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