include/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 /*
  15  * Allocates a new page and creates a new grant reference.
  16  */
  17 #define IOCTL_GNTALLOC_ALLOC_GREF \
  18 _IOC(_IOC_NONE, 'G', 5, sizeof(struct ioctl_gntalloc_alloc_gref))
  19 struct ioctl_gntalloc_alloc_gref {
  20         /* IN parameters */
  21         /* The ID of the domain to be given access to the grants. */
  22         uint16_t domid;
  23         /* Flags for this mapping */
  24         uint16_t flags;
  25         /* Number of pages to map */
  26         uint32_t count;
  27         /* OUT parameters */
  28         /* The offset to be used on a subsequent call to mmap(). */
  29         uint64_t index;
  30         /* The grant references of the newly created grant, one per page */
  31         /* Variable size, depending on count */
  32         uint32_t gref_ids[1];
  33 };
  34
  35 #define GNTALLOC_FLAG_WRITABLE 1
  36
  37 /*
  38  * Deallocates the grant reference, allowing the associated page to be freed if
  39  * no other domains are using it.
  40  */
  41 #define IOCTL_GNTALLOC_DEALLOC_GREF \
  42 _IOC(_IOC_NONE, 'G', 6, sizeof(struct ioctl_gntalloc_dealloc_gref))
  43 struct ioctl_gntalloc_dealloc_gref {
  44         /* IN parameters */
  45         /* The offset returned in the map operation */
  46         uint64_t index;
  47         /* Number of references to unmap */
  48         uint32_t count;
  49 };
  50
  51 /*
  52  * Sets up an unmap notification within the page, so that the other side can do
  53  * cleanup if this side crashes. Required to implement cross-domain robust
  54  * mutexes or close notification on communication channels.
  55  *
  56  * Each mapped page only supports one notification; multiple calls referring to
  57  * the same page overwrite the previous notification. You must clear the
  58  * notification prior to the IOCTL_GNTALLOC_DEALLOC_GREF if you do not want it
  59  * to occur.
  60  */
  61 #define IOCTL_GNTALLOC_SET_UNMAP_NOTIFY \
  62 _IOC(_IOC_NONE, 'G', 7, sizeof(struct ioctl_gntalloc_unmap_notify))
  63 struct ioctl_gntalloc_unmap_notify {
  64         /* IN parameters */
  65         /* Offset in the file descriptor for a byte within the page (same as
  66          * used in mmap). If using UNMAP_NOTIFY_CLEAR_BYTE, this is the byte to
  67          * be cleared. Otherwise, it can be any byte in the page whose
  68          * notification we are adjusting.
  69          */
  70         uint64_t index;
  71         /* Action(s) to take on unmap */
  72         uint32_t action;
  73         /* Event channel to notify */
  74         uint32_t event_channel_port;
  75 };
  76
  77 /* Clear (set to zero) the byte specified by index */
  78 #define UNMAP_NOTIFY_CLEAR_BYTE 0x1
  79 /* Send an interrupt on the indicated event channel */
  80 #define UNMAP_NOTIFY_SEND_EVENT 0x2
  81
  82 #endif /* __LINUX_PUBLIC_GNTALLOC_H__ */