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 #define pr_fmt(fmt) "kvm-guest: " fmt
12 #include <linux/context_tracking.h>
13 #include <linux/init.h>
14 #include <linux/irq.h>
15 #include <linux/kernel.h>
16 #include <linux/kvm_para.h>
17 #include <linux/cpu.h>
19 #include <linux/highmem.h>
20 #include <linux/hardirq.h>
21 #include <linux/notifier.h>
22 #include <linux/reboot.h>
23 #include <linux/hash.h>
24 #include <linux/sched.h>
25 #include <linux/slab.h>
26 #include <linux/kprobes.h>
27 #include <linux/nmi.h>
28 #include <linux/swait.h>
29 #include <linux/syscore_ops.h>
30 #include <asm/timer.h>
32 #include <asm/traps.h>
34 #include <asm/tlbflush.h>
36 #include <asm/apicdef.h>
37 #include <asm/hypervisor.h>
39 #include <asm/cpuidle_haltpoll.h>
40 #include <asm/ptrace.h>
41 #include <asm/reboot.h>
44 DEFINE_STATIC_KEY_FALSE(kvm_async_pf_enabled);
46 static int kvmapf = 1;
48 static int __init parse_no_kvmapf(char *arg)
54 early_param("no-kvmapf", parse_no_kvmapf);
56 static int steal_acc = 1;
57 static int __init parse_no_stealacc(char *arg)
63 early_param("no-steal-acc", parse_no_stealacc);
65 static DEFINE_PER_CPU_DECRYPTED(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
66 DEFINE_PER_CPU_DECRYPTED(struct kvm_steal_time, steal_time) __aligned(64) __visible;
67 static int has_steal_clock = 0;
69 static int has_guest_poll = 0;
71 * No need for any "IO delay" on KVM
73 static void kvm_io_delay(void)
77 #define KVM_TASK_SLEEP_HASHBITS 8
78 #define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS)
80 struct kvm_task_sleep_node {
81 struct hlist_node link;
82 struct swait_queue_head wq;
87 static struct kvm_task_sleep_head {
89 struct hlist_head list;
90 } async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];
92 static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b,
97 hlist_for_each(p, &b->list) {
98 struct kvm_task_sleep_node *n =
99 hlist_entry(p, typeof(*n), link);
100 if (n->token == token)
107 static bool kvm_async_pf_queue_task(u32 token, struct kvm_task_sleep_node *n)
109 u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
110 struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
111 struct kvm_task_sleep_node *e;
113 raw_spin_lock(&b->lock);
114 e = _find_apf_task(b, token);
116 /* dummy entry exist -> wake up was delivered ahead of PF */
118 raw_spin_unlock(&b->lock);
124 n->cpu = smp_processor_id();
125 init_swait_queue_head(&n->wq);
126 hlist_add_head(&n->link, &b->list);
127 raw_spin_unlock(&b->lock);
132 * kvm_async_pf_task_wait_schedule - Wait for pagefault to be handled
133 * @token: Token to identify the sleep node entry
135 * Invoked from the async pagefault handling code or from the VM exit page
136 * fault handler. In both cases RCU is watching.
138 void kvm_async_pf_task_wait_schedule(u32 token)
140 struct kvm_task_sleep_node n;
141 DECLARE_SWAITQUEUE(wait);
143 lockdep_assert_irqs_disabled();
145 if (!kvm_async_pf_queue_task(token, &n))
149 prepare_to_swait_exclusive(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
150 if (hlist_unhashed(&n.link))
157 finish_swait(&n.wq, &wait);
159 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait_schedule);
161 static void apf_task_wake_one(struct kvm_task_sleep_node *n)
163 hlist_del_init(&n->link);
164 if (swq_has_sleeper(&n->wq))
165 swake_up_one(&n->wq);
168 static void apf_task_wake_all(void)
172 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
173 struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
174 struct kvm_task_sleep_node *n;
175 struct hlist_node *p, *next;
177 raw_spin_lock(&b->lock);
178 hlist_for_each_safe(p, next, &b->list) {
179 n = hlist_entry(p, typeof(*n), link);
180 if (n->cpu == smp_processor_id())
181 apf_task_wake_one(n);
183 raw_spin_unlock(&b->lock);
187 void kvm_async_pf_task_wake(u32 token)
189 u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
190 struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
191 struct kvm_task_sleep_node *n, *dummy = NULL;
199 raw_spin_lock(&b->lock);
200 n = _find_apf_task(b, token);
203 * Async #PF not yet handled, add a dummy entry for the token.
204 * Allocating the token must be down outside of the raw lock
205 * as the allocator is preemptible on PREEMPT_RT kernels.
208 raw_spin_unlock(&b->lock);
209 dummy = kzalloc(sizeof(*dummy), GFP_ATOMIC);
212 * Continue looping on allocation failure, eventually
213 * the async #PF will be handled and allocating a new
214 * node will be unnecessary.
220 * Recheck for async #PF completion before enqueueing
221 * the dummy token to avoid duplicate list entries.
225 dummy->token = token;
226 dummy->cpu = smp_processor_id();
227 init_swait_queue_head(&dummy->wq);
228 hlist_add_head(&dummy->link, &b->list);
231 apf_task_wake_one(n);
233 raw_spin_unlock(&b->lock);
235 /* A dummy token might be allocated and ultimately not used. */
239 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
241 noinstr u32 kvm_read_and_reset_apf_flags(void)
245 if (__this_cpu_read(apf_reason.enabled)) {
246 flags = __this_cpu_read(apf_reason.flags);
247 __this_cpu_write(apf_reason.flags, 0);
252 EXPORT_SYMBOL_GPL(kvm_read_and_reset_apf_flags);
254 noinstr bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token)
256 u32 flags = kvm_read_and_reset_apf_flags();
257 irqentry_state_t state;
262 state = irqentry_enter(regs);
263 instrumentation_begin();
266 * If the host managed to inject an async #PF into an interrupt
267 * disabled region, then die hard as this is not going to end well
268 * and the host side is seriously broken.
270 if (unlikely(!(regs->flags & X86_EFLAGS_IF)))
271 panic("Host injected async #PF in interrupt disabled region\n");
273 if (flags & KVM_PV_REASON_PAGE_NOT_PRESENT) {
274 if (unlikely(!(user_mode(regs))))
275 panic("Host injected async #PF in kernel mode\n");
276 /* Page is swapped out by the host. */
277 kvm_async_pf_task_wait_schedule(token);
279 WARN_ONCE(1, "Unexpected async PF flags: %x\n", flags);
282 instrumentation_end();
283 irqentry_exit(regs, state);
287 DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt)
289 struct pt_regs *old_regs = set_irq_regs(regs);
294 inc_irq_stat(irq_hv_callback_count);
296 if (__this_cpu_read(apf_reason.enabled)) {
297 token = __this_cpu_read(apf_reason.token);
298 kvm_async_pf_task_wake(token);
299 __this_cpu_write(apf_reason.token, 0);
300 wrmsrl(MSR_KVM_ASYNC_PF_ACK, 1);
303 set_irq_regs(old_regs);
306 static void __init paravirt_ops_setup(void)
308 pv_info.name = "KVM";
310 if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
311 pv_ops.cpu.io_delay = kvm_io_delay;
313 #ifdef CONFIG_X86_IO_APIC
318 static void kvm_register_steal_time(void)
320 int cpu = smp_processor_id();
321 struct kvm_steal_time *st = &per_cpu(steal_time, cpu);
323 if (!has_steal_clock)
326 wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED));
327 pr_info("stealtime: cpu %d, msr %llx\n", cpu,
328 (unsigned long long) slow_virt_to_phys(st));
331 static DEFINE_PER_CPU_DECRYPTED(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;
333 static notrace void kvm_guest_apic_eoi_write(u32 reg, u32 val)
336 * This relies on __test_and_clear_bit to modify the memory
337 * in a way that is atomic with respect to the local CPU.
338 * The hypervisor only accesses this memory from the local CPU so
339 * there's no need for lock or memory barriers.
340 * An optimization barrier is implied in apic write.
342 if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi)))
344 apic->native_eoi_write(APIC_EOI, APIC_EOI_ACK);
347 static void kvm_guest_cpu_init(void)
349 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
350 u64 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
352 WARN_ON_ONCE(!static_branch_likely(&kvm_async_pf_enabled));
354 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
355 pa |= KVM_ASYNC_PF_ENABLED | KVM_ASYNC_PF_DELIVERY_AS_INT;
357 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT))
358 pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT;
360 wrmsrl(MSR_KVM_ASYNC_PF_INT, HYPERVISOR_CALLBACK_VECTOR);
362 wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
363 __this_cpu_write(apf_reason.enabled, 1);
364 pr_info("KVM setup async PF for cpu %d\n", smp_processor_id());
367 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
370 /* Size alignment is implied but just to make it explicit. */
371 BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4);
372 __this_cpu_write(kvm_apic_eoi, 0);
373 pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi))
375 wrmsrl(MSR_KVM_PV_EOI_EN, pa);
379 kvm_register_steal_time();
382 static void kvm_pv_disable_apf(void)
384 if (!__this_cpu_read(apf_reason.enabled))
387 wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
388 __this_cpu_write(apf_reason.enabled, 0);
390 pr_info("Unregister pv shared memory for cpu %d\n", smp_processor_id());
393 static void kvm_disable_steal_time(void)
395 if (!has_steal_clock)
398 wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
401 static void kvm_pv_guest_cpu_reboot(void *unused)
404 * We disable PV EOI before we load a new kernel by kexec,
405 * since MSR_KVM_PV_EOI_EN stores a pointer into old kernel's memory.
406 * New kernel can re-enable when it boots.
408 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
409 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
410 kvm_pv_disable_apf();
411 kvm_disable_steal_time();
414 static int kvm_pv_reboot_notify(struct notifier_block *nb,
415 unsigned long code, void *unused)
417 if (code == SYS_RESTART)
418 on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
422 static struct notifier_block kvm_pv_reboot_nb = {
423 .notifier_call = kvm_pv_reboot_notify,
426 static u64 kvm_steal_clock(int cpu)
429 struct kvm_steal_time *src;
432 src = &per_cpu(steal_time, cpu);
434 version = src->version;
438 } while ((version & 1) || (version != src->version));
443 static inline void __set_percpu_decrypted(void *ptr, unsigned long size)
445 early_set_memory_decrypted((unsigned long) ptr, size);
449 * Iterate through all possible CPUs and map the memory region pointed
450 * by apf_reason, steal_time and kvm_apic_eoi as decrypted at once.
452 * Note: we iterate through all possible CPUs to ensure that CPUs
453 * hotplugged will have their per-cpu variable already mapped as
456 static void __init sev_map_percpu_data(void)
463 for_each_possible_cpu(cpu) {
464 __set_percpu_decrypted(&per_cpu(apf_reason, cpu), sizeof(apf_reason));
465 __set_percpu_decrypted(&per_cpu(steal_time, cpu), sizeof(steal_time));
466 __set_percpu_decrypted(&per_cpu(kvm_apic_eoi, cpu), sizeof(kvm_apic_eoi));
470 static bool pv_tlb_flush_supported(void)
472 return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
473 !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
474 kvm_para_has_feature(KVM_FEATURE_STEAL_TIME));
477 static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask);
479 static void kvm_guest_cpu_offline(bool shutdown)
481 kvm_disable_steal_time();
482 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
483 wrmsrl(MSR_KVM_PV_EOI_EN, 0);
484 kvm_pv_disable_apf();
490 static int kvm_cpu_online(unsigned int cpu)
494 local_irq_save(flags);
495 kvm_guest_cpu_init();
496 local_irq_restore(flags);
502 static bool pv_ipi_supported(void)
504 return kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI);
507 static bool pv_sched_yield_supported(void)
509 return (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) &&
510 !kvm_para_has_hint(KVM_HINTS_REALTIME) &&
511 kvm_para_has_feature(KVM_FEATURE_STEAL_TIME));
514 #define KVM_IPI_CLUSTER_SIZE (2 * BITS_PER_LONG)
516 static void __send_ipi_mask(const struct cpumask *mask, int vector)
519 int cpu, apic_id, icr;
520 int min = 0, max = 0;
522 __uint128_t ipi_bitmap = 0;
528 if (cpumask_empty(mask))
531 local_irq_save(flags);
535 icr = APIC_DM_FIXED | vector;
542 for_each_cpu(cpu, mask) {
543 apic_id = per_cpu(x86_cpu_to_apicid, cpu);
546 } else if (apic_id < min && max - apic_id < KVM_IPI_CLUSTER_SIZE) {
547 ipi_bitmap <<= min - apic_id;
549 } else if (apic_id > min && apic_id < min + KVM_IPI_CLUSTER_SIZE) {
550 max = apic_id < max ? max : apic_id;
552 ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
553 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
554 WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld",
559 __set_bit(apic_id - min, (unsigned long *)&ipi_bitmap);
563 ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
564 (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
565 WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld",
569 local_irq_restore(flags);
572 static void kvm_send_ipi_mask(const struct cpumask *mask, int vector)
574 __send_ipi_mask(mask, vector);
577 static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
579 unsigned int this_cpu = smp_processor_id();
580 struct cpumask *new_mask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
581 const struct cpumask *local_mask;
583 cpumask_copy(new_mask, mask);
584 cpumask_clear_cpu(this_cpu, new_mask);
585 local_mask = new_mask;
586 __send_ipi_mask(local_mask, vector);
590 * Set the IPI entry points
592 static void kvm_setup_pv_ipi(void)
594 apic->send_IPI_mask = kvm_send_ipi_mask;
595 apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself;
596 pr_info("setup PV IPIs\n");
599 static void kvm_smp_send_call_func_ipi(const struct cpumask *mask)
603 native_send_call_func_ipi(mask);
605 /* Make sure other vCPUs get a chance to run if they need to. */
606 for_each_cpu(cpu, mask) {
607 if (vcpu_is_preempted(cpu)) {
608 kvm_hypercall1(KVM_HC_SCHED_YIELD, per_cpu(x86_cpu_to_apicid, cpu));
614 static void __init kvm_smp_prepare_boot_cpu(void)
617 * Map the per-cpu variables as decrypted before kvm_guest_cpu_init()
618 * shares the guest physical address with the hypervisor.
620 sev_map_percpu_data();
622 kvm_guest_cpu_init();
623 native_smp_prepare_boot_cpu();
627 static int kvm_cpu_down_prepare(unsigned int cpu)
631 local_irq_save(flags);
632 kvm_guest_cpu_offline(false);
633 local_irq_restore(flags);
639 static int kvm_suspend(void)
643 kvm_guest_cpu_offline(false);
645 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
646 if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
647 rdmsrl(MSR_KVM_POLL_CONTROL, val);
648 has_guest_poll = !(val & 1);
653 static void kvm_resume(void)
655 kvm_cpu_online(raw_smp_processor_id());
657 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
658 if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL) && has_guest_poll)
659 wrmsrl(MSR_KVM_POLL_CONTROL, 0);
663 static struct syscore_ops kvm_syscore_ops = {
664 .suspend = kvm_suspend,
665 .resume = kvm_resume,
669 * After a PV feature is registered, the host will keep writing to the
670 * registered memory location. If the guest happens to shutdown, this memory
671 * won't be valid. In cases like kexec, in which you install a new kernel, this
672 * means a random memory location will be kept being written.
674 #ifdef CONFIG_KEXEC_CORE
675 static void kvm_crash_shutdown(struct pt_regs *regs)
677 kvm_guest_cpu_offline(true);
678 native_machine_crash_shutdown(regs);
682 static void kvm_flush_tlb_others(const struct cpumask *cpumask,
683 const struct flush_tlb_info *info)
687 struct kvm_steal_time *src;
688 struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
690 cpumask_copy(flushmask, cpumask);
692 * We have to call flush only on online vCPUs. And
693 * queue flush_on_enter for pre-empted vCPUs
695 for_each_cpu(cpu, flushmask) {
696 src = &per_cpu(steal_time, cpu);
697 state = READ_ONCE(src->preempted);
698 if ((state & KVM_VCPU_PREEMPTED)) {
699 if (try_cmpxchg(&src->preempted, &state,
700 state | KVM_VCPU_FLUSH_TLB))
701 __cpumask_clear_cpu(cpu, flushmask);
705 native_flush_tlb_others(flushmask, info);
708 static void __init kvm_guest_init(void)
712 paravirt_ops_setup();
713 register_reboot_notifier(&kvm_pv_reboot_nb);
714 for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
715 raw_spin_lock_init(&async_pf_sleepers[i].lock);
717 if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
719 pv_ops.time.steal_clock = kvm_steal_clock;
722 if (pv_tlb_flush_supported()) {
723 pv_ops.mmu.flush_tlb_others = kvm_flush_tlb_others;
724 pv_ops.mmu.tlb_remove_table = tlb_remove_table;
725 pr_info("KVM setup pv remote TLB flush\n");
728 if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
729 apic_set_eoi_write(kvm_guest_apic_eoi_write);
731 if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
732 static_branch_enable(&kvm_async_pf_enabled);
733 alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, asm_sysvec_kvm_asyncpf_interrupt);
737 smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
738 if (pv_sched_yield_supported()) {
739 smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi;
740 pr_info("setup PV sched yield\n");
742 if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online",
743 kvm_cpu_online, kvm_cpu_down_prepare) < 0)
744 pr_err("failed to install cpu hotplug callbacks\n");
746 sev_map_percpu_data();
747 kvm_guest_cpu_init();
750 #ifdef CONFIG_KEXEC_CORE
751 machine_ops.crash_shutdown = kvm_crash_shutdown;
754 register_syscore_ops(&kvm_syscore_ops);
757 * Hard lockup detection is enabled by default. Disable it, as guests
758 * can get false positives too easily, for example if the host is
761 hardlockup_detector_disable();
764 static noinline uint32_t __kvm_cpuid_base(void)
766 if (boot_cpu_data.cpuid_level < 0)
767 return 0; /* So we don't blow up on old processors */
769 if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
770 return hypervisor_cpuid_base("KVMKVMKVM\0\0\0", 0);
775 static inline uint32_t kvm_cpuid_base(void)
777 static int kvm_cpuid_base = -1;
779 if (kvm_cpuid_base == -1)
780 kvm_cpuid_base = __kvm_cpuid_base();
782 return kvm_cpuid_base;
785 bool kvm_para_available(void)
787 return kvm_cpuid_base() != 0;
789 EXPORT_SYMBOL_GPL(kvm_para_available);
791 unsigned int kvm_arch_para_features(void)
793 return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES);
796 unsigned int kvm_arch_para_hints(void)
798 return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES);
800 EXPORT_SYMBOL_GPL(kvm_arch_para_hints);
802 static uint32_t __init kvm_detect(void)
804 return kvm_cpuid_base();
807 static void __init kvm_apic_init(void)
809 #if defined(CONFIG_SMP)
810 if (pv_ipi_supported())
815 static void __init kvm_init_platform(void)
818 x86_platform.apic_post_init = kvm_apic_init;
821 #if defined(CONFIG_AMD_MEM_ENCRYPT)
822 static void kvm_sev_es_hcall_prepare(struct ghcb *ghcb, struct pt_regs *regs)
824 /* RAX and CPL are already in the GHCB */
825 ghcb_set_rbx(ghcb, regs->bx);
826 ghcb_set_rcx(ghcb, regs->cx);
827 ghcb_set_rdx(ghcb, regs->dx);
828 ghcb_set_rsi(ghcb, regs->si);
831 static bool kvm_sev_es_hcall_finish(struct ghcb *ghcb, struct pt_regs *regs)
833 /* No checking of the return state needed */
838 const __initconst struct hypervisor_x86 x86_hyper_kvm = {
840 .detect = kvm_detect,
841 .type = X86_HYPER_KVM,
842 .init.guest_late_init = kvm_guest_init,
843 .init.x2apic_available = kvm_para_available,
844 .init.init_platform = kvm_init_platform,
845 #if defined(CONFIG_AMD_MEM_ENCRYPT)
846 .runtime.sev_es_hcall_prepare = kvm_sev_es_hcall_prepare,
847 .runtime.sev_es_hcall_finish = kvm_sev_es_hcall_finish,
851 static __init int activate_jump_labels(void)
853 if (has_steal_clock) {
854 static_key_slow_inc(¶virt_steal_enabled);
856 static_key_slow_inc(¶virt_steal_rq_enabled);
861 arch_initcall(activate_jump_labels);
863 static __init int kvm_alloc_cpumask(void)
868 if (!kvm_para_available() || nopv)
871 if (pv_tlb_flush_supported())
874 #if defined(CONFIG_SMP)
875 if (pv_ipi_supported())
880 for_each_possible_cpu(cpu) {
881 zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu),
882 GFP_KERNEL, cpu_to_node(cpu));
887 arch_initcall(kvm_alloc_cpumask);
889 #ifdef CONFIG_PARAVIRT_SPINLOCKS
891 /* Kick a cpu by its apicid. Used to wake up a halted vcpu */
892 static void kvm_kick_cpu(int cpu)
895 unsigned long flags = 0;
897 apicid = per_cpu(x86_cpu_to_apicid, cpu);
898 kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid);
901 #include <asm/qspinlock.h>
903 static void kvm_wait(u8 *ptr, u8 val)
910 local_irq_save(flags);
912 if (READ_ONCE(*ptr) != val)
916 * halt until it's our turn and kicked. Note that we do safe halt
917 * for irq enabled case to avoid hang when lock info is overwritten
918 * in irq spinlock slowpath and no spurious interrupt occur to save us.
920 if (arch_irqs_disabled_flags(flags))
926 local_irq_restore(flags);
930 __visible bool __kvm_vcpu_is_preempted(long cpu)
932 struct kvm_steal_time *src = &per_cpu(steal_time, cpu);
934 return !!(src->preempted & KVM_VCPU_PREEMPTED);
936 PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted);
940 #include <asm/asm-offsets.h>
942 extern bool __raw_callee_save___kvm_vcpu_is_preempted(long);
945 * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and
946 * restoring to/from the stack.
949 ".pushsection .text;"
950 ".global __raw_callee_save___kvm_vcpu_is_preempted;"
951 ".type __raw_callee_save___kvm_vcpu_is_preempted, @function;"
952 "__raw_callee_save___kvm_vcpu_is_preempted:"
953 "movq __per_cpu_offset(,%rdi,8), %rax;"
954 "cmpb $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);"
957 ".size __raw_callee_save___kvm_vcpu_is_preempted, .-__raw_callee_save___kvm_vcpu_is_preempted;"
963 * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present.
965 void __init kvm_spinlock_init(void)
968 * In case host doesn't support KVM_FEATURE_PV_UNHALT there is still an
969 * advantage of keeping virt_spin_lock_key enabled: virt_spin_lock() is
970 * preferred over native qspinlock when vCPU is preempted.
972 if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT)) {
973 pr_info("PV spinlocks disabled, no host support\n");
978 * Disable PV spinlocks and use native qspinlock when dedicated pCPUs
981 if (kvm_para_has_hint(KVM_HINTS_REALTIME)) {
982 pr_info("PV spinlocks disabled with KVM_HINTS_REALTIME hints\n");
986 if (num_possible_cpus() == 1) {
987 pr_info("PV spinlocks disabled, single CPU\n");
992 pr_info("PV spinlocks disabled, forced by \"nopvspin\" parameter\n");
996 pr_info("PV spinlocks enabled\n");
998 __pv_init_lock_hash();
999 pv_ops.lock.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
1000 pv_ops.lock.queued_spin_unlock =
1001 PV_CALLEE_SAVE(__pv_queued_spin_unlock);
1002 pv_ops.lock.wait = kvm_wait;
1003 pv_ops.lock.kick = kvm_kick_cpu;
1005 if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
1006 pv_ops.lock.vcpu_is_preempted =
1007 PV_CALLEE_SAVE(__kvm_vcpu_is_preempted);
1010 * When PV spinlock is enabled which is preferred over
1011 * virt_spin_lock(), virt_spin_lock_key's value is meaningless.
1012 * Just disable it anyway.
1015 static_branch_disable(&virt_spin_lock_key);
1018 #endif /* CONFIG_PARAVIRT_SPINLOCKS */
1020 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
1022 static void kvm_disable_host_haltpoll(void *i)
1024 wrmsrl(MSR_KVM_POLL_CONTROL, 0);
1027 static void kvm_enable_host_haltpoll(void *i)
1029 wrmsrl(MSR_KVM_POLL_CONTROL, 1);
1032 void arch_haltpoll_enable(unsigned int cpu)
1034 if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) {
1035 pr_err_once("host does not support poll control\n");
1036 pr_err_once("host upgrade recommended\n");
1040 /* Enable guest halt poll disables host halt poll */
1041 smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1);
1043 EXPORT_SYMBOL_GPL(arch_haltpoll_enable);
1045 void arch_haltpoll_disable(unsigned int cpu)
1047 if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
1050 /* Disable guest halt poll enables host halt poll */
1051 smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1);
1053 EXPORT_SYMBOL_GPL(arch_haltpoll_disable);