1 /******************************************************************************
2  * gntalloc.h
3  *
4  * Interface to /dev/xen/gntalloc.
5  *
6  * Author: Daniel De Graaf <dgdegra@tycho.nsa.gov>
7  *
8  * This file is in the public domain.
9  */
10 
11 #ifndef __LINUX_PUBLIC_GNTALLOC_H__
12 #define __LINUX_PUBLIC_GNTALLOC_H__
13 
14 #include <linux/types.h>
15 
16 /*
17  * Allocates a new page and creates a new grant reference.
18  */
19 #define IOCTL_GNTALLOC_ALLOC_GREF \
20 _IOC(_IOC_NONE, 'G', 5, sizeof(struct ioctl_gntalloc_alloc_gref))
21 struct ioctl_gntalloc_alloc_gref {
22 	/* IN parameters */
23 	/* The ID of the domain to be given access to the grants. */
24 	__u16 domid;
25 	/* Flags for this mapping */
26 	__u16 flags;
27 	/* Number of pages to map */
28 	__u32 count;
29 	/* OUT parameters */
30 	/* The offset to be used on a subsequent call to mmap(). */
31 	__u64 index;
32 	/* The grant references of the newly created grant, one per page */
33 	/* Variable size, depending on count */
34 	__u32 gref_ids[1];
35 };
36 
37 #define GNTALLOC_FLAG_WRITABLE 1
38 
39 /*
40  * Deallocates the grant reference, allowing the associated page to be freed if
41  * no other domains are using it.
42  */
43 #define IOCTL_GNTALLOC_DEALLOC_GREF \
44 _IOC(_IOC_NONE, 'G', 6, sizeof(struct ioctl_gntalloc_dealloc_gref))
45 struct ioctl_gntalloc_dealloc_gref {
46 	/* IN parameters */
47 	/* The offset returned in the map operation */
48 	__u64 index;
49 	/* Number of references to unmap */
50 	__u32 count;
51 };
52 
53 /*
54  * Sets up an unmap notification within the page, so that the other side can do
55  * cleanup if this side crashes. Required to implement cross-domain robust
56  * mutexes or close notification on communication channels.
57  *
58  * Each mapped page only supports one notification; multiple calls referring to
59  * the same page overwrite the previous notification. You must clear the
60  * notification prior to the IOCTL_GNTALLOC_DEALLOC_GREF if you do not want it
61  * to occur.
62  */
63 #define IOCTL_GNTALLOC_SET_UNMAP_NOTIFY \
64 _IOC(_IOC_NONE, 'G', 7, sizeof(struct ioctl_gntalloc_unmap_notify))
65 struct ioctl_gntalloc_unmap_notify {
66 	/* IN parameters */
67 	/* Offset in the file descriptor for a byte within the page (same as
68 	 * used in mmap). If using UNMAP_NOTIFY_CLEAR_BYTE, this is the byte to
69 	 * be cleared. Otherwise, it can be any byte in the page whose
70 	 * notification we are adjusting.
71 	 */
72 	__u64 index;
73 	/* Action(s) to take on unmap */
74 	__u32 action;
75 	/* Event channel to notify */
76 	__u32 event_channel_port;
77 };
78 
79 /* Clear (set to zero) the byte specified by index */
80 #define UNMAP_NOTIFY_CLEAR_BYTE 0x1
81 /* Send an interrupt on the indicated event channel */
82 #define UNMAP_NOTIFY_SEND_EVENT 0x2
83 
84 #endif /* __LINUX_PUBLIC_GNTALLOC_H__ */
85