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 30 static 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 == U64_MAX) 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 */ 66 static 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 } 131 early_initcall(riscv_enable_runtime_services); 132 133 static void efi_virtmap_load(void) 134 { 135 preempt_disable(); 136 switch_mm(current->active_mm, &efi_mm, NULL); 137 } 138 139 static void efi_virtmap_unload(void) 140 { 141 switch_mm(&efi_mm, current->active_mm, NULL); 142 preempt_enable(); 143 } 144 145 void arch_efi_call_virt_setup(void) 146 { 147 sync_kernel_mappings(efi_mm.pgd); 148 efi_virtmap_load(); 149 } 150 151 void arch_efi_call_virt_teardown(void) 152 { 153 efi_virtmap_unload(); 154 } 155