WIP FPC-III support
[linux/fpc-iii.git] / arch / x86 / xen / smp_pv.c
blobc2ac319f11a4b785e07ac52041f54d8adc2c4e85
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Xen SMP support
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.
9 * IPIs are handled through the Xen event mechanism.
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.
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 #include <linux/stackprotector.h>
26 #include <linux/pgtable.h>
28 #include <asm/paravirt.h>
29 #include <asm/idtentry.h>
30 #include <asm/desc.h>
31 #include <asm/cpu.h>
32 #include <asm/io_apic.h>
34 #include <xen/interface/xen.h>
35 #include <xen/interface/vcpu.h>
36 #include <xen/interface/xenpmu.h>
38 #include <asm/spec-ctrl.h>
39 #include <asm/xen/interface.h>
40 #include <asm/xen/hypercall.h>
42 #include <xen/xen.h>
43 #include <xen/page.h>
44 #include <xen/events.h>
46 #include <xen/hvc-console.h>
47 #include "xen-ops.h"
48 #include "mmu.h"
49 #include "smp.h"
50 #include "pmu.h"
52 cpumask_var_t xen_cpu_initialized_map;
54 static DEFINE_PER_CPU(struct xen_common_irq, xen_irq_work) = { .irq = -1 };
55 static DEFINE_PER_CPU(struct xen_common_irq, xen_pmu_irq) = { .irq = -1 };
57 static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id);
58 void asm_cpu_bringup_and_idle(void);
60 static void cpu_bringup(void)
62 int cpu;
64 cr4_init();
65 cpu_init();
66 touch_softlockup_watchdog();
67 preempt_disable();
69 /* PVH runs in ring 0 and allows us to do native syscalls. Yay! */
70 if (!xen_feature(XENFEAT_supervisor_mode_kernel)) {
71 xen_enable_sysenter();
72 xen_enable_syscall();
74 cpu = smp_processor_id();
75 smp_store_cpu_info(cpu);
76 cpu_data(cpu).x86_max_cores = 1;
77 set_cpu_sibling_map(cpu);
79 speculative_store_bypass_ht_init();
81 xen_setup_cpu_clockevents();
83 notify_cpu_starting(cpu);
85 set_cpu_online(cpu, true);
87 cpu_set_state_online(cpu); /* Implies full memory barrier. */
89 /* We can take interrupts now: we're officially "up". */
90 local_irq_enable();
93 asmlinkage __visible void cpu_bringup_and_idle(void)
95 cpu_bringup();
96 cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
99 void xen_smp_intr_free_pv(unsigned int cpu)
101 if (per_cpu(xen_irq_work, cpu).irq >= 0) {
102 unbind_from_irqhandler(per_cpu(xen_irq_work, cpu).irq, NULL);
103 per_cpu(xen_irq_work, cpu).irq = -1;
104 kfree(per_cpu(xen_irq_work, cpu).name);
105 per_cpu(xen_irq_work, cpu).name = NULL;
108 if (per_cpu(xen_pmu_irq, cpu).irq >= 0) {
109 unbind_from_irqhandler(per_cpu(xen_pmu_irq, cpu).irq, NULL);
110 per_cpu(xen_pmu_irq, cpu).irq = -1;
111 kfree(per_cpu(xen_pmu_irq, cpu).name);
112 per_cpu(xen_pmu_irq, cpu).name = NULL;
116 int xen_smp_intr_init_pv(unsigned int cpu)
118 int rc;
119 char *callfunc_name, *pmu_name;
121 callfunc_name = kasprintf(GFP_KERNEL, "irqwork%d", cpu);
122 rc = bind_ipi_to_irqhandler(XEN_IRQ_WORK_VECTOR,
123 cpu,
124 xen_irq_work_interrupt,
125 IRQF_PERCPU|IRQF_NOBALANCING,
126 callfunc_name,
127 NULL);
128 if (rc < 0)
129 goto fail;
130 per_cpu(xen_irq_work, cpu).irq = rc;
131 per_cpu(xen_irq_work, cpu).name = callfunc_name;
133 if (is_xen_pmu(cpu)) {
134 pmu_name = kasprintf(GFP_KERNEL, "pmu%d", cpu);
135 rc = bind_virq_to_irqhandler(VIRQ_XENPMU, cpu,
136 xen_pmu_irq_handler,
137 IRQF_PERCPU|IRQF_NOBALANCING,
138 pmu_name, NULL);
139 if (rc < 0)
140 goto fail;
141 per_cpu(xen_pmu_irq, cpu).irq = rc;
142 per_cpu(xen_pmu_irq, cpu).name = pmu_name;
145 return 0;
147 fail:
148 xen_smp_intr_free_pv(cpu);
149 return rc;
152 static void __init xen_fill_possible_map(void)
154 int i, rc;
156 if (xen_initial_domain())
157 return;
159 for (i = 0; i < nr_cpu_ids; i++) {
160 rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL);
161 if (rc >= 0) {
162 num_processors++;
163 set_cpu_possible(i, true);
168 static void __init xen_filter_cpu_maps(void)
170 int i, rc;
171 unsigned int subtract = 0;
173 if (!xen_initial_domain())
174 return;
176 num_processors = 0;
177 disabled_cpus = 0;
178 for (i = 0; i < nr_cpu_ids; i++) {
179 rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL);
180 if (rc >= 0) {
181 num_processors++;
182 set_cpu_possible(i, true);
183 } else {
184 set_cpu_possible(i, false);
185 set_cpu_present(i, false);
186 subtract++;
189 #ifdef CONFIG_HOTPLUG_CPU
190 /* This is akin to using 'nr_cpus' on the Linux command line.
191 * Which is OK as when we use 'dom0_max_vcpus=X' we can only
192 * have up to X, while nr_cpu_ids is greater than X. This
193 * normally is not a problem, except when CPU hotplugging
194 * is involved and then there might be more than X CPUs
195 * in the guest - which will not work as there is no
196 * hypercall to expand the max number of VCPUs an already
197 * running guest has. So cap it up to X. */
198 if (subtract)
199 nr_cpu_ids = nr_cpu_ids - subtract;
200 #endif
204 static void __init xen_pv_smp_prepare_boot_cpu(void)
206 BUG_ON(smp_processor_id() != 0);
207 native_smp_prepare_boot_cpu();
209 if (!xen_feature(XENFEAT_writable_page_tables))
210 /* We've switched to the "real" per-cpu gdt, so make
211 * sure the old memory can be recycled. */
212 make_lowmem_page_readwrite(xen_initial_gdt);
214 xen_filter_cpu_maps();
215 xen_setup_vcpu_info_placement();
218 * The alternative logic (which patches the unlock/lock) runs before
219 * the smp bootup up code is activated. Hence we need to set this up
220 * the core kernel is being patched. Otherwise we will have only
221 * modules patched but not core code.
223 xen_init_spinlocks();
226 static void __init xen_pv_smp_prepare_cpus(unsigned int max_cpus)
228 unsigned cpu;
229 unsigned int i;
231 if (skip_ioapic_setup) {
232 char *m = (max_cpus == 0) ?
233 "The nosmp parameter is incompatible with Xen; " \
234 "use Xen dom0_max_vcpus=1 parameter" :
235 "The noapic parameter is incompatible with Xen";
237 xen_raw_printk(m);
238 panic(m);
240 xen_init_lock_cpu(0);
242 smp_store_boot_cpu_info();
243 cpu_data(0).x86_max_cores = 1;
245 for_each_possible_cpu(i) {
246 zalloc_cpumask_var(&per_cpu(cpu_sibling_map, i), GFP_KERNEL);
247 zalloc_cpumask_var(&per_cpu(cpu_core_map, i), GFP_KERNEL);
248 zalloc_cpumask_var(&per_cpu(cpu_die_map, i), GFP_KERNEL);
249 zalloc_cpumask_var(&per_cpu(cpu_llc_shared_map, i), GFP_KERNEL);
251 set_cpu_sibling_map(0);
253 speculative_store_bypass_ht_init();
255 xen_pmu_init(0);
257 if (xen_smp_intr_init(0) || xen_smp_intr_init_pv(0))
258 BUG();
260 if (!alloc_cpumask_var(&xen_cpu_initialized_map, GFP_KERNEL))
261 panic("could not allocate xen_cpu_initialized_map\n");
263 cpumask_copy(xen_cpu_initialized_map, cpumask_of(0));
265 /* Restrict the possible_map according to max_cpus. */
266 while ((num_possible_cpus() > 1) && (num_possible_cpus() > max_cpus)) {
267 for (cpu = nr_cpu_ids - 1; !cpu_possible(cpu); cpu--)
268 continue;
269 set_cpu_possible(cpu, false);
272 for_each_possible_cpu(cpu)
273 set_cpu_present(cpu, true);
276 static int
277 cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
279 struct vcpu_guest_context *ctxt;
280 struct desc_struct *gdt;
281 unsigned long gdt_mfn;
283 /* used to tell cpu_init() that it can proceed with initialization */
284 cpumask_set_cpu(cpu, cpu_callout_mask);
285 if (cpumask_test_and_set_cpu(cpu, xen_cpu_initialized_map))
286 return 0;
288 ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL);
289 if (ctxt == NULL)
290 return -ENOMEM;
292 gdt = get_cpu_gdt_rw(cpu);
294 memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt));
297 * Bring up the CPU in cpu_bringup_and_idle() with the stack
298 * pointing just below where pt_regs would be if it were a normal
299 * kernel entry.
301 ctxt->user_regs.eip = (unsigned long)asm_cpu_bringup_and_idle;
302 ctxt->flags = VGCF_IN_KERNEL;
303 ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */
304 ctxt->user_regs.ds = __USER_DS;
305 ctxt->user_regs.es = __USER_DS;
306 ctxt->user_regs.ss = __KERNEL_DS;
307 ctxt->user_regs.cs = __KERNEL_CS;
308 ctxt->user_regs.esp = (unsigned long)task_pt_regs(idle);
310 xen_copy_trap_info(ctxt->trap_ctxt);
312 ctxt->ldt_ents = 0;
314 BUG_ON((unsigned long)gdt & ~PAGE_MASK);
316 gdt_mfn = arbitrary_virt_to_mfn(gdt);
317 make_lowmem_page_readonly(gdt);
318 make_lowmem_page_readonly(mfn_to_virt(gdt_mfn));
320 ctxt->gdt_frames[0] = gdt_mfn;
321 ctxt->gdt_ents = GDT_ENTRIES;
324 * Set SS:SP that Xen will use when entering guest kernel mode
325 * from guest user mode. Subsequent calls to load_sp0() can
326 * change this value.
328 ctxt->kernel_ss = __KERNEL_DS;
329 ctxt->kernel_sp = task_top_of_stack(idle);
331 ctxt->gs_base_kernel = per_cpu_offset(cpu);
332 ctxt->event_callback_eip =
333 (unsigned long)xen_asm_exc_xen_hypervisor_callback;
334 ctxt->failsafe_callback_eip =
335 (unsigned long)xen_failsafe_callback;
336 per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir);
338 ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_gfn(swapper_pg_dir));
339 if (HYPERVISOR_vcpu_op(VCPUOP_initialise, xen_vcpu_nr(cpu), ctxt))
340 BUG();
342 kfree(ctxt);
343 return 0;
346 static int xen_pv_cpu_up(unsigned int cpu, struct task_struct *idle)
348 int rc;
350 rc = common_cpu_up(cpu, idle);
351 if (rc)
352 return rc;
354 xen_setup_runstate_info(cpu);
357 * PV VCPUs are always successfully taken down (see 'while' loop
358 * in xen_cpu_die()), so -EBUSY is an error.
360 rc = cpu_check_up_prepare(cpu);
361 if (rc)
362 return rc;
364 /* make sure interrupts start blocked */
365 per_cpu(xen_vcpu, cpu)->evtchn_upcall_mask = 1;
367 rc = cpu_initialize_context(cpu, idle);
368 if (rc)
369 return rc;
371 xen_pmu_init(cpu);
373 rc = HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL);
374 BUG_ON(rc);
376 while (cpu_report_state(cpu) != CPU_ONLINE)
377 HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
379 return 0;
382 #ifdef CONFIG_HOTPLUG_CPU
383 static int xen_pv_cpu_disable(void)
385 unsigned int cpu = smp_processor_id();
386 if (cpu == 0)
387 return -EBUSY;
389 cpu_disable_common();
391 load_cr3(swapper_pg_dir);
392 return 0;
395 static void xen_pv_cpu_die(unsigned int cpu)
397 while (HYPERVISOR_vcpu_op(VCPUOP_is_up,
398 xen_vcpu_nr(cpu), NULL)) {
399 __set_current_state(TASK_UNINTERRUPTIBLE);
400 schedule_timeout(HZ/10);
403 if (common_cpu_die(cpu) == 0) {
404 xen_smp_intr_free(cpu);
405 xen_uninit_lock_cpu(cpu);
406 xen_teardown_timer(cpu);
407 xen_pmu_finish(cpu);
411 static void xen_pv_play_dead(void) /* used only with HOTPLUG_CPU */
413 play_dead_common();
414 HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(smp_processor_id()), NULL);
415 cpu_bringup();
417 * commit 4b0c0f294 (tick: Cleanup NOHZ per cpu data on cpu down)
418 * clears certain data that the cpu_idle loop (which called us
419 * and that we return from) expects. The only way to get that
420 * data back is to call:
422 tick_nohz_idle_enter();
423 tick_nohz_idle_stop_tick_protected();
425 cpuhp_online_idle(CPUHP_AP_ONLINE_IDLE);
428 #else /* !CONFIG_HOTPLUG_CPU */
429 static int xen_pv_cpu_disable(void)
431 return -ENOSYS;
434 static void xen_pv_cpu_die(unsigned int cpu)
436 BUG();
439 static void xen_pv_play_dead(void)
441 BUG();
444 #endif
445 static void stop_self(void *v)
447 int cpu = smp_processor_id();
449 /* make sure we're not pinning something down */
450 load_cr3(swapper_pg_dir);
451 /* should set up a minimal gdt */
453 set_cpu_online(cpu, false);
455 HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(cpu), NULL);
456 BUG();
459 static void xen_pv_stop_other_cpus(int wait)
461 smp_call_function(stop_self, NULL, wait);
464 static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id)
466 irq_enter();
467 irq_work_run();
468 inc_irq_stat(apic_irq_work_irqs);
469 irq_exit();
471 return IRQ_HANDLED;
474 static const struct smp_ops xen_smp_ops __initconst = {
475 .smp_prepare_boot_cpu = xen_pv_smp_prepare_boot_cpu,
476 .smp_prepare_cpus = xen_pv_smp_prepare_cpus,
477 .smp_cpus_done = xen_smp_cpus_done,
479 .cpu_up = xen_pv_cpu_up,
480 .cpu_die = xen_pv_cpu_die,
481 .cpu_disable = xen_pv_cpu_disable,
482 .play_dead = xen_pv_play_dead,
484 .stop_other_cpus = xen_pv_stop_other_cpus,
485 .smp_send_reschedule = xen_smp_send_reschedule,
487 .send_call_func_ipi = xen_smp_send_call_function_ipi,
488 .send_call_func_single_ipi = xen_smp_send_call_function_single_ipi,
491 void __init xen_smp_init(void)
493 smp_ops = xen_smp_ops;
494 xen_fill_possible_map();