1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * KVM paravirt_ops implementation
5 * Copyright (C) 2007, Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
6 * Copyright IBM Corporation, 2007
7 * Authors: Anthony Liguori <aliguori@us.ibm.com>
10 #include <linux/context_tracking.h>
11 #include <linux/init.h>
12 #include <linux/kernel.h>
13 #include <linux/kvm_para.h>
14 #include <linux/cpu.h>
16 #include <linux/highmem.h>
17 #include <linux/hardirq.h>
18 #include <linux/notifier.h>
19 #include <linux/reboot.h>
20 #include <linux/hash.h>
21 #include <linux/sched.h>
22 #include <linux/slab.h>
23 #include <linux/kprobes.h>
24 #include <linux/debugfs.h>
25 #include <linux/nmi.h>
26 #include <linux/swait.h>
27 #include <asm/timer.h>
29 #include <asm/traps.h>
31 #include <asm/tlbflush.h>
33 #include <asm/apicdef.h>
34 #include <asm/hypervisor.h>
37 static int kvmapf = 1;
39 static int __init parse_no_kvmapf(char *arg)
45 early_param("no-kvmapf", parse_no_kvmapf);
47 static int steal_acc = 1;
48 static int __init parse_no_stealacc(char *arg)
54 early_param("no-steal-acc", parse_no_stealacc);
56 static DEFINE_PER_CPU_DECRYPTED(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
57 DEFINE_PER_CPU_DECRYPTED(struct kvm_steal_time, steal_time) __aligned(64) __visible;
58 static int has_steal_clock = 0;
61 * No need for any "IO delay" on KVM
63 static void kvm_io_delay(void)
67 #define KVM_TASK_SLEEP_HASHBITS 8
68 #define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS)
70 struct kvm_task_sleep_node {
71 struct hlist_node link;
72 struct swait_queue_head wq;
78 static struct kvm_task_sleep_head {
80 struct hlist_head list;
81 } async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];
83 static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b,
88 hlist_for_each(p, &b->list) {
89 struct kvm_task_sleep_node *n =
90 hlist_entry(p, typeof(*n), link);
91 if (n->token == token)
99 * @interrupt_kernel: Is this called from a routine which interrupts the kernel
100 * (other than user space)?
102 void kvm_async_pf_task_wait(u32 token, int interrupt_kernel)
104 u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
105 struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
106 struct kvm_task_sleep_node n, *e;
107 DECLARE_SWAITQUEUE(wait);
111 raw_spin_lock(&b->lock);
112 e = _find_apf_task(b, token);
114 /* dummy entry exist -> wake up was delivered ahead of PF */
117 raw_spin_unlock(&b->lock);
124 n.cpu = smp_processor_id();
125 n.halted = is_idle_task(current) ||
126 (IS_ENABLED(CONFIG_PREEMPT_COUNT)
127 ? preempt_count() > 1 || rcu_preempt_depth()
129 init_swait_queue_head(&n.wq);
130 hlist_add_head(&n.link, &b->list);
131 raw_spin_unlock(&b->lock);
135 prepare_to_swait_exclusive(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
136 if (hlist_unhashed(&n.link))
147 * We cannot reschedule. So halt.
156 finish_swait(&n.wq, &wait);
161 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait);
163 static void apf_task_wake_one(struct kvm_task_sleep_node *n)
165 hlist_del_init(&n->link);
167 smp_send_reschedule(n->cpu);
168 else if (swq_has_sleeper(&n->wq))
169 swake_up_one(&n->wq);
172 static void apf_task_wake_all(void)
176 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
177 struct hlist_node *p, *next;
178 struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
179 raw_spin_lock(&b->lock);
180 hlist_for_each_safe(p, next, &b->list) {
181 struct kvm_task_sleep_node *n =
182 hlist_entry(p, typeof(*n), link);
183 if (n->cpu == smp_processor_id())
184 apf_task_wake_one(n);
186 raw_spin_unlock(&b->lock);
190 void kvm_async_pf_task_wake(u32 token)
192 u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
193 struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
194 struct kvm_task_sleep_node *n;
202 raw_spin_lock(&b->lock);
203 n = _find_apf_task(b, token);
206 * async PF was not yet handled.
207 * Add dummy entry for the token.
209 n = kzalloc(sizeof(*n), GFP_ATOMIC);
212 * Allocation failed! Busy wait while other cpu
215 raw_spin_unlock(&b->lock);
220 n->cpu = smp_processor_id();
221 init_swait_queue_head(&n->wq);
222 hlist_add_head(&n->link, &b->list);
224 apf_task_wake_one(n);
225 raw_spin_unlock(&b->lock);
228 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
230 u32 kvm_read_and_reset_pf_reason(void)
234 if (__this_cpu_read(apf_reason.enabled)) {
235 reason = __this_cpu_read(apf_reason.reason);
236 __this_cpu_write(apf_reason.reason, 0);
241 EXPORT_SYMBOL_GPL(kvm_read_and_reset_pf_reason);
242 NOKPROBE_SYMBOL(kvm_read_and_reset_pf_reason);
245 do_async_page_fault(struct pt_regs *regs, unsigned long error_code, unsigned long address)
247 enum ctx_state prev_state;
249 switch (kvm_read_and_reset_pf_reason()) {
251 do_page_fault(regs, error_code, address);
253 case KVM_PV_REASON_PAGE_NOT_PRESENT:
254 /* page is swapped out by the host. */
255 prev_state = exception_enter();
256 kvm_async_pf_task_wait((u32)address, !user_mode(regs));
257 exception_exit(prev_state);
259 case KVM_PV_REASON_PAGE_READY:
261 kvm_async_pf_task_wake((u32)address);
266 NOKPROBE_SYMBOL(do_async_page_fault);
268 static void __init paravirt_ops_setup(void)
270 pv_info.name = "KVM";
272 if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
273 pv_ops.cpu.io_delay = kvm_io_delay;
275 #ifdef CONFIG_X86_IO_APIC
280 static void kvm_register_steal_time(void)
282 int cpu = smp_processor_id();
283 struct kvm_steal_time *st = &per_cpu(steal_time, cpu);
285 if (!has_steal_clock)
288 wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED));
289 pr_info("kvm-stealtime: cpu %d, msr %llx\n",
290 cpu, (unsigned long long) slow_virt_to_phys(st));
293 static DEFINE_PER_CPU_DECRYPTED(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;
295 static notrace void kvm_guest_apic_eoi_write(u32 reg, u32 val)
298 * This relies on __test_and_clear_bit to modify the memory
299 * in a way that is atomic with respect to the local CPU.
300 * The hypervisor only accesses this memory from the local CPU so
301 * there's no need for lock or memory barriers.
302 * An optimization barrier is implied in apic write.
304 if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi)))
306 apic->native_eoi_write(APIC_EOI, APIC_EOI_ACK);
309 static void kvm_guest_cpu_init(void)
311 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF) && kvmapf) {
312 u64 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
314 #ifdef CONFIG_PREEMPTION
315 pa |= KVM_ASYNC_PF_SEND_ALWAYS;
317 pa |= KVM_ASYNC_PF_ENABLED;
319 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT))
320 pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT;
322 wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
323 __this_cpu_write(apf_reason.enabled, 1);
324 printk(KERN_INFO"KVM setup async PF for cpu %d\n",
328 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
330 /* Size alignment is implied but just to make it explicit. */
331 BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4);
332 __this_cpu_write(kvm_apic_eoi, 0);
333 pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi))
335 wrmsrl(MSR_KVM_PV_EOI_EN, pa);
339 kvm_register_steal_time();
342 static void kvm_pv_disable_apf(void)
344 if (!__this_cpu_read(apf_reason.enabled))
347 wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
348 __this_cpu_write(apf_reason.enabled, 0);
350 printk(KERN_INFO"Unregister pv shared memory for cpu %d\n",
354 static void kvm_pv_guest_cpu_reboot(void *unused)
357 * We disable PV EOI before we load a new kernel by kexec,
358 * since MSR_KVM_PV_EOI_EN stores a pointer into old kernel's memory.
359 * New kernel can re-enable when it boots.
361 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
362 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
363 kvm_pv_disable_apf();
364 kvm_disable_steal_time();
367 static int kvm_pv_reboot_notify(struct notifier_block *nb,
368 unsigned long code, void *unused)
370 if (code == SYS_RESTART)
371 on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
375 static struct notifier_block kvm_pv_reboot_nb = {
376 .notifier_call = kvm_pv_reboot_notify,
379 static u64 kvm_steal_clock(int cpu)
382 struct kvm_steal_time *src;
385 src = &per_cpu(steal_time, cpu);
387 version = src->version;
391 } while ((version & 1) || (version != src->version));
396 void kvm_disable_steal_time(void)
398 if (!has_steal_clock)
401 wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
404 static inline void __set_percpu_decrypted(void *ptr, unsigned long size)
406 early_set_memory_decrypted((unsigned long) ptr, size);
410 * Iterate through all possible CPUs and map the memory region pointed
411 * by apf_reason, steal_time and kvm_apic_eoi as decrypted at once.
413 * Note: we iterate through all possible CPUs to ensure that CPUs
414 * hotplugged will have their per-cpu variable already mapped as
417 static void __init sev_map_percpu_data(void)
424 for_each_possible_cpu(cpu) {
425 __set_percpu_decrypted(&per_cpu(apf_reason, cpu), sizeof(apf_reason));
426 __set_percpu_decrypted(&per_cpu(steal_time, cpu), sizeof(steal_time));
427 __set_percpu_decrypted(&per_cpu(kvm_apic_eoi, cpu), sizeof(kvm_apic_eoi));
432 #define KVM_IPI_CLUSTER_SIZE (2 * BITS_PER_LONG)
434 static void __send_ipi_mask(const struct cpumask *mask, int vector)
437 int cpu, apic_id, icr;
438 int min = 0, max = 0;
440 __uint128_t ipi_bitmap = 0;
446 if (cpumask_empty(mask))
449 local_irq_save(flags);
453 icr = APIC_DM_FIXED | vector;
460 for_each_cpu(cpu, mask) {
461 apic_id = per_cpu(x86_cpu_to_apicid, cpu);
464 } else if (apic_id < min && max - apic_id < KVM_IPI_CLUSTER_SIZE) {
465 ipi_bitmap <<= min - apic_id;
467 } else if (apic_id < min + KVM_IPI_CLUSTER_SIZE) {
468 max = apic_id < max ? max : apic_id;
470 ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
471 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
472 WARN_ONCE(ret < 0, "KVM: failed to send PV IPI: %ld", ret);
476 __set_bit(apic_id - min, (unsigned long *)&ipi_bitmap);
480 ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
481 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
482 WARN_ONCE(ret < 0, "KVM: failed to send PV IPI: %ld", ret);
485 local_irq_restore(flags);
488 static void kvm_send_ipi_mask(const struct cpumask *mask, int vector)
490 __send_ipi_mask(mask, vector);
493 static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
495 unsigned int this_cpu = smp_processor_id();
496 struct cpumask new_mask;
497 const struct cpumask *local_mask;
499 cpumask_copy(&new_mask, mask);
500 cpumask_clear_cpu(this_cpu, &new_mask);
501 local_mask = &new_mask;
502 __send_ipi_mask(local_mask, vector);
506 * Set the IPI entry points
508 static void kvm_setup_pv_ipi(void)
510 apic->send_IPI_mask = kvm_send_ipi_mask;
511 apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself;
512 pr_info("KVM setup pv IPIs\n");
515 static void kvm_smp_send_call_func_ipi(const struct cpumask *mask)
519 native_send_call_func_ipi(mask);
521 /* Make sure other vCPUs get a chance to run if they need to. */
522 for_each_cpu(cpu, mask) {
523 if (vcpu_is_preempted(cpu)) {
524 kvm_hypercall1(KVM_HC_SCHED_YIELD, per_cpu(x86_cpu_to_apicid, cpu));
530 static void __init kvm_smp_prepare_cpus(unsigned int max_cpus)
532 native_smp_prepare_cpus(max_cpus);
533 if (kvm_para_has_hint(KVM_HINTS_REALTIME))
534 static_branch_disable(&virt_spin_lock_key);
537 static void __init kvm_smp_prepare_boot_cpu(void)
540 * Map the per-cpu variables as decrypted before kvm_guest_cpu_init()
541 * shares the guest physical address with the hypervisor.
543 sev_map_percpu_data();
545 kvm_guest_cpu_init();
546 native_smp_prepare_boot_cpu();
550 static void kvm_guest_cpu_offline(void)
552 kvm_disable_steal_time();
553 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
554 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
555 kvm_pv_disable_apf();
559 static int kvm_cpu_online(unsigned int cpu)
562 kvm_guest_cpu_init();
567 static int kvm_cpu_down_prepare(unsigned int cpu)
570 kvm_guest_cpu_offline();
576 static void __init kvm_apf_trap_init(void)
578 update_intr_gate(X86_TRAP_PF, async_page_fault);
581 static DEFINE_PER_CPU(cpumask_var_t, __pv_tlb_mask);
583 static void kvm_flush_tlb_others(const struct cpumask *cpumask,
584 const struct flush_tlb_info *info)
588 struct kvm_steal_time *src;
589 struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_tlb_mask);
591 cpumask_copy(flushmask, cpumask);
593 * We have to call flush only on online vCPUs. And
594 * queue flush_on_enter for pre-empted vCPUs
596 for_each_cpu(cpu, flushmask) {
597 src = &per_cpu(steal_time, cpu);
598 state = READ_ONCE(src->preempted);
599 if ((state & KVM_VCPU_PREEMPTED)) {
600 if (try_cmpxchg(&src->preempted, &state,
601 state | KVM_VCPU_FLUSH_TLB))
602 __cpumask_clear_cpu(cpu, flushmask);
606 native_flush_tlb_others(flushmask, info);
609 static void __init kvm_guest_init(void)
613 paravirt_ops_setup();
614 register_reboot_notifier(&kvm_pv_reboot_nb);
615 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
616 raw_spin_lock_init(&async_pf_sleepers[i].lock);
617 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF))
618 x86_init.irqs.trap_init = kvm_apf_trap_init;
620 if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
622 pv_ops.time.steal_clock = kvm_steal_clock;
625 if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
626 !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
627 kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
628 pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others;
629 pv_ops.mmu.tlb_remove_table = tlb_remove_table;
632 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
633 apic_set_eoi_write(kvm_guest_apic_eoi_write);
636 smp_ops.smp_prepare_cpus = kvm_smp_prepare_cpus;
637 smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
638 if (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) &&
639 !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
640 kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
641 smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi;
642 pr_info("KVM setup pv sched yield\n");
644 if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online",
645 kvm_cpu_online, kvm_cpu_down_prepare) < 0)
646 pr_err("kvm_guest: Failed to install cpu hotplug callbacks\n");
648 sev_map_percpu_data();
649 kvm_guest_cpu_init();
653 * Hard lockup detection is enabled by default. Disable it, as guests
654 * can get false positives too easily, for example if the host is
657 hardlockup_detector_disable();
660 static noinline uint32_t __kvm_cpuid_base(void)
662 if (boot_cpu_data.cpuid_level < 0)
663 return 0; /* So we don't blow up on old processors */
665 if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
666 return hypervisor_cpuid_base("KVMKVMKVM\0\0\0", 0);
671 static inline uint32_t kvm_cpuid_base(void)
673 static int kvm_cpuid_base = -1;
675 if (kvm_cpuid_base == -1)
676 kvm_cpuid_base = __kvm_cpuid_base();
678 return kvm_cpuid_base;
681 bool kvm_para_available(void)
683 return kvm_cpuid_base() != 0;
685 EXPORT_SYMBOL_GPL(kvm_para_available);
687 unsigned int kvm_arch_para_features(void)
689 return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES);
692 unsigned int kvm_arch_para_hints(void)
694 return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES);
696 EXPORT_SYMBOL_GPL(kvm_arch_para_hints);
698 static uint32_t __init kvm_detect(void)
700 return kvm_cpuid_base();
703 static void __init kvm_apic_init(void)
705 #if defined(CONFIG_SMP)
706 if (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI))
711 static void __init kvm_init_platform(void)
714 x86_platform.apic_post_init = kvm_apic_init;
717 const __initconst struct hypervisor_x86 x86_hyper_kvm = {
719 .detect = kvm_detect,
720 .type = X86_HYPER_KVM,
721 .init.guest_late_init = kvm_guest_init,
722 .init.x2apic_available = kvm_para_available,
723 .init.init_platform = kvm_init_platform,
726 static __init int activate_jump_labels(void)
728 if (has_steal_clock) {
729 static_key_slow_inc(¶virt_steal_enabled);
731 static_key_slow_inc(¶virt_steal_rq_enabled);
736 arch_initcall(activate_jump_labels);
738 static __init int kvm_setup_pv_tlb_flush(void)
742 if (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
743 !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
744 kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
745 for_each_possible_cpu(cpu) {
746 zalloc_cpumask_var_node(per_cpu_ptr(&__pv_tlb_mask, cpu),
747 GFP_KERNEL, cpu_to_node(cpu));
749 pr_info("KVM setup pv remote TLB flush\n");
754 arch_initcall(kvm_setup_pv_tlb_flush);
756 #ifdef CONFIG_PARAVIRT_SPINLOCKS
758 /* Kick a cpu by its apicid. Used to wake up a halted vcpu */
759 static void kvm_kick_cpu(int cpu)
762 unsigned long flags = 0;
764 apicid = per_cpu(x86_cpu_to_apicid, cpu);
765 kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid);
768 #include <asm/qspinlock.h>
770 static void kvm_wait(u8 *ptr, u8 val)
777 local_irq_save(flags);
779 if (READ_ONCE(*ptr) != val)
783 * halt until it's our turn and kicked. Note that we do safe halt
784 * for irq enabled case to avoid hang when lock info is overwritten
785 * in irq spinlock slowpath and no spurious interrupt occur to save us.
787 if (arch_irqs_disabled_flags(flags))
793 local_irq_restore(flags);
797 __visible bool __kvm_vcpu_is_preempted(long cpu)
799 struct kvm_steal_time *src = &per_cpu(steal_time, cpu);
801 return !!(src->preempted & KVM_VCPU_PREEMPTED);
803 PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted);
807 #include <asm/asm-offsets.h>
809 extern bool __raw_callee_save___kvm_vcpu_is_preempted(long);
812 * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and
813 * restoring to/from the stack.
816 ".pushsection .text;"
817 ".global __raw_callee_save___kvm_vcpu_is_preempted;"
818 ".type __raw_callee_save___kvm_vcpu_is_preempted, @function;"
819 "__raw_callee_save___kvm_vcpu_is_preempted:"
820 "movq __per_cpu_offset(,%rdi,8), %rax;"
821 "cmpb $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);"
824 ".size __raw_callee_save___kvm_vcpu_is_preempted, .-__raw_callee_save___kvm_vcpu_is_preempted;"
830 * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present.
832 void __init kvm_spinlock_init(void)
834 /* Does host kernel support KVM_FEATURE_PV_UNHALT? */
835 if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT))
838 if (kvm_para_has_hint(KVM_HINTS_REALTIME))
841 /* Don't use the pvqspinlock code if there is only 1 vCPU. */
842 if (num_possible_cpus() == 1)
845 __pv_init_lock_hash();
846 pv_ops.lock.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
847 pv_ops.lock.queued_spin_unlock =
848 PV_CALLEE_SAVE(__pv_queued_spin_unlock);
849 pv_ops.lock.wait = kvm_wait;
850 pv_ops.lock.kick = kvm_kick_cpu;
852 if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
853 pv_ops.lock.vcpu_is_preempted =
854 PV_CALLEE_SAVE(__kvm_vcpu_is_preempted);
858 #endif /* CONFIG_PARAVIRT_SPINLOCKS */
860 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
862 static void kvm_disable_host_haltpoll(void *i)
864 wrmsrl(MSR_KVM_POLL_CONTROL, 0);
867 static void kvm_enable_host_haltpoll(void *i)
869 wrmsrl(MSR_KVM_POLL_CONTROL, 1);
872 void arch_haltpoll_enable(unsigned int cpu)
874 if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) {
875 pr_err_once("kvm: host does not support poll control\n");
876 pr_err_once("kvm: host upgrade recommended\n");
880 /* Enable guest halt poll disables host halt poll */
881 smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1);
883 EXPORT_SYMBOL_GPL(arch_haltpoll_enable);
885 void arch_haltpoll_disable(unsigned int cpu)
887 if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
890 /* Enable guest halt poll disables host halt poll */
891 smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1);
893 EXPORT_SYMBOL_GPL(arch_haltpoll_disable);