gntalloc.h

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/******************************************************************************
 * gntalloc.h
 *
 * Interface to /dev/xen/gntalloc.
 *
 * Author: Daniel De Graaf <[email protected]>
 *
 * 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__ */