riscv-runtime.c

  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/pgalloc.h>
 18#include <linux/pgtable.h>
 19#include <linux/preempt.h>
 20#include <linux/rbtree.h>
 21#include <linux/rwsem.h>
 22#include <linux/sched.h>
 23#include <linux/slab.h>
 24#include <linux/spinlock.h>
 25
 26#include <asm/cacheflush.h>
 27#include <asm/efi.h>
 28#include <asm/mmu.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		if (!(md->attribute & EFI_MEMORY_RUNTIME))
 40			continue;
 41		if (md->virt_addr == U64_MAX)
 42			return false;
 43
 44		efi_create_mapping(&efi_mm, md);
 45	}
 46
 47	if (efi_memattr_apply_permissions(&efi_mm, efi_set_mapping_permissions))
 48		return false;
 49
 50	return true;
 51}
 52
 53/*
 54 * Enable the UEFI Runtime Services if all prerequisites are in place, i.e.,
 55 * non-early mapping of the UEFI system table and virtual mappings for all
 56 * EFI_MEMORY_RUNTIME regions.
 57 */
 58static int __init riscv_enable_runtime_services(void)
 59{
 60	u64 mapsize;
 61
 62	if (!efi_enabled(EFI_BOOT)) {
 63		pr_info("EFI services will not be available.\n");
 64		return 0;
 65	}
 66
 67	efi_memmap_unmap();
 68
 69	mapsize = efi.memmap.desc_size * efi.memmap.nr_map;
 70
 71	if (efi_memmap_init_late(efi.memmap.phys_map, mapsize)) {
 72		pr_err("Failed to remap EFI memory map\n");
 73		return 0;
 74	}
 75
 76	if (efi_soft_reserve_enabled()) {
 77		efi_memory_desc_t *md;
 78
 79		for_each_efi_memory_desc(md) {
 80			u64 md_size = md->num_pages << EFI_PAGE_SHIFT;
 81			struct resource *res;
 82
 83			if (!(md->attribute & EFI_MEMORY_SP))
 84				continue;
 85
 86			res = kzalloc(sizeof(*res), GFP_KERNEL);
 87			if (WARN_ON(!res))
 88				break;
 89
 90			res->start	= md->phys_addr;
 91			res->end	= md->phys_addr + md_size - 1;
 92			res->name	= "Soft Reserved";
 93			res->flags	= IORESOURCE_MEM;
 94			res->desc	= IORES_DESC_SOFT_RESERVED;
 95
 96			insert_resource(&iomem_resource, res);
 97		}
 98	}
 99
100	if (efi_runtime_disabled()) {
101		pr_info("EFI runtime services will be disabled.\n");
102		return 0;
103	}
104
105	if (efi_enabled(EFI_RUNTIME_SERVICES)) {
106		pr_info("EFI runtime services access via paravirt.\n");
107		return 0;
108	}
109
110	pr_info("Remapping and enabling EFI services.\n");
111
112	if (!efi_virtmap_init()) {
113		pr_err("UEFI virtual mapping missing or invalid -- runtime services will not be available\n");
114		return -ENOMEM;
115	}
116
117	/* Set up runtime services function pointers */
118	efi_native_runtime_setup();
119	set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
120
121	return 0;
122}
123early_initcall(riscv_enable_runtime_services);
124
125static void efi_virtmap_load(void)
126{
127	preempt_disable();
128	switch_mm(current->active_mm, &efi_mm, NULL);
129}
130
131static void efi_virtmap_unload(void)
132{
133	switch_mm(&efi_mm, current->active_mm, NULL);
134	preempt_enable();
135}
136
137void arch_efi_call_virt_setup(void)
138{
139	sync_kernel_mappings(efi_mm.pgd);
140	efi_virtmap_load();
141}
142
143void arch_efi_call_virt_teardown(void)
144{
145	efi_virtmap_unload();
146}
147
148static int __init riscv_dmi_init(void)
149{
150	/*
151	 * On riscv, DMI depends on UEFI, and dmi_setup() needs to
152	 * be called early because dmi_id_init(), which is an arch_initcall
153	 * itself, depends on dmi_scan_machine() having been called already.
154	 */
155	dmi_setup();
156
157	return 0;
158}
159core_initcall(riscv_dmi_init);