arch/x86/xen/grant-table.c

   1 // SPDX-License-Identifier: GPL-2.0 OR MIT
   2 /******************************************************************************
   3  * grant_table.c
   4  * x86 specific part
   5  *
   6  * Granting foreign access to our memory reservation.
   7  *
   8  * Copyright (c) 2005-2006, Christopher Clark
   9  * Copyright (c) 2004-2005, K A Fraser
  10  * Copyright (c) 2008 Isaku Yamahata <yamahata at valinux co jp>
  11  *                    VA Linux Systems Japan. Split out x86 specific part.
  12  */
  13
  14 #include <linux/sched.h>
  15 #include <linux/mm.h>
  16 #include <linux/slab.h>
  17 #include <linux/vmalloc.h>
  18
  19 #include <xen/interface/xen.h>
  20 #include <xen/page.h>
  21 #include <xen/grant_table.h>
  22 #include <xen/xen.h>
  23
  24
  25 static struct gnttab_vm_area {
  26         struct vm_struct *area;
  27         pte_t **ptes;
  28 } gnttab_shared_vm_area, gnttab_status_vm_area;
  29
  30 int arch_gnttab_map_shared(unsigned long *frames, unsigned long nr_gframes,
  31                            unsigned long max_nr_gframes,
  32                            void **__shared)
  33 {
  34         void *shared = *__shared;
  35         unsigned long addr;
  36         unsigned long i;
  37
  38         if (shared == NULL)
  39                 *__shared = shared = gnttab_shared_vm_area.area->addr;
  40
  41         addr = (unsigned long)shared;
  42
  43         for (i = 0; i < nr_gframes; i++) {
  44                 set_pte_at(&init_mm, addr, gnttab_shared_vm_area.ptes[i],
  45                            mfn_pte(frames[i], PAGE_KERNEL));
  46                 addr += PAGE_SIZE;
  47         }
  48
  49         return 0;
  50 }
  51
  52 int arch_gnttab_map_status(uint64_t *frames, unsigned long nr_gframes,
  53                            unsigned long max_nr_gframes,
  54                            grant_status_t **__shared)
  55 {
  56         grant_status_t *shared = *__shared;
  57         unsigned long addr;
  58         unsigned long i;
  59
  60         if (shared == NULL)
  61                 *__shared = shared = gnttab_status_vm_area.area->addr;
  62
  63         addr = (unsigned long)shared;
  64
  65         for (i = 0; i < nr_gframes; i++) {
  66                 set_pte_at(&init_mm, addr, gnttab_status_vm_area.ptes[i],
  67                            mfn_pte(frames[i], PAGE_KERNEL));
  68                 addr += PAGE_SIZE;
  69         }
  70
  71         return 0;
  72 }
  73
  74 void arch_gnttab_unmap(void *shared, unsigned long nr_gframes)
  75 {
  76         pte_t **ptes;
  77         unsigned long addr;
  78         unsigned long i;
  79
  80         if (shared == gnttab_status_vm_area.area->addr)
  81                 ptes = gnttab_status_vm_area.ptes;
  82         else
  83                 ptes = gnttab_shared_vm_area.ptes;
  84
  85         addr = (unsigned long)shared;
  86
  87         for (i = 0; i < nr_gframes; i++) {
  88                 set_pte_at(&init_mm, addr, ptes[i], __pte(0));
  89                 addr += PAGE_SIZE;
  90         }
  91 }
  92
  93 static int arch_gnttab_valloc(struct gnttab_vm_area *area, unsigned nr_frames)
  94 {
  95         area->ptes = kmalloc_array(nr_frames, sizeof(*area->ptes), GFP_KERNEL);
  96         if (area->ptes == NULL)
  97                 return -ENOMEM;
  98
  99         area->area = alloc_vm_area(PAGE_SIZE * nr_frames, area->ptes);
 100         if (area->area == NULL) {
 101                 kfree(area->ptes);
 102                 return -ENOMEM;
 103         }
 104
 105         return 0;
 106 }
 107
 108 static void arch_gnttab_vfree(struct gnttab_vm_area *area)
 109 {
 110         free_vm_area(area->area);
 111         kfree(area->ptes);
 112 }
 113
 114 int arch_gnttab_init(unsigned long nr_shared, unsigned long nr_status)
 115 {
 116         int ret;
 117
 118         if (!xen_pv_domain())
 119                 return 0;
 120
 121         ret = arch_gnttab_valloc(&gnttab_shared_vm_area, nr_shared);
 122         if (ret < 0)
 123                 return ret;
 124
 125         /*
 126          * Always allocate the space for the status frames in case
 127          * we're migrated to a host with V2 support.
 128          */
 129         ret = arch_gnttab_valloc(&gnttab_status_vm_area, nr_status);
 130         if (ret < 0)
 131                 goto err;
 132
 133         return 0;
 134 err:
 135         arch_gnttab_vfree(&gnttab_shared_vm_area);
 136         return -ENOMEM;
 137 }
 138
 139 #ifdef CONFIG_XEN_PVH
 140 #include <xen/events.h>
 141 #include <xen/xen-ops.h>
 142 static int __init xen_pvh_gnttab_setup(void)
 143 {
 144         if (!xen_pvh_domain())
 145                 return -ENODEV;
 146
 147         xen_auto_xlat_grant_frames.count = gnttab_max_grant_frames();
 148
 149         return xen_xlate_map_ballooned_pages(&xen_auto_xlat_grant_frames.pfn,
 150                                              &xen_auto_xlat_grant_frames.vaddr,
 151                                              xen_auto_xlat_grant_frames.count);
 152 }
 153 /* Call it _before_ __gnttab_init as we need to initialize the
 154  * xen_auto_xlat_grant_frames first. */
 155 core_initcall(xen_pvh_gnttab_setup);
 156 #endif