1 /* 2 * Xen SMP support 3 * 4 * This file implements the Xen versions of smp_ops. SMP under Xen is 5 * very straightforward. Bringing a CPU up is simply a matter of 6 * loading its initial context and setting it running. 7 * 8 * IPIs are handled through the Xen event mechanism. 9 * 10 * Because virtual CPUs can be scheduled onto any real CPU, there's no 11 * useful topology information for the kernel to make use of. As a 12 * result, all CPUs are treated as if they're single-core and 13 * single-threaded. 14 */ 15 #include <linux/sched.h> 16 #include <linux/err.h> 17 #include <linux/slab.h> 18 #include <linux/smp.h> 19 20 #include <asm/paravirt.h> 21 #include <asm/desc.h> 22 #include <asm/pgtable.h> 23 #include <asm/cpu.h> 24 25 #include <xen/interface/xen.h> 26 #include <xen/interface/vcpu.h> 27 28 #include <asm/xen/interface.h> 29 #include <asm/xen/hypercall.h> 30 31 #include <xen/xen.h> 32 #include <xen/page.h> 33 #include <xen/events.h> 34 35 #include "xen-ops.h" 36 #include "mmu.h" 37 38 cpumask_var_t xen_cpu_initialized_map; 39 40 static DEFINE_PER_CPU(int, xen_resched_irq); 41 static DEFINE_PER_CPU(int, xen_callfunc_irq); 42 static DEFINE_PER_CPU(int, xen_callfuncsingle_irq); 43 static DEFINE_PER_CPU(int, xen_debug_irq) = -1; 44 45 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id); 46 static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id); 47 48 /* 49 * Reschedule call back. 50 */ 51 static irqreturn_t xen_reschedule_interrupt(int irq, void *dev_id) 52 { 53 inc_irq_stat(irq_resched_count); 54 scheduler_ipi(); 55 56 return IRQ_HANDLED; 57 } 58 59 static void __cpuinit cpu_bringup(void) 60 { 61 int cpu = smp_processor_id(); 62 63 cpu_init(); 64 touch_softlockup_watchdog(); 65 preempt_disable(); 66 67 xen_enable_sysenter(); 68 xen_enable_syscall(); 69 70 cpu = smp_processor_id(); 71 smp_store_cpu_info(cpu); 72 cpu_data(cpu).x86_max_cores = 1; 73 set_cpu_sibling_map(cpu); 74 75 xen_setup_cpu_clockevents(); 76 77 set_cpu_online(cpu, true); 78 percpu_write(cpu_state, CPU_ONLINE); 79 wmb(); 80 81 /* We can take interrupts now: we're officially "up". */ 82 local_irq_enable(); 83 84 wmb(); /* make sure everything is out */ 85 } 86 87 static void __cpuinit cpu_bringup_and_idle(void) 88 { 89 cpu_bringup(); 90 cpu_idle(); 91 } 92 93 static int xen_smp_intr_init(unsigned int cpu) 94 { 95 int rc; 96 const char *resched_name, *callfunc_name, *debug_name; 97 98 resched_name = kasprintf(GFP_KERNEL, "resched%d", cpu); 99 rc = bind_ipi_to_irqhandler(XEN_RESCHEDULE_VECTOR, 100 cpu, 101 xen_reschedule_interrupt, 102 IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING, 103 resched_name, 104 NULL); 105 if (rc < 0) 106 goto fail; 107 per_cpu(xen_resched_irq, cpu) = rc; 108 109 callfunc_name = kasprintf(GFP_KERNEL, "callfunc%d", cpu); 110 rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_VECTOR, 111 cpu, 112 xen_call_function_interrupt, 113 IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING, 114 callfunc_name, 115 NULL); 116 if (rc < 0) 117 goto fail; 118 per_cpu(xen_callfunc_irq, cpu) = rc; 119 120 debug_name = kasprintf(GFP_KERNEL, "debug%d", cpu); 121 rc = bind_virq_to_irqhandler(VIRQ_DEBUG, cpu, xen_debug_interrupt, 122 IRQF_DISABLED | IRQF_PERCPU | IRQF_NOBALANCING, 123 debug_name, NULL); 124 if (rc < 0) 125 goto fail; 126 per_cpu(xen_debug_irq, cpu) = rc; 127 128 callfunc_name = kasprintf(GFP_KERNEL, "callfuncsingle%d", cpu); 129 rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_SINGLE_VECTOR, 130 cpu, 131 xen_call_function_single_interrupt, 132 IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING, 133 callfunc_name, 134 NULL); 135 if (rc < 0) 136 goto fail; 137 per_cpu(xen_callfuncsingle_irq, cpu) = rc; 138 139 return 0; 140 141 fail: 142 if (per_cpu(xen_resched_irq, cpu) >= 0) 143 unbind_from_irqhandler(per_cpu(xen_resched_irq, cpu), NULL); 144 if (per_cpu(xen_callfunc_irq, cpu) >= 0) 145 unbind_from_irqhandler(per_cpu(xen_callfunc_irq, cpu), NULL); 146 if (per_cpu(xen_debug_irq, cpu) >= 0) 147 unbind_from_irqhandler(per_cpu(xen_debug_irq, cpu), NULL); 148 if (per_cpu(xen_callfuncsingle_irq, cpu) >= 0) 149 unbind_from_irqhandler(per_cpu(xen_callfuncsingle_irq, cpu), 150 NULL); 151 152 return rc; 153 } 154 155 static void __init xen_fill_possible_map(void) 156 { 157 int i, rc; 158 159 if (xen_initial_domain()) 160 return; 161 162 for (i = 0; i < nr_cpu_ids; i++) { 163 rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL); 164 if (rc >= 0) { 165 num_processors++; 166 set_cpu_possible(i, true); 167 } 168 } 169 } 170 171 static void __init xen_filter_cpu_maps(void) 172 { 173 int i, rc; 174 175 if (!xen_initial_domain()) 176 return; 177 178 num_processors = 0; 179 disabled_cpus = 0; 180 for (i = 0; i < nr_cpu_ids; i++) { 181 rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL); 182 if (rc >= 0) { 183 num_processors++; 184 set_cpu_possible(i, true); 185 } else { 186 set_cpu_possible(i, false); 187 set_cpu_present(i, false); 188 } 189 } 190 } 191 192 static void __init xen_smp_prepare_boot_cpu(void) 193 { 194 BUG_ON(smp_processor_id() != 0); 195 native_smp_prepare_boot_cpu(); 196 197 /* We've switched to the "real" per-cpu gdt, so make sure the 198 old memory can be recycled */ 199 make_lowmem_page_readwrite(xen_initial_gdt); 200 201 xen_filter_cpu_maps(); 202 xen_setup_vcpu_info_placement(); 203 } 204 205 static void __init xen_smp_prepare_cpus(unsigned int max_cpus) 206 { 207 unsigned cpu; 208 unsigned int i; 209 210 xen_init_lock_cpu(0); 211 212 smp_store_cpu_info(0); 213 cpu_data(0).x86_max_cores = 1; 214 215 for_each_possible_cpu(i) { 216 zalloc_cpumask_var(&per_cpu(cpu_sibling_map, i), GFP_KERNEL); 217 zalloc_cpumask_var(&per_cpu(cpu_core_map, i), GFP_KERNEL); 218 zalloc_cpumask_var(&per_cpu(cpu_llc_shared_map, i), GFP_KERNEL); 219 } 220 set_cpu_sibling_map(0); 221 222 if (xen_smp_intr_init(0)) 223 BUG(); 224 225 if (!alloc_cpumask_var(&xen_cpu_initialized_map, GFP_KERNEL)) 226 panic("could not allocate xen_cpu_initialized_map\n"); 227 228 cpumask_copy(xen_cpu_initialized_map, cpumask_of(0)); 229 230 /* Restrict the possible_map according to max_cpus. */ 231 while ((num_possible_cpus() > 1) && (num_possible_cpus() > max_cpus)) { 232 for (cpu = nr_cpu_ids - 1; !cpu_possible(cpu); cpu--) 233 continue; 234 set_cpu_possible(cpu, false); 235 } 236 237 for_each_possible_cpu (cpu) { 238 struct task_struct *idle; 239 240 if (cpu == 0) 241 continue; 242 243 idle = fork_idle(cpu); 244 if (IS_ERR(idle)) 245 panic("failed fork for CPU %d", cpu); 246 247 set_cpu_present(cpu, true); 248 } 249 } 250 251 static int __cpuinit 252 cpu_initialize_context(unsigned int cpu, struct task_struct *idle) 253 { 254 struct vcpu_guest_context *ctxt; 255 struct desc_struct *gdt; 256 unsigned long gdt_mfn; 257 258 if (cpumask_test_and_set_cpu(cpu, xen_cpu_initialized_map)) 259 return 0; 260 261 ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL); 262 if (ctxt == NULL) 263 return -ENOMEM; 264 265 gdt = get_cpu_gdt_table(cpu); 266 267 ctxt->flags = VGCF_IN_KERNEL; 268 ctxt->user_regs.ds = __USER_DS; 269 ctxt->user_regs.es = __USER_DS; 270 ctxt->user_regs.ss = __KERNEL_DS; 271 #ifdef CONFIG_X86_32 272 ctxt->user_regs.fs = __KERNEL_PERCPU; 273 ctxt->user_regs.gs = __KERNEL_STACK_CANARY; 274 #else 275 ctxt->gs_base_kernel = per_cpu_offset(cpu); 276 #endif 277 ctxt->user_regs.eip = (unsigned long)cpu_bringup_and_idle; 278 ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */ 279 280 memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt)); 281 282 xen_copy_trap_info(ctxt->trap_ctxt); 283 284 ctxt->ldt_ents = 0; 285 286 BUG_ON((unsigned long)gdt & ~PAGE_MASK); 287 288 gdt_mfn = arbitrary_virt_to_mfn(gdt); 289 make_lowmem_page_readonly(gdt); 290 make_lowmem_page_readonly(mfn_to_virt(gdt_mfn)); 291 292 ctxt->gdt_frames[0] = gdt_mfn; 293 ctxt->gdt_ents = GDT_ENTRIES; 294 295 ctxt->user_regs.cs = __KERNEL_CS; 296 ctxt->user_regs.esp = idle->thread.sp0 - sizeof(struct pt_regs); 297 298 ctxt->kernel_ss = __KERNEL_DS; 299 ctxt->kernel_sp = idle->thread.sp0; 300 301 #ifdef CONFIG_X86_32 302 ctxt->event_callback_cs = __KERNEL_CS; 303 ctxt->failsafe_callback_cs = __KERNEL_CS; 304 #endif 305 ctxt->event_callback_eip = (unsigned long)xen_hypervisor_callback; 306 ctxt->failsafe_callback_eip = (unsigned long)xen_failsafe_callback; 307 308 per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir); 309 ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir)); 310 311 if (HYPERVISOR_vcpu_op(VCPUOP_initialise, cpu, ctxt)) 312 BUG(); 313 314 kfree(ctxt); 315 return 0; 316 } 317 318 static int __cpuinit xen_cpu_up(unsigned int cpu) 319 { 320 struct task_struct *idle = idle_task(cpu); 321 int rc; 322 323 per_cpu(current_task, cpu) = idle; 324 #ifdef CONFIG_X86_32 325 irq_ctx_init(cpu); 326 #else 327 clear_tsk_thread_flag(idle, TIF_FORK); 328 per_cpu(kernel_stack, cpu) = 329 (unsigned long)task_stack_page(idle) - 330 KERNEL_STACK_OFFSET + THREAD_SIZE; 331 #endif 332 xen_setup_runstate_info(cpu); 333 xen_setup_timer(cpu); 334 xen_init_lock_cpu(cpu); 335 336 per_cpu(cpu_state, cpu) = CPU_UP_PREPARE; 337 338 /* make sure interrupts start blocked */ 339 per_cpu(xen_vcpu, cpu)->evtchn_upcall_mask = 1; 340 341 rc = cpu_initialize_context(cpu, idle); 342 if (rc) 343 return rc; 344 345 if (num_online_cpus() == 1) 346 alternatives_smp_switch(1); 347 348 rc = xen_smp_intr_init(cpu); 349 if (rc) 350 return rc; 351 352 rc = HYPERVISOR_vcpu_op(VCPUOP_up, cpu, NULL); 353 BUG_ON(rc); 354 355 while(per_cpu(cpu_state, cpu) != CPU_ONLINE) { 356 HYPERVISOR_sched_op(SCHEDOP_yield, NULL); 357 barrier(); 358 } 359 360 return 0; 361 } 362 363 static void xen_smp_cpus_done(unsigned int max_cpus) 364 { 365 } 366 367 #ifdef CONFIG_HOTPLUG_CPU 368 static int xen_cpu_disable(void) 369 { 370 unsigned int cpu = smp_processor_id(); 371 if (cpu == 0) 372 return -EBUSY; 373 374 cpu_disable_common(); 375 376 load_cr3(swapper_pg_dir); 377 return 0; 378 } 379 380 static void xen_cpu_die(unsigned int cpu) 381 { 382 while (HYPERVISOR_vcpu_op(VCPUOP_is_up, cpu, NULL)) { 383 current->state = TASK_UNINTERRUPTIBLE; 384 schedule_timeout(HZ/10); 385 } 386 unbind_from_irqhandler(per_cpu(xen_resched_irq, cpu), NULL); 387 unbind_from_irqhandler(per_cpu(xen_callfunc_irq, cpu), NULL); 388 unbind_from_irqhandler(per_cpu(xen_debug_irq, cpu), NULL); 389 unbind_from_irqhandler(per_cpu(xen_callfuncsingle_irq, cpu), NULL); 390 xen_uninit_lock_cpu(cpu); 391 xen_teardown_timer(cpu); 392 393 if (num_online_cpus() == 1) 394 alternatives_smp_switch(0); 395 } 396 397 static void __cpuinit xen_play_dead(void) /* used only with HOTPLUG_CPU */ 398 { 399 play_dead_common(); 400 HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL); 401 cpu_bringup(); 402 } 403 404 #else /* !CONFIG_HOTPLUG_CPU */ 405 static int xen_cpu_disable(void) 406 { 407 return -ENOSYS; 408 } 409 410 static void xen_cpu_die(unsigned int cpu) 411 { 412 BUG(); 413 } 414 415 static void xen_play_dead(void) 416 { 417 BUG(); 418 } 419 420 #endif 421 static void stop_self(void *v) 422 { 423 int cpu = smp_processor_id(); 424 425 /* make sure we're not pinning something down */ 426 load_cr3(swapper_pg_dir); 427 /* should set up a minimal gdt */ 428 429 set_cpu_online(cpu, false); 430 431 HYPERVISOR_vcpu_op(VCPUOP_down, cpu, NULL); 432 BUG(); 433 } 434 435 static void xen_stop_other_cpus(int wait) 436 { 437 smp_call_function(stop_self, NULL, wait); 438 } 439 440 static void xen_smp_send_reschedule(int cpu) 441 { 442 xen_send_IPI_one(cpu, XEN_RESCHEDULE_VECTOR); 443 } 444 445 static void xen_send_IPI_mask(const struct cpumask *mask, 446 enum ipi_vector vector) 447 { 448 unsigned cpu; 449 450 for_each_cpu_and(cpu, mask, cpu_online_mask) 451 xen_send_IPI_one(cpu, vector); 452 } 453 454 static void xen_smp_send_call_function_ipi(const struct cpumask *mask) 455 { 456 int cpu; 457 458 xen_send_IPI_mask(mask, XEN_CALL_FUNCTION_VECTOR); 459 460 /* Make sure other vcpus get a chance to run if they need to. */ 461 for_each_cpu(cpu, mask) { 462 if (xen_vcpu_stolen(cpu)) { 463 HYPERVISOR_sched_op(SCHEDOP_yield, NULL); 464 break; 465 } 466 } 467 } 468 469 static void xen_smp_send_call_function_single_ipi(int cpu) 470 { 471 xen_send_IPI_mask(cpumask_of(cpu), 472 XEN_CALL_FUNCTION_SINGLE_VECTOR); 473 } 474 475 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id) 476 { 477 irq_enter(); 478 generic_smp_call_function_interrupt(); 479 inc_irq_stat(irq_call_count); 480 irq_exit(); 481 482 return IRQ_HANDLED; 483 } 484 485 static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id) 486 { 487 irq_enter(); 488 generic_smp_call_function_single_interrupt(); 489 inc_irq_stat(irq_call_count); 490 irq_exit(); 491 492 return IRQ_HANDLED; 493 } 494 495 static const struct smp_ops xen_smp_ops __initconst = { 496 .smp_prepare_boot_cpu = xen_smp_prepare_boot_cpu, 497 .smp_prepare_cpus = xen_smp_prepare_cpus, 498 .smp_cpus_done = xen_smp_cpus_done, 499 500 .cpu_up = xen_cpu_up, 501 .cpu_die = xen_cpu_die, 502 .cpu_disable = xen_cpu_disable, 503 .play_dead = xen_play_dead, 504 505 .stop_other_cpus = xen_stop_other_cpus, 506 .smp_send_reschedule = xen_smp_send_reschedule, 507 508 .send_call_func_ipi = xen_smp_send_call_function_ipi, 509 .send_call_func_single_ipi = xen_smp_send_call_function_single_ipi, 510 }; 511 512 void __init xen_smp_init(void) 513 { 514 smp_ops = xen_smp_ops; 515 xen_fill_possible_map(); 516 xen_init_spinlocks(); 517 } 518 519 static void __init xen_hvm_smp_prepare_cpus(unsigned int max_cpus) 520 { 521 native_smp_prepare_cpus(max_cpus); 522 WARN_ON(xen_smp_intr_init(0)); 523 524 if (!xen_have_vector_callback) 525 return; 526 xen_init_lock_cpu(0); 527 xen_init_spinlocks(); 528 } 529 530 static int __cpuinit xen_hvm_cpu_up(unsigned int cpu) 531 { 532 int rc; 533 rc = native_cpu_up(cpu); 534 WARN_ON (xen_smp_intr_init(cpu)); 535 return rc; 536 } 537 538 static void xen_hvm_cpu_die(unsigned int cpu) 539 { 540 unbind_from_irqhandler(per_cpu(xen_resched_irq, cpu), NULL); 541 unbind_from_irqhandler(per_cpu(xen_callfunc_irq, cpu), NULL); 542 unbind_from_irqhandler(per_cpu(xen_debug_irq, cpu), NULL); 543 unbind_from_irqhandler(per_cpu(xen_callfuncsingle_irq, cpu), NULL); 544 native_cpu_die(cpu); 545 } 546 547 void __init xen_hvm_smp_init(void) 548 { 549 smp_ops.smp_prepare_cpus = xen_hvm_smp_prepare_cpus; 550 smp_ops.smp_send_reschedule = xen_smp_send_reschedule; 551 smp_ops.cpu_up = xen_hvm_cpu_up; 552 smp_ops.cpu_die = xen_hvm_cpu_die; 553 smp_ops.send_call_func_ipi = xen_smp_send_call_function_ipi; 554 smp_ops.send_call_func_single_ipi = xen_smp_send_call_function_single_ipi; 555 } 556