1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2017 ARM Ltd. 4 * Author: Marc Zyngier <marc.zyngier@arm.com> 5 */ 6 7 #include <linux/kvm_host.h> 8 #include <linux/random.h> 9 #include <linux/memblock.h> 10 #include <asm/alternative.h> 11 #include <asm/debug-monitors.h> 12 #include <asm/insn.h> 13 #include <asm/kvm_mmu.h> 14 #include <asm/memory.h> 15 16 /* 17 * The LSB of the HYP VA tag 18 */ 19 static u8 tag_lsb; 20 /* 21 * The HYP VA tag value with the region bit 22 */ 23 static u64 tag_val; 24 static u64 va_mask; 25 26 /* 27 * Compute HYP VA by using the same computation as kern_hyp_va(). 28 */ 29 static u64 __early_kern_hyp_va(u64 addr) 30 { 31 addr &= va_mask; 32 addr |= tag_val << tag_lsb; 33 return addr; 34 } 35 36 /* 37 * Store a hyp VA <-> PA offset into a EL2-owned variable. 38 */ 39 static void init_hyp_physvirt_offset(void) 40 { 41 u64 kern_va, hyp_va; 42 43 /* Compute the offset from the hyp VA and PA of a random symbol. */ 44 kern_va = (u64)lm_alias(__hyp_text_start); 45 hyp_va = __early_kern_hyp_va(kern_va); 46 hyp_physvirt_offset = (s64)__pa(kern_va) - (s64)hyp_va; 47 } 48 49 /* 50 * We want to generate a hyp VA with the following format (with V == 51 * vabits_actual): 52 * 53 * 63 ... V | V-1 | V-2 .. tag_lsb | tag_lsb - 1 .. 0 54 * --------------------------------------------------------- 55 * | 0000000 | hyp_va_msb | random tag | kern linear VA | 56 * |--------- tag_val -----------|----- va_mask ---| 57 * 58 * which does not conflict with the idmap regions. 59 */ 60 __init void kvm_compute_layout(void) 61 { 62 phys_addr_t idmap_addr = __pa_symbol(__hyp_idmap_text_start); 63 u64 hyp_va_msb; 64 65 /* Where is my RAM region? */ 66 hyp_va_msb = idmap_addr & BIT(vabits_actual - 1); 67 hyp_va_msb ^= BIT(vabits_actual - 1); 68 69 tag_lsb = fls64((u64)phys_to_virt(memblock_start_of_DRAM()) ^ 70 (u64)(high_memory - 1)); 71 72 va_mask = GENMASK_ULL(tag_lsb - 1, 0); 73 tag_val = hyp_va_msb; 74 75 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && tag_lsb != (vabits_actual - 1)) { 76 /* We have some free bits to insert a random tag. */ 77 tag_val |= get_random_long() & GENMASK_ULL(vabits_actual - 2, tag_lsb); 78 } 79 tag_val >>= tag_lsb; 80 81 init_hyp_physvirt_offset(); 82 } 83 84 /* 85 * The .hyp.reloc ELF section contains a list of kimg positions that 86 * contains kimg VAs but will be accessed only in hyp execution context. 87 * Convert them to hyp VAs. See gen-hyprel.c for more details. 88 */ 89 __init void kvm_apply_hyp_relocations(void) 90 { 91 int32_t *rel; 92 int32_t *begin = (int32_t *)__hyp_reloc_begin; 93 int32_t *end = (int32_t *)__hyp_reloc_end; 94 95 for (rel = begin; rel < end; ++rel) { 96 uintptr_t *ptr, kimg_va; 97 98 /* 99 * Each entry contains a 32-bit relative offset from itself 100 * to a kimg VA position. 101 */ 102 ptr = (uintptr_t *)lm_alias((char *)rel + *rel); 103 104 /* Read the kimg VA value at the relocation address. */ 105 kimg_va = *ptr; 106 107 /* Convert to hyp VA and store back to the relocation address. */ 108 *ptr = __early_kern_hyp_va((uintptr_t)lm_alias(kimg_va)); 109 } 110 } 111 112 static u32 compute_instruction(int n, u32 rd, u32 rn) 113 { 114 u32 insn = AARCH64_BREAK_FAULT; 115 116 switch (n) { 117 case 0: 118 insn = aarch64_insn_gen_logical_immediate(AARCH64_INSN_LOGIC_AND, 119 AARCH64_INSN_VARIANT_64BIT, 120 rn, rd, va_mask); 121 break; 122 123 case 1: 124 /* ROR is a variant of EXTR with Rm = Rn */ 125 insn = aarch64_insn_gen_extr(AARCH64_INSN_VARIANT_64BIT, 126 rn, rn, rd, 127 tag_lsb); 128 break; 129 130 case 2: 131 insn = aarch64_insn_gen_add_sub_imm(rd, rn, 132 tag_val & GENMASK(11, 0), 133 AARCH64_INSN_VARIANT_64BIT, 134 AARCH64_INSN_ADSB_ADD); 135 break; 136 137 case 3: 138 insn = aarch64_insn_gen_add_sub_imm(rd, rn, 139 tag_val & GENMASK(23, 12), 140 AARCH64_INSN_VARIANT_64BIT, 141 AARCH64_INSN_ADSB_ADD); 142 break; 143 144 case 4: 145 /* ROR is a variant of EXTR with Rm = Rn */ 146 insn = aarch64_insn_gen_extr(AARCH64_INSN_VARIANT_64BIT, 147 rn, rn, rd, 64 - tag_lsb); 148 break; 149 } 150 151 return insn; 152 } 153 154 void __init kvm_update_va_mask(struct alt_instr *alt, 155 __le32 *origptr, __le32 *updptr, int nr_inst) 156 { 157 int i; 158 159 BUG_ON(nr_inst != 5); 160 161 for (i = 0; i < nr_inst; i++) { 162 u32 rd, rn, insn, oinsn; 163 164 /* 165 * VHE doesn't need any address translation, let's NOP 166 * everything. 167 * 168 * Alternatively, if the tag is zero (because the layout 169 * dictates it and we don't have any spare bits in the 170 * address), NOP everything after masking the kernel VA. 171 */ 172 if (cpus_have_cap(ARM64_HAS_VIRT_HOST_EXTN) || (!tag_val && i > 0)) { 173 updptr[i] = cpu_to_le32(aarch64_insn_gen_nop()); 174 continue; 175 } 176 177 oinsn = le32_to_cpu(origptr[i]); 178 rd = aarch64_insn_decode_register(AARCH64_INSN_REGTYPE_RD, oinsn); 179 rn = aarch64_insn_decode_register(AARCH64_INSN_REGTYPE_RN, oinsn); 180 181 insn = compute_instruction(i, rd, rn); 182 BUG_ON(insn == AARCH64_BREAK_FAULT); 183 184 updptr[i] = cpu_to_le32(insn); 185 } 186 } 187 188 void kvm_patch_vector_branch(struct alt_instr *alt, 189 __le32 *origptr, __le32 *updptr, int nr_inst) 190 { 191 u64 addr; 192 u32 insn; 193 194 BUG_ON(nr_inst != 4); 195 196 if (!cpus_have_cap(ARM64_SPECTRE_V3A) || 197 WARN_ON_ONCE(cpus_have_cap(ARM64_HAS_VIRT_HOST_EXTN))) 198 return; 199 200 /* 201 * Compute HYP VA by using the same computation as kern_hyp_va() 202 */ 203 addr = __early_kern_hyp_va((u64)kvm_ksym_ref(__kvm_hyp_vector)); 204 205 /* Use PC[10:7] to branch to the same vector in KVM */ 206 addr |= ((u64)origptr & GENMASK_ULL(10, 7)); 207 208 /* 209 * Branch over the preamble in order to avoid the initial store on 210 * the stack (which we already perform in the hardening vectors). 211 */ 212 addr += KVM_VECTOR_PREAMBLE; 213 214 /* movz x0, #(addr & 0xffff) */ 215 insn = aarch64_insn_gen_movewide(AARCH64_INSN_REG_0, 216 (u16)addr, 217 0, 218 AARCH64_INSN_VARIANT_64BIT, 219 AARCH64_INSN_MOVEWIDE_ZERO); 220 *updptr++ = cpu_to_le32(insn); 221 222 /* movk x0, #((addr >> 16) & 0xffff), lsl #16 */ 223 insn = aarch64_insn_gen_movewide(AARCH64_INSN_REG_0, 224 (u16)(addr >> 16), 225 16, 226 AARCH64_INSN_VARIANT_64BIT, 227 AARCH64_INSN_MOVEWIDE_KEEP); 228 *updptr++ = cpu_to_le32(insn); 229 230 /* movk x0, #((addr >> 32) & 0xffff), lsl #32 */ 231 insn = aarch64_insn_gen_movewide(AARCH64_INSN_REG_0, 232 (u16)(addr >> 32), 233 32, 234 AARCH64_INSN_VARIANT_64BIT, 235 AARCH64_INSN_MOVEWIDE_KEEP); 236 *updptr++ = cpu_to_le32(insn); 237 238 /* br x0 */ 239 insn = aarch64_insn_gen_branch_reg(AARCH64_INSN_REG_0, 240 AARCH64_INSN_BRANCH_NOLINK); 241 *updptr++ = cpu_to_le32(insn); 242 } 243 244 static void generate_mov_q(u64 val, __le32 *origptr, __le32 *updptr, int nr_inst) 245 { 246 u32 insn, oinsn, rd; 247 248 BUG_ON(nr_inst != 4); 249 250 /* Compute target register */ 251 oinsn = le32_to_cpu(*origptr); 252 rd = aarch64_insn_decode_register(AARCH64_INSN_REGTYPE_RD, oinsn); 253 254 /* movz rd, #(val & 0xffff) */ 255 insn = aarch64_insn_gen_movewide(rd, 256 (u16)val, 257 0, 258 AARCH64_INSN_VARIANT_64BIT, 259 AARCH64_INSN_MOVEWIDE_ZERO); 260 *updptr++ = cpu_to_le32(insn); 261 262 /* movk rd, #((val >> 16) & 0xffff), lsl #16 */ 263 insn = aarch64_insn_gen_movewide(rd, 264 (u16)(val >> 16), 265 16, 266 AARCH64_INSN_VARIANT_64BIT, 267 AARCH64_INSN_MOVEWIDE_KEEP); 268 *updptr++ = cpu_to_le32(insn); 269 270 /* movk rd, #((val >> 32) & 0xffff), lsl #32 */ 271 insn = aarch64_insn_gen_movewide(rd, 272 (u16)(val >> 32), 273 32, 274 AARCH64_INSN_VARIANT_64BIT, 275 AARCH64_INSN_MOVEWIDE_KEEP); 276 *updptr++ = cpu_to_le32(insn); 277 278 /* movk rd, #((val >> 48) & 0xffff), lsl #48 */ 279 insn = aarch64_insn_gen_movewide(rd, 280 (u16)(val >> 48), 281 48, 282 AARCH64_INSN_VARIANT_64BIT, 283 AARCH64_INSN_MOVEWIDE_KEEP); 284 *updptr++ = cpu_to_le32(insn); 285 } 286 287 void kvm_get_kimage_voffset(struct alt_instr *alt, 288 __le32 *origptr, __le32 *updptr, int nr_inst) 289 { 290 generate_mov_q(kimage_voffset, origptr, updptr, nr_inst); 291 } 292 293 void kvm_compute_final_ctr_el0(struct alt_instr *alt, 294 __le32 *origptr, __le32 *updptr, int nr_inst) 295 { 296 generate_mov_q(read_sanitised_ftr_reg(SYS_CTR_EL0), 297 origptr, updptr, nr_inst); 298 } 299