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 * This does not handle HOTPLUG_CPU yet. 16 */ 17 #include <linux/sched.h> 18 #include <linux/err.h> 19 #include <linux/smp.h> 20 21 #include <asm/paravirt.h> 22 #include <asm/desc.h> 23 #include <asm/pgtable.h> 24 #include <asm/cpu.h> 25 26 #include <xen/interface/xen.h> 27 #include <xen/interface/vcpu.h> 28 29 #include <asm/xen/interface.h> 30 #include <asm/xen/hypercall.h> 31 32 #include <xen/page.h> 33 #include <xen/events.h> 34 35 #include "xen-ops.h" 36 #include "mmu.h" 37 38 static cpumask_t xen_cpu_initialized_map; 39 static DEFINE_PER_CPU(int, resched_irq) = -1; 40 static DEFINE_PER_CPU(int, callfunc_irq) = -1; 41 static DEFINE_PER_CPU(int, debug_irq) = -1; 42 43 /* 44 * Structure and data for smp_call_function(). This is designed to minimise 45 * static memory requirements. It also looks cleaner. 46 */ 47 static DEFINE_SPINLOCK(call_lock); 48 49 struct call_data_struct { 50 void (*func) (void *info); 51 void *info; 52 atomic_t started; 53 atomic_t finished; 54 int wait; 55 }; 56 57 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id); 58 59 static struct call_data_struct *call_data; 60 61 /* 62 * Reschedule call back. Nothing to do, 63 * all the work is done automatically when 64 * we return from the interrupt. 65 */ 66 static irqreturn_t xen_reschedule_interrupt(int irq, void *dev_id) 67 { 68 return IRQ_HANDLED; 69 } 70 71 static __cpuinit void cpu_bringup_and_idle(void) 72 { 73 int cpu = smp_processor_id(); 74 75 cpu_init(); 76 xen_enable_sysenter(); 77 78 preempt_disable(); 79 per_cpu(cpu_state, cpu) = CPU_ONLINE; 80 81 xen_setup_cpu_clockevents(); 82 83 /* We can take interrupts now: we're officially "up". */ 84 local_irq_enable(); 85 86 wmb(); /* make sure everything is out */ 87 cpu_idle(); 88 } 89 90 static int xen_smp_intr_init(unsigned int cpu) 91 { 92 int rc; 93 const char *resched_name, *callfunc_name, *debug_name; 94 95 resched_name = kasprintf(GFP_KERNEL, "resched%d", cpu); 96 rc = bind_ipi_to_irqhandler(XEN_RESCHEDULE_VECTOR, 97 cpu, 98 xen_reschedule_interrupt, 99 IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING, 100 resched_name, 101 NULL); 102 if (rc < 0) 103 goto fail; 104 per_cpu(resched_irq, cpu) = rc; 105 106 callfunc_name = kasprintf(GFP_KERNEL, "callfunc%d", cpu); 107 rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_VECTOR, 108 cpu, 109 xen_call_function_interrupt, 110 IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING, 111 callfunc_name, 112 NULL); 113 if (rc < 0) 114 goto fail; 115 per_cpu(callfunc_irq, cpu) = rc; 116 117 debug_name = kasprintf(GFP_KERNEL, "debug%d", cpu); 118 rc = bind_virq_to_irqhandler(VIRQ_DEBUG, cpu, xen_debug_interrupt, 119 IRQF_DISABLED | IRQF_PERCPU | IRQF_NOBALANCING, 120 debug_name, NULL); 121 if (rc < 0) 122 goto fail; 123 per_cpu(debug_irq, cpu) = rc; 124 125 return 0; 126 127 fail: 128 if (per_cpu(resched_irq, cpu) >= 0) 129 unbind_from_irqhandler(per_cpu(resched_irq, cpu), NULL); 130 if (per_cpu(callfunc_irq, cpu) >= 0) 131 unbind_from_irqhandler(per_cpu(callfunc_irq, cpu), NULL); 132 if (per_cpu(debug_irq, cpu) >= 0) 133 unbind_from_irqhandler(per_cpu(debug_irq, cpu), NULL); 134 return rc; 135 } 136 137 void __init xen_fill_possible_map(void) 138 { 139 int i, rc; 140 141 for (i = 0; i < NR_CPUS; i++) { 142 rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL); 143 if (rc >= 0) 144 cpu_set(i, cpu_possible_map); 145 } 146 } 147 148 void __init xen_smp_prepare_boot_cpu(void) 149 { 150 int cpu; 151 152 BUG_ON(smp_processor_id() != 0); 153 native_smp_prepare_boot_cpu(); 154 155 /* We've switched to the "real" per-cpu gdt, so make sure the 156 old memory can be recycled */ 157 make_lowmem_page_readwrite(&per_cpu__gdt_page); 158 159 for_each_possible_cpu(cpu) { 160 cpus_clear(per_cpu(cpu_sibling_map, cpu)); 161 /* 162 * cpu_core_map lives in a per cpu area that is cleared 163 * when the per cpu array is allocated. 164 * 165 * cpus_clear(per_cpu(cpu_core_map, cpu)); 166 */ 167 } 168 169 xen_setup_vcpu_info_placement(); 170 } 171 172 void __init xen_smp_prepare_cpus(unsigned int max_cpus) 173 { 174 unsigned cpu; 175 176 for_each_possible_cpu(cpu) { 177 cpus_clear(per_cpu(cpu_sibling_map, cpu)); 178 /* 179 * cpu_core_ map will be zeroed when the per 180 * cpu area is allocated. 181 * 182 * cpus_clear(per_cpu(cpu_core_map, cpu)); 183 */ 184 } 185 186 smp_store_cpu_info(0); 187 set_cpu_sibling_map(0); 188 189 if (xen_smp_intr_init(0)) 190 BUG(); 191 192 xen_cpu_initialized_map = cpumask_of_cpu(0); 193 194 /* Restrict the possible_map according to max_cpus. */ 195 while ((num_possible_cpus() > 1) && (num_possible_cpus() > max_cpus)) { 196 for (cpu = NR_CPUS - 1; !cpu_possible(cpu); cpu--) 197 continue; 198 cpu_clear(cpu, cpu_possible_map); 199 } 200 201 for_each_possible_cpu (cpu) { 202 struct task_struct *idle; 203 204 if (cpu == 0) 205 continue; 206 207 idle = fork_idle(cpu); 208 if (IS_ERR(idle)) 209 panic("failed fork for CPU %d", cpu); 210 211 cpu_set(cpu, cpu_present_map); 212 } 213 214 //init_xenbus_allowed_cpumask(); 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 gdt_page *gdt = &per_cpu(gdt_page, cpu); 222 223 if (cpu_test_and_set(cpu, xen_cpu_initialized_map)) 224 return 0; 225 226 ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL); 227 if (ctxt == NULL) 228 return -ENOMEM; 229 230 ctxt->flags = VGCF_IN_KERNEL; 231 ctxt->user_regs.ds = __USER_DS; 232 ctxt->user_regs.es = __USER_DS; 233 ctxt->user_regs.fs = __KERNEL_PERCPU; 234 ctxt->user_regs.gs = 0; 235 ctxt->user_regs.ss = __KERNEL_DS; 236 ctxt->user_regs.eip = (unsigned long)cpu_bringup_and_idle; 237 ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */ 238 239 memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt)); 240 241 xen_copy_trap_info(ctxt->trap_ctxt); 242 243 ctxt->ldt_ents = 0; 244 245 BUG_ON((unsigned long)gdt->gdt & ~PAGE_MASK); 246 make_lowmem_page_readonly(gdt->gdt); 247 248 ctxt->gdt_frames[0] = virt_to_mfn(gdt->gdt); 249 ctxt->gdt_ents = ARRAY_SIZE(gdt->gdt); 250 251 ctxt->user_regs.cs = __KERNEL_CS; 252 ctxt->user_regs.esp = idle->thread.sp0 - sizeof(struct pt_regs); 253 254 ctxt->kernel_ss = __KERNEL_DS; 255 ctxt->kernel_sp = idle->thread.sp0; 256 257 ctxt->event_callback_cs = __KERNEL_CS; 258 ctxt->event_callback_eip = (unsigned long)xen_hypervisor_callback; 259 ctxt->failsafe_callback_cs = __KERNEL_CS; 260 ctxt->failsafe_callback_eip = (unsigned long)xen_failsafe_callback; 261 262 per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir); 263 ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir)); 264 265 if (HYPERVISOR_vcpu_op(VCPUOP_initialise, cpu, ctxt)) 266 BUG(); 267 268 kfree(ctxt); 269 return 0; 270 } 271 272 int __cpuinit xen_cpu_up(unsigned int cpu) 273 { 274 struct task_struct *idle = idle_task(cpu); 275 int rc; 276 277 #if 0 278 rc = cpu_up_check(cpu); 279 if (rc) 280 return rc; 281 #endif 282 283 init_gdt(cpu); 284 per_cpu(current_task, cpu) = idle; 285 irq_ctx_init(cpu); 286 xen_setup_timer(cpu); 287 288 /* make sure interrupts start blocked */ 289 per_cpu(xen_vcpu, cpu)->evtchn_upcall_mask = 1; 290 291 rc = cpu_initialize_context(cpu, idle); 292 if (rc) 293 return rc; 294 295 if (num_online_cpus() == 1) 296 alternatives_smp_switch(1); 297 298 rc = xen_smp_intr_init(cpu); 299 if (rc) 300 return rc; 301 302 smp_store_cpu_info(cpu); 303 set_cpu_sibling_map(cpu); 304 /* This must be done before setting cpu_online_map */ 305 wmb(); 306 307 cpu_set(cpu, cpu_online_map); 308 309 rc = HYPERVISOR_vcpu_op(VCPUOP_up, cpu, NULL); 310 BUG_ON(rc); 311 312 return 0; 313 } 314 315 void xen_smp_cpus_done(unsigned int max_cpus) 316 { 317 } 318 319 static void stop_self(void *v) 320 { 321 int cpu = smp_processor_id(); 322 323 /* make sure we're not pinning something down */ 324 load_cr3(swapper_pg_dir); 325 /* should set up a minimal gdt */ 326 327 HYPERVISOR_vcpu_op(VCPUOP_down, cpu, NULL); 328 BUG(); 329 } 330 331 void xen_smp_send_stop(void) 332 { 333 smp_call_function(stop_self, NULL, 0, 0); 334 } 335 336 void xen_smp_send_reschedule(int cpu) 337 { 338 xen_send_IPI_one(cpu, XEN_RESCHEDULE_VECTOR); 339 } 340 341 342 static void xen_send_IPI_mask(cpumask_t mask, enum ipi_vector vector) 343 { 344 unsigned cpu; 345 346 cpus_and(mask, mask, cpu_online_map); 347 348 for_each_cpu_mask(cpu, mask) 349 xen_send_IPI_one(cpu, vector); 350 } 351 352 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id) 353 { 354 void (*func) (void *info) = call_data->func; 355 void *info = call_data->info; 356 int wait = call_data->wait; 357 358 /* 359 * Notify initiating CPU that I've grabbed the data and am 360 * about to execute the function 361 */ 362 mb(); 363 atomic_inc(&call_data->started); 364 /* 365 * At this point the info structure may be out of scope unless wait==1 366 */ 367 irq_enter(); 368 (*func)(info); 369 __get_cpu_var(irq_stat).irq_call_count++; 370 irq_exit(); 371 372 if (wait) { 373 mb(); /* commit everything before setting finished */ 374 atomic_inc(&call_data->finished); 375 } 376 377 return IRQ_HANDLED; 378 } 379 380 int xen_smp_call_function_mask(cpumask_t mask, void (*func)(void *), 381 void *info, int wait) 382 { 383 struct call_data_struct data; 384 int cpus, cpu; 385 bool yield; 386 387 /* Holding any lock stops cpus from going down. */ 388 spin_lock(&call_lock); 389 390 cpu_clear(smp_processor_id(), mask); 391 392 cpus = cpus_weight(mask); 393 if (!cpus) { 394 spin_unlock(&call_lock); 395 return 0; 396 } 397 398 /* Can deadlock when called with interrupts disabled */ 399 WARN_ON(irqs_disabled()); 400 401 data.func = func; 402 data.info = info; 403 atomic_set(&data.started, 0); 404 data.wait = wait; 405 if (wait) 406 atomic_set(&data.finished, 0); 407 408 call_data = &data; 409 mb(); /* write everything before IPI */ 410 411 /* Send a message to other CPUs and wait for them to respond */ 412 xen_send_IPI_mask(mask, XEN_CALL_FUNCTION_VECTOR); 413 414 /* Make sure other vcpus get a chance to run if they need to. */ 415 yield = false; 416 for_each_cpu_mask(cpu, mask) 417 if (xen_vcpu_stolen(cpu)) 418 yield = true; 419 420 if (yield) 421 HYPERVISOR_sched_op(SCHEDOP_yield, 0); 422 423 /* Wait for response */ 424 while (atomic_read(&data.started) != cpus || 425 (wait && atomic_read(&data.finished) != cpus)) 426 cpu_relax(); 427 428 spin_unlock(&call_lock); 429 430 return 0; 431 } 432