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, 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 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 cpu_set(cpu, cpu_online_map); 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(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(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(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(callfuncsingle_irq, cpu) = rc; 137 138 return 0; 139 140 fail: 141 if (per_cpu(resched_irq, cpu) >= 0) 142 unbind_from_irqhandler(per_cpu(resched_irq, cpu), NULL); 143 if (per_cpu(callfunc_irq, cpu) >= 0) 144 unbind_from_irqhandler(per_cpu(callfunc_irq, cpu), NULL); 145 if (per_cpu(debug_irq, cpu) >= 0) 146 unbind_from_irqhandler(per_cpu(debug_irq, cpu), NULL); 147 if (per_cpu(callfuncsingle_irq, cpu) >= 0) 148 unbind_from_irqhandler(per_cpu(callfuncsingle_irq, cpu), NULL); 149 150 return rc; 151 } 152 153 static void __init xen_fill_possible_map(void) 154 { 155 int i, rc; 156 157 for (i = 0; i < nr_cpu_ids; i++) { 158 rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL); 159 if (rc >= 0) { 160 num_processors++; 161 set_cpu_possible(i, true); 162 } 163 } 164 } 165 166 static void __init xen_smp_prepare_boot_cpu(void) 167 { 168 BUG_ON(smp_processor_id() != 0); 169 native_smp_prepare_boot_cpu(); 170 171 /* We've switched to the "real" per-cpu gdt, so make sure the 172 old memory can be recycled */ 173 make_lowmem_page_readwrite(xen_initial_gdt); 174 175 xen_setup_vcpu_info_placement(); 176 } 177 178 static void __init xen_smp_prepare_cpus(unsigned int max_cpus) 179 { 180 unsigned cpu; 181 182 xen_init_lock_cpu(0); 183 184 smp_store_cpu_info(0); 185 cpu_data(0).x86_max_cores = 1; 186 set_cpu_sibling_map(0); 187 188 if (xen_smp_intr_init(0)) 189 BUG(); 190 191 if (!alloc_cpumask_var(&xen_cpu_initialized_map, GFP_KERNEL)) 192 panic("could not allocate xen_cpu_initialized_map\n"); 193 194 cpumask_copy(xen_cpu_initialized_map, cpumask_of(0)); 195 196 /* Restrict the possible_map according to max_cpus. */ 197 while ((num_possible_cpus() > 1) && (num_possible_cpus() > max_cpus)) { 198 for (cpu = nr_cpu_ids - 1; !cpu_possible(cpu); cpu--) 199 continue; 200 set_cpu_possible(cpu, false); 201 } 202 203 for_each_possible_cpu (cpu) { 204 struct task_struct *idle; 205 206 if (cpu == 0) 207 continue; 208 209 idle = fork_idle(cpu); 210 if (IS_ERR(idle)) 211 panic("failed fork for CPU %d", cpu); 212 213 set_cpu_present(cpu, true); 214 } 215 } 216 217 static __cpuinit int 218 cpu_initialize_context(unsigned int cpu, struct task_struct *idle) 219 { 220 struct vcpu_guest_context *ctxt; 221 struct desc_struct *gdt; 222 unsigned long gdt_mfn; 223 224 if (cpumask_test_and_set_cpu(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 ctxt->user_regs.gs = __KERNEL_STACK_CANARY; 240 #else 241 ctxt->gs_base_kernel = per_cpu_offset(cpu); 242 #endif 243 ctxt->user_regs.eip = (unsigned long)cpu_bringup_and_idle; 244 ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */ 245 246 memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt)); 247 248 xen_copy_trap_info(ctxt->trap_ctxt); 249 250 ctxt->ldt_ents = 0; 251 252 BUG_ON((unsigned long)gdt & ~PAGE_MASK); 253 254 gdt_mfn = arbitrary_virt_to_mfn(gdt); 255 make_lowmem_page_readonly(gdt); 256 make_lowmem_page_readonly(mfn_to_virt(gdt_mfn)); 257 258 ctxt->gdt_frames[0] = gdt_mfn; 259 ctxt->gdt_ents = GDT_ENTRIES; 260 261 ctxt->user_regs.cs = __KERNEL_CS; 262 ctxt->user_regs.esp = idle->thread.sp0 - sizeof(struct pt_regs); 263 264 ctxt->kernel_ss = __KERNEL_DS; 265 ctxt->kernel_sp = idle->thread.sp0; 266 267 #ifdef CONFIG_X86_32 268 ctxt->event_callback_cs = __KERNEL_CS; 269 ctxt->failsafe_callback_cs = __KERNEL_CS; 270 #endif 271 ctxt->event_callback_eip = (unsigned long)xen_hypervisor_callback; 272 ctxt->failsafe_callback_eip = (unsigned long)xen_failsafe_callback; 273 274 per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir); 275 ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir)); 276 277 if (HYPERVISOR_vcpu_op(VCPUOP_initialise, cpu, ctxt)) 278 BUG(); 279 280 kfree(ctxt); 281 return 0; 282 } 283 284 static int __cpuinit xen_cpu_up(unsigned int cpu) 285 { 286 struct task_struct *idle = idle_task(cpu); 287 int rc; 288 289 per_cpu(current_task, cpu) = idle; 290 #ifdef CONFIG_X86_32 291 irq_ctx_init(cpu); 292 #else 293 clear_tsk_thread_flag(idle, TIF_FORK); 294 per_cpu(kernel_stack, cpu) = 295 (unsigned long)task_stack_page(idle) - 296 KERNEL_STACK_OFFSET + THREAD_SIZE; 297 #endif 298 xen_setup_timer(cpu); 299 xen_init_lock_cpu(cpu); 300 301 per_cpu(cpu_state, cpu) = CPU_UP_PREPARE; 302 303 /* make sure interrupts start blocked */ 304 per_cpu(xen_vcpu, cpu)->evtchn_upcall_mask = 1; 305 306 rc = cpu_initialize_context(cpu, idle); 307 if (rc) 308 return rc; 309 310 if (num_online_cpus() == 1) 311 alternatives_smp_switch(1); 312 313 rc = xen_smp_intr_init(cpu); 314 if (rc) 315 return rc; 316 317 rc = HYPERVISOR_vcpu_op(VCPUOP_up, cpu, NULL); 318 BUG_ON(rc); 319 320 while(per_cpu(cpu_state, cpu) != CPU_ONLINE) { 321 HYPERVISOR_sched_op(SCHEDOP_yield, NULL); 322 barrier(); 323 } 324 325 return 0; 326 } 327 328 static void xen_smp_cpus_done(unsigned int max_cpus) 329 { 330 } 331 332 #ifdef CONFIG_HOTPLUG_CPU 333 static int xen_cpu_disable(void) 334 { 335 unsigned int cpu = smp_processor_id(); 336 if (cpu == 0) 337 return -EBUSY; 338 339 cpu_disable_common(); 340 341 load_cr3(swapper_pg_dir); 342 return 0; 343 } 344 345 static void xen_cpu_die(unsigned int cpu) 346 { 347 while (HYPERVISOR_vcpu_op(VCPUOP_is_up, cpu, NULL)) { 348 current->state = TASK_UNINTERRUPTIBLE; 349 schedule_timeout(HZ/10); 350 } 351 unbind_from_irqhandler(per_cpu(resched_irq, cpu), NULL); 352 unbind_from_irqhandler(per_cpu(callfunc_irq, cpu), NULL); 353 unbind_from_irqhandler(per_cpu(debug_irq, cpu), NULL); 354 unbind_from_irqhandler(per_cpu(callfuncsingle_irq, cpu), NULL); 355 xen_uninit_lock_cpu(cpu); 356 xen_teardown_timer(cpu); 357 358 if (num_online_cpus() == 1) 359 alternatives_smp_switch(0); 360 } 361 362 static void __cpuinit xen_play_dead(void) /* used only with CPU_HOTPLUG */ 363 { 364 play_dead_common(); 365 HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL); 366 cpu_bringup(); 367 } 368 369 #else /* !CONFIG_HOTPLUG_CPU */ 370 static int xen_cpu_disable(void) 371 { 372 return -ENOSYS; 373 } 374 375 static void xen_cpu_die(unsigned int cpu) 376 { 377 BUG(); 378 } 379 380 static void xen_play_dead(void) 381 { 382 BUG(); 383 } 384 385 #endif 386 static void stop_self(void *v) 387 { 388 int cpu = smp_processor_id(); 389 390 /* make sure we're not pinning something down */ 391 load_cr3(swapper_pg_dir); 392 /* should set up a minimal gdt */ 393 394 HYPERVISOR_vcpu_op(VCPUOP_down, cpu, NULL); 395 BUG(); 396 } 397 398 static void xen_smp_send_stop(void) 399 { 400 smp_call_function(stop_self, NULL, 0); 401 } 402 403 static void xen_smp_send_reschedule(int cpu) 404 { 405 xen_send_IPI_one(cpu, XEN_RESCHEDULE_VECTOR); 406 } 407 408 static void xen_send_IPI_mask(const struct cpumask *mask, 409 enum ipi_vector vector) 410 { 411 unsigned cpu; 412 413 for_each_cpu_and(cpu, mask, cpu_online_mask) 414 xen_send_IPI_one(cpu, vector); 415 } 416 417 static void xen_smp_send_call_function_ipi(const struct cpumask *mask) 418 { 419 int cpu; 420 421 xen_send_IPI_mask(mask, XEN_CALL_FUNCTION_VECTOR); 422 423 /* Make sure other vcpus get a chance to run if they need to. */ 424 for_each_cpu(cpu, mask) { 425 if (xen_vcpu_stolen(cpu)) { 426 HYPERVISOR_sched_op(SCHEDOP_yield, NULL); 427 break; 428 } 429 } 430 } 431 432 static void xen_smp_send_call_function_single_ipi(int cpu) 433 { 434 xen_send_IPI_mask(cpumask_of(cpu), 435 XEN_CALL_FUNCTION_SINGLE_VECTOR); 436 } 437 438 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id) 439 { 440 irq_enter(); 441 generic_smp_call_function_interrupt(); 442 inc_irq_stat(irq_call_count); 443 irq_exit(); 444 445 return IRQ_HANDLED; 446 } 447 448 static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id) 449 { 450 irq_enter(); 451 generic_smp_call_function_single_interrupt(); 452 inc_irq_stat(irq_call_count); 453 irq_exit(); 454 455 return IRQ_HANDLED; 456 } 457 458 static const struct smp_ops xen_smp_ops __initdata = { 459 .smp_prepare_boot_cpu = xen_smp_prepare_boot_cpu, 460 .smp_prepare_cpus = xen_smp_prepare_cpus, 461 .smp_cpus_done = xen_smp_cpus_done, 462 463 .cpu_up = xen_cpu_up, 464 .cpu_die = xen_cpu_die, 465 .cpu_disable = xen_cpu_disable, 466 .play_dead = xen_play_dead, 467 468 .smp_send_stop = xen_smp_send_stop, 469 .smp_send_reschedule = xen_smp_send_reschedule, 470 471 .send_call_func_ipi = xen_smp_send_call_function_ipi, 472 .send_call_func_single_ipi = xen_smp_send_call_function_single_ipi, 473 }; 474 475 void __init xen_smp_init(void) 476 { 477 smp_ops = xen_smp_ops; 478 xen_fill_possible_map(); 479 xen_init_spinlocks(); 480 } 481