include/uapi/xen/gntalloc.h

   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         union {
  35                 __u32 gref_ids[1];
  36                 __DECLARE_FLEX_ARRAY(__u32, gref_ids_flex);
  37         };
  38 };
  39
  40 #define GNTALLOC_FLAG_WRITABLE 1
  41
  42 /*
  43  * Deallocates the grant reference, allowing the associated page to be freed if
  44  * no other domains are using it.
  45  */
  46 #define IOCTL_GNTALLOC_DEALLOC_GREF \
  47 _IOC(_IOC_NONE, 'G', 6, sizeof(struct ioctl_gntalloc_dealloc_gref))
  48 struct ioctl_gntalloc_dealloc_gref {
  49         /* IN parameters */
  50         /* The offset returned in the map operation */
  51         __u64 index;
  52         /* Number of references to unmap */
  53         __u32 count;
  54 };
  55
  56 /*
  57  * Sets up an unmap notification within the page, so that the other side can do
  58  * cleanup if this side crashes. Required to implement cross-domain robust
  59  * mutexes or close notification on communication channels.
  60  *
  61  * Each mapped page only supports one notification; multiple calls referring to
  62  * the same page overwrite the previous notification. You must clear the
  63  * notification prior to the IOCTL_GNTALLOC_DEALLOC_GREF if you do not want it
  64  * to occur.
  65  */
  66 #define IOCTL_GNTALLOC_SET_UNMAP_NOTIFY \
  67 _IOC(_IOC_NONE, 'G', 7, sizeof(struct ioctl_gntalloc_unmap_notify))
  68 struct ioctl_gntalloc_unmap_notify {
  69         /* IN parameters */
  70         /* Offset in the file descriptor for a byte within the page (same as
  71          * used in mmap). If using UNMAP_NOTIFY_CLEAR_BYTE, this is the byte to
  72          * be cleared. Otherwise, it can be any byte in the page whose
  73          * notification we are adjusting.
  74          */
  75         __u64 index;
  76         /* Action(s) to take on unmap */
  77         __u32 action;
  78         /* Event channel to notify */
  79         __u32 event_channel_port;
  80 };
  81
  82 /* Clear (set to zero) the byte specified by index */
  83 #define UNMAP_NOTIFY_CLEAR_BYTE 0x1
  84 /* Send an interrupt on the indicated event channel */
  85 #define UNMAP_NOTIFY_SEND_EVENT 0x2
  86
  87 #endif /* __LINUX_PUBLIC_GNTALLOC_H__ */