cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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kvm.c (28586B)


      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 * KVM paravirt_ops implementation
      4 *
      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>
      8 */
      9
     10#define pr_fmt(fmt) "kvm-guest: " fmt
     11
     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>
     18#include <linux/mm.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 <linux/cc_platform.h>
     31#include <linux/efi.h>
     32#include <asm/timer.h>
     33#include <asm/cpu.h>
     34#include <asm/traps.h>
     35#include <asm/desc.h>
     36#include <asm/tlbflush.h>
     37#include <asm/apic.h>
     38#include <asm/apicdef.h>
     39#include <asm/hypervisor.h>
     40#include <asm/tlb.h>
     41#include <asm/cpuidle_haltpoll.h>
     42#include <asm/ptrace.h>
     43#include <asm/reboot.h>
     44#include <asm/svm.h>
     45#include <asm/e820/api.h>
     46
     47DEFINE_STATIC_KEY_FALSE(kvm_async_pf_enabled);
     48
     49static int kvmapf = 1;
     50
     51static int __init parse_no_kvmapf(char *arg)
     52{
     53        kvmapf = 0;
     54        return 0;
     55}
     56
     57early_param("no-kvmapf", parse_no_kvmapf);
     58
     59static int steal_acc = 1;
     60static int __init parse_no_stealacc(char *arg)
     61{
     62        steal_acc = 0;
     63        return 0;
     64}
     65
     66early_param("no-steal-acc", parse_no_stealacc);
     67
     68static DEFINE_PER_CPU_DECRYPTED(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
     69DEFINE_PER_CPU_DECRYPTED(struct kvm_steal_time, steal_time) __aligned(64) __visible;
     70static int has_steal_clock = 0;
     71
     72static int has_guest_poll = 0;
     73/*
     74 * No need for any "IO delay" on KVM
     75 */
     76static void kvm_io_delay(void)
     77{
     78}
     79
     80#define KVM_TASK_SLEEP_HASHBITS 8
     81#define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS)
     82
     83struct kvm_task_sleep_node {
     84	struct hlist_node link;
     85	struct swait_queue_head wq;
     86	u32 token;
     87	int cpu;
     88};
     89
     90static struct kvm_task_sleep_head {
     91	raw_spinlock_t lock;
     92	struct hlist_head list;
     93} async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];
     94
     95static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b,
     96						  u32 token)
     97{
     98	struct hlist_node *p;
     99
    100	hlist_for_each(p, &b->list) {
    101		struct kvm_task_sleep_node *n =
    102			hlist_entry(p, typeof(*n), link);
    103		if (n->token == token)
    104			return n;
    105	}
    106
    107	return NULL;
    108}
    109
    110static bool kvm_async_pf_queue_task(u32 token, struct kvm_task_sleep_node *n)
    111{
    112	u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
    113	struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
    114	struct kvm_task_sleep_node *e;
    115
    116	raw_spin_lock(&b->lock);
    117	e = _find_apf_task(b, token);
    118	if (e) {
    119		/* dummy entry exist -> wake up was delivered ahead of PF */
    120		hlist_del(&e->link);
    121		raw_spin_unlock(&b->lock);
    122		kfree(e);
    123		return false;
    124	}
    125
    126	n->token = token;
    127	n->cpu = smp_processor_id();
    128	init_swait_queue_head(&n->wq);
    129	hlist_add_head(&n->link, &b->list);
    130	raw_spin_unlock(&b->lock);
    131	return true;
    132}
    133
    134/*
    135 * kvm_async_pf_task_wait_schedule - Wait for pagefault to be handled
    136 * @token:	Token to identify the sleep node entry
    137 *
    138 * Invoked from the async pagefault handling code or from the VM exit page
    139 * fault handler. In both cases RCU is watching.
    140 */
    141void kvm_async_pf_task_wait_schedule(u32 token)
    142{
    143	struct kvm_task_sleep_node n;
    144	DECLARE_SWAITQUEUE(wait);
    145
    146	lockdep_assert_irqs_disabled();
    147
    148	if (!kvm_async_pf_queue_task(token, &n))
    149		return;
    150
    151	for (;;) {
    152		prepare_to_swait_exclusive(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
    153		if (hlist_unhashed(&n.link))
    154			break;
    155
    156		local_irq_enable();
    157		schedule();
    158		local_irq_disable();
    159	}
    160	finish_swait(&n.wq, &wait);
    161}
    162EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait_schedule);
    163
    164static void apf_task_wake_one(struct kvm_task_sleep_node *n)
    165{
    166	hlist_del_init(&n->link);
    167	if (swq_has_sleeper(&n->wq))
    168		swake_up_one(&n->wq);
    169}
    170
    171static void apf_task_wake_all(void)
    172{
    173	int i;
    174
    175	for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
    176		struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
    177		struct kvm_task_sleep_node *n;
    178		struct hlist_node *p, *next;
    179
    180		raw_spin_lock(&b->lock);
    181		hlist_for_each_safe(p, next, &b->list) {
    182			n = hlist_entry(p, typeof(*n), link);
    183			if (n->cpu == smp_processor_id())
    184				apf_task_wake_one(n);
    185		}
    186		raw_spin_unlock(&b->lock);
    187	}
    188}
    189
    190void kvm_async_pf_task_wake(u32 token)
    191{
    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, *dummy = NULL;
    195
    196	if (token == ~0) {
    197		apf_task_wake_all();
    198		return;
    199	}
    200
    201again:
    202	raw_spin_lock(&b->lock);
    203	n = _find_apf_task(b, token);
    204	if (!n) {
    205		/*
    206		 * Async #PF not yet handled, add a dummy entry for the token.
    207		 * Allocating the token must be down outside of the raw lock
    208		 * as the allocator is preemptible on PREEMPT_RT kernels.
    209		 */
    210		if (!dummy) {
    211			raw_spin_unlock(&b->lock);
    212			dummy = kzalloc(sizeof(*dummy), GFP_ATOMIC);
    213
    214			/*
    215			 * Continue looping on allocation failure, eventually
    216			 * the async #PF will be handled and allocating a new
    217			 * node will be unnecessary.
    218			 */
    219			if (!dummy)
    220				cpu_relax();
    221
    222			/*
    223			 * Recheck for async #PF completion before enqueueing
    224			 * the dummy token to avoid duplicate list entries.
    225			 */
    226			goto again;
    227		}
    228		dummy->token = token;
    229		dummy->cpu = smp_processor_id();
    230		init_swait_queue_head(&dummy->wq);
    231		hlist_add_head(&dummy->link, &b->list);
    232		dummy = NULL;
    233	} else {
    234		apf_task_wake_one(n);
    235	}
    236	raw_spin_unlock(&b->lock);
    237
    238	/* A dummy token might be allocated and ultimately not used.  */
    239	if (dummy)
    240		kfree(dummy);
    241}
    242EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
    243
    244noinstr u32 kvm_read_and_reset_apf_flags(void)
    245{
    246	u32 flags = 0;
    247
    248	if (__this_cpu_read(apf_reason.enabled)) {
    249		flags = __this_cpu_read(apf_reason.flags);
    250		__this_cpu_write(apf_reason.flags, 0);
    251	}
    252
    253	return flags;
    254}
    255EXPORT_SYMBOL_GPL(kvm_read_and_reset_apf_flags);
    256
    257noinstr bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token)
    258{
    259	u32 flags = kvm_read_and_reset_apf_flags();
    260	irqentry_state_t state;
    261
    262	if (!flags)
    263		return false;
    264
    265	state = irqentry_enter(regs);
    266	instrumentation_begin();
    267
    268	/*
    269	 * If the host managed to inject an async #PF into an interrupt
    270	 * disabled region, then die hard as this is not going to end well
    271	 * and the host side is seriously broken.
    272	 */
    273	if (unlikely(!(regs->flags & X86_EFLAGS_IF)))
    274		panic("Host injected async #PF in interrupt disabled region\n");
    275
    276	if (flags & KVM_PV_REASON_PAGE_NOT_PRESENT) {
    277		if (unlikely(!(user_mode(regs))))
    278			panic("Host injected async #PF in kernel mode\n");
    279		/* Page is swapped out by the host. */
    280		kvm_async_pf_task_wait_schedule(token);
    281	} else {
    282		WARN_ONCE(1, "Unexpected async PF flags: %x\n", flags);
    283	}
    284
    285	instrumentation_end();
    286	irqentry_exit(regs, state);
    287	return true;
    288}
    289
    290DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt)
    291{
    292	struct pt_regs *old_regs = set_irq_regs(regs);
    293	u32 token;
    294
    295	ack_APIC_irq();
    296
    297	inc_irq_stat(irq_hv_callback_count);
    298
    299	if (__this_cpu_read(apf_reason.enabled)) {
    300		token = __this_cpu_read(apf_reason.token);
    301		kvm_async_pf_task_wake(token);
    302		__this_cpu_write(apf_reason.token, 0);
    303		wrmsrl(MSR_KVM_ASYNC_PF_ACK, 1);
    304	}
    305
    306	set_irq_regs(old_regs);
    307}
    308
    309static void __init paravirt_ops_setup(void)
    310{
    311	pv_info.name = "KVM";
    312
    313	if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
    314		pv_ops.cpu.io_delay = kvm_io_delay;
    315
    316#ifdef CONFIG_X86_IO_APIC
    317	no_timer_check = 1;
    318#endif
    319}
    320
    321static void kvm_register_steal_time(void)
    322{
    323	int cpu = smp_processor_id();
    324	struct kvm_steal_time *st = &per_cpu(steal_time, cpu);
    325
    326	if (!has_steal_clock)
    327		return;
    328
    329	wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED));
    330	pr_debug("stealtime: cpu %d, msr %llx\n", cpu,
    331		(unsigned long long) slow_virt_to_phys(st));
    332}
    333
    334static DEFINE_PER_CPU_DECRYPTED(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;
    335
    336static notrace void kvm_guest_apic_eoi_write(u32 reg, u32 val)
    337{
    338	/**
    339	 * This relies on __test_and_clear_bit to modify the memory
    340	 * in a way that is atomic with respect to the local CPU.
    341	 * The hypervisor only accesses this memory from the local CPU so
    342	 * there's no need for lock or memory barriers.
    343	 * An optimization barrier is implied in apic write.
    344	 */
    345	if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi)))
    346		return;
    347	apic->native_eoi_write(APIC_EOI, APIC_EOI_ACK);
    348}
    349
    350static void kvm_guest_cpu_init(void)
    351{
    352	if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
    353		u64 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
    354
    355		WARN_ON_ONCE(!static_branch_likely(&kvm_async_pf_enabled));
    356
    357		pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
    358		pa |= KVM_ASYNC_PF_ENABLED | KVM_ASYNC_PF_DELIVERY_AS_INT;
    359
    360		if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT))
    361			pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT;
    362
    363		wrmsrl(MSR_KVM_ASYNC_PF_INT, HYPERVISOR_CALLBACK_VECTOR);
    364
    365		wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
    366		__this_cpu_write(apf_reason.enabled, 1);
    367		pr_debug("setup async PF for cpu %d\n", smp_processor_id());
    368	}
    369
    370	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
    371		unsigned long pa;
    372
    373		/* Size alignment is implied but just to make it explicit. */
    374		BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4);
    375		__this_cpu_write(kvm_apic_eoi, 0);
    376		pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi))
    377			| KVM_MSR_ENABLED;
    378		wrmsrl(MSR_KVM_PV_EOI_EN, pa);
    379	}
    380
    381	if (has_steal_clock)
    382		kvm_register_steal_time();
    383}
    384
    385static void kvm_pv_disable_apf(void)
    386{
    387	if (!__this_cpu_read(apf_reason.enabled))
    388		return;
    389
    390	wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
    391	__this_cpu_write(apf_reason.enabled, 0);
    392
    393	pr_debug("disable async PF for cpu %d\n", smp_processor_id());
    394}
    395
    396static void kvm_disable_steal_time(void)
    397{
    398	if (!has_steal_clock)
    399		return;
    400
    401	wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
    402}
    403
    404static u64 kvm_steal_clock(int cpu)
    405{
    406	u64 steal;
    407	struct kvm_steal_time *src;
    408	int version;
    409
    410	src = &per_cpu(steal_time, cpu);
    411	do {
    412		version = src->version;
    413		virt_rmb();
    414		steal = src->steal;
    415		virt_rmb();
    416	} while ((version & 1) || (version != src->version));
    417
    418	return steal;
    419}
    420
    421static inline void __set_percpu_decrypted(void *ptr, unsigned long size)
    422{
    423	early_set_memory_decrypted((unsigned long) ptr, size);
    424}
    425
    426/*
    427 * Iterate through all possible CPUs and map the memory region pointed
    428 * by apf_reason, steal_time and kvm_apic_eoi as decrypted at once.
    429 *
    430 * Note: we iterate through all possible CPUs to ensure that CPUs
    431 * hotplugged will have their per-cpu variable already mapped as
    432 * decrypted.
    433 */
    434static void __init sev_map_percpu_data(void)
    435{
    436	int cpu;
    437
    438	if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
    439		return;
    440
    441	for_each_possible_cpu(cpu) {
    442		__set_percpu_decrypted(&per_cpu(apf_reason, cpu), sizeof(apf_reason));
    443		__set_percpu_decrypted(&per_cpu(steal_time, cpu), sizeof(steal_time));
    444		__set_percpu_decrypted(&per_cpu(kvm_apic_eoi, cpu), sizeof(kvm_apic_eoi));
    445	}
    446}
    447
    448static void kvm_guest_cpu_offline(bool shutdown)
    449{
    450	kvm_disable_steal_time();
    451	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
    452		wrmsrl(MSR_KVM_PV_EOI_EN, 0);
    453	if (kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL))
    454		wrmsrl(MSR_KVM_MIGRATION_CONTROL, 0);
    455	kvm_pv_disable_apf();
    456	if (!shutdown)
    457		apf_task_wake_all();
    458	kvmclock_disable();
    459}
    460
    461static int kvm_cpu_online(unsigned int cpu)
    462{
    463	unsigned long flags;
    464
    465	local_irq_save(flags);
    466	kvm_guest_cpu_init();
    467	local_irq_restore(flags);
    468	return 0;
    469}
    470
    471#ifdef CONFIG_SMP
    472
    473static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask);
    474
    475static bool pv_tlb_flush_supported(void)
    476{
    477	return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
    478		!kvm_para_has_hint(KVM_HINTS_REALTIME) &&
    479		kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) &&
    480		!boot_cpu_has(X86_FEATURE_MWAIT) &&
    481		(num_possible_cpus() != 1));
    482}
    483
    484static bool pv_ipi_supported(void)
    485{
    486	return (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI) &&
    487	       (num_possible_cpus() != 1));
    488}
    489
    490static bool pv_sched_yield_supported(void)
    491{
    492	return (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) &&
    493		!kvm_para_has_hint(KVM_HINTS_REALTIME) &&
    494	    kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) &&
    495	    !boot_cpu_has(X86_FEATURE_MWAIT) &&
    496	    (num_possible_cpus() != 1));
    497}
    498
    499#define KVM_IPI_CLUSTER_SIZE	(2 * BITS_PER_LONG)
    500
    501static void __send_ipi_mask(const struct cpumask *mask, int vector)
    502{
    503	unsigned long flags;
    504	int cpu, apic_id, icr;
    505	int min = 0, max = 0;
    506#ifdef CONFIG_X86_64
    507	__uint128_t ipi_bitmap = 0;
    508#else
    509	u64 ipi_bitmap = 0;
    510#endif
    511	long ret;
    512
    513	if (cpumask_empty(mask))
    514		return;
    515
    516	local_irq_save(flags);
    517
    518	switch (vector) {
    519	default:
    520		icr = APIC_DM_FIXED | vector;
    521		break;
    522	case NMI_VECTOR:
    523		icr = APIC_DM_NMI;
    524		break;
    525	}
    526
    527	for_each_cpu(cpu, mask) {
    528		apic_id = per_cpu(x86_cpu_to_apicid, cpu);
    529		if (!ipi_bitmap) {
    530			min = max = apic_id;
    531		} else if (apic_id < min && max - apic_id < KVM_IPI_CLUSTER_SIZE) {
    532			ipi_bitmap <<= min - apic_id;
    533			min = apic_id;
    534		} else if (apic_id > min && apic_id < min + KVM_IPI_CLUSTER_SIZE) {
    535			max = apic_id < max ? max : apic_id;
    536		} else {
    537			ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
    538				(unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
    539			WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld",
    540				  ret);
    541			min = max = apic_id;
    542			ipi_bitmap = 0;
    543		}
    544		__set_bit(apic_id - min, (unsigned long *)&ipi_bitmap);
    545	}
    546
    547	if (ipi_bitmap) {
    548		ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
    549			(unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
    550		WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld",
    551			  ret);
    552	}
    553
    554	local_irq_restore(flags);
    555}
    556
    557static void kvm_send_ipi_mask(const struct cpumask *mask, int vector)
    558{
    559	__send_ipi_mask(mask, vector);
    560}
    561
    562static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
    563{
    564	unsigned int this_cpu = smp_processor_id();
    565	struct cpumask *new_mask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
    566	const struct cpumask *local_mask;
    567
    568	cpumask_copy(new_mask, mask);
    569	cpumask_clear_cpu(this_cpu, new_mask);
    570	local_mask = new_mask;
    571	__send_ipi_mask(local_mask, vector);
    572}
    573
    574static int __init setup_efi_kvm_sev_migration(void)
    575{
    576	efi_char16_t efi_sev_live_migration_enabled[] = L"SevLiveMigrationEnabled";
    577	efi_guid_t efi_variable_guid = AMD_SEV_MEM_ENCRYPT_GUID;
    578	efi_status_t status;
    579	unsigned long size;
    580	bool enabled;
    581
    582	if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) ||
    583	    !kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL))
    584		return 0;
    585
    586	if (!efi_enabled(EFI_BOOT))
    587		return 0;
    588
    589	if (!efi_enabled(EFI_RUNTIME_SERVICES)) {
    590		pr_info("%s : EFI runtime services are not enabled\n", __func__);
    591		return 0;
    592	}
    593
    594	size = sizeof(enabled);
    595
    596	/* Get variable contents into buffer */
    597	status = efi.get_variable(efi_sev_live_migration_enabled,
    598				  &efi_variable_guid, NULL, &size, &enabled);
    599
    600	if (status == EFI_NOT_FOUND) {
    601		pr_info("%s : EFI live migration variable not found\n", __func__);
    602		return 0;
    603	}
    604
    605	if (status != EFI_SUCCESS) {
    606		pr_info("%s : EFI variable retrieval failed\n", __func__);
    607		return 0;
    608	}
    609
    610	if (enabled == 0) {
    611		pr_info("%s: live migration disabled in EFI\n", __func__);
    612		return 0;
    613	}
    614
    615	pr_info("%s : live migration enabled in EFI\n", __func__);
    616	wrmsrl(MSR_KVM_MIGRATION_CONTROL, KVM_MIGRATION_READY);
    617
    618	return 1;
    619}
    620
    621late_initcall(setup_efi_kvm_sev_migration);
    622
    623/*
    624 * Set the IPI entry points
    625 */
    626static void kvm_setup_pv_ipi(void)
    627{
    628	apic->send_IPI_mask = kvm_send_ipi_mask;
    629	apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself;
    630	pr_info("setup PV IPIs\n");
    631}
    632
    633static void kvm_smp_send_call_func_ipi(const struct cpumask *mask)
    634{
    635	int cpu;
    636
    637	native_send_call_func_ipi(mask);
    638
    639	/* Make sure other vCPUs get a chance to run if they need to. */
    640	for_each_cpu(cpu, mask) {
    641		if (!idle_cpu(cpu) && vcpu_is_preempted(cpu)) {
    642			kvm_hypercall1(KVM_HC_SCHED_YIELD, per_cpu(x86_cpu_to_apicid, cpu));
    643			break;
    644		}
    645	}
    646}
    647
    648static void kvm_flush_tlb_multi(const struct cpumask *cpumask,
    649			const struct flush_tlb_info *info)
    650{
    651	u8 state;
    652	int cpu;
    653	struct kvm_steal_time *src;
    654	struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
    655
    656	cpumask_copy(flushmask, cpumask);
    657	/*
    658	 * We have to call flush only on online vCPUs. And
    659	 * queue flush_on_enter for pre-empted vCPUs
    660	 */
    661	for_each_cpu(cpu, flushmask) {
    662		/*
    663		 * The local vCPU is never preempted, so we do not explicitly
    664		 * skip check for local vCPU - it will never be cleared from
    665		 * flushmask.
    666		 */
    667		src = &per_cpu(steal_time, cpu);
    668		state = READ_ONCE(src->preempted);
    669		if ((state & KVM_VCPU_PREEMPTED)) {
    670			if (try_cmpxchg(&src->preempted, &state,
    671					state | KVM_VCPU_FLUSH_TLB))
    672				__cpumask_clear_cpu(cpu, flushmask);
    673		}
    674	}
    675
    676	native_flush_tlb_multi(flushmask, info);
    677}
    678
    679static __init int kvm_alloc_cpumask(void)
    680{
    681	int cpu;
    682
    683	if (!kvm_para_available() || nopv)
    684		return 0;
    685
    686	if (pv_tlb_flush_supported() || pv_ipi_supported())
    687		for_each_possible_cpu(cpu) {
    688			zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu),
    689				GFP_KERNEL, cpu_to_node(cpu));
    690		}
    691
    692	return 0;
    693}
    694arch_initcall(kvm_alloc_cpumask);
    695
    696static void __init kvm_smp_prepare_boot_cpu(void)
    697{
    698	/*
    699	 * Map the per-cpu variables as decrypted before kvm_guest_cpu_init()
    700	 * shares the guest physical address with the hypervisor.
    701	 */
    702	sev_map_percpu_data();
    703
    704	kvm_guest_cpu_init();
    705	native_smp_prepare_boot_cpu();
    706	kvm_spinlock_init();
    707}
    708
    709static int kvm_cpu_down_prepare(unsigned int cpu)
    710{
    711	unsigned long flags;
    712
    713	local_irq_save(flags);
    714	kvm_guest_cpu_offline(false);
    715	local_irq_restore(flags);
    716	return 0;
    717}
    718
    719#endif
    720
    721static int kvm_suspend(void)
    722{
    723	u64 val = 0;
    724
    725	kvm_guest_cpu_offline(false);
    726
    727#ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
    728	if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
    729		rdmsrl(MSR_KVM_POLL_CONTROL, val);
    730	has_guest_poll = !(val & 1);
    731#endif
    732	return 0;
    733}
    734
    735static void kvm_resume(void)
    736{
    737	kvm_cpu_online(raw_smp_processor_id());
    738
    739#ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
    740	if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL) && has_guest_poll)
    741		wrmsrl(MSR_KVM_POLL_CONTROL, 0);
    742#endif
    743}
    744
    745static struct syscore_ops kvm_syscore_ops = {
    746	.suspend	= kvm_suspend,
    747	.resume		= kvm_resume,
    748};
    749
    750static void kvm_pv_guest_cpu_reboot(void *unused)
    751{
    752	kvm_guest_cpu_offline(true);
    753}
    754
    755static int kvm_pv_reboot_notify(struct notifier_block *nb,
    756				unsigned long code, void *unused)
    757{
    758	if (code == SYS_RESTART)
    759		on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
    760	return NOTIFY_DONE;
    761}
    762
    763static struct notifier_block kvm_pv_reboot_nb = {
    764	.notifier_call = kvm_pv_reboot_notify,
    765};
    766
    767/*
    768 * After a PV feature is registered, the host will keep writing to the
    769 * registered memory location. If the guest happens to shutdown, this memory
    770 * won't be valid. In cases like kexec, in which you install a new kernel, this
    771 * means a random memory location will be kept being written.
    772 */
    773#ifdef CONFIG_KEXEC_CORE
    774static void kvm_crash_shutdown(struct pt_regs *regs)
    775{
    776	kvm_guest_cpu_offline(true);
    777	native_machine_crash_shutdown(regs);
    778}
    779#endif
    780
    781#if defined(CONFIG_X86_32) || !defined(CONFIG_SMP)
    782bool __kvm_vcpu_is_preempted(long cpu);
    783
    784__visible bool __kvm_vcpu_is_preempted(long cpu)
    785{
    786	struct kvm_steal_time *src = &per_cpu(steal_time, cpu);
    787
    788	return !!(src->preempted & KVM_VCPU_PREEMPTED);
    789}
    790PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted);
    791
    792#else
    793
    794#include <asm/asm-offsets.h>
    795
    796extern bool __raw_callee_save___kvm_vcpu_is_preempted(long);
    797
    798/*
    799 * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and
    800 * restoring to/from the stack.
    801 */
    802asm(
    803".pushsection .text;"
    804".global __raw_callee_save___kvm_vcpu_is_preempted;"
    805".type __raw_callee_save___kvm_vcpu_is_preempted, @function;"
    806"__raw_callee_save___kvm_vcpu_is_preempted:"
    807ASM_ENDBR
    808"movq	__per_cpu_offset(,%rdi,8), %rax;"
    809"cmpb	$0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);"
    810"setne	%al;"
    811ASM_RET
    812".size __raw_callee_save___kvm_vcpu_is_preempted, .-__raw_callee_save___kvm_vcpu_is_preempted;"
    813".popsection");
    814
    815#endif
    816
    817static void __init kvm_guest_init(void)
    818{
    819	int i;
    820
    821	paravirt_ops_setup();
    822	register_reboot_notifier(&kvm_pv_reboot_nb);
    823	for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
    824		raw_spin_lock_init(&async_pf_sleepers[i].lock);
    825
    826	if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
    827		has_steal_clock = 1;
    828		static_call_update(pv_steal_clock, kvm_steal_clock);
    829
    830		pv_ops.lock.vcpu_is_preempted =
    831			PV_CALLEE_SAVE(__kvm_vcpu_is_preempted);
    832	}
    833
    834	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
    835		apic_set_eoi_write(kvm_guest_apic_eoi_write);
    836
    837	if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
    838		static_branch_enable(&kvm_async_pf_enabled);
    839		alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, asm_sysvec_kvm_asyncpf_interrupt);
    840	}
    841
    842#ifdef CONFIG_SMP
    843	if (pv_tlb_flush_supported()) {
    844		pv_ops.mmu.flush_tlb_multi = kvm_flush_tlb_multi;
    845		pv_ops.mmu.tlb_remove_table = tlb_remove_table;
    846		pr_info("KVM setup pv remote TLB flush\n");
    847	}
    848
    849	smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
    850	if (pv_sched_yield_supported()) {
    851		smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi;
    852		pr_info("setup PV sched yield\n");
    853	}
    854	if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online",
    855				      kvm_cpu_online, kvm_cpu_down_prepare) < 0)
    856		pr_err("failed to install cpu hotplug callbacks\n");
    857#else
    858	sev_map_percpu_data();
    859	kvm_guest_cpu_init();
    860#endif
    861
    862#ifdef CONFIG_KEXEC_CORE
    863	machine_ops.crash_shutdown = kvm_crash_shutdown;
    864#endif
    865
    866	register_syscore_ops(&kvm_syscore_ops);
    867
    868	/*
    869	 * Hard lockup detection is enabled by default. Disable it, as guests
    870	 * can get false positives too easily, for example if the host is
    871	 * overcommitted.
    872	 */
    873	hardlockup_detector_disable();
    874}
    875
    876static noinline uint32_t __kvm_cpuid_base(void)
    877{
    878	if (boot_cpu_data.cpuid_level < 0)
    879		return 0;	/* So we don't blow up on old processors */
    880
    881	if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
    882		return hypervisor_cpuid_base(KVM_SIGNATURE, 0);
    883
    884	return 0;
    885}
    886
    887static inline uint32_t kvm_cpuid_base(void)
    888{
    889	static int kvm_cpuid_base = -1;
    890
    891	if (kvm_cpuid_base == -1)
    892		kvm_cpuid_base = __kvm_cpuid_base();
    893
    894	return kvm_cpuid_base;
    895}
    896
    897bool kvm_para_available(void)
    898{
    899	return kvm_cpuid_base() != 0;
    900}
    901EXPORT_SYMBOL_GPL(kvm_para_available);
    902
    903unsigned int kvm_arch_para_features(void)
    904{
    905	return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES);
    906}
    907
    908unsigned int kvm_arch_para_hints(void)
    909{
    910	return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES);
    911}
    912EXPORT_SYMBOL_GPL(kvm_arch_para_hints);
    913
    914static uint32_t __init kvm_detect(void)
    915{
    916	return kvm_cpuid_base();
    917}
    918
    919static void __init kvm_apic_init(void)
    920{
    921#ifdef CONFIG_SMP
    922	if (pv_ipi_supported())
    923		kvm_setup_pv_ipi();
    924#endif
    925}
    926
    927static bool __init kvm_msi_ext_dest_id(void)
    928{
    929	return kvm_para_has_feature(KVM_FEATURE_MSI_EXT_DEST_ID);
    930}
    931
    932static void kvm_sev_hc_page_enc_status(unsigned long pfn, int npages, bool enc)
    933{
    934	kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, pfn << PAGE_SHIFT, npages,
    935			   KVM_MAP_GPA_RANGE_ENC_STAT(enc) | KVM_MAP_GPA_RANGE_PAGE_SZ_4K);
    936}
    937
    938static void __init kvm_init_platform(void)
    939{
    940	if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) &&
    941	    kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) {
    942		unsigned long nr_pages;
    943		int i;
    944
    945		pv_ops.mmu.notify_page_enc_status_changed =
    946			kvm_sev_hc_page_enc_status;
    947
    948		/*
    949		 * Reset the host's shared pages list related to kernel
    950		 * specific page encryption status settings before we load a
    951		 * new kernel by kexec. Reset the page encryption status
    952		 * during early boot intead of just before kexec to avoid SMP
    953		 * races during kvm_pv_guest_cpu_reboot().
    954		 * NOTE: We cannot reset the complete shared pages list
    955		 * here as we need to retain the UEFI/OVMF firmware
    956		 * specific settings.
    957		 */
    958
    959		for (i = 0; i < e820_table->nr_entries; i++) {
    960			struct e820_entry *entry = &e820_table->entries[i];
    961
    962			if (entry->type != E820_TYPE_RAM)
    963				continue;
    964
    965			nr_pages = DIV_ROUND_UP(entry->size, PAGE_SIZE);
    966
    967			kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, entry->addr,
    968				       nr_pages,
    969				       KVM_MAP_GPA_RANGE_ENCRYPTED | KVM_MAP_GPA_RANGE_PAGE_SZ_4K);
    970		}
    971
    972		/*
    973		 * Ensure that _bss_decrypted section is marked as decrypted in the
    974		 * shared pages list.
    975		 */
    976		nr_pages = DIV_ROUND_UP(__end_bss_decrypted - __start_bss_decrypted,
    977					PAGE_SIZE);
    978		early_set_mem_enc_dec_hypercall((unsigned long)__start_bss_decrypted,
    979						nr_pages, 0);
    980
    981		/*
    982		 * If not booted using EFI, enable Live migration support.
    983		 */
    984		if (!efi_enabled(EFI_BOOT))
    985			wrmsrl(MSR_KVM_MIGRATION_CONTROL,
    986			       KVM_MIGRATION_READY);
    987	}
    988	kvmclock_init();
    989	x86_platform.apic_post_init = kvm_apic_init;
    990}
    991
    992#if defined(CONFIG_AMD_MEM_ENCRYPT)
    993static void kvm_sev_es_hcall_prepare(struct ghcb *ghcb, struct pt_regs *regs)
    994{
    995	/* RAX and CPL are already in the GHCB */
    996	ghcb_set_rbx(ghcb, regs->bx);
    997	ghcb_set_rcx(ghcb, regs->cx);
    998	ghcb_set_rdx(ghcb, regs->dx);
    999	ghcb_set_rsi(ghcb, regs->si);
   1000}
   1001
   1002static bool kvm_sev_es_hcall_finish(struct ghcb *ghcb, struct pt_regs *regs)
   1003{
   1004	/* No checking of the return state needed */
   1005	return true;
   1006}
   1007#endif
   1008
   1009const __initconst struct hypervisor_x86 x86_hyper_kvm = {
   1010	.name				= "KVM",
   1011	.detect				= kvm_detect,
   1012	.type				= X86_HYPER_KVM,
   1013	.init.guest_late_init		= kvm_guest_init,
   1014	.init.x2apic_available		= kvm_para_available,
   1015	.init.msi_ext_dest_id		= kvm_msi_ext_dest_id,
   1016	.init.init_platform		= kvm_init_platform,
   1017#if defined(CONFIG_AMD_MEM_ENCRYPT)
   1018	.runtime.sev_es_hcall_prepare	= kvm_sev_es_hcall_prepare,
   1019	.runtime.sev_es_hcall_finish	= kvm_sev_es_hcall_finish,
   1020#endif
   1021};
   1022
   1023static __init int activate_jump_labels(void)
   1024{
   1025	if (has_steal_clock) {
   1026		static_key_slow_inc(&paravirt_steal_enabled);
   1027		if (steal_acc)
   1028			static_key_slow_inc(&paravirt_steal_rq_enabled);
   1029	}
   1030
   1031	return 0;
   1032}
   1033arch_initcall(activate_jump_labels);
   1034
   1035#ifdef CONFIG_PARAVIRT_SPINLOCKS
   1036
   1037/* Kick a cpu by its apicid. Used to wake up a halted vcpu */
   1038static void kvm_kick_cpu(int cpu)
   1039{
   1040	int apicid;
   1041	unsigned long flags = 0;
   1042
   1043	apicid = per_cpu(x86_cpu_to_apicid, cpu);
   1044	kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid);
   1045}
   1046
   1047#include <asm/qspinlock.h>
   1048
   1049static void kvm_wait(u8 *ptr, u8 val)
   1050{
   1051	if (in_nmi())
   1052		return;
   1053
   1054	/*
   1055	 * halt until it's our turn and kicked. Note that we do safe halt
   1056	 * for irq enabled case to avoid hang when lock info is overwritten
   1057	 * in irq spinlock slowpath and no spurious interrupt occur to save us.
   1058	 */
   1059	if (irqs_disabled()) {
   1060		if (READ_ONCE(*ptr) == val)
   1061			halt();
   1062	} else {
   1063		local_irq_disable();
   1064
   1065		/* safe_halt() will enable IRQ */
   1066		if (READ_ONCE(*ptr) == val)
   1067			safe_halt();
   1068		else
   1069			local_irq_enable();
   1070	}
   1071}
   1072
   1073/*
   1074 * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present.
   1075 */
   1076void __init kvm_spinlock_init(void)
   1077{
   1078	/*
   1079	 * In case host doesn't support KVM_FEATURE_PV_UNHALT there is still an
   1080	 * advantage of keeping virt_spin_lock_key enabled: virt_spin_lock() is
   1081	 * preferred over native qspinlock when vCPU is preempted.
   1082	 */
   1083	if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT)) {
   1084		pr_info("PV spinlocks disabled, no host support\n");
   1085		return;
   1086	}
   1087
   1088	/*
   1089	 * Disable PV spinlocks and use native qspinlock when dedicated pCPUs
   1090	 * are available.
   1091	 */
   1092	if (kvm_para_has_hint(KVM_HINTS_REALTIME)) {
   1093		pr_info("PV spinlocks disabled with KVM_HINTS_REALTIME hints\n");
   1094		goto out;
   1095	}
   1096
   1097	if (num_possible_cpus() == 1) {
   1098		pr_info("PV spinlocks disabled, single CPU\n");
   1099		goto out;
   1100	}
   1101
   1102	if (nopvspin) {
   1103		pr_info("PV spinlocks disabled, forced by \"nopvspin\" parameter\n");
   1104		goto out;
   1105	}
   1106
   1107	pr_info("PV spinlocks enabled\n");
   1108
   1109	__pv_init_lock_hash();
   1110	pv_ops.lock.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
   1111	pv_ops.lock.queued_spin_unlock =
   1112		PV_CALLEE_SAVE(__pv_queued_spin_unlock);
   1113	pv_ops.lock.wait = kvm_wait;
   1114	pv_ops.lock.kick = kvm_kick_cpu;
   1115
   1116	/*
   1117	 * When PV spinlock is enabled which is preferred over
   1118	 * virt_spin_lock(), virt_spin_lock_key's value is meaningless.
   1119	 * Just disable it anyway.
   1120	 */
   1121out:
   1122	static_branch_disable(&virt_spin_lock_key);
   1123}
   1124
   1125#endif	/* CONFIG_PARAVIRT_SPINLOCKS */
   1126
   1127#ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
   1128
   1129static void kvm_disable_host_haltpoll(void *i)
   1130{
   1131	wrmsrl(MSR_KVM_POLL_CONTROL, 0);
   1132}
   1133
   1134static void kvm_enable_host_haltpoll(void *i)
   1135{
   1136	wrmsrl(MSR_KVM_POLL_CONTROL, 1);
   1137}
   1138
   1139void arch_haltpoll_enable(unsigned int cpu)
   1140{
   1141	if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) {
   1142		pr_err_once("host does not support poll control\n");
   1143		pr_err_once("host upgrade recommended\n");
   1144		return;
   1145	}
   1146
   1147	/* Enable guest halt poll disables host halt poll */
   1148	smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1);
   1149}
   1150EXPORT_SYMBOL_GPL(arch_haltpoll_enable);
   1151
   1152void arch_haltpoll_disable(unsigned int cpu)
   1153{
   1154	if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
   1155		return;
   1156
   1157	/* Disable guest halt poll enables host halt poll */
   1158	smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1);
   1159}
   1160EXPORT_SYMBOL_GPL(arch_haltpoll_disable);
   1161#endif