1 /* 2 * kvm guest debug support 3 * 4 * Copyright IBM Corp. 2014 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License (version 2 only) 8 * as published by the Free Software Foundation. 9 * 10 * Author(s): David Hildenbrand <dahi@linux.vnet.ibm.com> 11 */ 12 #include <linux/kvm_host.h> 13 #include <linux/errno.h> 14 #include "kvm-s390.h" 15 #include "gaccess.h" 16 17 /* 18 * Extends the address range given by *start and *stop to include the address 19 * range starting with estart and the length len. Takes care of overflowing 20 * intervals and tries to minimize the overall interval size. 21 */ 22 static void extend_address_range(u64 *start, u64 *stop, u64 estart, int len) 23 { 24 u64 estop; 25 26 if (len > 0) 27 len--; 28 else 29 len = 0; 30 31 estop = estart + len; 32 33 /* 0-0 range represents "not set" */ 34 if ((*start == 0) && (*stop == 0)) { 35 *start = estart; 36 *stop = estop; 37 } else if (*start <= *stop) { 38 /* increase the existing range */ 39 if (estart < *start) 40 *start = estart; 41 if (estop > *stop) 42 *stop = estop; 43 } else { 44 /* "overflowing" interval, whereby *stop > *start */ 45 if (estart <= *stop) { 46 if (estop > *stop) 47 *stop = estop; 48 } else if (estop > *start) { 49 if (estart < *start) 50 *start = estart; 51 } 52 /* minimize the range */ 53 else if ((estop - *stop) < (*start - estart)) 54 *stop = estop; 55 else 56 *start = estart; 57 } 58 } 59 60 #define MAX_INST_SIZE 6 61 62 static void enable_all_hw_bp(struct kvm_vcpu *vcpu) 63 { 64 unsigned long start, len; 65 u64 *cr9 = &vcpu->arch.sie_block->gcr[9]; 66 u64 *cr10 = &vcpu->arch.sie_block->gcr[10]; 67 u64 *cr11 = &vcpu->arch.sie_block->gcr[11]; 68 int i; 69 70 if (vcpu->arch.guestdbg.nr_hw_bp <= 0 || 71 vcpu->arch.guestdbg.hw_bp_info == NULL) 72 return; 73 74 /* 75 * If the guest is not interested in branching events, we can safely 76 * limit them to the PER address range. 77 */ 78 if (!(*cr9 & PER_EVENT_BRANCH)) 79 *cr9 |= PER_CONTROL_BRANCH_ADDRESS; 80 *cr9 |= PER_EVENT_IFETCH | PER_EVENT_BRANCH; 81 82 for (i = 0; i < vcpu->arch.guestdbg.nr_hw_bp; i++) { 83 start = vcpu->arch.guestdbg.hw_bp_info[i].addr; 84 len = vcpu->arch.guestdbg.hw_bp_info[i].len; 85 86 /* 87 * The instruction in front of the desired bp has to 88 * report instruction-fetching events 89 */ 90 if (start < MAX_INST_SIZE) { 91 len += start; 92 start = 0; 93 } else { 94 start -= MAX_INST_SIZE; 95 len += MAX_INST_SIZE; 96 } 97 98 extend_address_range(cr10, cr11, start, len); 99 } 100 } 101 102 static void enable_all_hw_wp(struct kvm_vcpu *vcpu) 103 { 104 unsigned long start, len; 105 u64 *cr9 = &vcpu->arch.sie_block->gcr[9]; 106 u64 *cr10 = &vcpu->arch.sie_block->gcr[10]; 107 u64 *cr11 = &vcpu->arch.sie_block->gcr[11]; 108 int i; 109 110 if (vcpu->arch.guestdbg.nr_hw_wp <= 0 || 111 vcpu->arch.guestdbg.hw_wp_info == NULL) 112 return; 113 114 /* if host uses storage alternation for special address 115 * spaces, enable all events and give all to the guest */ 116 if (*cr9 & PER_EVENT_STORE && *cr9 & PER_CONTROL_ALTERATION) { 117 *cr9 &= ~PER_CONTROL_ALTERATION; 118 *cr10 = 0; 119 *cr11 = -1UL; 120 } else { 121 *cr9 &= ~PER_CONTROL_ALTERATION; 122 *cr9 |= PER_EVENT_STORE; 123 124 for (i = 0; i < vcpu->arch.guestdbg.nr_hw_wp; i++) { 125 start = vcpu->arch.guestdbg.hw_wp_info[i].addr; 126 len = vcpu->arch.guestdbg.hw_wp_info[i].len; 127 128 extend_address_range(cr10, cr11, start, len); 129 } 130 } 131 } 132 133 void kvm_s390_backup_guest_per_regs(struct kvm_vcpu *vcpu) 134 { 135 vcpu->arch.guestdbg.cr0 = vcpu->arch.sie_block->gcr[0]; 136 vcpu->arch.guestdbg.cr9 = vcpu->arch.sie_block->gcr[9]; 137 vcpu->arch.guestdbg.cr10 = vcpu->arch.sie_block->gcr[10]; 138 vcpu->arch.guestdbg.cr11 = vcpu->arch.sie_block->gcr[11]; 139 } 140 141 void kvm_s390_restore_guest_per_regs(struct kvm_vcpu *vcpu) 142 { 143 vcpu->arch.sie_block->gcr[0] = vcpu->arch.guestdbg.cr0; 144 vcpu->arch.sie_block->gcr[9] = vcpu->arch.guestdbg.cr9; 145 vcpu->arch.sie_block->gcr[10] = vcpu->arch.guestdbg.cr10; 146 vcpu->arch.sie_block->gcr[11] = vcpu->arch.guestdbg.cr11; 147 } 148 149 void kvm_s390_patch_guest_per_regs(struct kvm_vcpu *vcpu) 150 { 151 /* 152 * TODO: if guest psw has per enabled, otherwise 0s! 153 * This reduces the amount of reported events. 154 * Need to intercept all psw changes! 155 */ 156 157 if (guestdbg_sstep_enabled(vcpu)) { 158 /* disable timer (clock-comparator) interrupts */ 159 vcpu->arch.sie_block->gcr[0] &= ~0x800ul; 160 vcpu->arch.sie_block->gcr[9] |= PER_EVENT_IFETCH; 161 vcpu->arch.sie_block->gcr[10] = 0; 162 vcpu->arch.sie_block->gcr[11] = -1UL; 163 } 164 165 if (guestdbg_hw_bp_enabled(vcpu)) { 166 enable_all_hw_bp(vcpu); 167 enable_all_hw_wp(vcpu); 168 } 169 170 /* TODO: Instruction-fetching-nullification not allowed for now */ 171 if (vcpu->arch.sie_block->gcr[9] & PER_EVENT_NULLIFICATION) 172 vcpu->arch.sie_block->gcr[9] &= ~PER_EVENT_NULLIFICATION; 173 } 174 175 #define MAX_WP_SIZE 100 176 177 static int __import_wp_info(struct kvm_vcpu *vcpu, 178 struct kvm_hw_breakpoint *bp_data, 179 struct kvm_hw_wp_info_arch *wp_info) 180 { 181 int ret = 0; 182 wp_info->len = bp_data->len; 183 wp_info->addr = bp_data->addr; 184 wp_info->phys_addr = bp_data->phys_addr; 185 wp_info->old_data = NULL; 186 187 if (wp_info->len < 0 || wp_info->len > MAX_WP_SIZE) 188 return -EINVAL; 189 190 wp_info->old_data = kmalloc(bp_data->len, GFP_KERNEL); 191 if (!wp_info->old_data) 192 return -ENOMEM; 193 /* try to backup the original value */ 194 ret = read_guest_abs(vcpu, wp_info->phys_addr, wp_info->old_data, 195 wp_info->len); 196 if (ret) { 197 kfree(wp_info->old_data); 198 wp_info->old_data = NULL; 199 } 200 201 return ret; 202 } 203 204 #define MAX_BP_COUNT 50 205 206 int kvm_s390_import_bp_data(struct kvm_vcpu *vcpu, 207 struct kvm_guest_debug *dbg) 208 { 209 int ret = 0, nr_wp = 0, nr_bp = 0, i; 210 struct kvm_hw_breakpoint *bp_data = NULL; 211 struct kvm_hw_wp_info_arch *wp_info = NULL; 212 struct kvm_hw_bp_info_arch *bp_info = NULL; 213 214 if (dbg->arch.nr_hw_bp <= 0 || !dbg->arch.hw_bp) 215 return 0; 216 else if (dbg->arch.nr_hw_bp > MAX_BP_COUNT) 217 return -EINVAL; 218 219 bp_data = memdup_user(dbg->arch.hw_bp, 220 sizeof(*bp_data) * dbg->arch.nr_hw_bp); 221 if (IS_ERR(bp_data)) 222 return PTR_ERR(bp_data); 223 224 for (i = 0; i < dbg->arch.nr_hw_bp; i++) { 225 switch (bp_data[i].type) { 226 case KVM_HW_WP_WRITE: 227 nr_wp++; 228 break; 229 case KVM_HW_BP: 230 nr_bp++; 231 break; 232 default: 233 break; 234 } 235 } 236 237 if (nr_wp > 0) { 238 wp_info = kmalloc_array(nr_wp, 239 sizeof(*wp_info), 240 GFP_KERNEL); 241 if (!wp_info) { 242 ret = -ENOMEM; 243 goto error; 244 } 245 } 246 if (nr_bp > 0) { 247 bp_info = kmalloc_array(nr_bp, 248 sizeof(*bp_info), 249 GFP_KERNEL); 250 if (!bp_info) { 251 ret = -ENOMEM; 252 goto error; 253 } 254 } 255 256 for (nr_wp = 0, nr_bp = 0, i = 0; i < dbg->arch.nr_hw_bp; i++) { 257 switch (bp_data[i].type) { 258 case KVM_HW_WP_WRITE: 259 ret = __import_wp_info(vcpu, &bp_data[i], 260 &wp_info[nr_wp]); 261 if (ret) 262 goto error; 263 nr_wp++; 264 break; 265 case KVM_HW_BP: 266 bp_info[nr_bp].len = bp_data[i].len; 267 bp_info[nr_bp].addr = bp_data[i].addr; 268 nr_bp++; 269 break; 270 } 271 } 272 273 vcpu->arch.guestdbg.nr_hw_bp = nr_bp; 274 vcpu->arch.guestdbg.hw_bp_info = bp_info; 275 vcpu->arch.guestdbg.nr_hw_wp = nr_wp; 276 vcpu->arch.guestdbg.hw_wp_info = wp_info; 277 return 0; 278 error: 279 kfree(bp_data); 280 kfree(wp_info); 281 kfree(bp_info); 282 return ret; 283 } 284 285 void kvm_s390_clear_bp_data(struct kvm_vcpu *vcpu) 286 { 287 int i; 288 struct kvm_hw_wp_info_arch *hw_wp_info = NULL; 289 290 for (i = 0; i < vcpu->arch.guestdbg.nr_hw_wp; i++) { 291 hw_wp_info = &vcpu->arch.guestdbg.hw_wp_info[i]; 292 kfree(hw_wp_info->old_data); 293 hw_wp_info->old_data = NULL; 294 } 295 kfree(vcpu->arch.guestdbg.hw_wp_info); 296 vcpu->arch.guestdbg.hw_wp_info = NULL; 297 298 kfree(vcpu->arch.guestdbg.hw_bp_info); 299 vcpu->arch.guestdbg.hw_bp_info = NULL; 300 301 vcpu->arch.guestdbg.nr_hw_wp = 0; 302 vcpu->arch.guestdbg.nr_hw_bp = 0; 303 } 304 305 static inline int in_addr_range(u64 addr, u64 a, u64 b) 306 { 307 if (a <= b) 308 return (addr >= a) && (addr <= b); 309 else 310 /* "overflowing" interval */ 311 return (addr <= a) && (addr >= b); 312 } 313 314 #define end_of_range(bp_info) (bp_info->addr + bp_info->len - 1) 315 316 static struct kvm_hw_bp_info_arch *find_hw_bp(struct kvm_vcpu *vcpu, 317 unsigned long addr) 318 { 319 struct kvm_hw_bp_info_arch *bp_info = vcpu->arch.guestdbg.hw_bp_info; 320 int i; 321 322 if (vcpu->arch.guestdbg.nr_hw_bp == 0) 323 return NULL; 324 325 for (i = 0; i < vcpu->arch.guestdbg.nr_hw_bp; i++) { 326 /* addr is directly the start or in the range of a bp */ 327 if (addr == bp_info->addr) 328 goto found; 329 if (bp_info->len > 0 && 330 in_addr_range(addr, bp_info->addr, end_of_range(bp_info))) 331 goto found; 332 333 bp_info++; 334 } 335 336 return NULL; 337 found: 338 return bp_info; 339 } 340 341 static struct kvm_hw_wp_info_arch *any_wp_changed(struct kvm_vcpu *vcpu) 342 { 343 int i; 344 struct kvm_hw_wp_info_arch *wp_info = NULL; 345 void *temp = NULL; 346 347 if (vcpu->arch.guestdbg.nr_hw_wp == 0) 348 return NULL; 349 350 for (i = 0; i < vcpu->arch.guestdbg.nr_hw_wp; i++) { 351 wp_info = &vcpu->arch.guestdbg.hw_wp_info[i]; 352 if (!wp_info || !wp_info->old_data || wp_info->len <= 0) 353 continue; 354 355 temp = kmalloc(wp_info->len, GFP_KERNEL); 356 if (!temp) 357 continue; 358 359 /* refetch the wp data and compare it to the old value */ 360 if (!read_guest_abs(vcpu, wp_info->phys_addr, temp, 361 wp_info->len)) { 362 if (memcmp(temp, wp_info->old_data, wp_info->len)) { 363 kfree(temp); 364 return wp_info; 365 } 366 } 367 kfree(temp); 368 temp = NULL; 369 } 370 371 return NULL; 372 } 373 374 void kvm_s390_prepare_debug_exit(struct kvm_vcpu *vcpu) 375 { 376 vcpu->run->exit_reason = KVM_EXIT_DEBUG; 377 vcpu->guest_debug &= ~KVM_GUESTDBG_EXIT_PENDING; 378 } 379 380 #define PER_CODE_MASK (PER_EVENT_MASK >> 24) 381 #define PER_CODE_BRANCH (PER_EVENT_BRANCH >> 24) 382 #define PER_CODE_IFETCH (PER_EVENT_IFETCH >> 24) 383 #define PER_CODE_STORE (PER_EVENT_STORE >> 24) 384 #define PER_CODE_STORE_REAL (PER_EVENT_STORE_REAL >> 24) 385 386 #define per_bp_event(code) \ 387 (code & (PER_CODE_IFETCH | PER_CODE_BRANCH)) 388 #define per_write_wp_event(code) \ 389 (code & (PER_CODE_STORE | PER_CODE_STORE_REAL)) 390 391 static int debug_exit_required(struct kvm_vcpu *vcpu) 392 { 393 u8 perc = vcpu->arch.sie_block->perc; 394 struct kvm_debug_exit_arch *debug_exit = &vcpu->run->debug.arch; 395 struct kvm_hw_wp_info_arch *wp_info = NULL; 396 struct kvm_hw_bp_info_arch *bp_info = NULL; 397 unsigned long addr = vcpu->arch.sie_block->gpsw.addr; 398 unsigned long peraddr = vcpu->arch.sie_block->peraddr; 399 400 if (guestdbg_hw_bp_enabled(vcpu)) { 401 if (per_write_wp_event(perc) && 402 vcpu->arch.guestdbg.nr_hw_wp > 0) { 403 wp_info = any_wp_changed(vcpu); 404 if (wp_info) { 405 debug_exit->addr = wp_info->addr; 406 debug_exit->type = KVM_HW_WP_WRITE; 407 goto exit_required; 408 } 409 } 410 if (per_bp_event(perc) && 411 vcpu->arch.guestdbg.nr_hw_bp > 0) { 412 bp_info = find_hw_bp(vcpu, addr); 413 /* remove duplicate events if PC==PER address */ 414 if (bp_info && (addr != peraddr)) { 415 debug_exit->addr = addr; 416 debug_exit->type = KVM_HW_BP; 417 vcpu->arch.guestdbg.last_bp = addr; 418 goto exit_required; 419 } 420 /* breakpoint missed */ 421 bp_info = find_hw_bp(vcpu, peraddr); 422 if (bp_info && vcpu->arch.guestdbg.last_bp != peraddr) { 423 debug_exit->addr = peraddr; 424 debug_exit->type = KVM_HW_BP; 425 goto exit_required; 426 } 427 } 428 } 429 if (guestdbg_sstep_enabled(vcpu) && per_bp_event(perc)) { 430 debug_exit->addr = addr; 431 debug_exit->type = KVM_SINGLESTEP; 432 goto exit_required; 433 } 434 435 return 0; 436 exit_required: 437 return 1; 438 } 439 440 #define guest_per_enabled(vcpu) \ 441 (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PER) 442 443 int kvm_s390_handle_per_ifetch_icpt(struct kvm_vcpu *vcpu) 444 { 445 const u8 ilen = kvm_s390_get_ilen(vcpu); 446 struct kvm_s390_pgm_info pgm_info = { 447 .code = PGM_PER, 448 .per_code = PER_CODE_IFETCH, 449 .per_address = __rewind_psw(vcpu->arch.sie_block->gpsw, ilen), 450 }; 451 452 /* 453 * The PSW points to the next instruction, therefore the intercepted 454 * instruction generated a PER i-fetch event. PER address therefore 455 * points at the previous PSW address (could be an EXECUTE function). 456 */ 457 return kvm_s390_inject_prog_irq(vcpu, &pgm_info); 458 } 459 460 static void filter_guest_per_event(struct kvm_vcpu *vcpu) 461 { 462 const u8 perc = vcpu->arch.sie_block->perc; 463 u64 peraddr = vcpu->arch.sie_block->peraddr; 464 u64 addr = vcpu->arch.sie_block->gpsw.addr; 465 u64 cr9 = vcpu->arch.sie_block->gcr[9]; 466 u64 cr10 = vcpu->arch.sie_block->gcr[10]; 467 u64 cr11 = vcpu->arch.sie_block->gcr[11]; 468 /* filter all events, demanded by the guest */ 469 u8 guest_perc = perc & (cr9 >> 24) & PER_CODE_MASK; 470 471 if (!guest_per_enabled(vcpu)) 472 guest_perc = 0; 473 474 /* filter "successful-branching" events */ 475 if (guest_perc & PER_CODE_BRANCH && 476 cr9 & PER_CONTROL_BRANCH_ADDRESS && 477 !in_addr_range(addr, cr10, cr11)) 478 guest_perc &= ~PER_CODE_BRANCH; 479 480 /* filter "instruction-fetching" events */ 481 if (guest_perc & PER_CODE_IFETCH && 482 !in_addr_range(peraddr, cr10, cr11)) 483 guest_perc &= ~PER_CODE_IFETCH; 484 485 /* All other PER events will be given to the guest */ 486 /* TODO: Check altered address/address space */ 487 488 vcpu->arch.sie_block->perc = guest_perc; 489 490 if (!guest_perc) 491 vcpu->arch.sie_block->iprcc &= ~PGM_PER; 492 } 493 494 #define pssec(vcpu) (vcpu->arch.sie_block->gcr[1] & _ASCE_SPACE_SWITCH) 495 #define hssec(vcpu) (vcpu->arch.sie_block->gcr[13] & _ASCE_SPACE_SWITCH) 496 #define old_ssec(vcpu) ((vcpu->arch.sie_block->tecmc >> 31) & 0x1) 497 #define old_as_is_home(vcpu) !(vcpu->arch.sie_block->tecmc & 0xffff) 498 499 void kvm_s390_handle_per_event(struct kvm_vcpu *vcpu) 500 { 501 int new_as; 502 503 if (debug_exit_required(vcpu)) 504 vcpu->guest_debug |= KVM_GUESTDBG_EXIT_PENDING; 505 506 filter_guest_per_event(vcpu); 507 508 /* 509 * Only RP, SAC, SACF, PT, PTI, PR, PC instructions can trigger 510 * a space-switch event. PER events enforce space-switch events 511 * for these instructions. So if no PER event for the guest is left, 512 * we might have to filter the space-switch element out, too. 513 */ 514 if (vcpu->arch.sie_block->iprcc == PGM_SPACE_SWITCH) { 515 vcpu->arch.sie_block->iprcc = 0; 516 new_as = psw_bits(vcpu->arch.sie_block->gpsw).as; 517 518 /* 519 * If the AS changed from / to home, we had RP, SAC or SACF 520 * instruction. Check primary and home space-switch-event 521 * controls. (theoretically home -> home produced no event) 522 */ 523 if (((new_as == PSW_AS_HOME) ^ old_as_is_home(vcpu)) && 524 (pssec(vcpu) || hssec(vcpu))) 525 vcpu->arch.sie_block->iprcc = PGM_SPACE_SWITCH; 526 527 /* 528 * PT, PTI, PR, PC instruction operate on primary AS only. Check 529 * if the primary-space-switch-event control was or got set. 530 */ 531 if (new_as == PSW_AS_PRIMARY && !old_as_is_home(vcpu) && 532 (pssec(vcpu) || old_ssec(vcpu))) 533 vcpu->arch.sie_block->iprcc = PGM_SPACE_SWITCH; 534 } 535 } 536