Revert "cpumask: introduce new APIs"
[linux-2.6.git] / arch / x86 / xen / smp.c
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_nr(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_nr(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 }