1 // SPDX-License-Identifier: GPL-2.0
3 #include <linux/slab.h>
4 #include <linux/memblock.h>
5 #include <linux/mem_encrypt.h>
7 #include <asm/set_memory.h>
8 #include <asm/pgtable.h>
9 #include <asm/realmode.h>
10 #include <asm/tlbflush.h>
12 struct real_mode_header *real_mode_header;
13 u32 *trampoline_cr4_features;
15 /* Hold the pgd entry used on booting additional CPUs */
16 pgd_t trampoline_pgd_entry;
18 void __init reserve_real_mode(void)
21 size_t size = real_mode_size_needed();
26 WARN_ON(slab_is_available());
28 /* Has to be under 1M so we can execute real-mode AP code. */
29 mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE);
31 pr_info("No sub-1M memory is available for the trampoline\n");
35 memblock_reserve(mem, size);
36 set_real_mode_mem(mem);
39 static void __init setup_real_mode(void)
45 unsigned long phys_base;
46 struct trampoline_header *trampoline_header;
47 size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
53 base = (unsigned char *)real_mode_header;
56 * If SME is active, the trampoline area will need to be in
57 * decrypted memory in order to bring up other processors
58 * successfully. This is not needed for SEV.
61 set_memory_decrypted((unsigned long)base, size >> PAGE_SHIFT);
63 memcpy(base, real_mode_blob, size);
65 phys_base = __pa(base);
66 real_mode_seg = phys_base >> 4;
68 rel = (u32 *) real_mode_relocs;
70 /* 16-bit segment relocations. */
73 u16 *seg = (u16 *) (base + *rel++);
77 /* 32-bit linear relocations. */
80 u32 *ptr = (u32 *) (base + *rel++);
84 /* Must be perfomed *after* relocation. */
85 trampoline_header = (struct trampoline_header *)
86 __va(real_mode_header->trampoline_header);
89 trampoline_header->start = __pa_symbol(startup_32_smp);
90 trampoline_header->gdt_limit = __BOOT_DS + 7;
91 trampoline_header->gdt_base = __pa_symbol(boot_gdt);
94 * Some AMD processors will #GP(0) if EFER.LMA is set in WRMSR
95 * so we need to mask it out.
97 rdmsrl(MSR_EFER, efer);
98 trampoline_header->efer = efer & ~EFER_LMA;
100 trampoline_header->start = (u64) secondary_startup_64;
101 trampoline_cr4_features = &trampoline_header->cr4;
102 *trampoline_cr4_features = mmu_cr4_features;
104 trampoline_header->flags = 0;
106 trampoline_header->flags |= TH_FLAGS_SME_ACTIVE;
108 trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd);
109 trampoline_pgd[0] = trampoline_pgd_entry.pgd;
110 trampoline_pgd[511] = init_top_pgt[511].pgd;
115 * reserve_real_mode() gets called very early, to guarantee the
116 * availability of low memory. This is before the proper kernel page
117 * tables are set up, so we cannot set page permissions in that
118 * function. Also trampoline code will be executed by APs so we
119 * need to mark it executable at do_pre_smp_initcalls() at least,
120 * thus run it as a early_initcall().
122 static void __init set_real_mode_permissions(void)
124 unsigned char *base = (unsigned char *) real_mode_header;
125 size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
128 PAGE_ALIGN(real_mode_header->ro_end) -
132 PAGE_ALIGN(real_mode_header->ro_end) -
133 real_mode_header->text_start;
135 unsigned long text_start =
136 (unsigned long) __va(real_mode_header->text_start);
138 set_memory_nx((unsigned long) base, size >> PAGE_SHIFT);
139 set_memory_ro((unsigned long) base, ro_size >> PAGE_SHIFT);
140 set_memory_x((unsigned long) text_start, text_size >> PAGE_SHIFT);
143 static int __init init_real_mode(void)
145 if (!real_mode_header)
146 panic("Real mode trampoline was not allocated");
149 set_real_mode_permissions();
153 early_initcall(init_real_mode);