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_each_possible_cpu(cpu) {
150 cpus_clear(per_cpu(cpu_sibling_map, cpu));
151 /*
152 * cpu_core_map lives in a per cpu area that is cleared
153 * when the per cpu array is allocated.
154 *
155 * cpus_clear(per_cpu(cpu_core_map, cpu));
156 */
157 }
158
159 xen_setup_vcpu_info_placement();
160 }
161
162 void __init xen_smp_prepare_cpus(unsigned int max_cpus)
163 {
164 unsigned cpu;
165
166 for_each_possible_cpu(cpu) {
167 cpus_clear(per_cpu(cpu_sibling_map, cpu));
168 /*
169 * cpu_core_ map will be zeroed when the per
170 * cpu area is allocated.
171 *
172 * cpus_clear(per_cpu(cpu_core_map, cpu));
173 */
174 }
175
176 smp_store_cpu_info(0);
177 set_cpu_sibling_map(0);
178
179 if (xen_smp_intr_init(0))
180 BUG();
181
182 cpu_initialized_map = cpumask_of_cpu(0);
183
184 /* Restrict the possible_map according to max_cpus. */
185 while ((num_possible_cpus() > 1) && (num_possible_cpus() > max_cpus)) {
186 for (cpu = NR_CPUS-1; !cpu_isset(cpu, cpu_possible_map); cpu--)
187 continue;
188 cpu_clear(cpu, cpu_possible_map);
189 }
190
191 for_each_possible_cpu (cpu) {
192 struct task_struct *idle;
193
194 if (cpu == 0)
195 continue;
196
197 idle = fork_idle(cpu);
198 if (IS_ERR(idle))
199 panic("failed fork for CPU %d", cpu);
200
201 cpu_set(cpu, cpu_present_map);
202 }
203
204 //init_xenbus_allowed_cpumask();
205 }
206
207 static __cpuinit int
208 cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
209 {
210 struct vcpu_guest_context *ctxt;
211 struct gdt_page *gdt = &per_cpu(gdt_page, cpu);
212
213 if (cpu_test_and_set(cpu, cpu_initialized_map))
214 return 0;
215
216 ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL);
217 if (ctxt == NULL)
218 return -ENOMEM;
219
220 ctxt->flags = VGCF_IN_KERNEL;
221 ctxt->user_regs.ds = __USER_DS;
222 ctxt->user_regs.es = __USER_DS;
223 ctxt->user_regs.fs = __KERNEL_PERCPU;
224 ctxt->user_regs.gs = 0;
225 ctxt->user_regs.ss = __KERNEL_DS;
226 ctxt->user_regs.eip = (unsigned long)cpu_bringup_and_idle;
227 ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */
228
229 memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt));
230
231 xen_copy_trap_info(ctxt->trap_ctxt);
232
233 ctxt->ldt_ents = 0;
234
235 BUG_ON((unsigned long)gdt->gdt & ~PAGE_MASK);
236 make_lowmem_page_readonly(gdt->gdt);
237
238 ctxt->gdt_frames[0] = virt_to_mfn(gdt->gdt);
239 ctxt->gdt_ents = ARRAY_SIZE(gdt->gdt);
240
241 ctxt->user_regs.cs = __KERNEL_CS;
242 ctxt->user_regs.esp = idle->thread.sp0 - sizeof(struct pt_regs);
243
244 ctxt->kernel_ss = __KERNEL_DS;
245 ctxt->kernel_sp = idle->thread.sp0;
246
247 ctxt->event_callback_cs = __KERNEL_CS;
248 ctxt->event_callback_eip = (unsigned long)xen_hypervisor_callback;
249 ctxt->failsafe_callback_cs = __KERNEL_CS;
250 ctxt->failsafe_callback_eip = (unsigned long)xen_failsafe_callback;
251
252 per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir);
253 ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir));
254
255 if (HYPERVISOR_vcpu_op(VCPUOP_initialise, cpu, ctxt))
256 BUG();
257
258 kfree(ctxt);
259 return 0;
260 }
261
262 int __cpuinit xen_cpu_up(unsigned int cpu)
263 {
264 struct task_struct *idle = idle_task(cpu);
265 int rc;
266
267 #if 0
268 rc = cpu_up_check(cpu);
269 if (rc)
270 return rc;
271 #endif
272
273 init_gdt(cpu);
274 per_cpu(current_task, cpu) = idle;
275 irq_ctx_init(cpu);
276 xen_setup_timer(cpu);
277
278 /* make sure interrupts start blocked */
279 per_cpu(xen_vcpu, cpu)->evtchn_upcall_mask = 1;
280
281 rc = cpu_initialize_context(cpu, idle);
282 if (rc)
283 return rc;
284
285 if (num_online_cpus() == 1)
286 alternatives_smp_switch(1);
287
288 rc = xen_smp_intr_init(cpu);
289 if (rc)
290 return rc;
291
292 smp_store_cpu_info(cpu);
293 set_cpu_sibling_map(cpu);
294 /* This must be done before setting cpu_online_map */
295 wmb();
296
297 cpu_set(cpu, cpu_online_map);
298
299 rc = HYPERVISOR_vcpu_op(VCPUOP_up, cpu, NULL);
300 BUG_ON(rc);
301
302 return 0;
303 }
304
305 void xen_smp_cpus_done(unsigned int max_cpus)
306 {
307 }
308
309 static void stop_self(void *v)
310 {
311 int cpu = smp_processor_id();
312
313 /* make sure we're not pinning something down */
314 load_cr3(swapper_pg_dir);
315 /* should set up a minimal gdt */
316
317 HYPERVISOR_vcpu_op(VCPUOP_down, cpu, NULL);
318 BUG();
319 }
320
321 void xen_smp_send_stop(void)
322 {
323 smp_call_function(stop_self, NULL, 0, 0);
324 }
325
326 void xen_smp_send_reschedule(int cpu)
327 {
328 xen_send_IPI_one(cpu, XEN_RESCHEDULE_VECTOR);
329 }
330
331
332 static void xen_send_IPI_mask(cpumask_t mask, enum ipi_vector vector)
333 {
334 unsigned cpu;
335
336 cpus_and(mask, mask, cpu_online_map);
337
338 for_each_cpu_mask(cpu, mask)
339 xen_send_IPI_one(cpu, vector);
340 }
341
342 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id)
343 {
344 void (*func) (void *info) = call_data->func;
345 void *info = call_data->info;
346 int wait = call_data->wait;
347
348 /*
349 * Notify initiating CPU that I've grabbed the data and am
350 * about to execute the function
351 */
352 mb();
353 atomic_inc(&call_data->started);
354 /*
355 * At this point the info structure may be out of scope unless wait==1
356 */
357 irq_enter();
358 (*func)(info);
359 __get_cpu_var(irq_stat).irq_call_count++;
360 irq_exit();
361
362 if (wait) {
363 mb(); /* commit everything before setting finished */
364 atomic_inc(&call_data->finished);
365 }
366
367 return IRQ_HANDLED;
368 }
369
370 int xen_smp_call_function_mask(cpumask_t mask, void (*func)(void *),
371 void *info, int wait)
372 {
373 struct call_data_struct data;
374 int cpus, cpu;
375 bool yield;
376
377 /* Holding any lock stops cpus from going down. */
378 spin_lock(&call_lock);
379
380 cpu_clear(smp_processor_id(), mask);
381
382 cpus = cpus_weight(mask);
383 if (!cpus) {
384 spin_unlock(&call_lock);
385 return 0;
386 }
387
388 /* Can deadlock when called with interrupts disabled */
389 WARN_ON(irqs_disabled());
390
391 data.func = func;
392 data.info = info;
393 atomic_set(&data.started, 0);
394 data.wait = wait;
395 if (wait)
396 atomic_set(&data.finished, 0);
397
398 call_data = &data;
399 mb(); /* write everything before IPI */
400
401 /* Send a message to other CPUs and wait for them to respond */
402 xen_send_IPI_mask(mask, XEN_CALL_FUNCTION_VECTOR);
403
404 /* Make sure other vcpus get a chance to run if they need to. */
405 yield = false;
406 for_each_cpu_mask(cpu, mask)
407 if (xen_vcpu_stolen(cpu))
408 yield = true;
409
410 if (yield)
411 HYPERVISOR_sched_op(SCHEDOP_yield, 0);
412
413 /* Wait for response */
414 while (atomic_read(&data.started) != cpus ||
415 (wait && atomic_read(&data.finished) != cpus))
416 cpu_relax();
417
418 spin_unlock(&call_lock);
419
420 return 0;
421 }
422
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