mirror of https://github.com/acidanthera/audk.git
429 lines
16 KiB
C
429 lines
16 KiB
C
/******************************************************************************
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* grant_table.h
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*
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* Interface for granting foreign access to page frames, and receiving
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* page-ownership transfers.
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*
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* SPDX-License-Identifier: MIT
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*
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* Copyright (c) 2004, K A Fraser
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*/
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#ifndef __XEN_PUBLIC_GRANT_TABLE_H__
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#define __XEN_PUBLIC_GRANT_TABLE_H__
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#include "xen.h"
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/*
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* `incontents 150 gnttab Grant Tables
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*
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* Xen's grant tables provide a generic mechanism to memory sharing
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* between domains. This shared memory interface underpins the split
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* device drivers for block and network IO.
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*
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* Each domain has its own grant table. This is a data structure that
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* is shared with Xen; it allows the domain to tell Xen what kind of
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* permissions other domains have on its pages. Entries in the grant
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* table are identified by grant references. A grant reference is an
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* integer, which indexes into the grant table. It acts as a
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* capability which the grantee can use to perform operations on the
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* granter's memory.
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*
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* This capability-based system allows shared-memory communications
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* between unprivileged domains. A grant reference also encapsulates
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* the details of a shared page, removing the need for a domain to
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* know the real machine address of a page it is sharing. This makes
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* it possible to share memory correctly with domains running in
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* fully virtualised memory.
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*/
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/***********************************
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* GRANT TABLE REPRESENTATION
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*/
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/* Some rough guidelines on accessing and updating grant-table entries
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* in a concurrency-safe manner. For more information, Linux contains a
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* reference implementation for guest OSes (drivers/xen/grant_table.c, see
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* http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob;f=drivers/xen/grant-table.c;hb=HEAD
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*
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* NB. WMB is a no-op on current-generation x86 processors. However, a
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* compiler barrier will still be required.
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*
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* Introducing a valid entry into the grant table:
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* 1. Write ent->domid.
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* 2. Write ent->frame:
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* GTF_permit_access: Frame to which access is permitted.
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* GTF_accept_transfer: Pseudo-phys frame slot being filled by new
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* frame, or zero if none.
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* 3. Write memory barrier (WMB).
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* 4. Write ent->flags, inc. valid type.
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*
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* Invalidating an unused GTF_permit_access entry:
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* 1. flags = ent->flags.
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* 2. Observe that !(flags & (GTF_reading|GTF_writing)).
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* 3. Check result of SMP-safe CMPXCHG(&ent->flags, flags, 0).
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* NB. No need for WMB as reuse of entry is control-dependent on success of
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* step 3, and all architectures guarantee ordering of ctrl-dep writes.
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*
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* Invalidating an in-use GTF_permit_access entry:
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* This cannot be done directly. Request assistance from the domain controller
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* which can set a timeout on the use of a grant entry and take necessary
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* action. (NB. This is not yet implemented!).
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*
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* Invalidating an unused GTF_accept_transfer entry:
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* 1. flags = ent->flags.
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* 2. Observe that !(flags & GTF_transfer_committed). [*]
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* 3. Check result of SMP-safe CMPXCHG(&ent->flags, flags, 0).
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* NB. No need for WMB as reuse of entry is control-dependent on success of
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* step 3, and all architectures guarantee ordering of ctrl-dep writes.
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* [*] If GTF_transfer_committed is set then the grant entry is 'committed'.
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* The guest must /not/ modify the grant entry until the address of the
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* transferred frame is written. It is safe for the guest to spin waiting
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* for this to occur (detect by observing GTF_transfer_completed in
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* ent->flags).
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*
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* Invalidating a committed GTF_accept_transfer entry:
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* 1. Wait for (ent->flags & GTF_transfer_completed).
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*
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* Changing a GTF_permit_access from writable to read-only:
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* Use SMP-safe CMPXCHG to set GTF_readonly, while checking !GTF_writing.
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*
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* Changing a GTF_permit_access from read-only to writable:
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* Use SMP-safe bit-setting instruction.
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*/
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/*
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* Reference to a grant entry in a specified domain's grant table.
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*/
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typedef UINT32 grant_ref_t;
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/*
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* A grant table comprises a packed array of grant entries in one or more
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* page frames shared between Xen and a guest.
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* [XEN]: This field is written by Xen and read by the sharing guest.
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* [GST]: This field is written by the guest and read by Xen.
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*/
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/*
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* Version 1 of the grant table entry structure is maintained purely
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* for backwards compatibility. New guests should use version 2.
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*/
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#if __XEN_INTERFACE_VERSION__ < 0x0003020a
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#define grant_entry_v1 grant_entry
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#define grant_entry_v1_t grant_entry_t
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#endif
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struct grant_entry_v1 {
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/* GTF_xxx: various type and flag information. [XEN,GST] */
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UINT16 flags;
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/* The domain being granted foreign privileges. [GST] */
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domid_t domid;
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/*
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* GTF_permit_access: Frame that @domid is allowed to map and access. [GST]
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* GTF_accept_transfer: Frame whose ownership transferred by @domid. [XEN]
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*/
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UINT32 frame;
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};
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typedef struct grant_entry_v1 grant_entry_v1_t;
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/* The first few grant table entries will be preserved across grant table
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* version changes and may be pre-populated at domain creation by tools.
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*/
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#define GNTTAB_NR_RESERVED_ENTRIES 8
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#define GNTTAB_RESERVED_CONSOLE 0
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#define GNTTAB_RESERVED_XENSTORE 1
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/*
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* Type of grant entry.
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* GTF_invalid: This grant entry grants no privileges.
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* GTF_permit_access: Allow @domid to map/access @frame.
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* GTF_accept_transfer: Allow @domid to transfer ownership of one page frame
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* to this guest. Xen writes the page number to @frame.
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* GTF_transitive: Allow @domid to transitively access a subrange of
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* @trans_grant in @trans_domid. No mappings are allowed.
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*/
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#define GTF_invalid (0U<<0)
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#define GTF_permit_access (1U<<0)
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#define GTF_accept_transfer (2U<<0)
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#define GTF_transitive (3U<<0)
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#define GTF_type_mask (3U<<0)
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/*
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* Subflags for GTF_permit_access.
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* GTF_readonly: Restrict @domid to read-only mappings and accesses. [GST]
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* GTF_reading: Grant entry is currently mapped for reading by @domid. [XEN]
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* GTF_writing: Grant entry is currently mapped for writing by @domid. [XEN]
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* GTF_PAT, GTF_PWT, GTF_PCD: (x86) cache attribute flags for the grant [GST]
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* GTF_sub_page: Grant access to only a subrange of the page. @domid
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* will only be allowed to copy from the grant, and not
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* map it. [GST]
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*/
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#define _GTF_readonly (2)
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#define GTF_readonly (1U<<_GTF_readonly)
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#define _GTF_reading (3)
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#define GTF_reading (1U<<_GTF_reading)
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#define _GTF_writing (4)
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#define GTF_writing (1U<<_GTF_writing)
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#define _GTF_PWT (5)
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#define GTF_PWT (1U<<_GTF_PWT)
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#define _GTF_PCD (6)
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#define GTF_PCD (1U<<_GTF_PCD)
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#define _GTF_PAT (7)
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#define GTF_PAT (1U<<_GTF_PAT)
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#define _GTF_sub_page (8)
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#define GTF_sub_page (1U<<_GTF_sub_page)
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/*
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* Subflags for GTF_accept_transfer:
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* GTF_transfer_committed: Xen sets this flag to indicate that it is committed
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* to transferring ownership of a page frame. When a guest sees this flag
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* it must /not/ modify the grant entry until GTF_transfer_completed is
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* set by Xen.
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* GTF_transfer_completed: It is safe for the guest to spin-wait on this flag
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* after reading GTF_transfer_committed. Xen will always write the frame
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* address, followed by ORing this flag, in a timely manner.
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*/
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#define _GTF_transfer_committed (2)
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#define GTF_transfer_committed (1U<<_GTF_transfer_committed)
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#define _GTF_transfer_completed (3)
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#define GTF_transfer_completed (1U<<_GTF_transfer_completed)
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/*
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* Version 2 grant table entries. These fulfil the same role as
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* version 1 entries, but can represent more complicated operations.
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* Any given domain will have either a version 1 or a version 2 table,
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* and every entry in the table will be the same version.
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*
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* The interface by which domains use grant references does not depend
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* on the grant table version in use by the other domain.
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*/
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#if __XEN_INTERFACE_VERSION__ >= 0x0003020a
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/*
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* Version 1 and version 2 grant entries share a common prefix. The
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* fields of the prefix are documented as part of struct
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* grant_entry_v1.
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*/
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struct grant_entry_header {
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UINT16 flags;
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domid_t domid;
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};
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typedef struct grant_entry_header grant_entry_header_t;
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/*
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* Version 2 of the grant entry structure.
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*/
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union grant_entry_v2 {
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grant_entry_header_t hdr;
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/*
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* This member is used for V1-style full page grants, where either:
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*
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* -- hdr.type is GTF_accept_transfer, or
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* -- hdr.type is GTF_permit_access and GTF_sub_page is not set.
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*
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* In that case, the frame field has the same semantics as the
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* field of the same name in the V1 entry structure.
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*/
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struct {
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grant_entry_header_t hdr;
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UINT32 pad0;
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UINT64 frame;
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} full_page;
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/*
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* If the grant type is GTF_grant_access and GTF_sub_page is set,
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* @domid is allowed to access bytes [@page_off,@page_off+@length)
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* in frame @frame.
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*/
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struct {
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grant_entry_header_t hdr;
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UINT16 page_off;
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UINT16 length;
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UINT64 frame;
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} sub_page;
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/*
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* If the grant is GTF_transitive, @domid is allowed to use the
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* grant @gref in domain @trans_domid, as if it was the local
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* domain. Obviously, the transitive access must be compatible
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* with the original grant.
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*
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* The current version of Xen does not allow transitive grants
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* to be mapped.
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*/
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struct {
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grant_entry_header_t hdr;
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domid_t trans_domid;
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UINT16 pad0;
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grant_ref_t gref;
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} transitive;
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UINT32 __spacer[4]; /* Pad to a power of two */
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};
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typedef union grant_entry_v2 grant_entry_v2_t;
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typedef UINT16 grant_status_t;
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#endif /* __XEN_INTERFACE_VERSION__ */
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/***********************************
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* GRANT TABLE QUERIES AND USES
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*/
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/* ` enum neg_errnoval
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* ` HYPERVISOR_grant_table_op(enum grant_table_op cmd,
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* ` VOID *args,
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* ` UINT32 count)
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* `
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*
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* @args points to an array of a per-command data structure. The array
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* has @count members
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*/
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/* ` enum grant_table_op { // GNTTABOP_* => struct gnttab_* */
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#define GNTTABOP_map_grant_ref 0
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#define GNTTABOP_unmap_grant_ref 1
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/* ` } */
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/*
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* Handle to track a mapping created via a grant reference.
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*/
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typedef UINT32 grant_handle_t;
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/*
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* GNTTABOP_map_grant_ref: Map the grant entry (<dom>,<ref>) for access
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* by devices and/or host CPUs. If successful, <handle> is a tracking number
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* that must be presented later to destroy the mapping(s). On error, <handle>
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* is a negative status code.
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* NOTES:
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* 1. If GNTMAP_device_map is specified then <dev_bus_addr> is the address
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* via which I/O devices may access the granted frame.
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* 2. If GNTMAP_host_map is specified then a mapping will be added at
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* either a host virtual address in the current address space, or at
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* a PTE at the specified machine address. The type of mapping to
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* perform is selected through the GNTMAP_contains_pte flag, and the
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* address is specified in <host_addr>.
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* 3. Mappings should only be destroyed via GNTTABOP_unmap_grant_ref. If a
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* host mapping is destroyed by other means then it is *NOT* guaranteed
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* to be accounted to the correct grant reference!
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*/
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struct gnttab_map_grant_ref {
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/* IN parameters. */
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UINT64 host_addr;
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UINT32 flags; /* GNTMAP_* */
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grant_ref_t ref;
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domid_t dom;
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/* OUT parameters. */
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INT16 status; /* => enum grant_status */
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grant_handle_t handle;
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UINT64 dev_bus_addr;
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};
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typedef struct gnttab_map_grant_ref gnttab_map_grant_ref_t;
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DEFINE_XEN_GUEST_HANDLE(gnttab_map_grant_ref_t);
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/*
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* GNTTABOP_unmap_grant_ref: Destroy one or more grant-reference mappings
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* tracked by <handle>. If <host_addr> or <dev_bus_addr> is zero, that
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* field is ignored. If non-zero, they must refer to a device/host mapping
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* that is tracked by <handle>
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* NOTES:
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* 1. The call may fail in an undefined manner if either mapping is not
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* tracked by <handle>.
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* 3. After executing a batch of unmaps, it is guaranteed that no stale
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* mappings will remain in the device or host TLBs.
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*/
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struct gnttab_unmap_grant_ref {
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/* IN parameters. */
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UINT64 host_addr;
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UINT64 dev_bus_addr;
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grant_handle_t handle;
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/* OUT parameters. */
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INT16 status; /* => enum grant_status */
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};
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typedef struct gnttab_unmap_grant_ref gnttab_unmap_grant_ref_t;
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DEFINE_XEN_GUEST_HANDLE(gnttab_unmap_grant_ref_t);
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/*
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* Bitfield values for gnttab_map_grant_ref.flags.
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*/
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/* Map the grant entry for access by I/O devices. */
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#define _GNTMAP_device_map (0)
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#define GNTMAP_device_map (1<<_GNTMAP_device_map)
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/* Map the grant entry for access by host CPUs. */
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#define _GNTMAP_host_map (1)
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#define GNTMAP_host_map (1<<_GNTMAP_host_map)
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/* Accesses to the granted frame will be restricted to read-only access. */
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#define _GNTMAP_readonly (2)
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#define GNTMAP_readonly (1<<_GNTMAP_readonly)
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/*
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* GNTMAP_host_map subflag:
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* 0 => The host mapping is usable only by the guest OS.
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* 1 => The host mapping is usable by guest OS + current application.
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*/
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#define _GNTMAP_application_map (3)
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#define GNTMAP_application_map (1<<_GNTMAP_application_map)
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/*
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* GNTMAP_contains_pte subflag:
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* 0 => This map request contains a host virtual address.
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* 1 => This map request contains the machine addess of the PTE to update.
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*/
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#define _GNTMAP_contains_pte (4)
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#define GNTMAP_contains_pte (1<<_GNTMAP_contains_pte)
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#define _GNTMAP_can_fail (5)
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#define GNTMAP_can_fail (1<<_GNTMAP_can_fail)
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/*
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* Bits to be placed in guest kernel available PTE bits (architecture
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* dependent; only supported when XENFEAT_gnttab_map_avail_bits is set).
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*/
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#define _GNTMAP_guest_avail0 (16)
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#define GNTMAP_guest_avail_mask ((UINT32)~0 << _GNTMAP_guest_avail0)
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/*
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* Values for error status returns. All errors are -ve.
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*/
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/* ` enum grant_status { */
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#define GNTST_okay (0) /* Normal return. */
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#define GNTST_general_error (-1) /* General undefined error. */
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#define GNTST_bad_domain (-2) /* Unrecognsed domain id. */
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#define GNTST_bad_gntref (-3) /* Unrecognised or inappropriate gntref. */
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#define GNTST_bad_handle (-4) /* Unrecognised or inappropriate handle. */
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#define GNTST_bad_virt_addr (-5) /* Inappropriate virtual address to map. */
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#define GNTST_bad_dev_addr (-6) /* Inappropriate device address to unmap.*/
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#define GNTST_no_device_space (-7) /* Out of space in I/O MMU. */
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#define GNTST_permission_denied (-8) /* Not enough privilege for operation. */
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#define GNTST_bad_page (-9) /* Specified page was invalid for op. */
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#define GNTST_bad_copy_arg (-10) /* copy arguments cross page boundary. */
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#define GNTST_address_too_big (-11) /* transfer page address too large. */
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#define GNTST_eagain (-12) /* Operation not done; try again. */
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/* ` } */
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#define GNTTABOP_error_msgs { \
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"okay", \
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"undefined error", \
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"unrecognised domain id", \
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"invalid grant reference", \
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"invalid mapping handle", \
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"invalid virtual address", \
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"invalid device address", \
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"no spare translation slot in the I/O MMU", \
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"permission denied", \
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"bad page", \
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"copy arguments cross page boundary", \
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"page address size too large", \
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"operation not done; try again" \
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}
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#endif /* __XEN_PUBLIC_GRANT_TABLE_H__ */
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/*
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* Local variables:
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* mode: C
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* c-file-style: "BSD"
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* c-basic-offset: 4
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* tab-width: 4
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* indent-tabs-mode: nil
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* End:
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*/
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