/******************************************************************************
   * grant_table.c
   * x86 specific part
   *
   * Granting foreign access to our memory reservation.
   *
   * Copyright (c) 2005-2006, Christopher Clark
   * Copyright (c) 2004-2005, K A Fraser
   * Copyright (c) 2008 Isaku Yamahata <yamahata at valinux co jp>
   *                    VA Linux Systems Japan. Split out x86 specific part.
   *
   * 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.
   */
  
  #include <linux/sched.h>
  #include <linux/mm.h>
  #include <linux/vmalloc.h>
  
  #include <xen/interface/xen.h>
  #include <xen/page.h>
  #include <xen/grant_table.h>
  
  #include <asm/pgtable.h>
  
  static int map_pte_fn(pte_t *pte, struct page *pmd_page,
  		      unsigned long addr, void *data)
  {
  	unsigned long **frames = (unsigned long **)data;
  
  	set_pte_at(&init_mm, addr, pte, mfn_pte((*frames)[0], PAGE_KERNEL));
  	(*frames)++;
  	return 0;
  }
  
  /*
   * This function is used to map shared frames to store grant status. It is
   * different from map_pte_fn above, the frames type here is uint64_t.
   */
  static int map_pte_fn_status(pte_t *pte, struct page *pmd_page,
  			     unsigned long addr, void *data)
  {
  	uint64_t **frames = (uint64_t **)data;
  
  	set_pte_at(&init_mm, addr, pte, mfn_pte((*frames)[0], PAGE_KERNEL));
  	(*frames)++;
  	return 0;
  }
  
  static int unmap_pte_fn(pte_t *pte, struct page *pmd_page,
  			unsigned long addr, void *data)
  {
  
  	set_pte_at(&init_mm, addr, pte, __pte(0));
  	return 0;
  }
  
  int arch_gnttab_map_shared(unsigned long *frames, unsigned long nr_gframes,
  			   unsigned long max_nr_gframes,
  			   void **__shared)
  {
  	int rc;
  	void *shared = *__shared;
  
  	if (shared == NULL) {
  		struct vm_struct *area =
  			alloc_vm_area(PAGE_SIZE * max_nr_gframes, NULL);
  		BUG_ON(area == NULL);
  		shared = area->addr;
  		*__shared = shared;
  	}
  
  	rc = apply_to_page_range(&init_mm, (unsigned long)shared,
  				 PAGE_SIZE * nr_gframes,
  				 map_pte_fn, &frames);
  	return rc;
  }
  
  int arch_gnttab_map_status(uint64_t *frames, unsigned long nr_gframes,
  			   unsigned long max_nr_gframes,
  			   grant_status_t **__shared)
  {
  	int rc;
  	grant_status_t *shared = *__shared;
  
  	if (shared == NULL) {
  		/* No need to pass in PTE as we are going to do it
  		 * in apply_to_page_range anyhow. */
  		struct vm_struct *area =
  			alloc_vm_area(PAGE_SIZE * max_nr_gframes, NULL);
  		BUG_ON(area == NULL);
  		shared = area->addr;
  		*__shared = shared;
  	}
  
  	rc = apply_to_page_range(&init_mm, (unsigned long)shared,
  				 PAGE_SIZE * nr_gframes,
  				 map_pte_fn_status, &frames);
  	return rc;
  }
  
  void arch_gnttab_unmap(void *shared, unsigned long nr_gframes)
  {
  	apply_to_page_range(&init_mm, (unsigned long)shared,
  			    PAGE_SIZE * nr_gframes, unmap_pte_fn, NULL);
  }
  #ifdef CONFIG_XEN_PVH
  #include <xen/balloon.h>
  #include <xen/events.h>
  #include <xen/xen.h>
  #include <linux/slab.h>
  static int __init xlated_setup_gnttab_pages(void)
  {
  	struct page **pages;
  	xen_pfn_t *pfns;
  	void *vaddr;
  	int rc;
  	unsigned int i;
  	unsigned long nr_grant_frames = gnttab_max_grant_frames();
  
  	BUG_ON(nr_grant_frames == 0);
  	pages = kcalloc(nr_grant_frames, sizeof(pages[0]), GFP_KERNEL);
  	if (!pages)
  		return -ENOMEM;
  
  	pfns = kcalloc(nr_grant_frames, sizeof(pfns[0]), GFP_KERNEL);
  	if (!pfns) {
  		kfree(pages);
  		return -ENOMEM;
  	}
  	rc = alloc_xenballooned_pages(nr_grant_frames, pages, 0 /* lowmem */);
  	if (rc) {
  		pr_warn("%s Couldn't balloon alloc %ld pfns rc:%d
  ", __func__,
  			nr_grant_frames, rc);
  		kfree(pages);
  		kfree(pfns);
  		return rc;
  	}
  	for (i = 0; i < nr_grant_frames; i++)
  		pfns[i] = page_to_pfn(pages[i]);
  
  	vaddr = vmap(pages, nr_grant_frames, 0, PAGE_KERNEL);
  	if (!vaddr) {
  		pr_warn("%s Couldn't map %ld pfns rc:%d
  ", __func__,
  			nr_grant_frames, rc);
  		free_xenballooned_pages(nr_grant_frames, pages);
  		kfree(pages);
  		kfree(pfns);
  		return -ENOMEM;
  	}
  	kfree(pages);
  
  	xen_auto_xlat_grant_frames.pfn = pfns;
  	xen_auto_xlat_grant_frames.count = nr_grant_frames;
  	xen_auto_xlat_grant_frames.vaddr = vaddr;
  
  	return 0;
  }
  
  static int __init xen_pvh_gnttab_setup(void)
  {
  	if (!xen_pvh_domain())
  		return -ENODEV;
  
  	return xlated_setup_gnttab_pages();
  }
  /* Call it _before_ __gnttab_init as we need to initialize the
   * xen_auto_xlat_grant_frames first. */
  core_initcall(xen_pvh_gnttab_setup);
  #endif