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/* SPDX-License-Identifier: MIT */
/******************************************************************************
* grant_table.h
*
* Interface for granting foreign access to page frames, and receiving
* page-ownership transfers.
*
* 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 (drivers/xen/grant_table.c, see
* http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob;f=drivers/xen/grant-table.c;hb=HEAD
*
* 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.
*/
/*
* Reference to a grant entry in a specified domain's grant table.
*/
typedef uint32_t grant_ref_t;
/*
* 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.
*/
/*
* Version 1 of the grant table entry structure is maintained largely for
* backwards compatibility. New guests are recommended to support using
* version 2 to overcome version 1 limitations, but to default to version 1.
*/
struct grant_entry_v1 {
/* 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: GFN that @domid is allowed to map and access. [GST]
* GTF_accept_transfer: GFN that @domid is allowed to transfer into. [GST]
* GTF_transfer_completed: MFN whose ownership transferred by @domid
* (non-translated guests only). [XEN]
*/
uint32_t frame;
};
/* The first few grant table entries will be preserved across grant table
* version changes and may be pre-populated at domain creation by tools.
*/
#define GNTTAB_NR_RESERVED_ENTRIES 8
#define GNTTAB_RESERVED_CONSOLE 0
#define GNTTAB_RESERVED_XENSTORE 1
/*
* 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.
* GTF_transitive: Allow @domid to transitively access a subrange of
* @trans_grant in @trans_domid. No mappings are allowed.
*/
#define GTF_invalid (0U<<0)
#define GTF_permit_access (1U<<0)
#define GTF_accept_transfer (2U<<0)
#define GTF_transitive (3U<<0)
#define GTF_type_mask (3U<<0)
/*
* Subflags for GTF_permit_access and GTF_transitive.
* 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]
* Further subflags for GTF_permit_access only.
* GTF_PAT, GTF_PWT, GTF_PCD: (x86) cache attribute flags to be used for
* mappings of the grant [GST]
* GTF_sub_page: Grant access to only a subrange of the page. @domid
* will only be allowed to copy from the grant, and not
* map it. [GST]
*/
#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)
#define _GTF_PWT (5)
#define GTF_PWT (1U<<_GTF_PWT)
#define _GTF_PCD (6)
#define GTF_PCD (1U<<_GTF_PCD)
#define _GTF_PAT (7)
#define GTF_PAT (1U<<_GTF_PAT)
#define _GTF_sub_page (8)
#define GTF_sub_page (1U<<_GTF_sub_page)
/*
* 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)
/*
* Version 2 grant table entries. These fulfil the same role as
* version 1 entries, but can represent more complicated operations.
* Any given domain will have either a version 1 or a version 2 table,
* and every entry in the table will be the same version.
*
* The interface by which domains use grant references does not depend
* on the grant table version in use by the other domain.
*/
/*
* Version 1 and version 2 grant entries share a common prefix. The
* fields of the prefix are documented as part of struct
* grant_entry_v1.
*/
struct grant_entry_header {
uint16_t flags;
domid_t domid;
};
/*
* Version 2 of the grant entry structure.
*/
union grant_entry_v2 {
struct grant_entry_header hdr;
/*
* This member is used for V1-style full page grants, where either:
*
* -- hdr.type is GTF_accept_transfer, or
* -- hdr.type is GTF_permit_access and GTF_sub_page is not set.
*
* In that case, the frame field has the same semantics as the
* field of the same name in the V1 entry structure.
*/
struct {
struct grant_entry_header hdr;
uint32_t pad0;
uint64_t frame;
} full_page;
/*
* If the grant type is GTF_grant_access and GTF_sub_page is set,
* @domid is allowed to access bytes [@page_off,@page_off+@length)
* in frame @frame.
*/
struct {
struct grant_entry_header hdr;
uint16_t page_off;
uint16_t length;
uint64_t frame;
} sub_page;
/*
* If the grant is GTF_transitive, @domid is allowed to use the
* grant @gref in domain @trans_domid, as if it was the local
* domain. Obviously, the transitive access must be compatible
* with the original grant.
*
* The current version of Xen does not allow transitive grants
* to be mapped.
*/
struct {
struct grant_entry_header hdr;
domid_t trans_domid;
uint16_t pad0;
grant_ref_t gref;
} transitive;
uint32_t __spacer[4]; /* Pad to a power of two */
};
typedef uint16_t grant_status_t;
/***********************************
* GRANT TABLE QUERIES AND USES
*/
#define GNTTABOP_map_grant_ref 0
#define GNTTABOP_unmap_grant_ref 1
#define GNTTABOP_setup_table 2
#define GNTTABOP_dump_table 3
#define GNTTABOP_transfer 4
#define GNTTABOP_copy 5
#define GNTTABOP_query_size 6
#define GNTTABOP_unmap_and_replace 7
#define GNTTABOP_set_version 8
#define GNTTABOP_get_status_frames 9
#define GNTTABOP_get_version 10
#define GNTTABOP_swap_grant_ref 11
#define GNTTABOP_cache_flush 12
/* ` } */
/*
* 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, <status>
* 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!
*/
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.
*/
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.
*/
struct gnttab_setup_table {
/* IN parameters. */
domid_t dom;
uint32_t nr_frames;
/* OUT parameters. */
int16_t status; /* GNTST_* */
GUEST_HANDLE(xen_pfn_t) 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.
*/
struct gnttab_dump_table {
/* IN parameters. */
domid_t dom;
/* OUT parameters. */
int16_t status; /* GNTST_* */
};
DEFINE_GUEST_HANDLE_STRUCT(gnttab_dump_table);
/*
* GNTTABOP_transfer: 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.
*
* Note further that only PV guests can use this operation.
*/
struct gnttab_transfer {
/* IN parameters. */
xen_pfn_t 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)
struct gnttab_copy {
/* IN parameters. */
struct gnttab_copy_ptr {
union {
grant_ref_t ref;
xen_pfn_t 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.
*/
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);
/*
* GNTTABOP_unmap_and_replace: Destroy one or more grant-reference mappings
* tracked by <handle> but atomically replace the page table entry with one
* pointing to the machine address under <new_addr>. <new_addr> will be
* redirected to the null entry.
* NOTES:
* 1. The call may fail in an undefined manner if either mapping is not
* tracked by <handle>.
* 2. After executing a batch of unmaps, it is guaranteed that no stale
* mappings will remain in the device or host TLBs.
*/
struct gnttab_unmap_and_replace {
/* IN parameters. */
uint64_t host_addr;
uint64_t new_addr;
grant_handle_t handle;
/* OUT parameters. */
int16_t status; /* GNTST_* */
};
DEFINE_GUEST_HANDLE_STRUCT(gnttab_unmap_and_replace);
/*
* GNTTABOP_set_version: Request a particular version of the grant
* table shared table structure. This operation may be used to toggle
* between different versions, but must be performed while no grants
* are active. The only defined versions are 1 and 2.
*/
struct gnttab_set_version {
/* IN/OUT parameters */
uint32_t version;
};
DEFINE_GUEST_HANDLE_STRUCT(gnttab_set_version);
/*
* GNTTABOP_get_status_frames: Get the list of frames used to store grant
* status for <dom>. In grant format version 2, the status is separated
* from the other shared grant fields to allow more efficient synchronization
* using barriers instead of atomic cmpexch operations.
* <nr_frames> specify the size of vector <frame_list>.
* The frame addresses are returned in the <frame_list>.
* Only <nr_frames> addresses are returned, 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.
*/
struct gnttab_get_status_frames {
/* IN parameters. */
uint32_t nr_frames;
domid_t dom;
/* OUT parameters. */
int16_t status; /* GNTST_* */
GUEST_HANDLE(uint64_t) frame_list;
};
DEFINE_GUEST_HANDLE_STRUCT(gnttab_get_status_frames);
/*
* GNTTABOP_get_version: Get the grant table version which is in
* effect for domain <dom>.
*/
struct gnttab_get_version {
/* IN parameters */
domid_t dom;
uint16_t pad;
/* OUT parameters */
uint32_t version;
};
DEFINE_GUEST_HANDLE_STRUCT(gnttab_get_version);
/*
* GNTTABOP_swap_grant_ref: Swap the contents of two grant entries.
*/
struct gnttab_swap_grant_ref {
/* IN parameters */
grant_ref_t ref_a;
grant_ref_t ref_b;
/* OUT parameters */
int16_t status; /* GNTST_* */
};
DEFINE_GUEST_HANDLE_STRUCT(gnttab_swap_grant_ref);
/*
* Issue one or more cache maintenance operations on a portion of a
* page granted to the calling domain by a foreign domain.
*/
struct gnttab_cache_flush {
union {
uint64_t dev_bus_addr;
grant_ref_t ref;
} a;
uint16_t offset; /* offset from start of grant */
uint16_t length; /* size within the grant */
#define GNTTAB_CACHE_CLEAN (1u<<0)
#define GNTTAB_CACHE_INVAL (1u<<1)
#define GNTTAB_CACHE_SOURCE_GREF (1u<<31)
uint32_t op;
};
DEFINE_GUEST_HANDLE_STRUCT(gnttab_cache_flush);
/*
* Bitfield values for gnttab_map_grant_ref.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)
/*
* Bits to be placed in guest kernel available PTE bits (architecture
* dependent; only supported when XENFEAT_gnttab_map_avail_bits is set).
*/
#define _GNTMAP_guest_avail0 (16)
#define GNTMAP_guest_avail_mask ((uint32_t)~0 << _GNTMAP_guest_avail0)
/*
* 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 GNTST_address_too_big (-11) /* transfer page address too large. */
#define GNTST_eagain (-12) /* Operation not done; try again. */
#define GNTST_no_space (-13) /* Out of space (handles etc). */
#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", \
"page address size too large", \
"operation not done; try again", \
"out of space", \
}
#endif /* __XEN_PUBLIC_GRANT_TABLE_H__ */