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 cpu_initialized_map; 39 static DEFINE_PER_CPU(int, resched_irq); 40 static DEFINE_PER_CPU(int, callfunc_irq); 41 42 /* 43 * Structure and data for smp_call_function(). This is designed to minimise 44 * static memory requirements. It also looks cleaner. 45 */ 46 static DEFINE_SPINLOCK(call_lock); 47 48 struct call_data_struct { 49 void (*func) (void *info); 50 void *info; 51 atomic_t started; 52 atomic_t finished; 53 int wait; 54 }; 55 56 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id); 57 58 static struct call_data_struct *call_data; 59 60 /* 61 * Reschedule call back. Nothing to do, 62 * all the work is done automatically when 63 * we return from the interrupt. 64 */ 65 static irqreturn_t xen_reschedule_interrupt(int irq, void *dev_id) 66 { 67 return IRQ_HANDLED; 68 } 69 70 static __cpuinit void cpu_bringup_and_idle(void) 71 { 72 int cpu = smp_processor_id(); 73 74 cpu_init(); 75 76 preempt_disable(); 77 per_cpu(cpu_state, cpu) = CPU_ONLINE; 78 79 xen_setup_cpu_clockevents(); 80 81 /* We can take interrupts now: we're officially "up". */ 82 local_irq_enable(); 83 84 wmb(); /* make sure everything is out */ 85 cpu_idle(); 86 } 87 88 static int xen_smp_intr_init(unsigned int cpu) 89 { 90 int rc; 91 const char *resched_name, *callfunc_name; 92 93 per_cpu(resched_irq, cpu) = per_cpu(callfunc_irq, cpu) = -1; 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 return 0; 118 119 fail: 120 if (per_cpu(resched_irq, cpu) >= 0) 121 unbind_from_irqhandler(per_cpu(resched_irq, cpu), NULL); 122 if (per_cpu(callfunc_irq, cpu) >= 0) 123 unbind_from_irqhandler(per_cpu(callfunc_irq, cpu), NULL); 124 return rc; 125 } 126 127 void __init xen_fill_possible_map(void) 128 { 129 int i, rc; 130 131 for (i = 0; i < NR_CPUS; i++) { 132 rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL); 133 if (rc >= 0) 134 cpu_set(i, cpu_possible_map); 135 } 136 } 137 138 void __init xen_smp_prepare_boot_cpu(void) 139 { 140 int cpu; 141 142 BUG_ON(smp_processor_id() != 0); 143 native_smp_prepare_boot_cpu(); 144 145 /* We've switched to the "real" per-cpu gdt, so make sure the 146 old memory can be recycled */ 147 make_lowmem_page_readwrite(&per_cpu__gdt_page); 148 149 for (cpu = 0; cpu < NR_CPUS; cpu++) { 150 cpus_clear(cpu_sibling_map[cpu]); 151 cpus_clear(cpu_core_map[cpu]); 152 } 153 154 xen_setup_vcpu_info_placement(); 155 } 156 157 void __init xen_smp_prepare_cpus(unsigned int max_cpus) 158 { 159 unsigned cpu; 160 161 for (cpu = 0; cpu < NR_CPUS; cpu++) { 162 cpus_clear(cpu_sibling_map[cpu]); 163 cpus_clear(cpu_core_map[cpu]); 164 } 165 166 smp_store_cpu_info(0); 167 set_cpu_sibling_map(0); 168 169 if (xen_smp_intr_init(0)) 170 BUG(); 171 172 cpu_initialized_map = cpumask_of_cpu(0); 173 174 /* Restrict the possible_map according to max_cpus. */ 175 while ((num_possible_cpus() > 1) && (num_possible_cpus() > max_cpus)) { 176 for (cpu = NR_CPUS-1; !cpu_isset(cpu, cpu_possible_map); cpu--) 177 continue; 178 cpu_clear(cpu, cpu_possible_map); 179 } 180 181 for_each_possible_cpu (cpu) { 182 struct task_struct *idle; 183 184 if (cpu == 0) 185 continue; 186 187 idle = fork_idle(cpu); 188 if (IS_ERR(idle)) 189 panic("failed fork for CPU %d", cpu); 190 191 cpu_set(cpu, cpu_present_map); 192 } 193 194 //init_xenbus_allowed_cpumask(); 195 } 196 197 static __cpuinit int 198 cpu_initialize_context(unsigned int cpu, struct task_struct *idle) 199 { 200 struct vcpu_guest_context *ctxt; 201 struct gdt_page *gdt = &per_cpu(gdt_page, cpu); 202 203 if (cpu_test_and_set(cpu, cpu_initialized_map)) 204 return 0; 205 206 ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL); 207 if (ctxt == NULL) 208 return -ENOMEM; 209 210 ctxt->flags = VGCF_IN_KERNEL; 211 ctxt->user_regs.ds = __USER_DS; 212 ctxt->user_regs.es = __USER_DS; 213 ctxt->user_regs.fs = __KERNEL_PERCPU; 214 ctxt->user_regs.gs = 0; 215 ctxt->user_regs.ss = __KERNEL_DS; 216 ctxt->user_regs.eip = (unsigned long)cpu_bringup_and_idle; 217 ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */ 218 219 memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt)); 220 221 xen_copy_trap_info(ctxt->trap_ctxt); 222 223 ctxt->ldt_ents = 0; 224 225 BUG_ON((unsigned long)gdt->gdt & ~PAGE_MASK); 226 make_lowmem_page_readonly(gdt->gdt); 227 228 ctxt->gdt_frames[0] = virt_to_mfn(gdt->gdt); 229 ctxt->gdt_ents = ARRAY_SIZE(gdt->gdt); 230 231 ctxt->user_regs.cs = __KERNEL_CS; 232 ctxt->user_regs.esp = idle->thread.esp0 - sizeof(struct pt_regs); 233 234 ctxt->kernel_ss = __KERNEL_DS; 235 ctxt->kernel_sp = idle->thread.esp0; 236 237 ctxt->event_callback_cs = __KERNEL_CS; 238 ctxt->event_callback_eip = (unsigned long)xen_hypervisor_callback; 239 ctxt->failsafe_callback_cs = __KERNEL_CS; 240 ctxt->failsafe_callback_eip = (unsigned long)xen_failsafe_callback; 241 242 per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir); 243 ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir)); 244 245 if (HYPERVISOR_vcpu_op(VCPUOP_initialise, cpu, ctxt)) 246 BUG(); 247 248 kfree(ctxt); 249 return 0; 250 } 251 252 int __cpuinit xen_cpu_up(unsigned int cpu) 253 { 254 struct task_struct *idle = idle_task(cpu); 255 int rc; 256 257 #if 0 258 rc = cpu_up_check(cpu); 259 if (rc) 260 return rc; 261 #endif 262 263 init_gdt(cpu); 264 per_cpu(current_task, cpu) = idle; 265 irq_ctx_init(cpu); 266 xen_setup_timer(cpu); 267 268 /* make sure interrupts start blocked */ 269 per_cpu(xen_vcpu, cpu)->evtchn_upcall_mask = 1; 270 271 rc = cpu_initialize_context(cpu, idle); 272 if (rc) 273 return rc; 274 275 if (num_online_cpus() == 1) 276 alternatives_smp_switch(1); 277 278 rc = xen_smp_intr_init(cpu); 279 if (rc) 280 return rc; 281 282 smp_store_cpu_info(cpu); 283 set_cpu_sibling_map(cpu); 284 /* This must be done before setting cpu_online_map */ 285 wmb(); 286 287 cpu_set(cpu, cpu_online_map); 288 289 rc = HYPERVISOR_vcpu_op(VCPUOP_up, cpu, NULL); 290 BUG_ON(rc); 291 292 return 0; 293 } 294 295 void xen_smp_cpus_done(unsigned int max_cpus) 296 { 297 } 298 299 static void stop_self(void *v) 300 { 301 int cpu = smp_processor_id(); 302 303 /* make sure we're not pinning something down */ 304 load_cr3(swapper_pg_dir); 305 /* should set up a minimal gdt */ 306 307 HYPERVISOR_vcpu_op(VCPUOP_down, cpu, NULL); 308 BUG(); 309 } 310 311 void xen_smp_send_stop(void) 312 { 313 smp_call_function(stop_self, NULL, 0, 0); 314 } 315 316 void xen_smp_send_reschedule(int cpu) 317 { 318 xen_send_IPI_one(cpu, XEN_RESCHEDULE_VECTOR); 319 } 320 321 322 static void xen_send_IPI_mask(cpumask_t mask, enum ipi_vector vector) 323 { 324 unsigned cpu; 325 326 cpus_and(mask, mask, cpu_online_map); 327 328 for_each_cpu_mask(cpu, mask) 329 xen_send_IPI_one(cpu, vector); 330 } 331 332 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id) 333 { 334 void (*func) (void *info) = call_data->func; 335 void *info = call_data->info; 336 int wait = call_data->wait; 337 338 /* 339 * Notify initiating CPU that I've grabbed the data and am 340 * about to execute the function 341 */ 342 mb(); 343 atomic_inc(&call_data->started); 344 /* 345 * At this point the info structure may be out of scope unless wait==1 346 */ 347 irq_enter(); 348 (*func)(info); 349 irq_exit(); 350 351 if (wait) { 352 mb(); /* commit everything before setting finished */ 353 atomic_inc(&call_data->finished); 354 } 355 356 return IRQ_HANDLED; 357 } 358 359 int xen_smp_call_function_mask(cpumask_t mask, void (*func)(void *), 360 void *info, int wait) 361 { 362 struct call_data_struct data; 363 int cpus; 364 365 /* Holding any lock stops cpus from going down. */ 366 spin_lock(&call_lock); 367 368 cpu_clear(smp_processor_id(), mask); 369 370 cpus = cpus_weight(mask); 371 if (!cpus) { 372 spin_unlock(&call_lock); 373 return 0; 374 } 375 376 /* Can deadlock when called with interrupts disabled */ 377 WARN_ON(irqs_disabled()); 378 379 data.func = func; 380 data.info = info; 381 atomic_set(&data.started, 0); 382 data.wait = wait; 383 if (wait) 384 atomic_set(&data.finished, 0); 385 386 call_data = &data; 387 mb(); /* write everything before IPI */ 388 389 /* Send a message to other CPUs and wait for them to respond */ 390 xen_send_IPI_mask(mask, XEN_CALL_FUNCTION_VECTOR); 391 392 /* Make sure other vcpus get a chance to run. 393 XXX too severe? Maybe we should check the other CPU's states? */ 394 HYPERVISOR_sched_op(SCHEDOP_yield, 0); 395 396 /* Wait for response */ 397 while (atomic_read(&data.started) != cpus || 398 (wait && atomic_read(&data.finished) != cpus)) 399 cpu_relax(); 400 401 spin_unlock(&call_lock); 402 403 return 0; 404 } 405