linux/drivers/firmware/efi/riscv-runtime.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Extensible Firmware Interface
   4 *
   5 * Copyright (C) 2020 Western Digital Corporation or its affiliates.
   6 *
   7 * Based on Extensible Firmware Interface Specification version 2.4
   8 * Adapted from drivers/firmware/efi/arm-runtime.c
   9 *
  10 */
  11
  12#include <linux/dmi.h>
  13#include <linux/efi.h>
  14#include <linux/io.h>
  15#include <linux/memblock.h>
  16#include <linux/mm_types.h>
  17#include <linux/preempt.h>
  18#include <linux/rbtree.h>
  19#include <linux/rwsem.h>
  20#include <linux/sched.h>
  21#include <linux/slab.h>
  22#include <linux/spinlock.h>
  23#include <linux/pgtable.h>
  24
  25#include <asm/cacheflush.h>
  26#include <asm/efi.h>
  27#include <asm/mmu.h>
  28#include <asm/pgalloc.h>
  29
  30static bool __init efi_virtmap_init(void)
  31{
  32        efi_memory_desc_t *md;
  33
  34        efi_mm.pgd = pgd_alloc(&efi_mm);
  35        mm_init_cpumask(&efi_mm);
  36        init_new_context(NULL, &efi_mm);
  37
  38        for_each_efi_memory_desc(md) {
  39                phys_addr_t phys = md->phys_addr;
  40                int ret;
  41
  42                if (!(md->attribute & EFI_MEMORY_RUNTIME))
  43                        continue;
  44                if (md->virt_addr == 0)
  45                        return false;
  46
  47                ret = efi_create_mapping(&efi_mm, md);
  48                if (ret) {
  49                        pr_warn("  EFI remap %pa: failed to create mapping (%d)\n",
  50                                &phys, ret);
  51                        return false;
  52                }
  53        }
  54
  55        if (efi_memattr_apply_permissions(&efi_mm, efi_set_mapping_permissions))
  56                return false;
  57
  58        return true;
  59}
  60
  61/*
  62 * Enable the UEFI Runtime Services if all prerequisites are in place, i.e.,
  63 * non-early mapping of the UEFI system table and virtual mappings for all
  64 * EFI_MEMORY_RUNTIME regions.
  65 */
  66static int __init riscv_enable_runtime_services(void)
  67{
  68        u64 mapsize;
  69
  70        if (!efi_enabled(EFI_BOOT)) {
  71                pr_info("EFI services will not be available.\n");
  72                return 0;
  73        }
  74
  75        efi_memmap_unmap();
  76
  77        mapsize = efi.memmap.desc_size * efi.memmap.nr_map;
  78
  79        if (efi_memmap_init_late(efi.memmap.phys_map, mapsize)) {
  80                pr_err("Failed to remap EFI memory map\n");
  81                return 0;
  82        }
  83
  84        if (efi_soft_reserve_enabled()) {
  85                efi_memory_desc_t *md;
  86
  87                for_each_efi_memory_desc(md) {
  88                        int md_size = md->num_pages << EFI_PAGE_SHIFT;
  89                        struct resource *res;
  90
  91                        if (!(md->attribute & EFI_MEMORY_SP))
  92                                continue;
  93
  94                        res = kzalloc(sizeof(*res), GFP_KERNEL);
  95                        if (WARN_ON(!res))
  96                                break;
  97
  98                        res->start      = md->phys_addr;
  99                        res->end        = md->phys_addr + md_size - 1;
 100                        res->name       = "Soft Reserved";
 101                        res->flags      = IORESOURCE_MEM;
 102                        res->desc       = IORES_DESC_SOFT_RESERVED;
 103
 104                        insert_resource(&iomem_resource, res);
 105                }
 106        }
 107
 108        if (efi_runtime_disabled()) {
 109                pr_info("EFI runtime services will be disabled.\n");
 110                return 0;
 111        }
 112
 113        if (efi_enabled(EFI_RUNTIME_SERVICES)) {
 114                pr_info("EFI runtime services access via paravirt.\n");
 115                return 0;
 116        }
 117
 118        pr_info("Remapping and enabling EFI services.\n");
 119
 120        if (!efi_virtmap_init()) {
 121                pr_err("UEFI virtual mapping missing or invalid -- runtime services will not be available\n");
 122                return -ENOMEM;
 123        }
 124
 125        /* Set up runtime services function pointers */
 126        efi_native_runtime_setup();
 127        set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
 128
 129        return 0;
 130}
 131early_initcall(riscv_enable_runtime_services);
 132
 133void efi_virtmap_load(void)
 134{
 135        preempt_disable();
 136        switch_mm(current->active_mm, &efi_mm, NULL);
 137}
 138
 139void efi_virtmap_unload(void)
 140{
 141        switch_mm(&efi_mm, current->active_mm, NULL);
 142        preempt_enable();
 143}
 144