1 // SPDX-License-Identifier: GPL-2.0
3 #include <linux/slab.h>
4 #include <linux/memblock.h>
5 #include <linux/mem_encrypt.h>
6 #include <linux/pgtable.h>
8 #include <asm/set_memory.h>
9 #include <asm/realmode.h>
10 #include <asm/tlbflush.h>
11 #include <asm/crash.h>
13 struct real_mode_header *real_mode_header;
14 u32 *trampoline_cr4_features;
16 /* Hold the pgd entry used on booting additional CPUs */
17 pgd_t trampoline_pgd_entry;
19 void __init reserve_real_mode(void)
22 size_t size = real_mode_size_needed();
27 WARN_ON(slab_is_available());
29 /* Has to be under 1M so we can execute real-mode AP code. */
30 mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE);
32 pr_info("No sub-1M memory is available for the trampoline\n");
36 memblock_reserve(mem, size);
37 set_real_mode_mem(mem);
38 crash_reserve_low_1M();
41 static void __init setup_real_mode(void)
47 unsigned long phys_base;
48 struct trampoline_header *trampoline_header;
49 size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
55 base = (unsigned char *)real_mode_header;
58 * If SME is active, the trampoline area will need to be in
59 * decrypted memory in order to bring up other processors
60 * successfully. This is not needed for SEV.
63 set_memory_decrypted((unsigned long)base, size >> PAGE_SHIFT);
65 memcpy(base, real_mode_blob, size);
67 phys_base = __pa(base);
68 real_mode_seg = phys_base >> 4;
70 rel = (u32 *) real_mode_relocs;
72 /* 16-bit segment relocations. */
75 u16 *seg = (u16 *) (base + *rel++);
79 /* 32-bit linear relocations. */
82 u32 *ptr = (u32 *) (base + *rel++);
86 /* Must be perfomed *after* relocation. */
87 trampoline_header = (struct trampoline_header *)
88 __va(real_mode_header->trampoline_header);
91 trampoline_header->start = __pa_symbol(startup_32_smp);
92 trampoline_header->gdt_limit = __BOOT_DS + 7;
93 trampoline_header->gdt_base = __pa_symbol(boot_gdt);
96 * Some AMD processors will #GP(0) if EFER.LMA is set in WRMSR
97 * so we need to mask it out.
99 rdmsrl(MSR_EFER, efer);
100 trampoline_header->efer = efer & ~EFER_LMA;
102 trampoline_header->start = (u64) secondary_startup_64;
103 trampoline_cr4_features = &trampoline_header->cr4;
104 *trampoline_cr4_features = mmu_cr4_features;
106 trampoline_header->flags = 0;
108 trampoline_header->flags |= TH_FLAGS_SME_ACTIVE;
110 trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd);
111 trampoline_pgd[0] = trampoline_pgd_entry.pgd;
112 trampoline_pgd[511] = init_top_pgt[511].pgd;
117 * reserve_real_mode() gets called very early, to guarantee the
118 * availability of low memory. This is before the proper kernel page
119 * tables are set up, so we cannot set page permissions in that
120 * function. Also trampoline code will be executed by APs so we
121 * need to mark it executable at do_pre_smp_initcalls() at least,
122 * thus run it as a early_initcall().
124 static void __init set_real_mode_permissions(void)
126 unsigned char *base = (unsigned char *) real_mode_header;
127 size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
130 PAGE_ALIGN(real_mode_header->ro_end) -
134 PAGE_ALIGN(real_mode_header->ro_end) -
135 real_mode_header->text_start;
137 unsigned long text_start =
138 (unsigned long) __va(real_mode_header->text_start);
140 set_memory_nx((unsigned long) base, size >> PAGE_SHIFT);
141 set_memory_ro((unsigned long) base, ro_size >> PAGE_SHIFT);
142 set_memory_x((unsigned long) text_start, text_size >> PAGE_SHIFT);
145 static int __init init_real_mode(void)
147 if (!real_mode_header)
148 panic("Real mode trampoline was not allocated");
151 set_real_mode_permissions();
155 early_initcall(init_real_mode);