_query_size);

 /*
  * Bitfield values for update_pin_status.flags.
  */
  /* Map the grant entry for access by I/O devices. */
 #define _GNTMAP_device_map      (0)
 #define GNTMAP_device_map       (1<<_GNTMAP_device_map)
  /* Map the grant entry for access by host CPUs. */
 #define _GNTMAP_host_map        (1)
 #define GNTMAP_host_map         (1<<_GNTMAP_host_map)
  /* Accesses to the granted frame will be restricted to read-only access. */
 #define _GNTMAP_readonly        (2)
 #define GNTMAP_readonly         (1<<_GNTMAP_readonly)
  /*
   * GNTMAP_host_map subflag:
   *  0 => The host mapping is usable only by the guest OS.
   *  1 => The host mapping is usable by guest OS + current application.
   */
 #define _GNTMAP_application_map (3)
 #define GNTMAP_application_map  (1<<_GNTMAP_application_map)

  /*
   * GNTMAP_contains_pte subflag:
   *  0 => This map request contains a host virtual address.
   *  1 => This map request contains the machine addess of the PTE to update.
   */
 #define _GNTMAP_contains_pte    (4)
 #define GNTMAP_contains_pte     (1<<_GNTMAP_contains_pte)

 /*
  * Values for error status returns. All errors are -ve.
  */
 #define GNTST_okay             (0)  /* Normal return.                        */
 #define GNTST_general_error    (-1) /* General undefined error.              */
 #define GNTST_bad_domain       (-2) /* Unrecognsed domain id.                */
 #define GNTST_bad_gntref       (-3) /* Unrecognised or inappropriate gntref. */
 #define GNTST_bad_handle       (-4) /* Unrecognised or inappropriate handle. */
 #define GNTST_bad_virt_addr    (-5) /* Inappropriate virtual address to map. */
 #define GNTST_bad_dev_addr     (-6) /* Inappropriate device address to unmap.*/
 #define GNTST_no_device_space  (-7) /* Out of space in I/O MMU.              */
 #define GNTST_permission_denied (-8) /* Not enough privilege for operation.  */
 #define GNTST_bad_page         (-9) /* Specified page was invalid for op.    */
 #define GNTST_bad_copy_arg    (-10) /* copy arguments cross page boundary */

 #define GNTTABOP_error_msgs {                   \
     "okay",                                     \
     "undefined error",                          \
     "unrecognised domain id",                   \
     "invalid grant reference",                  \
     "invalid mapping handle",                   \
     "invalid virtual address",                  \
     "invalid device address",                   \
     "no spare translation slot in the I/O MMU", \
     "permission denied",                        \
     "bad page",                                 \
     "copy arguments cross page boundary"        \
 }

 #endif /* __XEN_PUBLIC_GRANT_TABLE_H__ */
	/******************************************************************************
	* grant_table.h
	*
	* Interface for granting foreign access to page frames, and receiving
	* page-ownership transfers.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a copy
	* of this software and associated documentation files (the "Software"), to
	* deal in the Software without restriction, including without limitation the
	* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
	* sell copies of the Software, and to permit persons to whom the Software is
	* furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
	* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
	* DEALINGS IN THE SOFTWARE.
	*
	* Copyright (c) 2004, K A Fraser
	*/

	#ifndef __XEN_PUBLIC_GRANT_TABLE_H__
	#define __XEN_PUBLIC_GRANT_TABLE_H__

	#include <xen/interface/xen.h>

	/***********************************
	* GRANT TABLE REPRESENTATION
	*/

	/* Some rough guidelines on accessing and updating grant-table entries
	* in a concurrency-safe manner. For more information, Linux contains a
	* reference implementation for guest OSes (arch/xen/kernel/grant_table.c).
	*
	* NB. WMB is a no-op on current-generation x86 processors. However, a
	* compiler barrier will still be required.
	*
	* Introducing a valid entry into the grant table:
	* 1. Write ent->domid.
	* 2. Write ent->frame:
	* GTF_permit_access: Frame to which access is permitted.
	* GTF_accept_transfer: Pseudo-phys frame slot being filled by new
	* frame, or zero if none.
	* 3. Write memory barrier (WMB).
	* 4. Write ent->flags, inc. valid type.
	*
	* Invalidating an unused GTF_permit_access entry:
	* 1. flags = ent->flags.
	* 2. Observe that !(flags & (GTF_reading\|GTF_writing)).
	* 3. Check result of SMP-safe CMPXCHG(&ent->flags, flags, 0).
	* NB. No need for WMB as reuse of entry is control-dependent on success of
	* step 3, and all architectures guarantee ordering of ctrl-dep writes.
	*
	* Invalidating an in-use GTF_permit_access entry:
	* This cannot be done directly. Request assistance from the domain controller
	* which can set a timeout on the use of a grant entry and take necessary
	* action. (NB. This is not yet implemented!).
	*
	* Invalidating an unused GTF_accept_transfer entry:
	* 1. flags = ent->flags.
	* 2. Observe that !(flags & GTF_transfer_committed). [*]
	* 3. Check result of SMP-safe CMPXCHG(&ent->flags, flags, 0).
	* NB. No need for WMB as reuse of entry is control-dependent on success of
	* step 3, and all architectures guarantee ordering of ctrl-dep writes.
	* [*] If GTF_transfer_committed is set then the grant entry is 'committed'.
	* The guest must /not/ modify the grant entry until the address of the
	* transferred frame is written. It is safe for the guest to spin waiting
	* for this to occur (detect by observing GTF_transfer_completed in
	* ent->flags).
	*
	* Invalidating a committed GTF_accept_transfer entry:
	* 1. Wait for (ent->flags & GTF_transfer_completed).
	*
	* Changing a GTF_permit_access from writable to read-only:
	* Use SMP-safe CMPXCHG to set GTF_readonly, while checking !GTF_writing.
	*
	* Changing a GTF_permit_access from read-only to writable:
	* Use SMP-safe bit-setting instruction.
	*/

	/*
	* A grant table comprises a packed array of grant entries in one or more
	* page frames shared between Xen and a guest.
	* [XEN]: This field is written by Xen and read by the sharing guest.
	* [GST]: This field is written by the guest and read by Xen.
	*/
	struct grant_entry {
	/* GTF_xxx: various type and flag information. [XEN,GST] */
	uint16_t flags;
	/* The domain being granted foreign privileges. [GST] */
	domid_t domid;
	/*
	* GTF_permit_access: Frame that @domid is allowed to map and access. [GST]
	* GTF_accept_transfer: Frame whose ownership transferred by @domid. [XEN]
	*/
	uint32_t frame;
	};

	/*
	* Type of grant entry.
	* GTF_invalid: This grant entry grants no privileges.
	* GTF_permit_access: Allow @domid to map/access @frame.
	* GTF_accept_transfer: Allow @domid to transfer ownership of one page frame
	* to this guest. Xen writes the page number to @frame.
	*/
	#define GTF_invalid (0U<<0)
	#define GTF_permit_access (1U<<0)
	#define GTF_accept_transfer (2U<<0)
	#define GTF_type_mask (3U<<0)

	/*
	* Subflags for GTF_permit_access.
	* GTF_readonly: Restrict @domid to read-only mappings and accesses. [GST]
	* GTF_reading: Grant entry is currently mapped for reading by @domid. [XEN]
	* GTF_writing: Grant entry is currently mapped for writing by @domid. [XEN]
	*/
	#define _GTF_readonly (2)
	#define GTF_readonly (1U<<_GTF_readonly)
	#define _GTF_reading (3)
	#define GTF_reading (1U<<_GTF_reading)
	#define _GTF_writing (4)
	#define GTF_writing (1U<<_GTF_writing)

	/*
	* Subflags for GTF_accept_transfer:
	* GTF_transfer_committed: Xen sets this flag to indicate that it is committed
	* to transferring ownership of a page frame. When a guest sees this flag
	* it must /not/ modify the grant entry until GTF_transfer_completed is
	* set by Xen.
	* GTF_transfer_completed: It is safe for the guest to spin-wait on this flag
	* after reading GTF_transfer_committed. Xen will always write the frame
	* address, followed by ORing this flag, in a timely manner.
	*/
	#define _GTF_transfer_committed (2)
	#define GTF_transfer_committed (1U<<_GTF_transfer_committed)
	#define _GTF_transfer_completed (3)
	#define GTF_transfer_completed (1U<<_GTF_transfer_completed)


	/***********************************
	* GRANT TABLE QUERIES AND USES
	*/

	/*
	* Reference to a grant entry in a specified domain's grant table.
	*/
	typedef uint32_t grant_ref_t;

	/*
	* Handle to track a mapping created via a grant reference.
	*/
	typedef uint32_t grant_handle_t;

	/*
	* GNTTABOP_map_grant_ref: Map the grant entry (<dom>,<ref>) for access
	* by devices and/or host CPUs. If successful, <handle> is a tracking number
	* that must be presented later to destroy the mapping(s). On error, <handle>
	* is a negative status code.
	* NOTES:
	* 1. If GNTMAP_device_map is specified then <dev_bus_addr> is the address
	* via which I/O devices may access the granted frame.
	* 2. If GNTMAP_host_map is specified then a mapping will be added at
	* either a host virtual address in the current address space, or at
	* a PTE at the specified machine address. The type of mapping to
	* perform is selected through the GNTMAP_contains_pte flag, and the
	* address is specified in <host_addr>.
	* 3. Mappings should only be destroyed via GNTTABOP_unmap_grant_ref. If a
	* host mapping is destroyed by other means then it is NOT guaranteed
	* to be accounted to the correct grant reference!
	*/
	#define GNTTABOP_map_grant_ref 0
	struct gnttab_map_grant_ref {
	/* IN parameters. */
	uint64_t host_addr;
	uint32_t flags; /* GNTMAP_* */
	grant_ref_t ref;
	domid_t dom;
	/* OUT parameters. */
	int16_t status; /* GNTST_* */
	grant_handle_t handle;
	uint64_t dev_bus_addr;
	};
	DEFINE_GUEST_HANDLE_STRUCT(gnttab_map_grant_ref);

	/*
	* GNTTABOP_unmap_grant_ref: Destroy one or more grant-reference mappings
	* tracked by <handle>. If <host_addr> or <dev_bus_addr> is zero, that
	* field is ignored. If non-zero, they must refer to a device/host mapping
	* that is tracked by <handle>
	* NOTES:
	* 1. The call may fail in an undefined manner if either mapping is not
	* tracked by <handle>.
	* 3. After executing a batch of unmaps, it is guaranteed that no stale
	* mappings will remain in the device or host TLBs.
	*/
	#define GNTTABOP_unmap_grant_ref 1
	struct gnttab_unmap_grant_ref {
	/* IN parameters. */
	uint64_t host_addr;
	uint64_t dev_bus_addr;
	grant_handle_t handle;
	/* OUT parameters. */
	int16_t status; /* GNTST_* */
	};
	DEFINE_GUEST_HANDLE_STRUCT(gnttab_unmap_grant_ref);

	/*
	* GNTTABOP_setup_table: Set up a grant table for <dom> comprising at least
	* <nr_frames> pages. The frame addresses are written to the <frame_list>.
	* Only <nr_frames> addresses are written, even if the table is larger.
	* NOTES:
	* 1. <dom> may be specified as DOMID_SELF.
	* 2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF.
	* 3. Xen may not support more than a single grant-table page per domain.
	*/
	#define GNTTABOP_setup_table 2
	struct gnttab_setup_table {
	/* IN parameters. */
	domid_t dom;
	uint32_t nr_frames;
	/* OUT parameters. */
	int16_t status; /* GNTST_* */
	GUEST_HANDLE(ulong) frame_list;
	};
	DEFINE_GUEST_HANDLE_STRUCT(gnttab_setup_table);

	/*
	* GNTTABOP_dump_table: Dump the contents of the grant table to the
	* xen console. Debugging use only.
	*/
	#define GNTTABOP_dump_table 3
	struct gnttab_dump_table {
	/* IN parameters. */
	domid_t dom;
	/* OUT parameters. */
	int16_t status; /* GNTST_* */
	};
	DEFINE_GUEST_HANDLE_STRUCT(gnttab_dump_table);

	/*
	* GNTTABOP_transfer_grant_ref: Transfer <frame> to a foreign domain. The
	* foreign domain has previously registered its interest in the transfer via
	* <domid, ref>.
	*
	* Note that, even if the transfer fails, the specified page no longer belongs
	* to the calling domain unless the error is GNTST_bad_page.
	*/
	#define GNTTABOP_transfer 4
	struct gnttab_transfer {
	/* IN parameters. */
	unsigned long mfn;
	domid_t domid;
	grant_ref_t ref;
	/* OUT parameters. */
	int16_t status;
	};
	DEFINE_GUEST_HANDLE_STRUCT(gnttab_transfer);

	/*
	* GNTTABOP_copy: Hypervisor based copy
	* source and destinations can be eithers MFNs or, for foreign domains,
	* grant references. the foreign domain has to grant read/write access
	* in its grant table.
	*
	* The flags specify what type source and destinations are (either MFN
	* or grant reference).
	*
	* Note that this can also be used to copy data between two domains
	* via a third party if the source and destination domains had previously
	* grant appropriate access to their pages to the third party.
	*
	* source_offset specifies an offset in the source frame, dest_offset
	* the offset in the target frame and len specifies the number of
	* bytes to be copied.
	*/

	#define _GNTCOPY_source_gref (0)
	#define GNTCOPY_source_gref (1<<_GNTCOPY_source_gref)
	#define _GNTCOPY_dest_gref (1)
	#define GNTCOPY_dest_gref (1<<_GNTCOPY_dest_gref)

	#define GNTTABOP_copy 5
	struct gnttab_copy {
	/* IN parameters. */
	struct {
	union {
	grant_ref_t ref;
	unsigned long gmfn;
	} u;
	domid_t domid;
	uint16_t offset;
	} source, dest;
	uint16_t len;
	uint16_t flags; /* GNTCOPY_* */
	/* OUT parameters. */
	int16_t status;
	};
	DEFINE_GUEST_HANDLE_STRUCT(gnttab_copy);

	/*
	* GNTTABOP_query_size: Query the current and maximum sizes of the shared
	* grant table.
	* NOTES:
	* 1. <dom> may be specified as DOMID_SELF.
	* 2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF.
	*/
	#define GNTTABOP_query_size 6
	struct gnttab_query_size {
	/* IN parameters. */
	domid_t dom;
	/* OUT parameters. */
	uint32_t nr_frames;
	uint32_t max_nr_frames;
	int16_t status; /* GNTST_* */
	};
	DEFINE_GUEST_HANDLE_STRUCT(gnttab_query_size);

	/*
	* Bitfield values for update_pin_status.flags.
	*/
	/* Map the grant entry for access by I/O devices. */
	#define _GNTMAP_device_map (0)
	#define GNTMAP_device_map (1<<_GNTMAP_device_map)
	/* Map the grant entry for access by host CPUs. */
	#define _GNTMAP_host_map (1)
	#define GNTMAP_host_map (1<<_GNTMAP_host_map)
	/* Accesses to the granted frame will be restricted to read-only access. */
	#define _GNTMAP_readonly (2)
	#define GNTMAP_readonly (1<<_GNTMAP_readonly)
	/*
	* GNTMAP_host_map subflag:
	* 0 => The host mapping is usable only by the guest OS.
	* 1 => The host mapping is usable by guest OS + current application.
	*/
	#define _GNTMAP_application_map (3)
	#define GNTMAP_application_map (1<<_GNTMAP_application_map)

	/*
	* GNTMAP_contains_pte subflag:
	* 0 => This map request contains a host virtual address.
	* 1 => This map request contains the machine addess of the PTE to update.
	*/
	#define _GNTMAP_contains_pte (4)
	#define GNTMAP_contains_pte (1<<_GNTMAP_contains_pte)

	/*
	* Values for error status returns. All errors are -ve.
	*/
	#define GNTST_okay (0) /* Normal return. */
	#define GNTST_general_error (-1) /* General undefined error. */
	#define GNTST_bad_domain (-2) /* Unrecognsed domain id. */
	#define GNTST_bad_gntref (-3) /* Unrecognised or inappropriate gntref. */
	#define GNTST_bad_handle (-4) /* Unrecognised or inappropriate handle. */
	#define GNTST_bad_virt_addr (-5) /* Inappropriate virtual address to map. */
	#define GNTST_bad_dev_addr (-6) /* Inappropriate device address to unmap.*/
	#define GNTST_no_device_space (-7) /* Out of space in I/O MMU. */
	#define GNTST_permission_denied (-8) /* Not enough privilege for operation. */
	#define GNTST_bad_page (-9) /* Specified page was invalid for op. */
	#define GNTST_bad_copy_arg (-10) /* copy arguments cross page boundary */

	#define GNTTABOP_error_msgs { \
	"okay", \
	"undefined error", \
	"unrecognised domain id", \
	"invalid grant reference", \
	"invalid mapping handle", \
	"invalid virtual address", \
	"invalid device address", \
	"no spare translation slot in the I/O MMU", \
	"permission denied", \
	"bad page", \
	"copy arguments cross page boundary" \
	}

	#endif /* __XEN_PUBLIC_GRANT_TABLE_H__ */