/******************************************************************************
   * gntalloc.h
   *
   * Interface to /dev/xen/gntalloc.
   *
   * Author: Daniel De Graaf <dgdegra@tycho.nsa.gov>
   *
   * This file is in the public domain.
   */
  
  #ifndef __LINUX_PUBLIC_GNTALLOC_H__
  #define __LINUX_PUBLIC_GNTALLOC_H__
  
  /*
   * Allocates a new page and creates a new grant reference.
   */
  #define IOCTL_GNTALLOC_ALLOC_GREF \
  _IOC(_IOC_NONE, 'G', 5, sizeof(struct ioctl_gntalloc_alloc_gref))
  struct ioctl_gntalloc_alloc_gref {
  	/* IN parameters */
  	/* The ID of the domain to be given access to the grants. */
  	uint16_t domid;
  	/* Flags for this mapping */
  	uint16_t flags;
  	/* Number of pages to map */
  	uint32_t count;
  	/* OUT parameters */
  	/* The offset to be used on a subsequent call to mmap(). */
  	uint64_t index;
  	/* The grant references of the newly created grant, one per page */
  	/* Variable size, depending on count */
  	uint32_t gref_ids[1];
  };
  
  #define GNTALLOC_FLAG_WRITABLE 1
  
  /*
   * Deallocates the grant reference, allowing the associated page to be freed if
   * no other domains are using it.
   */
  #define IOCTL_GNTALLOC_DEALLOC_GREF \
  _IOC(_IOC_NONE, 'G', 6, sizeof(struct ioctl_gntalloc_dealloc_gref))
  struct ioctl_gntalloc_dealloc_gref {
  	/* IN parameters */
  	/* The offset returned in the map operation */
  	uint64_t index;
  	/* Number of references to unmap */
  	uint32_t count;
  };
  
  /*
   * Sets up an unmap notification within the page, so that the other side can do
   * cleanup if this side crashes. Required to implement cross-domain robust
   * mutexes or close notification on communication channels.
   *
   * Each mapped page only supports one notification; multiple calls referring to
   * the same page overwrite the previous notification. You must clear the
   * notification prior to the IOCTL_GNTALLOC_DEALLOC_GREF if you do not want it
   * to occur.
   */
  #define IOCTL_GNTALLOC_SET_UNMAP_NOTIFY \
  _IOC(_IOC_NONE, 'G', 7, sizeof(struct ioctl_gntalloc_unmap_notify))
  struct ioctl_gntalloc_unmap_notify {
  	/* IN parameters */
  	/* Offset in the file descriptor for a byte within the page (same as
  	 * used in mmap). If using UNMAP_NOTIFY_CLEAR_BYTE, this is the byte to
  	 * be cleared. Otherwise, it can be any byte in the page whose
  	 * notification we are adjusting.
  	 */
  	uint64_t index;
  	/* Action(s) to take on unmap */
  	uint32_t action;
  	/* Event channel to notify */
  	uint32_t event_channel_port;
  };
  
  /* Clear (set to zero) the byte specified by index */
  #define UNMAP_NOTIFY_CLEAR_BYTE 0x1
  /* Send an interrupt on the indicated event channel */
  #define UNMAP_NOTIFY_SEND_EVENT 0x2
  
  #endif /* __LINUX_PUBLIC_GNTALLOC_H__ */