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 #include <linux/pgtable.h> 7 8 #include <asm/set_memory.h> 9 #include <asm/realmode.h> 10 #include <asm/tlbflush.h> 11 #include <asm/crash.h> 12 #include <asm/sev-es.h> 13 14 struct real_mode_header *real_mode_header; 15 u32 *trampoline_cr4_features; 16 17 /* Hold the pgd entry used on booting additional CPUs */ 18 pgd_t trampoline_pgd_entry; 19 20 void __init reserve_real_mode(void) 21 { 22 phys_addr_t mem; 23 size_t size = real_mode_size_needed(); 24 25 if (!size) 26 return; 27 28 WARN_ON(slab_is_available()); 29 30 /* Has to be under 1M so we can execute real-mode AP code. */ 31 mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE); 32 if (!mem) { 33 pr_info("No sub-1M memory is available for the trampoline\n"); 34 return; 35 } 36 37 memblock_reserve(mem, size); 38 set_real_mode_mem(mem); 39 crash_reserve_low_1M(); 40 } 41 42 static void sme_sev_setup_real_mode(struct trampoline_header *th) 43 { 44 #ifdef CONFIG_AMD_MEM_ENCRYPT 45 if (sme_active()) 46 th->flags |= TH_FLAGS_SME_ACTIVE; 47 48 if (sev_es_active()) { 49 /* 50 * Skip the call to verify_cpu() in secondary_startup_64 as it 51 * will cause #VC exceptions when the AP can't handle them yet. 52 */ 53 th->start = (u64) secondary_startup_64_no_verify; 54 55 if (sev_es_setup_ap_jump_table(real_mode_header)) 56 panic("Failed to get/update SEV-ES AP Jump Table"); 57 } 58 #endif 59 } 60 61 static void __init setup_real_mode(void) 62 { 63 u16 real_mode_seg; 64 const u32 *rel; 65 u32 count; 66 unsigned char *base; 67 unsigned long phys_base; 68 struct trampoline_header *trampoline_header; 69 size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob); 70 #ifdef CONFIG_X86_64 71 u64 *trampoline_pgd; 72 u64 efer; 73 #endif 74 75 base = (unsigned char *)real_mode_header; 76 77 /* 78 * If SME is active, the trampoline area will need to be in 79 * decrypted memory in order to bring up other processors 80 * successfully. This is not needed for SEV. 81 */ 82 if (sme_active()) 83 set_memory_decrypted((unsigned long)base, size >> PAGE_SHIFT); 84 85 memcpy(base, real_mode_blob, size); 86 87 phys_base = __pa(base); 88 real_mode_seg = phys_base >> 4; 89 90 rel = (u32 *) real_mode_relocs; 91 92 /* 16-bit segment relocations. */ 93 count = *rel++; 94 while (count--) { 95 u16 *seg = (u16 *) (base + *rel++); 96 *seg = real_mode_seg; 97 } 98 99 /* 32-bit linear relocations. */ 100 count = *rel++; 101 while (count--) { 102 u32 *ptr = (u32 *) (base + *rel++); 103 *ptr += phys_base; 104 } 105 106 /* Must be performed *after* relocation. */ 107 trampoline_header = (struct trampoline_header *) 108 __va(real_mode_header->trampoline_header); 109 110 #ifdef CONFIG_X86_32 111 trampoline_header->start = __pa_symbol(startup_32_smp); 112 trampoline_header->gdt_limit = __BOOT_DS + 7; 113 trampoline_header->gdt_base = __pa_symbol(boot_gdt); 114 #else 115 /* 116 * Some AMD processors will #GP(0) if EFER.LMA is set in WRMSR 117 * so we need to mask it out. 118 */ 119 rdmsrl(MSR_EFER, efer); 120 trampoline_header->efer = efer & ~EFER_LMA; 121 122 trampoline_header->start = (u64) secondary_startup_64; 123 trampoline_cr4_features = &trampoline_header->cr4; 124 *trampoline_cr4_features = mmu_cr4_features; 125 126 trampoline_header->flags = 0; 127 128 trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd); 129 trampoline_pgd[0] = trampoline_pgd_entry.pgd; 130 trampoline_pgd[511] = init_top_pgt[511].pgd; 131 #endif 132 133 sme_sev_setup_real_mode(trampoline_header); 134 } 135 136 /* 137 * reserve_real_mode() gets called very early, to guarantee the 138 * availability of low memory. This is before the proper kernel page 139 * tables are set up, so we cannot set page permissions in that 140 * function. Also trampoline code will be executed by APs so we 141 * need to mark it executable at do_pre_smp_initcalls() at least, 142 * thus run it as a early_initcall(). 143 */ 144 static void __init set_real_mode_permissions(void) 145 { 146 unsigned char *base = (unsigned char *) real_mode_header; 147 size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob); 148 149 size_t ro_size = 150 PAGE_ALIGN(real_mode_header->ro_end) - 151 __pa(base); 152 153 size_t text_size = 154 PAGE_ALIGN(real_mode_header->ro_end) - 155 real_mode_header->text_start; 156 157 unsigned long text_start = 158 (unsigned long) __va(real_mode_header->text_start); 159 160 set_memory_nx((unsigned long) base, size >> PAGE_SHIFT); 161 set_memory_ro((unsigned long) base, ro_size >> PAGE_SHIFT); 162 set_memory_x((unsigned long) text_start, text_size >> PAGE_SHIFT); 163 } 164 165 static int __init init_real_mode(void) 166 { 167 if (!real_mode_header) 168 panic("Real mode trampoline was not allocated"); 169 170 setup_real_mode(); 171 set_real_mode_permissions(); 172 173 return 0; 174 } 175 early_initcall(init_real_mode); 176