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/smp.h> 18 19 #include <asm/paravirt.h> 20 #include <asm/desc.h> 21 #include <asm/pgtable.h> 22 #include <asm/cpu.h> 23 24 #include <xen/interface/xen.h> 25 #include <xen/interface/vcpu.h> 26 27 #include <asm/xen/interface.h> 28 #include <asm/xen/hypercall.h> 29 30 #include <xen/page.h> 31 #include <xen/events.h> 32 33 #include "xen-ops.h" 34 #include "mmu.h" 35 36 cpumask_t xen_cpu_initialized_map; 37 38 static DEFINE_PER_CPU(int, resched_irq); 39 static DEFINE_PER_CPU(int, callfunc_irq); 40 static DEFINE_PER_CPU(int, callfuncsingle_irq); 41 static DEFINE_PER_CPU(int, debug_irq) = -1; 42 43 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id); 44 static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id); 45 46 /* 47 * Reschedule call back. Nothing to do, 48 * all the work is done automatically when 49 * we return from the interrupt. 50 */ 51 static irqreturn_t xen_reschedule_interrupt(int irq, void *dev_id) 52 { 53 #ifdef CONFIG_X86_32 54 __get_cpu_var(irq_stat).irq_resched_count++; 55 #else 56 add_pda(irq_resched_count, 1); 57 #endif 58 59 return IRQ_HANDLED; 60 } 61 62 static __cpuinit void cpu_bringup(void) 63 { 64 int cpu = smp_processor_id(); 65 66 cpu_init(); 67 touch_softlockup_watchdog(); 68 preempt_disable(); 69 70 xen_enable_sysenter(); 71 xen_enable_syscall(); 72 73 cpu = smp_processor_id(); 74 smp_store_cpu_info(cpu); 75 cpu_data(cpu).x86_max_cores = 1; 76 set_cpu_sibling_map(cpu); 77 78 xen_setup_cpu_clockevents(); 79 80 cpu_set(cpu, cpu_online_map); 81 x86_write_percpu(cpu_state, CPU_ONLINE); 82 wmb(); 83 84 /* We can take interrupts now: we're officially "up". */ 85 local_irq_enable(); 86 87 wmb(); /* make sure everything is out */ 88 } 89 90 static __cpuinit void cpu_bringup_and_idle(void) 91 { 92 cpu_bringup(); 93 cpu_idle(); 94 } 95 96 static int xen_smp_intr_init(unsigned int cpu) 97 { 98 int rc; 99 const char *resched_name, *callfunc_name, *debug_name; 100 101 resched_name = kasprintf(GFP_KERNEL, "resched%d", cpu); 102 rc = bind_ipi_to_irqhandler(XEN_RESCHEDULE_VECTOR, 103 cpu, 104 xen_reschedule_interrupt, 105 IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING, 106 resched_name, 107 NULL); 108 if (rc < 0) 109 goto fail; 110 per_cpu(resched_irq, cpu) = rc; 111 112 callfunc_name = kasprintf(GFP_KERNEL, "callfunc%d", cpu); 113 rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_VECTOR, 114 cpu, 115 xen_call_function_interrupt, 116 IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING, 117 callfunc_name, 118 NULL); 119 if (rc < 0) 120 goto fail; 121 per_cpu(callfunc_irq, cpu) = rc; 122 123 debug_name = kasprintf(GFP_KERNEL, "debug%d", cpu); 124 rc = bind_virq_to_irqhandler(VIRQ_DEBUG, cpu, xen_debug_interrupt, 125 IRQF_DISABLED | IRQF_PERCPU | IRQF_NOBALANCING, 126 debug_name, NULL); 127 if (rc < 0) 128 goto fail; 129 per_cpu(debug_irq, cpu) = rc; 130 131 callfunc_name = kasprintf(GFP_KERNEL, "callfuncsingle%d", cpu); 132 rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_SINGLE_VECTOR, 133 cpu, 134 xen_call_function_single_interrupt, 135 IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING, 136 callfunc_name, 137 NULL); 138 if (rc < 0) 139 goto fail; 140 per_cpu(callfuncsingle_irq, cpu) = rc; 141 142 return 0; 143 144 fail: 145 if (per_cpu(resched_irq, cpu) >= 0) 146 unbind_from_irqhandler(per_cpu(resched_irq, cpu), NULL); 147 if (per_cpu(callfunc_irq, cpu) >= 0) 148 unbind_from_irqhandler(per_cpu(callfunc_irq, cpu), NULL); 149 if (per_cpu(debug_irq, cpu) >= 0) 150 unbind_from_irqhandler(per_cpu(debug_irq, cpu), NULL); 151 if (per_cpu(callfuncsingle_irq, cpu) >= 0) 152 unbind_from_irqhandler(per_cpu(callfuncsingle_irq, cpu), NULL); 153 154 return rc; 155 } 156 157 static void __init xen_fill_possible_map(void) 158 { 159 int i, rc; 160 161 for (i = 0; i < NR_CPUS; i++) { 162 rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL); 163 if (rc >= 0) { 164 num_processors++; 165 cpu_set(i, cpu_possible_map); 166 } 167 } 168 } 169 170 static void __init xen_smp_prepare_boot_cpu(void) 171 { 172 BUG_ON(smp_processor_id() != 0); 173 native_smp_prepare_boot_cpu(); 174 175 /* We've switched to the "real" per-cpu gdt, so make sure the 176 old memory can be recycled */ 177 make_lowmem_page_readwrite(&per_cpu_var(gdt_page)); 178 179 xen_setup_vcpu_info_placement(); 180 } 181 182 static void __init xen_smp_prepare_cpus(unsigned int max_cpus) 183 { 184 unsigned cpu; 185 186 xen_init_lock_cpu(0); 187 188 smp_store_cpu_info(0); 189 cpu_data(0).x86_max_cores = 1; 190 set_cpu_sibling_map(0); 191 192 if (xen_smp_intr_init(0)) 193 BUG(); 194 195 xen_cpu_initialized_map = cpumask_of_cpu(0); 196 197 /* Restrict the possible_map according to max_cpus. */ 198 while ((num_possible_cpus() > 1) && (num_possible_cpus() > max_cpus)) { 199 for (cpu = NR_CPUS - 1; !cpu_possible(cpu); cpu--) 200 continue; 201 cpu_clear(cpu, cpu_possible_map); 202 } 203 204 for_each_possible_cpu (cpu) { 205 struct task_struct *idle; 206 207 if (cpu == 0) 208 continue; 209 210 idle = fork_idle(cpu); 211 if (IS_ERR(idle)) 212 panic("failed fork for CPU %d", cpu); 213 214 cpu_set(cpu, cpu_present_map); 215 } 216 } 217 218 static __cpuinit int 219 cpu_initialize_context(unsigned int cpu, struct task_struct *idle) 220 { 221 struct vcpu_guest_context *ctxt; 222 struct desc_struct *gdt; 223 224 if (cpu_test_and_set(cpu, xen_cpu_initialized_map)) 225 return 0; 226 227 ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL); 228 if (ctxt == NULL) 229 return -ENOMEM; 230 231 gdt = get_cpu_gdt_table(cpu); 232 233 ctxt->flags = VGCF_IN_KERNEL; 234 ctxt->user_regs.ds = __USER_DS; 235 ctxt->user_regs.es = __USER_DS; 236 ctxt->user_regs.ss = __KERNEL_DS; 237 #ifdef CONFIG_X86_32 238 ctxt->user_regs.fs = __KERNEL_PERCPU; 239 #endif 240 ctxt->user_regs.eip = (unsigned long)cpu_bringup_and_idle; 241 ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */ 242 243 memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt)); 244 245 xen_copy_trap_info(ctxt->trap_ctxt); 246 247 ctxt->ldt_ents = 0; 248 249 BUG_ON((unsigned long)gdt & ~PAGE_MASK); 250 make_lowmem_page_readonly(gdt); 251 252 ctxt->gdt_frames[0] = virt_to_mfn(gdt); 253 ctxt->gdt_ents = GDT_ENTRIES; 254 255 ctxt->user_regs.cs = __KERNEL_CS; 256 ctxt->user_regs.esp = idle->thread.sp0 - sizeof(struct pt_regs); 257 258 ctxt->kernel_ss = __KERNEL_DS; 259 ctxt->kernel_sp = idle->thread.sp0; 260 261 #ifdef CONFIG_X86_32 262 ctxt->event_callback_cs = __KERNEL_CS; 263 ctxt->failsafe_callback_cs = __KERNEL_CS; 264 #endif 265 ctxt->event_callback_eip = (unsigned long)xen_hypervisor_callback; 266 ctxt->failsafe_callback_eip = (unsigned long)xen_failsafe_callback; 267 268 per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir); 269 ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir)); 270 271 if (HYPERVISOR_vcpu_op(VCPUOP_initialise, cpu, ctxt)) 272 BUG(); 273 274 kfree(ctxt); 275 return 0; 276 } 277 278 static int __cpuinit xen_cpu_up(unsigned int cpu) 279 { 280 struct task_struct *idle = idle_task(cpu); 281 int rc; 282 283 #ifdef CONFIG_X86_64 284 /* Allocate node local memory for AP pdas */ 285 WARN_ON(cpu == 0); 286 if (cpu > 0) { 287 rc = get_local_pda(cpu); 288 if (rc) 289 return rc; 290 } 291 #endif 292 293 #ifdef CONFIG_X86_32 294 init_gdt(cpu); 295 per_cpu(current_task, cpu) = idle; 296 irq_ctx_init(cpu); 297 #else 298 cpu_pda(cpu)->pcurrent = idle; 299 clear_tsk_thread_flag(idle, TIF_FORK); 300 #endif 301 xen_setup_timer(cpu); 302 xen_init_lock_cpu(cpu); 303 304 per_cpu(cpu_state, cpu) = CPU_UP_PREPARE; 305 306 /* make sure interrupts start blocked */ 307 per_cpu(xen_vcpu, cpu)->evtchn_upcall_mask = 1; 308 309 rc = cpu_initialize_context(cpu, idle); 310 if (rc) 311 return rc; 312 313 if (num_online_cpus() == 1) 314 alternatives_smp_switch(1); 315 316 rc = xen_smp_intr_init(cpu); 317 if (rc) 318 return rc; 319 320 rc = HYPERVISOR_vcpu_op(VCPUOP_up, cpu, NULL); 321 BUG_ON(rc); 322 323 while(per_cpu(cpu_state, cpu) != CPU_ONLINE) { 324 HYPERVISOR_sched_op(SCHEDOP_yield, 0); 325 barrier(); 326 } 327 328 return 0; 329 } 330 331 static void xen_smp_cpus_done(unsigned int max_cpus) 332 { 333 } 334 335 #ifdef CONFIG_HOTPLUG_CPU 336 static int xen_cpu_disable(void) 337 { 338 unsigned int cpu = smp_processor_id(); 339 if (cpu == 0) 340 return -EBUSY; 341 342 cpu_disable_common(); 343 344 load_cr3(swapper_pg_dir); 345 return 0; 346 } 347 348 static void xen_cpu_die(unsigned int cpu) 349 { 350 while (HYPERVISOR_vcpu_op(VCPUOP_is_up, cpu, NULL)) { 351 current->state = TASK_UNINTERRUPTIBLE; 352 schedule_timeout(HZ/10); 353 } 354 unbind_from_irqhandler(per_cpu(resched_irq, cpu), NULL); 355 unbind_from_irqhandler(per_cpu(callfunc_irq, cpu), NULL); 356 unbind_from_irqhandler(per_cpu(debug_irq, cpu), NULL); 357 unbind_from_irqhandler(per_cpu(callfuncsingle_irq, cpu), NULL); 358 xen_uninit_lock_cpu(cpu); 359 xen_teardown_timer(cpu); 360 361 if (num_online_cpus() == 1) 362 alternatives_smp_switch(0); 363 } 364 365 static void xen_play_dead(void) 366 { 367 play_dead_common(); 368 HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL); 369 cpu_bringup(); 370 } 371 372 #else /* !CONFIG_HOTPLUG_CPU */ 373 static int xen_cpu_disable(void) 374 { 375 return -ENOSYS; 376 } 377 378 static void xen_cpu_die(unsigned int cpu) 379 { 380 BUG(); 381 } 382 383 static void xen_play_dead(void) 384 { 385 BUG(); 386 } 387 388 #endif 389 static void stop_self(void *v) 390 { 391 int cpu = smp_processor_id(); 392 393 /* make sure we're not pinning something down */ 394 load_cr3(swapper_pg_dir); 395 /* should set up a minimal gdt */ 396 397 HYPERVISOR_vcpu_op(VCPUOP_down, cpu, NULL); 398 BUG(); 399 } 400 401 static void xen_smp_send_stop(void) 402 { 403 smp_call_function(stop_self, NULL, 0); 404 } 405 406 static void xen_smp_send_reschedule(int cpu) 407 { 408 xen_send_IPI_one(cpu, XEN_RESCHEDULE_VECTOR); 409 } 410 411 static void xen_send_IPI_mask(cpumask_t mask, enum ipi_vector vector) 412 { 413 unsigned cpu; 414 415 cpus_and(mask, mask, cpu_online_map); 416 417 for_each_cpu_mask_nr(cpu, mask) 418 xen_send_IPI_one(cpu, vector); 419 } 420 421 static void xen_smp_send_call_function_ipi(cpumask_t mask) 422 { 423 int cpu; 424 425 xen_send_IPI_mask(mask, XEN_CALL_FUNCTION_VECTOR); 426 427 /* Make sure other vcpus get a chance to run if they need to. */ 428 for_each_cpu_mask_nr(cpu, mask) { 429 if (xen_vcpu_stolen(cpu)) { 430 HYPERVISOR_sched_op(SCHEDOP_yield, 0); 431 break; 432 } 433 } 434 } 435 436 static void xen_smp_send_call_function_single_ipi(int cpu) 437 { 438 xen_send_IPI_mask(cpumask_of_cpu(cpu), XEN_CALL_FUNCTION_SINGLE_VECTOR); 439 } 440 441 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id) 442 { 443 irq_enter(); 444 generic_smp_call_function_interrupt(); 445 #ifdef CONFIG_X86_32 446 __get_cpu_var(irq_stat).irq_call_count++; 447 #else 448 add_pda(irq_call_count, 1); 449 #endif 450 irq_exit(); 451 452 return IRQ_HANDLED; 453 } 454 455 static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id) 456 { 457 irq_enter(); 458 generic_smp_call_function_single_interrupt(); 459 #ifdef CONFIG_X86_32 460 __get_cpu_var(irq_stat).irq_call_count++; 461 #else 462 add_pda(irq_call_count, 1); 463 #endif 464 irq_exit(); 465 466 return IRQ_HANDLED; 467 } 468 469 static const struct smp_ops xen_smp_ops __initdata = { 470 .smp_prepare_boot_cpu = xen_smp_prepare_boot_cpu, 471 .smp_prepare_cpus = xen_smp_prepare_cpus, 472 .smp_cpus_done = xen_smp_cpus_done, 473 474 .cpu_up = xen_cpu_up, 475 .cpu_die = xen_cpu_die, 476 .cpu_disable = xen_cpu_disable, 477 .play_dead = xen_play_dead, 478 479 .smp_send_stop = xen_smp_send_stop, 480 .smp_send_reschedule = xen_smp_send_reschedule, 481 482 .send_call_func_ipi = xen_smp_send_call_function_ipi, 483 .send_call_func_single_ipi = xen_smp_send_call_function_single_ipi, 484 }; 485 486 void __init xen_smp_init(void) 487 { 488 smp_ops = xen_smp_ops; 489 xen_fill_possible_map(); 490 xen_init_spinlocks(); 491 } 492