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
efi_virtmap_init(void)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 */
riscv_enable_runtime_services(void)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 u64 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
efi_virtmap_load(void)133 static void efi_virtmap_load(void)
134 {
135 preempt_disable();
136 switch_mm(current->active_mm, &efi_mm, NULL);
137 }
138
efi_virtmap_unload(void)139 static void efi_virtmap_unload(void)
140 {
141 switch_mm(&efi_mm, current->active_mm, NULL);
142 preempt_enable();
143 }
144
arch_efi_call_virt_setup(void)145 void arch_efi_call_virt_setup(void)
146 {
147 sync_kernel_mappings(efi_mm.pgd);
148 efi_virtmap_load();
149 }
150
arch_efi_call_virt_teardown(void)151 void arch_efi_call_virt_teardown(void)
152 {
153 efi_virtmap_unload();
154 }
155