text: /* SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR MIT) */
  /******************************************************************************
   * gntdev.h
   * 
   * Interface to /dev/xen/gntdev.
   * 
   * Copyright (c) 2007, D G Murray
   * Copyright (c) 2018, Oleksandr Andrushchenko, EPAM Systems Inc.
   * 
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License version 2
   * as published by the Free Software Foundation; or, when distributed
   * separately from the Linux kernel or incorporated into other
   * software packages, subject to the following license:
   * 
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this source file (the "Software"), to deal in the Software without
   * restriction, including without limitation the rights to use, copy, modify,
   * merge, publish, distribute, sublicense, and/or sell copies of the Software,
   * and to permit persons to whom the Software is furnished to do so, subject to
   * the following conditions:
   * 
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   * 
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
   * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
   * IN THE SOFTWARE.
   */
  
  #ifndef __LINUX_PUBLIC_GNTDEV_H__
  #define __LINUX_PUBLIC_GNTDEV_H__
  
  #include <linux/types.h>
  
  struct ioctl_gntdev_grant_ref {
  	/* The domain ID of the grant to be mapped. */
  	__u32 domid;
  	/* The grant reference of the grant to be mapped. */
  	__u32 ref;
  };
  
  /*
   * Inserts the grant references into the mapping table of an instance
   * of gntdev. N.B. This does not perform the mapping, which is deferred
   * until mmap() is called with @index as the offset.
   */
  #define IOCTL_GNTDEV_MAP_GRANT_REF \
  _IOC(_IOC_NONE, 'G', 0, sizeof(struct ioctl_gntdev_map_grant_ref))
  struct ioctl_gntdev_map_grant_ref {
  	/* IN parameters */
  	/* The number of grants to be mapped. */
  	__u32 count;
  	__u32 pad;
  	/* OUT parameters */
  	/* The offset to be used on a subsequent call to mmap(). */
  	__u64 index;
  	/* Variable IN parameter. */
  	/* Array of grant references, of size @count. */
  	struct ioctl_gntdev_grant_ref refs[1];
  };
  
  /*
   * Removes the grant references from the mapping table of an instance of
   * of gntdev. N.B. munmap() must be called on the relevant virtual address(es)
   * before this ioctl is called, or an error will result.
   */
  #define IOCTL_GNTDEV_UNMAP_GRANT_REF \
  _IOC(_IOC_NONE, 'G', 1, sizeof(struct ioctl_gntdev_unmap_grant_ref))
  struct ioctl_gntdev_unmap_grant_ref {
  	/* IN parameters */
  	/* The offset was returned by the corresponding map operation. */
  	__u64 index;
  	/* The number of pages to be unmapped. */
  	__u32 count;
  	__u32 pad;
  };
  
  /*
   * Returns the offset in the driver's address space that corresponds
   * to @vaddr. This can be used to perform a munmap(), followed by an
   * UNMAP_GRANT_REF ioctl, where no state about the offset is retained by
   * the caller. The number of pages that were allocated at the same time as
   * @vaddr is returned in @count.
   *
   * N.B. Where more than one page has been mapped into a contiguous range, the
   *      supplied @vaddr must correspond to the start of the range; otherwise
   *      an error will result. It is only possible to munmap() the entire
   *      contiguously-allocated range at once, and not any subrange thereof.
   */
  #define IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR \
  _IOC(_IOC_NONE, 'G', 2, sizeof(struct ioctl_gntdev_get_offset_for_vaddr))
  struct ioctl_gntdev_get_offset_for_vaddr {
  	/* IN parameters */
  	/* The virtual address of the first mapped page in a range. */
  	__u64 vaddr;
  	/* OUT parameters */
  	/* The offset that was used in the initial mmap() operation. */
  	__u64 offset;
  	/* The number of pages mapped in the VM area that begins at @vaddr. */
  	__u32 count;
  	__u32 pad;
  };
  
  /*
   * Sets the maximum number of grants that may mapped at once by this gntdev
   * instance.
   *
   * N.B. This must be called before any other ioctl is performed on the device.
   */
  #define IOCTL_GNTDEV_SET_MAX_GRANTS \
  _IOC(_IOC_NONE, 'G', 3, sizeof(struct ioctl_gntdev_set_max_grants))
  struct ioctl_gntdev_set_max_grants {
  	/* IN parameter */
  	/* The maximum number of grants that may be mapped at once. */
  	__u32 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_GNTDEV_SET_UNMAP_NOTIFY \
  _IOC(_IOC_NONE, 'G', 7, sizeof(struct ioctl_gntdev_unmap_notify))
  struct ioctl_gntdev_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.
  	 */
  	__u64 index;
  	/* Action(s) to take on unmap */
  	__u32 action;
  	/* Event channel to notify */
  	__u32 event_channel_port;
  };
  
  struct gntdev_grant_copy_segment {
  	union {
  		void *virt;
  		struct {
  			grant_ref_t ref;
  			__u16 offset;
  			domid_t domid;
  		} foreign;
  	} source, dest;
  	__u16 len;
  
  	__u16 flags;  /* GNTCOPY_* */
  	__s16 status; /* GNTST_* */
  };
  
  /*
   * Copy between grant references and local buffers.
   *
   * The copy is split into @count @segments, each of which can copy
   * to/from one grant reference.
   *
   * Each segment is similar to struct gnttab_copy in the hypervisor ABI
   * except the local buffer is specified using a virtual address
   * (instead of a GFN and offset).
   *
   * The local buffer may cross a Xen page boundary -- the driver will
   * split segments into multiple ops if required.
   *
   * Returns 0 if all segments have been processed and @status in each
   * segment is valid.  Note that one or more segments may have failed
   * (status != GNTST_okay).
   *
   * If the driver had to split a segment into two or more ops, @status
   * includes the status of the first failed op for that segment (or
   * GNTST_okay if all ops were successful).
   *
   * If -1 is returned, the status of all segments is undefined.
   *
   * EINVAL: A segment has local buffers for both source and
   *         destination.
   * EINVAL: A segment crosses the boundary of a foreign page.
   * EFAULT: A segment's local buffer is not accessible.
   */
  #define IOCTL_GNTDEV_GRANT_COPY \
  	_IOC(_IOC_NONE, 'G', 8, sizeof(struct ioctl_gntdev_grant_copy))
  struct ioctl_gntdev_grant_copy {
  	unsigned int count;
  	struct gntdev_grant_copy_segment *segments;
  };
  
  /* 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
  
  /*
   * Flags to be used while requesting memory mapping's backing storage
   * to be allocated with DMA API.
   */
  
  /*
   * The buffer is backed with memory allocated with dma_alloc_wc.
   */
  #define GNTDEV_DMA_FLAG_WC		(1 << 0)
  
  /*
   * The buffer is backed with memory allocated with dma_alloc_coherent.
   */
  #define GNTDEV_DMA_FLAG_COHERENT	(1 << 1)
  
  /*
   * Create a dma-buf [1] from grant references @refs of count @count provided
   * by the foreign domain @domid with flags @flags.
   *
   * By default dma-buf is backed by system memory pages, but by providing
   * one of the GNTDEV_DMA_FLAG_XXX flags it can also be created as
   * a DMA write-combine or coherent buffer, e.g. allocated with dma_alloc_wc/
   * dma_alloc_coherent.
   *
   * Returns 0 if dma-buf was successfully created and the corresponding
   * dma-buf's file descriptor is returned in @fd.
   *
   * [1] Documentation/driver-api/dma-buf.rst
   */
  
  #define IOCTL_GNTDEV_DMABUF_EXP_FROM_REFS \
  	_IOC(_IOC_NONE, 'G', 9, \
  	     sizeof(struct ioctl_gntdev_dmabuf_exp_from_refs))
  struct ioctl_gntdev_dmabuf_exp_from_refs {
  	/* IN parameters. */
  	/* Specific options for this dma-buf: see GNTDEV_DMA_FLAG_XXX. */
  	__u32 flags;
  	/* Number of grant references in @refs array. */
  	__u32 count;
  	/* OUT parameters. */
  	/* File descriptor of the dma-buf. */
  	__u32 fd;
  	/* The domain ID of the grant references to be mapped. */
  	__u32 domid;
  	/* Variable IN parameter. */
  	/* Array of grant references of size @count. */
  	__u32 refs[1];
  };
  
  /*
   * This will block until the dma-buf with the file descriptor @fd is
   * released. This is only valid for buffers created with
   * IOCTL_GNTDEV_DMABUF_EXP_FROM_REFS.
   *
   * If within @wait_to_ms milliseconds the buffer is not released
   * then -ETIMEDOUT error is returned.
   * If the buffer with the file descriptor @fd does not exist or has already
   * been released, then -ENOENT is returned. For valid file descriptors
   * this must not be treated as error.
   */
  #define IOCTL_GNTDEV_DMABUF_EXP_WAIT_RELEASED \
  	_IOC(_IOC_NONE, 'G', 10, \
  	     sizeof(struct ioctl_gntdev_dmabuf_exp_wait_released))
  struct ioctl_gntdev_dmabuf_exp_wait_released {
  	/* IN parameters */
  	__u32 fd;
  	__u32 wait_to_ms;
  };
  
  /*
   * Import a dma-buf with file descriptor @fd and export granted references
   * to the pages of that dma-buf into array @refs of size @count.
   */
  #define IOCTL_GNTDEV_DMABUF_IMP_TO_REFS \
  	_IOC(_IOC_NONE, 'G', 11, \
  	     sizeof(struct ioctl_gntdev_dmabuf_imp_to_refs))
  struct ioctl_gntdev_dmabuf_imp_to_refs {
  	/* IN parameters. */
  	/* File descriptor of the dma-buf. */
  	__u32 fd;
  	/* Number of grant references in @refs array. */
  	__u32 count;
  	/* The domain ID for which references to be granted. */
  	__u32 domid;
  	/* Reserved - must be zero. */
  	__u32 reserved;
  	/* OUT parameters. */
  	/* Array of grant references of size @count. */
  	__u32 refs[1];
  };
  
  /*
   * This will close all references to the imported buffer with file descriptor
   * @fd, so it can be released by the owner. This is only valid for buffers
   * created with IOCTL_GNTDEV_DMABUF_IMP_TO_REFS.
   */
  #define IOCTL_GNTDEV_DMABUF_IMP_RELEASE \
  	_IOC(_IOC_NONE, 'G', 12, \
  	     sizeof(struct ioctl_gntdev_dmabuf_imp_release))
  struct ioctl_gntdev_dmabuf_imp_release {
  	/* IN parameters */
  	__u32 fd;
  	__u32 reserved;
  };
  
  #endif /* __LINUX_PUBLIC_GNTDEV_H__ */