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 			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 
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