1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/io.h> 3 #include <linux/slab.h> 4 #include <linux/memblock.h> 5 #include <linux/mem_encrypt.h> 6 7 #include <asm/set_memory.h> 8 #include <asm/pgtable.h> 9 #include <asm/realmode.h> 10 #include <asm/tlbflush.h> 11 12 struct real_mode_header *real_mode_header; 13 u32 *trampoline_cr4_features; 14 15 /* Hold the pgd entry used on booting additional CPUs */ 16 pgd_t trampoline_pgd_entry; 17 18 void __init set_real_mode_mem(phys_addr_t mem, size_t size) 19 { 20 void *base = __va(mem); 21 22 real_mode_header = (struct real_mode_header *) base; 23 printk(KERN_DEBUG "Base memory trampoline at [%p] %llx size %zu\n", 24 base, (unsigned long long)mem, size); 25 } 26 27 void __init reserve_real_mode(void) 28 { 29 phys_addr_t mem; 30 size_t size = real_mode_size_needed(); 31 32 if (!size) 33 return; 34 35 WARN_ON(slab_is_available()); 36 37 /* Has to be under 1M so we can execute real-mode AP code. */ 38 mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE); 39 if (!mem) { 40 pr_info("No sub-1M memory is available for the trampoline\n"); 41 return; 42 } 43 44 memblock_reserve(mem, size); 45 set_real_mode_mem(mem, size); 46 } 47 48 static void __init setup_real_mode(void) 49 { 50 u16 real_mode_seg; 51 const u32 *rel; 52 u32 count; 53 unsigned char *base; 54 unsigned long phys_base; 55 struct trampoline_header *trampoline_header; 56 size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob); 57 #ifdef CONFIG_X86_64 58 u64 *trampoline_pgd; 59 u64 efer; 60 #endif 61 62 base = (unsigned char *)real_mode_header; 63 64 /* 65 * If SME is active, the trampoline area will need to be in 66 * decrypted memory in order to bring up other processors 67 * successfully. This is not needed for SEV. 68 */ 69 if (sme_active()) 70 set_memory_decrypted((unsigned long)base, size >> PAGE_SHIFT); 71 72 memcpy(base, real_mode_blob, size); 73 74 phys_base = __pa(base); 75 real_mode_seg = phys_base >> 4; 76 77 rel = (u32 *) real_mode_relocs; 78 79 /* 16-bit segment relocations. */ 80 count = *rel++; 81 while (count--) { 82 u16 *seg = (u16 *) (base + *rel++); 83 *seg = real_mode_seg; 84 } 85 86 /* 32-bit linear relocations. */ 87 count = *rel++; 88 while (count--) { 89 u32 *ptr = (u32 *) (base + *rel++); 90 *ptr += phys_base; 91 } 92 93 /* Must be perfomed *after* relocation. */ 94 trampoline_header = (struct trampoline_header *) 95 __va(real_mode_header->trampoline_header); 96 97 #ifdef CONFIG_X86_32 98 trampoline_header->start = __pa_symbol(startup_32_smp); 99 trampoline_header->gdt_limit = __BOOT_DS + 7; 100 trampoline_header->gdt_base = __pa_symbol(boot_gdt); 101 #else 102 /* 103 * Some AMD processors will #GP(0) if EFER.LMA is set in WRMSR 104 * so we need to mask it out. 105 */ 106 rdmsrl(MSR_EFER, efer); 107 trampoline_header->efer = efer & ~EFER_LMA; 108 109 trampoline_header->start = (u64) secondary_startup_64; 110 trampoline_cr4_features = &trampoline_header->cr4; 111 *trampoline_cr4_features = mmu_cr4_features; 112 113 trampoline_header->flags = 0; 114 if (sme_active()) 115 trampoline_header->flags |= TH_FLAGS_SME_ACTIVE; 116 117 trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd); 118 trampoline_pgd[0] = trampoline_pgd_entry.pgd; 119 trampoline_pgd[511] = init_top_pgt[511].pgd; 120 #endif 121 } 122 123 /* 124 * reserve_real_mode() gets called very early, to guarantee the 125 * availability of low memory. This is before the proper kernel page 126 * tables are set up, so we cannot set page permissions in that 127 * function. Also trampoline code will be executed by APs so we 128 * need to mark it executable at do_pre_smp_initcalls() at least, 129 * thus run it as a early_initcall(). 130 */ 131 static void __init set_real_mode_permissions(void) 132 { 133 unsigned char *base = (unsigned char *) real_mode_header; 134 size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob); 135 136 size_t ro_size = 137 PAGE_ALIGN(real_mode_header->ro_end) - 138 __pa(base); 139 140 size_t text_size = 141 PAGE_ALIGN(real_mode_header->ro_end) - 142 real_mode_header->text_start; 143 144 unsigned long text_start = 145 (unsigned long) __va(real_mode_header->text_start); 146 147 set_memory_nx((unsigned long) base, size >> PAGE_SHIFT); 148 set_memory_ro((unsigned long) base, ro_size >> PAGE_SHIFT); 149 set_memory_x((unsigned long) text_start, text_size >> PAGE_SHIFT); 150 } 151 152 static int __init init_real_mode(void) 153 { 154 if (!real_mode_header) 155 panic("Real mode trampoline was not allocated"); 156 157 setup_real_mode(); 158 set_real_mode_permissions(); 159 160 return 0; 161 } 162 early_initcall(init_real_mode); 163