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_var_t xen_cpu_initialized_map; 37 38 static DEFINE_PER_CPU(int, xen_resched_irq); 39 static DEFINE_PER_CPU(int, xen_callfunc_irq); 40 static DEFINE_PER_CPU(int, xen_callfuncsingle_irq); 41 static DEFINE_PER_CPU(int, xen_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 inc_irq_stat(irq_resched_count); 54 55 return IRQ_HANDLED; 56 } 57 58 static __cpuinit void cpu_bringup(void) 59 { 60 int cpu = smp_processor_id(); 61 62 cpu_init(); 63 touch_softlockup_watchdog(); 64 preempt_disable(); 65 66 xen_enable_sysenter(); 67 xen_enable_syscall(); 68 69 cpu = smp_processor_id(); 70 smp_store_cpu_info(cpu); 71 cpu_data(cpu).x86_max_cores = 1; 72 set_cpu_sibling_map(cpu); 73 74 xen_setup_cpu_clockevents(); 75 76 set_cpu_online(cpu, true); 77 percpu_write(cpu_state, CPU_ONLINE); 78 wmb(); 79 80 /* We can take interrupts now: we're officially "up". */ 81 local_irq_enable(); 82 83 wmb(); /* make sure everything is out */ 84 } 85 86 static __cpuinit void cpu_bringup_and_idle(void) 87 { 88 cpu_bringup(); 89 cpu_idle(); 90 } 91 92 static int xen_smp_intr_init(unsigned int cpu) 93 { 94 int rc; 95 const char *resched_name, *callfunc_name, *debug_name; 96 97 resched_name = kasprintf(GFP_KERNEL, "resched%d", cpu); 98 rc = bind_ipi_to_irqhandler(XEN_RESCHEDULE_VECTOR, 99 cpu, 100 xen_reschedule_interrupt, 101 IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING, 102 resched_name, 103 NULL); 104 if (rc < 0) 105 goto fail; 106 per_cpu(xen_resched_irq, cpu) = rc; 107 108 callfunc_name = kasprintf(GFP_KERNEL, "callfunc%d", cpu); 109 rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_VECTOR, 110 cpu, 111 xen_call_function_interrupt, 112 IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING, 113 callfunc_name, 114 NULL); 115 if (rc < 0) 116 goto fail; 117 per_cpu(xen_callfunc_irq, cpu) = rc; 118 119 debug_name = kasprintf(GFP_KERNEL, "debug%d", cpu); 120 rc = bind_virq_to_irqhandler(VIRQ_DEBUG, cpu, xen_debug_interrupt, 121 IRQF_DISABLED | IRQF_PERCPU | IRQF_NOBALANCING, 122 debug_name, NULL); 123 if (rc < 0) 124 goto fail; 125 per_cpu(xen_debug_irq, cpu) = rc; 126 127 callfunc_name = kasprintf(GFP_KERNEL, "callfuncsingle%d", cpu); 128 rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_SINGLE_VECTOR, 129 cpu, 130 xen_call_function_single_interrupt, 131 IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING, 132 callfunc_name, 133 NULL); 134 if (rc < 0) 135 goto fail; 136 per_cpu(xen_callfuncsingle_irq, cpu) = rc; 137 138 return 0; 139 140 fail: 141 if (per_cpu(xen_resched_irq, cpu) >= 0) 142 unbind_from_irqhandler(per_cpu(xen_resched_irq, cpu), NULL); 143 if (per_cpu(xen_callfunc_irq, cpu) >= 0) 144 unbind_from_irqhandler(per_cpu(xen_callfunc_irq, cpu), NULL); 145 if (per_cpu(xen_debug_irq, cpu) >= 0) 146 unbind_from_irqhandler(per_cpu(xen_debug_irq, cpu), NULL); 147 if (per_cpu(xen_callfuncsingle_irq, cpu) >= 0) 148 unbind_from_irqhandler(per_cpu(xen_callfuncsingle_irq, cpu), 149 NULL); 150 151 return rc; 152 } 153 154 static void __init xen_fill_possible_map(void) 155 { 156 int i, rc; 157 158 for (i = 0; i < nr_cpu_ids; i++) { 159 rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL); 160 if (rc >= 0) { 161 num_processors++; 162 set_cpu_possible(i, true); 163 } 164 } 165 } 166 167 static void __init xen_smp_prepare_boot_cpu(void) 168 { 169 BUG_ON(smp_processor_id() != 0); 170 native_smp_prepare_boot_cpu(); 171 172 /* We've switched to the "real" per-cpu gdt, so make sure the 173 old memory can be recycled */ 174 make_lowmem_page_readwrite(xen_initial_gdt); 175 176 xen_setup_vcpu_info_placement(); 177 } 178 179 static void __init xen_smp_prepare_cpus(unsigned int max_cpus) 180 { 181 unsigned cpu; 182 183 xen_init_lock_cpu(0); 184 185 smp_store_cpu_info(0); 186 cpu_data(0).x86_max_cores = 1; 187 set_cpu_sibling_map(0); 188 189 if (xen_smp_intr_init(0)) 190 BUG(); 191 192 if (!alloc_cpumask_var(&xen_cpu_initialized_map, GFP_KERNEL)) 193 panic("could not allocate xen_cpu_initialized_map\n"); 194 195 cpumask_copy(xen_cpu_initialized_map, cpumask_of(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_cpu_ids - 1; !cpu_possible(cpu); cpu--) 200 continue; 201 set_cpu_possible(cpu, false); 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 set_cpu_present(cpu, true); 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 unsigned long gdt_mfn; 224 225 if (cpumask_test_and_set_cpu(cpu, xen_cpu_initialized_map)) 226 return 0; 227 228 ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL); 229 if (ctxt == NULL) 230 return -ENOMEM; 231 232 gdt = get_cpu_gdt_table(cpu); 233 234 ctxt->flags = VGCF_IN_KERNEL; 235 ctxt->user_regs.ds = __USER_DS; 236 ctxt->user_regs.es = __USER_DS; 237 ctxt->user_regs.ss = __KERNEL_DS; 238 #ifdef CONFIG_X86_32 239 ctxt->user_regs.fs = __KERNEL_PERCPU; 240 ctxt->user_regs.gs = __KERNEL_STACK_CANARY; 241 #else 242 ctxt->gs_base_kernel = per_cpu_offset(cpu); 243 #endif 244 ctxt->user_regs.eip = (unsigned long)cpu_bringup_and_idle; 245 ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */ 246 247 memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt)); 248 249 xen_copy_trap_info(ctxt->trap_ctxt); 250 251 ctxt->ldt_ents = 0; 252 253 BUG_ON((unsigned long)gdt & ~PAGE_MASK); 254 255 gdt_mfn = arbitrary_virt_to_mfn(gdt); 256 make_lowmem_page_readonly(gdt); 257 make_lowmem_page_readonly(mfn_to_virt(gdt_mfn)); 258 259 ctxt->gdt_frames[0] = gdt_mfn; 260 ctxt->gdt_ents = GDT_ENTRIES; 261 262 ctxt->user_regs.cs = __KERNEL_CS; 263 ctxt->user_regs.esp = idle->thread.sp0 - sizeof(struct pt_regs); 264 265 ctxt->kernel_ss = __KERNEL_DS; 266 ctxt->kernel_sp = idle->thread.sp0; 267 268 #ifdef CONFIG_X86_32 269 ctxt->event_callback_cs = __KERNEL_CS; 270 ctxt->failsafe_callback_cs = __KERNEL_CS; 271 #endif 272 ctxt->event_callback_eip = (unsigned long)xen_hypervisor_callback; 273 ctxt->failsafe_callback_eip = (unsigned long)xen_failsafe_callback; 274 275 per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir); 276 ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir)); 277 278 if (HYPERVISOR_vcpu_op(VCPUOP_initialise, cpu, ctxt)) 279 BUG(); 280 281 kfree(ctxt); 282 return 0; 283 } 284 285 static int __cpuinit xen_cpu_up(unsigned int cpu) 286 { 287 struct task_struct *idle = idle_task(cpu); 288 int rc; 289 290 per_cpu(current_task, cpu) = idle; 291 #ifdef CONFIG_X86_32 292 irq_ctx_init(cpu); 293 #else 294 clear_tsk_thread_flag(idle, TIF_FORK); 295 per_cpu(kernel_stack, cpu) = 296 (unsigned long)task_stack_page(idle) - 297 KERNEL_STACK_OFFSET + THREAD_SIZE; 298 #endif 299 xen_setup_runstate_info(cpu); 300 xen_setup_timer(cpu); 301 xen_init_lock_cpu(cpu); 302 303 per_cpu(cpu_state, cpu) = CPU_UP_PREPARE; 304 305 /* make sure interrupts start blocked */ 306 per_cpu(xen_vcpu, cpu)->evtchn_upcall_mask = 1; 307 308 rc = cpu_initialize_context(cpu, idle); 309 if (rc) 310 return rc; 311 312 if (num_online_cpus() == 1) 313 alternatives_smp_switch(1); 314 315 rc = xen_smp_intr_init(cpu); 316 if (rc) 317 return rc; 318 319 rc = HYPERVISOR_vcpu_op(VCPUOP_up, cpu, NULL); 320 BUG_ON(rc); 321 322 while(per_cpu(cpu_state, cpu) != CPU_ONLINE) { 323 HYPERVISOR_sched_op(SCHEDOP_yield, NULL); 324 barrier(); 325 } 326 327 return 0; 328 } 329 330 static void xen_smp_cpus_done(unsigned int max_cpus) 331 { 332 } 333 334 #ifdef CONFIG_HOTPLUG_CPU 335 static int xen_cpu_disable(void) 336 { 337 unsigned int cpu = smp_processor_id(); 338 if (cpu == 0) 339 return -EBUSY; 340 341 cpu_disable_common(); 342 343 load_cr3(swapper_pg_dir); 344 return 0; 345 } 346 347 static void xen_cpu_die(unsigned int cpu) 348 { 349 while (HYPERVISOR_vcpu_op(VCPUOP_is_up, cpu, NULL)) { 350 current->state = TASK_UNINTERRUPTIBLE; 351 schedule_timeout(HZ/10); 352 } 353 unbind_from_irqhandler(per_cpu(xen_resched_irq, cpu), NULL); 354 unbind_from_irqhandler(per_cpu(xen_callfunc_irq, cpu), NULL); 355 unbind_from_irqhandler(per_cpu(xen_debug_irq, cpu), NULL); 356 unbind_from_irqhandler(per_cpu(xen_callfuncsingle_irq, cpu), NULL); 357 xen_uninit_lock_cpu(cpu); 358 xen_teardown_timer(cpu); 359 360 if (num_online_cpus() == 1) 361 alternatives_smp_switch(0); 362 } 363 364 static void __cpuinit xen_play_dead(void) /* used only with CPU_HOTPLUG */ 365 { 366 play_dead_common(); 367 HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL); 368 cpu_bringup(); 369 } 370 371 #else /* !CONFIG_HOTPLUG_CPU */ 372 static int xen_cpu_disable(void) 373 { 374 return -ENOSYS; 375 } 376 377 static void xen_cpu_die(unsigned int cpu) 378 { 379 BUG(); 380 } 381 382 static void xen_play_dead(void) 383 { 384 BUG(); 385 } 386 387 #endif 388 static void stop_self(void *v) 389 { 390 int cpu = smp_processor_id(); 391 392 /* make sure we're not pinning something down */ 393 load_cr3(swapper_pg_dir); 394 /* should set up a minimal gdt */ 395 396 HYPERVISOR_vcpu_op(VCPUOP_down, cpu, NULL); 397 BUG(); 398 } 399 400 static void xen_smp_send_stop(void) 401 { 402 smp_call_function(stop_self, NULL, 0); 403 } 404 405 static void xen_smp_send_reschedule(int cpu) 406 { 407 xen_send_IPI_one(cpu, XEN_RESCHEDULE_VECTOR); 408 } 409 410 static void xen_send_IPI_mask(const struct cpumask *mask, 411 enum ipi_vector vector) 412 { 413 unsigned cpu; 414 415 for_each_cpu_and(cpu, mask, cpu_online_mask) 416 xen_send_IPI_one(cpu, vector); 417 } 418 419 static void xen_smp_send_call_function_ipi(const struct cpumask *mask) 420 { 421 int cpu; 422 423 xen_send_IPI_mask(mask, XEN_CALL_FUNCTION_VECTOR); 424 425 /* Make sure other vcpus get a chance to run if they need to. */ 426 for_each_cpu(cpu, mask) { 427 if (xen_vcpu_stolen(cpu)) { 428 HYPERVISOR_sched_op(SCHEDOP_yield, NULL); 429 break; 430 } 431 } 432 } 433 434 static void xen_smp_send_call_function_single_ipi(int cpu) 435 { 436 xen_send_IPI_mask(cpumask_of(cpu), 437 XEN_CALL_FUNCTION_SINGLE_VECTOR); 438 } 439 440 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id) 441 { 442 irq_enter(); 443 generic_smp_call_function_interrupt(); 444 inc_irq_stat(irq_call_count); 445 irq_exit(); 446 447 return IRQ_HANDLED; 448 } 449 450 static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id) 451 { 452 irq_enter(); 453 generic_smp_call_function_single_interrupt(); 454 inc_irq_stat(irq_call_count); 455 irq_exit(); 456 457 return IRQ_HANDLED; 458 } 459 460 static const struct smp_ops xen_smp_ops __initdata = { 461 .smp_prepare_boot_cpu = xen_smp_prepare_boot_cpu, 462 .smp_prepare_cpus = xen_smp_prepare_cpus, 463 .smp_cpus_done = xen_smp_cpus_done, 464 465 .cpu_up = xen_cpu_up, 466 .cpu_die = xen_cpu_die, 467 .cpu_disable = xen_cpu_disable, 468 .play_dead = xen_play_dead, 469 470 .smp_send_stop = xen_smp_send_stop, 471 .smp_send_reschedule = xen_smp_send_reschedule, 472 473 .send_call_func_ipi = xen_smp_send_call_function_ipi, 474 .send_call_func_single_ipi = xen_smp_send_call_function_single_ipi, 475 }; 476 477 void __init xen_smp_init(void) 478 { 479 smp_ops = xen_smp_ops; 480 xen_fill_possible_map(); 481 xen_init_spinlocks(); 482 } 483