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.
8 * IPIs are handled through the Xen event mechanism.
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
15 * This does not handle HOTPLUG_CPU yet.
17 #include <linux/sched.h>
18 #include <linux/err.h>
19 #include <linux/smp.h>
21 #include <asm/paravirt.h>
23 #include <asm/pgtable.h>
26 #include <xen/interface/xen.h>
27 #include <xen/interface/vcpu.h>
29 #include <asm/xen/interface.h>
30 #include <asm/xen/hypercall.h>
33 #include <xen/events.h>
38 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;
44 * Structure and data for smp_call_function(). This is designed to minimise
45 * static memory requirements. It also looks cleaner.
47 static DEFINE_SPINLOCK(call_lock);
49 struct call_data_struct {
50 void (*func) (void *info);
57 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id);
59 static struct call_data_struct *call_data;
62 * Reschedule call back. Nothing to do,
63 * all the work is done automatically when
64 * we return from the interrupt.
66 static irqreturn_t xen_reschedule_interrupt(int irq, void *dev_id)
69 __get_cpu_var(irq_stat).irq_resched_count++;
71 add_pda(irq_resched_count, 1);
77 static __cpuinit void cpu_bringup_and_idle(void)
79 int cpu = smp_processor_id();
82 xen_enable_sysenter();
85 per_cpu(cpu_state, cpu) = CPU_ONLINE;
87 xen_setup_cpu_clockevents();
89 /* We can take interrupts now: we're officially "up". */
92 wmb(); /* make sure everything is out */
96 static int xen_smp_intr_init(unsigned int cpu)
99 const char *resched_name, *callfunc_name, *debug_name;
101 resched_name = kasprintf(GFP_KERNEL, "resched%d", cpu);
102 rc = bind_ipi_to_irqhandler(XEN_RESCHEDULE_VECTOR,
104 xen_reschedule_interrupt,
105 IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
110 per_cpu(resched_irq, cpu) = rc;
112 callfunc_name = kasprintf(GFP_KERNEL, "callfunc%d", cpu);
113 rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_VECTOR,
115 xen_call_function_interrupt,
116 IRQF_DISABLED|IRQF_PERCPU|IRQF_NOBALANCING,
121 per_cpu(callfunc_irq, cpu) = rc;
123 debug_name = kasprintf(GFP_KERNEL, "debug%d", cpu);
124 rc = bind_virq_to_irqhandler(VIRQ_DEBUG, cpu, xen_debug_interrupt,
125 IRQF_DISABLED | IRQF_PERCPU | IRQF_NOBALANCING,
129 per_cpu(debug_irq, cpu) = rc;
134 if (per_cpu(resched_irq, cpu) >= 0)
135 unbind_from_irqhandler(per_cpu(resched_irq, cpu), NULL);
136 if (per_cpu(callfunc_irq, cpu) >= 0)
137 unbind_from_irqhandler(per_cpu(callfunc_irq, cpu), NULL);
138 if (per_cpu(debug_irq, cpu) >= 0)
139 unbind_from_irqhandler(per_cpu(debug_irq, cpu), NULL);
143 void __init xen_fill_possible_map(void)
147 for (i = 0; i < NR_CPUS; i++) {
148 rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL);
150 cpu_set(i, cpu_possible_map);
154 void __init xen_smp_prepare_boot_cpu(void)
158 BUG_ON(smp_processor_id() != 0);
159 native_smp_prepare_boot_cpu();
161 /* We've switched to the "real" per-cpu gdt, so make sure the
162 old memory can be recycled */
163 make_lowmem_page_readwrite(&per_cpu__gdt_page);
165 for_each_possible_cpu(cpu) {
166 cpus_clear(per_cpu(cpu_sibling_map, cpu));
168 * cpu_core_map lives in a per cpu area that is cleared
169 * when the per cpu array is allocated.
171 * cpus_clear(per_cpu(cpu_core_map, cpu));
175 xen_setup_vcpu_info_placement();
178 void __init xen_smp_prepare_cpus(unsigned int max_cpus)
182 for_each_possible_cpu(cpu) {
183 cpus_clear(per_cpu(cpu_sibling_map, cpu));
185 * cpu_core_ map will be zeroed when the per
186 * cpu area is allocated.
188 * cpus_clear(per_cpu(cpu_core_map, cpu));
192 smp_store_cpu_info(0);
193 set_cpu_sibling_map(0);
195 if (xen_smp_intr_init(0))
198 xen_cpu_initialized_map = cpumask_of_cpu(0);
200 /* Restrict the possible_map according to max_cpus. */
201 while ((num_possible_cpus() > 1) && (num_possible_cpus() > max_cpus)) {
202 for (cpu = NR_CPUS - 1; !cpu_possible(cpu); cpu--)
204 cpu_clear(cpu, cpu_possible_map);
207 for_each_possible_cpu (cpu) {
208 struct task_struct *idle;
213 idle = fork_idle(cpu);
215 panic("failed fork for CPU %d", cpu);
217 cpu_set(cpu, cpu_present_map);
220 //init_xenbus_allowed_cpumask();
224 cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
226 struct vcpu_guest_context *ctxt;
227 struct gdt_page *gdt = &per_cpu(gdt_page, cpu);
229 if (cpu_test_and_set(cpu, xen_cpu_initialized_map))
232 ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL);
236 ctxt->flags = VGCF_IN_KERNEL;
237 ctxt->user_regs.ds = __USER_DS;
238 ctxt->user_regs.es = __USER_DS;
239 ctxt->user_regs.fs = __KERNEL_PERCPU;
240 ctxt->user_regs.gs = 0;
241 ctxt->user_regs.ss = __KERNEL_DS;
242 ctxt->user_regs.eip = (unsigned long)cpu_bringup_and_idle;
243 ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */
245 memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt));
247 xen_copy_trap_info(ctxt->trap_ctxt);
251 BUG_ON((unsigned long)gdt->gdt & ~PAGE_MASK);
252 make_lowmem_page_readonly(gdt->gdt);
254 ctxt->gdt_frames[0] = virt_to_mfn(gdt->gdt);
255 ctxt->gdt_ents = ARRAY_SIZE(gdt->gdt);
257 ctxt->user_regs.cs = __KERNEL_CS;
258 ctxt->user_regs.esp = idle->thread.sp0 - sizeof(struct pt_regs);
260 ctxt->kernel_ss = __KERNEL_DS;
261 ctxt->kernel_sp = idle->thread.sp0;
263 ctxt->event_callback_cs = __KERNEL_CS;
264 ctxt->event_callback_eip = (unsigned long)xen_hypervisor_callback;
265 ctxt->failsafe_callback_cs = __KERNEL_CS;
266 ctxt->failsafe_callback_eip = (unsigned long)xen_failsafe_callback;
268 per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir);
269 ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir));
271 if (HYPERVISOR_vcpu_op(VCPUOP_initialise, cpu, ctxt))
278 int __cpuinit xen_cpu_up(unsigned int cpu)
280 struct task_struct *idle = idle_task(cpu);
284 rc = cpu_up_check(cpu);
290 per_cpu(current_task, cpu) = idle;
292 xen_setup_timer(cpu);
294 /* make sure interrupts start blocked */
295 per_cpu(xen_vcpu, cpu)->evtchn_upcall_mask = 1;
297 rc = cpu_initialize_context(cpu, idle);
301 if (num_online_cpus() == 1)
302 alternatives_smp_switch(1);
304 rc = xen_smp_intr_init(cpu);
308 smp_store_cpu_info(cpu);
309 set_cpu_sibling_map(cpu);
310 /* This must be done before setting cpu_online_map */
313 cpu_set(cpu, cpu_online_map);
315 rc = HYPERVISOR_vcpu_op(VCPUOP_up, cpu, NULL);
321 void xen_smp_cpus_done(unsigned int max_cpus)
325 static void stop_self(void *v)
327 int cpu = smp_processor_id();
329 /* make sure we're not pinning something down */
330 load_cr3(swapper_pg_dir);
331 /* should set up a minimal gdt */
333 HYPERVISOR_vcpu_op(VCPUOP_down, cpu, NULL);
337 void xen_smp_send_stop(void)
339 smp_call_function(stop_self, NULL, 0, 0);
342 void xen_smp_send_reschedule(int cpu)
344 xen_send_IPI_one(cpu, XEN_RESCHEDULE_VECTOR);
348 static void xen_send_IPI_mask(cpumask_t mask, enum ipi_vector vector)
352 cpus_and(mask, mask, cpu_online_map);
354 for_each_cpu_mask(cpu, mask)
355 xen_send_IPI_one(cpu, vector);
358 static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id)
360 void (*func) (void *info) = call_data->func;
361 void *info = call_data->info;
362 int wait = call_data->wait;
365 * Notify initiating CPU that I've grabbed the data and am
366 * about to execute the function
369 atomic_inc(&call_data->started);
371 * At this point the info structure may be out of scope unless wait==1
375 __get_cpu_var(irq_stat).irq_call_count++;
379 mb(); /* commit everything before setting finished */
380 atomic_inc(&call_data->finished);
386 int xen_smp_call_function_mask(cpumask_t mask, void (*func)(void *),
387 void *info, int wait)
389 struct call_data_struct data;
393 /* Holding any lock stops cpus from going down. */
394 spin_lock(&call_lock);
396 cpu_clear(smp_processor_id(), mask);
398 cpus = cpus_weight(mask);
400 spin_unlock(&call_lock);
404 /* Can deadlock when called with interrupts disabled */
405 WARN_ON(irqs_disabled());
409 atomic_set(&data.started, 0);
412 atomic_set(&data.finished, 0);
415 mb(); /* write everything before IPI */
417 /* Send a message to other CPUs and wait for them to respond */
418 xen_send_IPI_mask(mask, XEN_CALL_FUNCTION_VECTOR);
420 /* Make sure other vcpus get a chance to run if they need to. */
422 for_each_cpu_mask(cpu, mask)
423 if (xen_vcpu_stolen(cpu))
427 HYPERVISOR_sched_op(SCHEDOP_yield, 0);
429 /* Wait for response */
430 while (atomic_read(&data.started) != cpus ||
431 (wait && atomic_read(&data.finished) != cpus))
434 spin_unlock(&call_lock);