arch/x86/xen/grant-table.c

   1 /******************************************************************************
   2  * grant_table.c
   3  * x86 specific part
   4  *
   5  * Granting foreign access to our memory reservation.
   6  *
   7  * Copyright (c) 2005-2006, Christopher Clark
   8  * Copyright (c) 2004-2005, K A Fraser
   9  * Copyright (c) 2008 Isaku Yamahata <yamahata at valinux co jp>
  10  *                    VA Linux Systems Japan. Split out x86 specific part.
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License version 2
  14  * as published by the Free Software Foundation; or, when distributed
  15  * separately from the Linux kernel or incorporated into other
  16  * software packages, subject to the following license:
  17  *
  18  * Permission is hereby granted, free of charge, to any person obtaining a copy
  19  * of this source file (the "Software"), to deal in the Software without
  20  * restriction, including without limitation the rights to use, copy, modify,
  21  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  22  * and to permit persons to whom the Software is furnished to do so, subject to
  23  * the following conditions:
  24  *
  25  * The above copyright notice and this permission notice shall be included in
  26  * all copies or substantial portions of the Software.
  27  *
  28  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  29  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  30  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  31  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  32  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  33  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  34  * IN THE SOFTWARE.
  35  */
  36
  37 #include <linux/sched.h>
  38 #include <linux/mm.h>
  39 #include <linux/vmalloc.h>
  40
  41 #include <xen/interface/xen.h>
  42 #include <xen/page.h>
  43 #include <xen/grant_table.h>
  44
  45 #include <asm/pgtable.h>
  46
  47 static int map_pte_fn(pte_t *pte, struct page *pmd_page,
  48                       unsigned long addr, void *data)
  49 {
  50         unsigned long **frames = (unsigned long **)data;
  51
  52         set_pte_at(&init_mm, addr, pte, mfn_pte((*frames)[0], PAGE_KERNEL));
  53         (*frames)++;
  54         return 0;
  55 }
  56
  57 /*
  58  * This function is used to map shared frames to store grant status. It is
  59  * different from map_pte_fn above, the frames type here is uint64_t.
  60  */
  61 static int map_pte_fn_status(pte_t *pte, struct page *pmd_page,
  62                              unsigned long addr, void *data)
  63 {
  64         uint64_t **frames = (uint64_t **)data;
  65
  66         set_pte_at(&init_mm, addr, pte, mfn_pte((*frames)[0], PAGE_KERNEL));
  67         (*frames)++;
  68         return 0;
  69 }
  70
  71 static int unmap_pte_fn(pte_t *pte, struct page *pmd_page,
  72                         unsigned long addr, void *data)
  73 {
  74
  75         set_pte_at(&init_mm, addr, pte, __pte(0));
  76         return 0;
  77 }
  78
  79 int arch_gnttab_map_shared(unsigned long *frames, unsigned long nr_gframes,
  80                            unsigned long max_nr_gframes,
  81                            void **__shared)
  82 {
  83         int rc;
  84         void *shared = *__shared;
  85
  86         if (shared == NULL) {
  87                 struct vm_struct *area =
  88                         alloc_vm_area(PAGE_SIZE * max_nr_gframes, NULL);
  89                 BUG_ON(area == NULL);
  90                 shared = area->addr;
  91                 *__shared = shared;
  92         }
  93
  94         rc = apply_to_page_range(&init_mm, (unsigned long)shared,
  95                                  PAGE_SIZE * nr_gframes,
  96                                  map_pte_fn, &frames);
  97         return rc;
  98 }
  99
 100 int arch_gnttab_map_status(uint64_t *frames, unsigned long nr_gframes,
 101                            unsigned long max_nr_gframes,
 102                            grant_status_t **__shared)
 103 {
 104         int rc;
 105         grant_status_t *shared = *__shared;
 106
 107         if (shared == NULL) {
 108                 /* No need to pass in PTE as we are going to do it
 109                  * in apply_to_page_range anyhow. */
 110                 struct vm_struct *area =
 111                         alloc_vm_area(PAGE_SIZE * max_nr_gframes, NULL);
 112                 BUG_ON(area == NULL);
 113                 shared = area->addr;
 114                 *__shared = shared;
 115         }
 116
 117         rc = apply_to_page_range(&init_mm, (unsigned long)shared,
 118                                  PAGE_SIZE * nr_gframes,
 119                                  map_pte_fn_status, &frames);
 120         return rc;
 121 }
 122
 123 void arch_gnttab_unmap(void *shared, unsigned long nr_gframes)
 124 {
 125         apply_to_page_range(&init_mm, (unsigned long)shared,
 126                             PAGE_SIZE * nr_gframes, unmap_pte_fn, NULL);
 127 }