1 /* SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR MIT) */
2 /******************************************************************************
3  * gntdev.h
4  *
5  * Interface to /dev/xen/gntdev.
6  *
7  * Copyright (c) 2007, D G Murray
8  * Copyright (c) 2018, Oleksandr Andrushchenko, EPAM Systems Inc.
9  *
10  * This program is free software; you can redistribute it and/or
11  * modify it under the terms of the GNU General Public License version 2
12  * as published by the Free Software Foundation; or, when distributed
13  * separately from the Linux kernel or incorporated into other
14  * software packages, subject to the following license:
15  *
16  * Permission is hereby granted, free of charge, to any person obtaining a copy
17  * of this source file (the "Software"), to deal in the Software without
18  * restriction, including without limitation the rights to use, copy, modify,
19  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
20  * and to permit persons to whom the Software is furnished to do so, subject to
21  * the following conditions:
22  *
23  * The above copyright notice and this permission notice shall be included in
24  * all copies or substantial portions of the Software.
25  *
26  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
27  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
28  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
29  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
30  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
31  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
32  * IN THE SOFTWARE.
33  */
34 
35 #ifndef __LINUX_PUBLIC_GNTDEV_H__
36 #define __LINUX_PUBLIC_GNTDEV_H__
37 
38 #include <linux/types.h>
39 
40 struct ioctl_gntdev_grant_ref {
41 	/* The domain ID of the grant to be mapped. */
42 	__u32 domid;
43 	/* The grant reference of the grant to be mapped. */
44 	__u32 ref;
45 };
46 
47 /*
48  * Inserts the grant references into the mapping table of an instance
49  * of gntdev. N.B. This does not perform the mapping, which is deferred
50  * until mmap() is called with @index as the offset. @index should be
51  * considered opaque to userspace, with one exception: if no grant
52  * references have ever been inserted into the mapping table of this
53  * instance, @index will be set to 0. This is necessary to use gntdev
54  * with userspace APIs that expect a file descriptor that can be
55  * mmap()'d at offset 0, such as Wayland. If @count is set to 0, this
56  * ioctl will fail.
57  */
58 #define IOCTL_GNTDEV_MAP_GRANT_REF \
59 _IOC(_IOC_NONE, 'G', 0, sizeof(struct ioctl_gntdev_map_grant_ref))
60 struct ioctl_gntdev_map_grant_ref {
61 	/* IN parameters */
62 	/* The number of grants to be mapped. */
63 	__u32 count;
64 	__u32 pad;
65 	/* OUT parameters */
66 	/* The offset to be used on a subsequent call to mmap(). */
67 	__u64 index;
68 	/* Variable IN parameter. */
69 	/* Array of grant references, of size @count. */
70 	struct ioctl_gntdev_grant_ref refs[1];
71 };
72 
73 /*
74  * Removes the grant references from the mapping table of an instance of
75  * gntdev. N.B. munmap() must be called on the relevant virtual address(es)
76  * before this ioctl is called, or an error will result.
77  */
78 #define IOCTL_GNTDEV_UNMAP_GRANT_REF \
79 _IOC(_IOC_NONE, 'G', 1, sizeof(struct ioctl_gntdev_unmap_grant_ref))
80 struct ioctl_gntdev_unmap_grant_ref {
81 	/* IN parameters */
82 	/* The offset was returned by the corresponding map operation. */
83 	__u64 index;
84 	/* The number of pages to be unmapped. */
85 	__u32 count;
86 	__u32 pad;
87 };
88 
89 /*
90  * Returns the offset in the driver's address space that corresponds
91  * to @vaddr. This can be used to perform a munmap(), followed by an
92  * UNMAP_GRANT_REF ioctl, where no state about the offset is retained by
93  * the caller. The number of pages that were allocated at the same time as
94  * @vaddr is returned in @count.
95  *
96  * N.B. Where more than one page has been mapped into a contiguous range, the
97  *      supplied @vaddr must correspond to the start of the range; otherwise
98  *      an error will result. It is only possible to munmap() the entire
99  *      contiguously-allocated range at once, and not any subrange thereof.
100  */
101 #define IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR \
102 _IOC(_IOC_NONE, 'G', 2, sizeof(struct ioctl_gntdev_get_offset_for_vaddr))
103 struct ioctl_gntdev_get_offset_for_vaddr {
104 	/* IN parameters */
105 	/* The virtual address of the first mapped page in a range. */
106 	__u64 vaddr;
107 	/* OUT parameters */
108 	/* The offset that was used in the initial mmap() operation. */
109 	__u64 offset;
110 	/* The number of pages mapped in the VM area that begins at @vaddr. */
111 	__u32 count;
112 	__u32 pad;
113 };
114 
115 /*
116  * Sets the maximum number of grants that may mapped at once by this gntdev
117  * instance.
118  *
119  * N.B. This must be called before any other ioctl is performed on the device.
120  */
121 #define IOCTL_GNTDEV_SET_MAX_GRANTS \
122 _IOC(_IOC_NONE, 'G', 3, sizeof(struct ioctl_gntdev_set_max_grants))
123 struct ioctl_gntdev_set_max_grants {
124 	/* IN parameter */
125 	/* The maximum number of grants that may be mapped at once. */
126 	__u32 count;
127 };
128 
129 /*
130  * Sets up an unmap notification within the page, so that the other side can do
131  * cleanup if this side crashes. Required to implement cross-domain robust
132  * mutexes or close notification on communication channels.
133  *
134  * Each mapped page only supports one notification; multiple calls referring to
135  * the same page overwrite the previous notification. You must clear the
136  * notification prior to the IOCTL_GNTALLOC_DEALLOC_GREF if you do not want it
137  * to occur.
138  */
139 #define IOCTL_GNTDEV_SET_UNMAP_NOTIFY \
140 _IOC(_IOC_NONE, 'G', 7, sizeof(struct ioctl_gntdev_unmap_notify))
141 struct ioctl_gntdev_unmap_notify {
142 	/* IN parameters */
143 	/* Offset in the file descriptor for a byte within the page (same as
144 	 * used in mmap). If using UNMAP_NOTIFY_CLEAR_BYTE, this is the byte to
145 	 * be cleared. Otherwise, it can be any byte in the page whose
146 	 * notification we are adjusting.
147 	 */
148 	__u64 index;
149 	/* Action(s) to take on unmap */
150 	__u32 action;
151 	/* Event channel to notify */
152 	__u32 event_channel_port;
153 };
154 
155 struct gntdev_grant_copy_segment {
156 	union {
157 		void __user *virt;
158 		struct {
159 			grant_ref_t ref;
160 			__u16 offset;
161 			domid_t domid;
162 		} foreign;
163 	} source, dest;
164 	__u16 len;
165 
166 	__u16 flags;  /* GNTCOPY_* */
167 	__s16 status; /* GNTST_* */
168 };
169 
170 /*
171  * Copy between grant references and local buffers.
172  *
173  * The copy is split into @count @segments, each of which can copy
174  * to/from one grant reference.
175  *
176  * Each segment is similar to struct gnttab_copy in the hypervisor ABI
177  * except the local buffer is specified using a virtual address
178  * (instead of a GFN and offset).
179  *
180  * The local buffer may cross a Xen page boundary -- the driver will
181  * split segments into multiple ops if required.
182  *
183  * Returns 0 if all segments have been processed and @status in each
184  * segment is valid.  Note that one or more segments may have failed
185  * (status != GNTST_okay).
186  *
187  * If the driver had to split a segment into two or more ops, @status
188  * includes the status of the first failed op for that segment (or
189  * GNTST_okay if all ops were successful).
190  *
191  * If -1 is returned, the status of all segments is undefined.
192  *
193  * EINVAL: A segment has local buffers for both source and
194  *         destination.
195  * EINVAL: A segment crosses the boundary of a foreign page.
196  * EFAULT: A segment's local buffer is not accessible.
197  */
198 #define IOCTL_GNTDEV_GRANT_COPY \
199 	_IOC(_IOC_NONE, 'G', 8, sizeof(struct ioctl_gntdev_grant_copy))
200 struct ioctl_gntdev_grant_copy {
201 	unsigned int count;
202 	struct gntdev_grant_copy_segment __user *segments;
203 };
204 
205 /* Clear (set to zero) the byte specified by index */
206 #define UNMAP_NOTIFY_CLEAR_BYTE 0x1
207 /* Send an interrupt on the indicated event channel */
208 #define UNMAP_NOTIFY_SEND_EVENT 0x2
209 
210 /*
211  * Flags to be used while requesting memory mapping's backing storage
212  * to be allocated with DMA API.
213  */
214 
215 /*
216  * The buffer is backed with memory allocated with dma_alloc_wc.
217  */
218 #define GNTDEV_DMA_FLAG_WC		(1 << 0)
219 
220 /*
221  * The buffer is backed with memory allocated with dma_alloc_coherent.
222  */
223 #define GNTDEV_DMA_FLAG_COHERENT	(1 << 1)
224 
225 /*
226  * Create a dma-buf [1] from grant references @refs of count @count provided
227  * by the foreign domain @domid with flags @flags.
228  *
229  * By default dma-buf is backed by system memory pages, but by providing
230  * one of the GNTDEV_DMA_FLAG_XXX flags it can also be created as
231  * a DMA write-combine or coherent buffer, e.g. allocated with dma_alloc_wc/
232  * dma_alloc_coherent.
233  *
234  * Returns 0 if dma-buf was successfully created and the corresponding
235  * dma-buf's file descriptor is returned in @fd.
236  *
237  * [1] Documentation/driver-api/dma-buf.rst
238  */
239 
240 #define IOCTL_GNTDEV_DMABUF_EXP_FROM_REFS \
241 	_IOC(_IOC_NONE, 'G', 9, \
242 	     sizeof(struct ioctl_gntdev_dmabuf_exp_from_refs))
243 struct ioctl_gntdev_dmabuf_exp_from_refs {
244 	/* IN parameters. */
245 	/* Specific options for this dma-buf: see GNTDEV_DMA_FLAG_XXX. */
246 	__u32 flags;
247 	/* Number of grant references in @refs array. */
248 	__u32 count;
249 	/* OUT parameters. */
250 	/* File descriptor of the dma-buf. */
251 	__u32 fd;
252 	/* The domain ID of the grant references to be mapped. */
253 	__u32 domid;
254 	/* Variable IN parameter. */
255 	/* Array of grant references of size @count. */
256 	__u32 refs[1];
257 };
258 
259 /*
260  * This will block until the dma-buf with the file descriptor @fd is
261  * released. This is only valid for buffers created with
262  * IOCTL_GNTDEV_DMABUF_EXP_FROM_REFS.
263  *
264  * If within @wait_to_ms milliseconds the buffer is not released
265  * then -ETIMEDOUT error is returned.
266  * If the buffer with the file descriptor @fd does not exist or has already
267  * been released, then -ENOENT is returned. For valid file descriptors
268  * this must not be treated as error.
269  */
270 #define IOCTL_GNTDEV_DMABUF_EXP_WAIT_RELEASED \
271 	_IOC(_IOC_NONE, 'G', 10, \
272 	     sizeof(struct ioctl_gntdev_dmabuf_exp_wait_released))
273 struct ioctl_gntdev_dmabuf_exp_wait_released {
274 	/* IN parameters */
275 	__u32 fd;
276 	__u32 wait_to_ms;
277 };
278 
279 /*
280  * Import a dma-buf with file descriptor @fd and export granted references
281  * to the pages of that dma-buf into array @refs of size @count.
282  */
283 #define IOCTL_GNTDEV_DMABUF_IMP_TO_REFS \
284 	_IOC(_IOC_NONE, 'G', 11, \
285 	     sizeof(struct ioctl_gntdev_dmabuf_imp_to_refs))
286 struct ioctl_gntdev_dmabuf_imp_to_refs {
287 	/* IN parameters. */
288 	/* File descriptor of the dma-buf. */
289 	__u32 fd;
290 	/* Number of grant references in @refs array. */
291 	__u32 count;
292 	/* The domain ID for which references to be granted. */
293 	__u32 domid;
294 	/* Reserved - must be zero. */
295 	__u32 reserved;
296 	/* OUT parameters. */
297 	/* Array of grant references of size @count. */
298 	__u32 refs[1];
299 };
300 
301 /*
302  * This will close all references to the imported buffer with file descriptor
303  * @fd, so it can be released by the owner. This is only valid for buffers
304  * created with IOCTL_GNTDEV_DMABUF_IMP_TO_REFS.
305  */
306 #define IOCTL_GNTDEV_DMABUF_IMP_RELEASE \
307 	_IOC(_IOC_NONE, 'G', 12, \
308 	     sizeof(struct ioctl_gntdev_dmabuf_imp_release))
309 struct ioctl_gntdev_dmabuf_imp_release {
310 	/* IN parameters */
311 	__u32 fd;
312 	__u32 reserved;
313 };
314 
315 #endif /* __LINUX_PUBLIC_GNTDEV_H__ */
316