ia64/xen-unstable

view xen/include/public/grant_table.h @ 6316:f7dfaa2af90c

merge?
author cl349@firebug.cl.cam.ac.uk
date Sun Aug 21 11:02:00 2005 +0000 (2005-08-21)
parents 1872e09bfba3
children 6721abf6b16d
line source
1 /******************************************************************************
2 * grant_table.h
3 *
4 * Interface for granting foreign access to page frames, and receiving
5 * page-ownership transfers.
6 *
7 * Copyright (c) 2004, K A Fraser
8 */
10 #ifndef __XEN_PUBLIC_GRANT_TABLE_H__
11 #define __XEN_PUBLIC_GRANT_TABLE_H__
14 /***********************************
15 * GRANT TABLE REPRESENTATION
16 */
18 /* Some rough guidelines on accessing and updating grant-table entries
19 * in a concurrency-safe manner. For more information, Linux contains a
20 * reference implementation for guest OSes (arch/xen/kernel/grant_table.c).
21 *
22 * NB. WMB is a no-op on current-generation x86 processors. However, a
23 * compiler barrier will still be required.
24 *
25 * Introducing a valid entry into the grant table:
26 * 1. Write ent->domid.
27 * 2. Write ent->frame:
28 * GTF_permit_access: Frame to which access is permitted.
29 * GTF_accept_transfer: Pseudo-phys frame slot being filled by new
30 * frame, or zero if none.
31 * 3. Write memory barrier (WMB).
32 * 4. Write ent->flags, inc. valid type.
33 *
34 * Invalidating an unused GTF_permit_access entry:
35 * 1. flags = ent->flags.
36 * 2. Observe that !(flags & (GTF_reading|GTF_writing)).
37 * 3. Check result of SMP-safe CMPXCHG(&ent->flags, flags, 0).
38 * NB. No need for WMB as reuse of entry is control-dependent on success of
39 * step 3, and all architectures guarantee ordering of ctrl-dep writes.
40 *
41 * Invalidating an in-use GTF_permit_access entry:
42 * This cannot be done directly. Request assistance from the domain controller
43 * which can set a timeout on the use of a grant entry and take necessary
44 * action. (NB. This is not yet implemented!).
45 *
46 * Invalidating an unused GTF_accept_transfer entry:
47 * 1. flags = ent->flags.
48 * 2. Observe that !(flags & GTF_transfer_committed). [*]
49 * 3. Check result of SMP-safe CMPXCHG(&ent->flags, flags, 0).
50 * NB. No need for WMB as reuse of entry is control-dependent on success of
51 * step 3, and all architectures guarantee ordering of ctrl-dep writes.
52 * [*] If GTF_transfer_committed is set then the grant entry is 'committed'.
53 * The guest must /not/ modify the grant entry until the address of the
54 * transferred frame is written. It is safe for the guest to spin waiting
55 * for this to occur (detect by observing GTF_transfer_completed in
56 * ent->flags).
57 *
58 * Invalidating a committed GTF_accept_transfer entry:
59 * 1. Wait for (ent->flags & GTF_transfer_completed).
60 *
61 * Changing a GTF_permit_access from writable to read-only:
62 * Use SMP-safe CMPXCHG to set GTF_readonly, while checking !GTF_writing.
63 *
64 * Changing a GTF_permit_access from read-only to writable:
65 * Use SMP-safe bit-setting instruction.
66 */
68 /*
69 * A grant table comprises a packed array of grant entries in one or more
70 * page frames shared between Xen and a guest.
71 * [XEN]: This field is written by Xen and read by the sharing guest.
72 * [GST]: This field is written by the guest and read by Xen.
73 */
74 typedef struct grant_entry {
75 /* GTF_xxx: various type and flag information. [XEN,GST] */
76 u16 flags;
77 /* The domain being granted foreign privileges. [GST] */
78 domid_t domid;
79 /*
80 * GTF_permit_access: Frame that @domid is allowed to map and access. [GST]
81 * GTF_accept_transfer: Frame whose ownership transferred by @domid. [XEN]
82 */
83 u32 frame;
84 } grant_entry_t;
86 /*
87 * Type of grant entry.
88 * GTF_invalid: This grant entry grants no privileges.
89 * GTF_permit_access: Allow @domid to map/access @frame.
90 * GTF_accept_transfer: Allow @domid to transfer ownership of one page frame
91 * to this guest. Xen writes the page number to @frame.
92 */
93 #define GTF_invalid (0U<<0)
94 #define GTF_permit_access (1U<<0)
95 #define GTF_accept_transfer (2U<<0)
96 #define GTF_type_mask (3U<<0)
98 /*
99 * Subflags for GTF_permit_access.
100 * GTF_readonly: Restrict @domid to read-only mappings and accesses. [GST]
101 * GTF_reading: Grant entry is currently mapped for reading by @domid. [XEN]
102 * GTF_writing: Grant entry is currently mapped for writing by @domid. [XEN]
103 */
104 #define _GTF_readonly (2)
105 #define GTF_readonly (1U<<_GTF_readonly)
106 #define _GTF_reading (3)
107 #define GTF_reading (1U<<_GTF_reading)
108 #define _GTF_writing (4)
109 #define GTF_writing (1U<<_GTF_writing)
111 /*
112 * Subflags for GTF_accept_transfer:
113 * GTF_transfer_committed: Xen sets this flag to indicate that it is committed
114 * to transferring ownership of a page frame. When a guest sees this flag
115 * it must /not/ modify the grant entry until GTF_transfer_completed is
116 * set by Xen.
117 * GTF_transfer_completed: It is safe for the guest to spin-wait on this flag
118 * after reading GTF_transfer_committed. Xen will always write the frame
119 * address, followed by ORing this flag, in a timely manner.
120 */
121 #define _GTF_transfer_committed (2)
122 #define GTF_transfer_committed (1U<<_GTF_transfer_committed)
123 #define _GTF_transfer_completed (3)
124 #define GTF_transfer_completed (1U<<_GTF_transfer_completed)
127 /***********************************
128 * GRANT TABLE QUERIES AND USES
129 */
131 /*
132 * Reference to a grant entry in a specified domain's grant table.
133 */
134 typedef u16 grant_ref_t;
136 /*
137 * GNTTABOP_map_grant_ref: Map the grant entry (<dom>,<ref>) for access
138 * by devices and/or host CPUs. If successful, <handle> is a tracking number
139 * that must be presented later to destroy the mapping(s). On error, <handle>
140 * is a negative status code.
141 * NOTES:
142 * 1. If GNTPIN_map_for_dev is specified then <dev_bus_addr> is the address
143 * via which I/O devices may access the granted frame.
144 * 2. If GNTPIN_map_for_host is specified then a mapping will be added at
145 * either a host virtual address in the current address space, or at
146 * a PTE at the specified machine address. The type of mapping to
147 * perform is selected through the GNTMAP_contains_pte flag, and the
148 * address is specified in <host_addr>.
149 * 3. Mappings should only be destroyed via GNTTABOP_unmap_grant_ref. If a
150 * host mapping is destroyed by other means then it is *NOT* guaranteed
151 * to be accounted to the correct grant reference!
152 */
153 #define GNTTABOP_map_grant_ref 0
154 typedef struct gnttab_map_grant_ref {
155 /* IN parameters. */
156 u64 host_addr;
157 domid_t dom;
158 grant_ref_t ref;
159 u16 flags; /* GNTMAP_* */
160 /* OUT parameters. */
161 s16 handle; /* +ve: handle; -ve: GNTST_* */
162 u64 dev_bus_addr;
163 } gnttab_map_grant_ref_t;
165 /*
166 * GNTTABOP_unmap_grant_ref: Destroy one or more grant-reference mappings
167 * tracked by <handle>. If <host_addr> or <dev_bus_addr> is zero, that
168 * field is ignored. If non-zero, they must refer to a device/host mapping
169 * that is tracked by <handle>
170 * NOTES:
171 * 1. The call may fail in an undefined manner if either mapping is not
172 * tracked by <handle>.
173 * 3. After executing a batch of unmaps, it is guaranteed that no stale
174 * mappings will remain in the device or host TLBs.
175 */
176 #define GNTTABOP_unmap_grant_ref 1
177 typedef struct gnttab_unmap_grant_ref {
178 /* IN parameters. */
179 u64 host_addr;
180 u64 dev_bus_addr;
181 u16 handle;
182 /* OUT parameters. */
183 s16 status; /* GNTST_* */
184 } gnttab_unmap_grant_ref_t;
186 #define GNTUNMAP_DEV_FROM_VIRT (~0U)
188 /*
189 * GNTTABOP_setup_table: Set up a grant table for <dom> comprising at least
190 * <nr_frames> pages. The frame addresses are written to the <frame_list>.
191 * Only <nr_frames> addresses are written, even if the table is larger.
192 * NOTES:
193 * 1. <dom> may be specified as DOMID_SELF.
194 * 2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF.
195 * 3. Xen may not support more than a single grant-table page per domain.
196 */
197 #define GNTTABOP_setup_table 2
198 typedef struct gnttab_setup_table {
199 /* IN parameters. */
200 domid_t dom;
201 u16 nr_frames;
202 /* OUT parameters. */
203 s16 status; /* GNTST_* */
204 unsigned long *frame_list;
205 } gnttab_setup_table_t;
207 /*
208 * GNTTABOP_dump_table: Dump the contents of the grant table to the
209 * xen console. Debugging use only.
210 */
211 #define GNTTABOP_dump_table 3
212 typedef struct gnttab_dump_table {
213 /* IN parameters. */
214 domid_t dom;
215 /* OUT parameters. */
216 s16 status; /* GNTST_* */
217 } gnttab_dump_table_t;
219 /*
220 * GNTTABOP_donate_grant_ref: Donate <frame> to a foreign domain. The
221 * foreign domain has previously registered the details of the transfer.
222 * These can be identified from <handle>, a grant reference.
223 */
224 #define GNTTABOP_donate 4
225 typedef struct {
226 unsigned long mfn; /* 0 */
227 domid_t domid; /* 4 */
228 u16 handle; /* 8 */
229 s16 status; /* 10: GNTST_* */
230 u32 __pad;
231 } gnttab_donate_t; /* 14 bytes */
233 /*
234 * Bitfield values for update_pin_status.flags.
235 */
236 /* Map the grant entry for access by I/O devices. */
237 #define _GNTMAP_device_map (0)
238 #define GNTMAP_device_map (1<<_GNTMAP_device_map)
239 /* Map the grant entry for access by host CPUs. */
240 #define _GNTMAP_host_map (1)
241 #define GNTMAP_host_map (1<<_GNTMAP_host_map)
242 /* Accesses to the granted frame will be restricted to read-only access. */
243 #define _GNTMAP_readonly (2)
244 #define GNTMAP_readonly (1<<_GNTMAP_readonly)
245 /*
246 * GNTMAP_host_map subflag:
247 * 0 => The host mapping is usable only by the guest OS.
248 * 1 => The host mapping is usable by guest OS + current application.
249 */
250 #define _GNTMAP_application_map (3)
251 #define GNTMAP_application_map (1<<_GNTMAP_application_map)
253 /*
254 * GNTMAP_contains_pte subflag:
255 * 0 => This map request contains a host virtual address.
256 * 1 => This map request contains the machine addess of the PTE to update.
257 */
258 #define _GNTMAP_contains_pte (4)
259 #define GNTMAP_contains_pte (1<<_GNTMAP_contains_pte)
261 /*
262 * Values for error status returns. All errors are -ve.
263 */
264 #define GNTST_okay (0) /* Normal return. */
265 #define GNTST_general_error (-1) /* General undefined error. */
266 #define GNTST_bad_domain (-2) /* Unrecognsed domain id. */
267 #define GNTST_bad_gntref (-3) /* Unrecognised or inappropriate gntref. */
268 #define GNTST_bad_handle (-4) /* Unrecognised or inappropriate handle. */
269 #define GNTST_bad_virt_addr (-5) /* Inappropriate virtual address to map. */
270 #define GNTST_bad_dev_addr (-6) /* Inappropriate device address to unmap.*/
271 #define GNTST_no_device_space (-7) /* Out of space in I/O MMU. */
272 #define GNTST_permission_denied (-8) /* Not enough privilege for operation. */
274 #define GNTTABOP_error_msgs { \
275 "okay", \
276 "undefined error", \
277 "unrecognised domain id", \
278 "invalid grant reference", \
279 "invalid mapping handle", \
280 "invalid virtual address", \
281 "invalid device address", \
282 "no spare translation slot in the I/O MMU", \
283 "permission denied" \
284 }
286 #endif /* __XEN_PUBLIC_GRANT_TABLE_H__ */