GNU Linux-libre 4.14.266-gnu1
[releases.git] / arch / x86 / xen / smp_pv.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Xen SMP support
4  *
5  * This file implements the Xen versions of smp_ops.  SMP under Xen is
6  * very straightforward.  Bringing a CPU up is simply a matter of
7  * loading its initial context and setting it running.
8  *
9  * IPIs are handled through the Xen event mechanism.
10  *
11  * Because virtual CPUs can be scheduled onto any real CPU, there's no
12  * useful topology information for the kernel to make use of.  As a
13  * result, all CPUs are treated as if they're single-core and
14  * single-threaded.
15  */
16 #include <linux/sched.h>
17 #include <linux/sched/task_stack.h>
18 #include <linux/err.h>
19 #include <linux/slab.h>
20 #include <linux/smp.h>
21 #include <linux/irq_work.h>
22 #include <linux/tick.h>
23 #include <linux/nmi.h>
24 #include <linux/cpuhotplug.h>
25
26 #include <asm/paravirt.h>
27 #include <asm/desc.h>
28 #include <asm/pgtable.h>
29 #include <asm/cpu.h>
30
31 #include <xen/interface/xen.h>
32 #include <xen/interface/vcpu.h>
33 #include <xen/interface/xenpmu.h>
34
35 #include <asm/spec-ctrl.h>
36 #include <asm/xen/interface.h>
37 #include <asm/xen/hypercall.h>
38
39 #include <xen/xen.h>
40 #include <xen/page.h>
41 #include <xen/events.h>
42
43 #include <xen/hvc-console.h>
44 #include "xen-ops.h"
45 #include "mmu.h"
46 #include "smp.h"
47 #include "pmu.h"
48
49 cpumask_var_t xen_cpu_initialized_map;
50
51 static DEFINE_PER_CPU(struct xen_common_irq, xen_irq_work) = { .irq = -1 };
52 static DEFINE_PER_CPU(struct xen_common_irq, xen_pmu_irq) = { .irq = -1 };
53
54 static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id);
55
56 static void cpu_bringup(void)
57 {
58         int cpu;
59
60         cpu_init();
61         touch_softlockup_watchdog();
62         preempt_disable();
63
64         /* PVH runs in ring 0 and allows us to do native syscalls. Yay! */
65         if (!xen_feature(XENFEAT_supervisor_mode_kernel)) {
66                 xen_enable_sysenter();
67                 xen_enable_syscall();
68         }
69         cpu = smp_processor_id();
70         smp_store_cpu_info(cpu);
71         cpu_data(cpu).x86_max_cores = 1;
72         set_cpu_sibling_map(cpu);
73
74         speculative_store_bypass_ht_init();
75
76         xen_setup_cpu_clockevents();
77
78         notify_cpu_starting(cpu);
79
80         set_cpu_online(cpu, true);
81
82         cpu_set_state_online(cpu);  /* Implies full memory barrier. */
83
84         /* We can take interrupts now: we're officially "up". */
85         local_irq_enable();
86 }
87
88 asmlinkage __visible void cpu_bringup_and_idle(void)
89 {
90         cpu_bringup();
91         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
92         prevent_tail_call_optimization();
93 }
94
95 void xen_smp_intr_free_pv(unsigned int cpu)
96 {
97         if (per_cpu(xen_irq_work, cpu).irq >= 0) {
98                 unbind_from_irqhandler(per_cpu(xen_irq_work, cpu).irq, NULL);
99                 per_cpu(xen_irq_work, cpu).irq = -1;
100                 kfree(per_cpu(xen_irq_work, cpu).name);
101                 per_cpu(xen_irq_work, cpu).name = NULL;
102         }
103
104         if (per_cpu(xen_pmu_irq, cpu).irq >= 0) {
105                 unbind_from_irqhandler(per_cpu(xen_pmu_irq, cpu).irq, NULL);
106                 per_cpu(xen_pmu_irq, cpu).irq = -1;
107                 kfree(per_cpu(xen_pmu_irq, cpu).name);
108                 per_cpu(xen_pmu_irq, cpu).name = NULL;
109         }
110 }
111
112 int xen_smp_intr_init_pv(unsigned int cpu)
113 {
114         int rc;
115         char *callfunc_name, *pmu_name;
116
117         callfunc_name = kasprintf(GFP_KERNEL, "irqwork%d", cpu);
118         rc = bind_ipi_to_irqhandler(XEN_IRQ_WORK_VECTOR,
119                                     cpu,
120                                     xen_irq_work_interrupt,
121                                     IRQF_PERCPU|IRQF_NOBALANCING,
122                                     callfunc_name,
123                                     NULL);
124         if (rc < 0)
125                 goto fail;
126         per_cpu(xen_irq_work, cpu).irq = rc;
127         per_cpu(xen_irq_work, cpu).name = callfunc_name;
128
129         if (is_xen_pmu(cpu)) {
130                 pmu_name = kasprintf(GFP_KERNEL, "pmu%d", cpu);
131                 rc = bind_virq_to_irqhandler(VIRQ_XENPMU, cpu,
132                                              xen_pmu_irq_handler,
133                                              IRQF_PERCPU|IRQF_NOBALANCING,
134                                              pmu_name, NULL);
135                 if (rc < 0)
136                         goto fail;
137                 per_cpu(xen_pmu_irq, cpu).irq = rc;
138                 per_cpu(xen_pmu_irq, cpu).name = pmu_name;
139         }
140
141         return 0;
142
143  fail:
144         xen_smp_intr_free_pv(cpu);
145         return rc;
146 }
147
148 static void __init xen_fill_possible_map(void)
149 {
150         int i, rc;
151
152         if (xen_initial_domain())
153                 return;
154
155         for (i = 0; i < nr_cpu_ids; i++) {
156                 rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL);
157                 if (rc >= 0) {
158                         num_processors++;
159                         set_cpu_possible(i, true);
160                 }
161         }
162 }
163
164 static void __init xen_filter_cpu_maps(void)
165 {
166         int i, rc;
167         unsigned int subtract = 0;
168
169         if (!xen_initial_domain())
170                 return;
171
172         num_processors = 0;
173         disabled_cpus = 0;
174         for (i = 0; i < nr_cpu_ids; i++) {
175                 rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL);
176                 if (rc >= 0) {
177                         num_processors++;
178                         set_cpu_possible(i, true);
179                 } else {
180                         set_cpu_possible(i, false);
181                         set_cpu_present(i, false);
182                         subtract++;
183                 }
184         }
185 #ifdef CONFIG_HOTPLUG_CPU
186         /* This is akin to using 'nr_cpus' on the Linux command line.
187          * Which is OK as when we use 'dom0_max_vcpus=X' we can only
188          * have up to X, while nr_cpu_ids is greater than X. This
189          * normally is not a problem, except when CPU hotplugging
190          * is involved and then there might be more than X CPUs
191          * in the guest - which will not work as there is no
192          * hypercall to expand the max number of VCPUs an already
193          * running guest has. So cap it up to X. */
194         if (subtract)
195                 nr_cpu_ids = nr_cpu_ids - subtract;
196 #endif
197
198 }
199
200 static void __init xen_pv_smp_prepare_boot_cpu(void)
201 {
202         BUG_ON(smp_processor_id() != 0);
203         native_smp_prepare_boot_cpu();
204
205         if (!xen_feature(XENFEAT_writable_page_tables))
206                 /* We've switched to the "real" per-cpu gdt, so make
207                  * sure the old memory can be recycled. */
208                 make_lowmem_page_readwrite(xen_initial_gdt);
209
210 #ifdef CONFIG_X86_32
211         /*
212          * Xen starts us with XEN_FLAT_RING1_DS, but linux code
213          * expects __USER_DS
214          */
215         loadsegment(ds, __USER_DS);
216         loadsegment(es, __USER_DS);
217 #endif
218
219         xen_filter_cpu_maps();
220         xen_setup_vcpu_info_placement();
221
222         /*
223          * The alternative logic (which patches the unlock/lock) runs before
224          * the smp bootup up code is activated. Hence we need to set this up
225          * the core kernel is being patched. Otherwise we will have only
226          * modules patched but not core code.
227          */
228         xen_init_spinlocks();
229 }
230
231 static void __init xen_pv_smp_prepare_cpus(unsigned int max_cpus)
232 {
233         unsigned cpu;
234         unsigned int i;
235
236         if (skip_ioapic_setup) {
237                 char *m = (max_cpus == 0) ?
238                         "The nosmp parameter is incompatible with Xen; " \
239                         "use Xen dom0_max_vcpus=1 parameter" :
240                         "The noapic parameter is incompatible with Xen";
241
242                 xen_raw_printk(m);
243                 panic(m);
244         }
245         xen_init_lock_cpu(0);
246
247         smp_store_boot_cpu_info();
248         cpu_data(0).x86_max_cores = 1;
249
250         for_each_possible_cpu(i) {
251                 zalloc_cpumask_var(&per_cpu(cpu_sibling_map, i), GFP_KERNEL);
252                 zalloc_cpumask_var(&per_cpu(cpu_core_map, i), GFP_KERNEL);
253                 zalloc_cpumask_var(&per_cpu(cpu_llc_shared_map, i), GFP_KERNEL);
254         }
255         set_cpu_sibling_map(0);
256
257         speculative_store_bypass_ht_init();
258
259         xen_pmu_init(0);
260
261         if (xen_smp_intr_init(0) || xen_smp_intr_init_pv(0))
262                 BUG();
263
264         if (!alloc_cpumask_var(&xen_cpu_initialized_map, GFP_KERNEL))
265                 panic("could not allocate xen_cpu_initialized_map\n");
266
267         cpumask_copy(xen_cpu_initialized_map, cpumask_of(0));
268
269         /* Restrict the possible_map according to max_cpus. */
270         while ((num_possible_cpus() > 1) && (num_possible_cpus() > max_cpus)) {
271                 for (cpu = nr_cpu_ids - 1; !cpu_possible(cpu); cpu--)
272                         continue;
273                 set_cpu_possible(cpu, false);
274         }
275
276         for_each_possible_cpu(cpu)
277                 set_cpu_present(cpu, true);
278 }
279
280 static int
281 cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
282 {
283         struct vcpu_guest_context *ctxt;
284         struct desc_struct *gdt;
285         unsigned long gdt_mfn;
286
287         /* used to tell cpu_init() that it can proceed with initialization */
288         cpumask_set_cpu(cpu, cpu_callout_mask);
289         if (cpumask_test_and_set_cpu(cpu, xen_cpu_initialized_map))
290                 return 0;
291
292         ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL);
293         if (ctxt == NULL)
294                 return -ENOMEM;
295
296         gdt = get_cpu_gdt_rw(cpu);
297
298 #ifdef CONFIG_X86_32
299         ctxt->user_regs.fs = __KERNEL_PERCPU;
300         ctxt->user_regs.gs = __KERNEL_STACK_CANARY;
301 #endif
302         memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt));
303
304         /*
305          * Bring up the CPU in cpu_bringup_and_idle() with the stack
306          * pointing just below where pt_regs would be if it were a normal
307          * kernel entry.
308          */
309         ctxt->user_regs.eip = (unsigned long)cpu_bringup_and_idle;
310         ctxt->flags = VGCF_IN_KERNEL;
311         ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */
312         ctxt->user_regs.ds = __USER_DS;
313         ctxt->user_regs.es = __USER_DS;
314         ctxt->user_regs.ss = __KERNEL_DS;
315         ctxt->user_regs.cs = __KERNEL_CS;
316         ctxt->user_regs.esp = (unsigned long)task_pt_regs(idle);
317
318         xen_copy_trap_info(ctxt->trap_ctxt);
319
320         ctxt->ldt_ents = 0;
321
322         BUG_ON((unsigned long)gdt & ~PAGE_MASK);
323
324         gdt_mfn = arbitrary_virt_to_mfn(gdt);
325         make_lowmem_page_readonly(gdt);
326         make_lowmem_page_readonly(mfn_to_virt(gdt_mfn));
327
328         ctxt->gdt_frames[0] = gdt_mfn;
329         ctxt->gdt_ents      = GDT_ENTRIES;
330
331         /*
332          * Set SS:SP that Xen will use when entering guest kernel mode
333          * from guest user mode.  Subsequent calls to load_sp0() can
334          * change this value.
335          */
336         ctxt->kernel_ss = __KERNEL_DS;
337         ctxt->kernel_sp = task_top_of_stack(idle);
338
339 #ifdef CONFIG_X86_32
340         ctxt->event_callback_cs     = __KERNEL_CS;
341         ctxt->failsafe_callback_cs  = __KERNEL_CS;
342 #else
343         ctxt->gs_base_kernel = per_cpu_offset(cpu);
344 #endif
345         ctxt->event_callback_eip    =
346                 (unsigned long)xen_hypervisor_callback;
347         ctxt->failsafe_callback_eip =
348                 (unsigned long)xen_failsafe_callback;
349         per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir);
350
351         ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_gfn(swapper_pg_dir));
352         if (HYPERVISOR_vcpu_op(VCPUOP_initialise, xen_vcpu_nr(cpu), ctxt))
353                 BUG();
354
355         kfree(ctxt);
356         return 0;
357 }
358
359 static int xen_pv_cpu_up(unsigned int cpu, struct task_struct *idle)
360 {
361         int rc;
362
363         common_cpu_up(cpu, idle);
364
365         xen_setup_runstate_info(cpu);
366
367         /*
368          * PV VCPUs are always successfully taken down (see 'while' loop
369          * in xen_cpu_die()), so -EBUSY is an error.
370          */
371         rc = cpu_check_up_prepare(cpu);
372         if (rc)
373                 return rc;
374
375         /* make sure interrupts start blocked */
376         per_cpu(xen_vcpu, cpu)->evtchn_upcall_mask = 1;
377
378         rc = cpu_initialize_context(cpu, idle);
379         if (rc)
380                 return rc;
381
382         xen_pmu_init(cpu);
383
384         rc = HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL);
385         BUG_ON(rc);
386
387         while (cpu_report_state(cpu) != CPU_ONLINE)
388                 HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
389
390         return 0;
391 }
392
393 #ifdef CONFIG_HOTPLUG_CPU
394 static int xen_pv_cpu_disable(void)
395 {
396         unsigned int cpu = smp_processor_id();
397         if (cpu == 0)
398                 return -EBUSY;
399
400         cpu_disable_common();
401
402         load_cr3(swapper_pg_dir);
403         return 0;
404 }
405
406 static void xen_pv_cpu_die(unsigned int cpu)
407 {
408         while (HYPERVISOR_vcpu_op(VCPUOP_is_up,
409                                   xen_vcpu_nr(cpu), NULL)) {
410                 __set_current_state(TASK_UNINTERRUPTIBLE);
411                 schedule_timeout(HZ/10);
412         }
413
414         if (common_cpu_die(cpu) == 0) {
415                 xen_smp_intr_free(cpu);
416                 xen_uninit_lock_cpu(cpu);
417                 xen_teardown_timer(cpu);
418                 xen_pmu_finish(cpu);
419         }
420 }
421
422 static void xen_pv_play_dead(void) /* used only with HOTPLUG_CPU */
423 {
424         play_dead_common();
425         HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(smp_processor_id()), NULL);
426         cpu_bringup();
427         /*
428          * commit 4b0c0f294 (tick: Cleanup NOHZ per cpu data on cpu down)
429          * clears certain data that the cpu_idle loop (which called us
430          * and that we return from) expects. The only way to get that
431          * data back is to call:
432          */
433         tick_nohz_idle_enter();
434
435         cpuhp_online_idle(CPUHP_AP_ONLINE_IDLE);
436 }
437
438 #else /* !CONFIG_HOTPLUG_CPU */
439 static int xen_pv_cpu_disable(void)
440 {
441         return -ENOSYS;
442 }
443
444 static void xen_pv_cpu_die(unsigned int cpu)
445 {
446         BUG();
447 }
448
449 static void xen_pv_play_dead(void)
450 {
451         BUG();
452 }
453
454 #endif
455 static void stop_self(void *v)
456 {
457         int cpu = smp_processor_id();
458
459         /* make sure we're not pinning something down */
460         load_cr3(swapper_pg_dir);
461         /* should set up a minimal gdt */
462
463         set_cpu_online(cpu, false);
464
465         HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(cpu), NULL);
466         BUG();
467 }
468
469 static void xen_pv_stop_other_cpus(int wait)
470 {
471         smp_call_function(stop_self, NULL, wait);
472 }
473
474 static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id)
475 {
476         irq_enter();
477         irq_work_run();
478         inc_irq_stat(apic_irq_work_irqs);
479         irq_exit();
480
481         return IRQ_HANDLED;
482 }
483
484 static const struct smp_ops xen_smp_ops __initconst = {
485         .smp_prepare_boot_cpu = xen_pv_smp_prepare_boot_cpu,
486         .smp_prepare_cpus = xen_pv_smp_prepare_cpus,
487         .smp_cpus_done = xen_smp_cpus_done,
488
489         .cpu_up = xen_pv_cpu_up,
490         .cpu_die = xen_pv_cpu_die,
491         .cpu_disable = xen_pv_cpu_disable,
492         .play_dead = xen_pv_play_dead,
493
494         .stop_other_cpus = xen_pv_stop_other_cpus,
495         .smp_send_reschedule = xen_smp_send_reschedule,
496
497         .send_call_func_ipi = xen_smp_send_call_function_ipi,
498         .send_call_func_single_ipi = xen_smp_send_call_function_single_ipi,
499 };
500
501 void __init xen_smp_init(void)
502 {
503         smp_ops = xen_smp_ops;
504         xen_fill_possible_map();
505 }