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 
47 DEFINE_STATIC_KEY_FALSE(kvm_async_pf_enabled);
48 
49 static int kvmapf = 1;
50 
parse_no_kvmapf(char * arg)51 static int __init parse_no_kvmapf(char *arg)
52 {
53         kvmapf = 0;
54         return 0;
55 }
56 
57 early_param("no-kvmapf", parse_no_kvmapf);
58 
59 static int steal_acc = 1;
parse_no_stealacc(char * arg)60 static int __init parse_no_stealacc(char *arg)
61 {
62         steal_acc = 0;
63         return 0;
64 }
65 
66 early_param("no-steal-acc", parse_no_stealacc);
67 
68 static DEFINE_PER_CPU_DECRYPTED(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
69 DEFINE_PER_CPU_DECRYPTED(struct kvm_steal_time, steal_time) __aligned(64) __visible;
70 static int has_steal_clock = 0;
71 
72 static int has_guest_poll = 0;
73 /*
74  * No need for any "IO delay" on KVM
75  */
kvm_io_delay(void)76 static 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 
83 struct kvm_task_sleep_node {
84 	struct hlist_node link;
85 	struct swait_queue_head wq;
86 	u32 token;
87 	int cpu;
88 };
89 
90 static struct kvm_task_sleep_head {
91 	raw_spinlock_t lock;
92 	struct hlist_head list;
93 } async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];
94 
_find_apf_task(struct kvm_task_sleep_head * b,u32 token)95 static 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 
kvm_async_pf_queue_task(u32 token,struct kvm_task_sleep_node * n)110 static 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  */
kvm_async_pf_task_wait_schedule(u32 token)141 void 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 }
162 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait_schedule);
163 
apf_task_wake_one(struct kvm_task_sleep_node * n)164 static 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 
apf_task_wake_all(void)171 static 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 
kvm_async_pf_task_wake(u32 token)190 void 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 
201 again:
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 }
242 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
243 
kvm_read_and_reset_apf_flags(void)244 noinstr 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 }
255 EXPORT_SYMBOL_GPL(kvm_read_and_reset_apf_flags);
256 
__kvm_handle_async_pf(struct pt_regs * regs,u32 token)257 noinstr 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 
DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt)290 DEFINE_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 
paravirt_ops_setup(void)309 static 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 
kvm_register_steal_time(void)321 static 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 
334 static DEFINE_PER_CPU_DECRYPTED(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;
335 
kvm_guest_apic_eoi_write(u32 reg,u32 val)336 static 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 
kvm_guest_cpu_init(void)350 static 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 
kvm_pv_disable_apf(void)385 static 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 
kvm_disable_steal_time(void)396 static 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 
kvm_steal_clock(int cpu)404 static 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 
__set_percpu_decrypted(void * ptr,unsigned long size)421 static 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  */
sev_map_percpu_data(void)434 static 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 
kvm_guest_cpu_offline(bool shutdown)448 static 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 
kvm_cpu_online(unsigned int cpu)461 static 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 
473 static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask);
474 
pv_tlb_flush_supported(void)475 static 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 
pv_ipi_supported(void)484 static bool pv_ipi_supported(void)
485 {
486 	return (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI) &&
487 	       (num_possible_cpus() != 1));
488 }
489 
pv_sched_yield_supported(void)490 static 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 
__send_ipi_mask(const struct cpumask * mask,int vector)501 static 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 
kvm_send_ipi_mask(const struct cpumask * mask,int vector)557 static void kvm_send_ipi_mask(const struct cpumask *mask, int vector)
558 {
559 	__send_ipi_mask(mask, vector);
560 }
561 
kvm_send_ipi_mask_allbutself(const struct cpumask * mask,int vector)562 static 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 
setup_efi_kvm_sev_migration(void)574 static 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 
621 late_initcall(setup_efi_kvm_sev_migration);
622 
623 /*
624  * Set the IPI entry points
625  */
kvm_setup_pv_ipi(void)626 static 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 
kvm_smp_send_call_func_ipi(const struct cpumask * mask)633 static 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 
kvm_flush_tlb_multi(const struct cpumask * cpumask,const struct flush_tlb_info * info)648 static 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 
kvm_alloc_cpumask(void)679 static __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 }
694 arch_initcall(kvm_alloc_cpumask);
695 
kvm_smp_prepare_boot_cpu(void)696 static 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 
kvm_cpu_down_prepare(unsigned int cpu)709 static 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 
kvm_suspend(void)721 static 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 
kvm_resume(void)735 static 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 
745 static struct syscore_ops kvm_syscore_ops = {
746 	.suspend	= kvm_suspend,
747 	.resume		= kvm_resume,
748 };
749 
kvm_pv_guest_cpu_reboot(void * unused)750 static void kvm_pv_guest_cpu_reboot(void *unused)
751 {
752 	kvm_guest_cpu_offline(true);
753 }
754 
kvm_pv_reboot_notify(struct notifier_block * nb,unsigned long code,void * unused)755 static 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 
763 static 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
kvm_crash_shutdown(struct pt_regs * regs)774 static 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)
782 bool __kvm_vcpu_is_preempted(long cpu);
783 
__kvm_vcpu_is_preempted(long cpu)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 }
790 PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted);
791 
792 #else
793 
794 #include <asm/asm-offsets.h>
795 
796 extern 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  */
802 asm(
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:"
807 ASM_ENDBR
808 "movq	__per_cpu_offset(,%rdi,8), %rax;"
809 "cmpb	$0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);"
810 "setne	%al;"
811 ASM_RET
812 ".size __raw_callee_save___kvm_vcpu_is_preempted, .-__raw_callee_save___kvm_vcpu_is_preempted;"
813 ".popsection");
814 
815 #endif
816 
kvm_guest_init(void)817 static 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 
__kvm_cpuid_base(void)876 static 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 
kvm_cpuid_base(void)887 static 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 
kvm_para_available(void)897 bool kvm_para_available(void)
898 {
899 	return kvm_cpuid_base() != 0;
900 }
901 EXPORT_SYMBOL_GPL(kvm_para_available);
902 
kvm_arch_para_features(void)903 unsigned int kvm_arch_para_features(void)
904 {
905 	return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES);
906 }
907 
kvm_arch_para_hints(void)908 unsigned int kvm_arch_para_hints(void)
909 {
910 	return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES);
911 }
912 EXPORT_SYMBOL_GPL(kvm_arch_para_hints);
913 
kvm_detect(void)914 static uint32_t __init kvm_detect(void)
915 {
916 	return kvm_cpuid_base();
917 }
918 
kvm_apic_init(void)919 static 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 
kvm_msi_ext_dest_id(void)927 static bool __init kvm_msi_ext_dest_id(void)
928 {
929 	return kvm_para_has_feature(KVM_FEATURE_MSI_EXT_DEST_ID);
930 }
931 
kvm_sev_hc_page_enc_status(unsigned long pfn,int npages,bool enc)932 static 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 
kvm_init_platform(void)938 static 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)
kvm_sev_es_hcall_prepare(struct ghcb * ghcb,struct pt_regs * regs)993 static 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 
kvm_sev_es_hcall_finish(struct ghcb * ghcb,struct pt_regs * regs)1002 static 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 
1009 const __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 
activate_jump_labels(void)1023 static __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 }
1033 arch_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 */
kvm_kick_cpu(int cpu)1038 static 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 
kvm_wait(u8 * ptr,u8 val)1049 static 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  */
kvm_spinlock_init(void)1076 void __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 	 */
1121 out:
1122 	static_branch_disable(&virt_spin_lock_key);
1123 }
1124 
1125 #endif	/* CONFIG_PARAVIRT_SPINLOCKS */
1126 
1127 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
1128 
kvm_disable_host_haltpoll(void * i)1129 static void kvm_disable_host_haltpoll(void *i)
1130 {
1131 	wrmsrl(MSR_KVM_POLL_CONTROL, 0);
1132 }
1133 
kvm_enable_host_haltpoll(void * i)1134 static void kvm_enable_host_haltpoll(void *i)
1135 {
1136 	wrmsrl(MSR_KVM_POLL_CONTROL, 1);
1137 }
1138 
arch_haltpoll_enable(unsigned int cpu)1139 void 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 }
1150 EXPORT_SYMBOL_GPL(arch_haltpoll_enable);
1151 
arch_haltpoll_disable(unsigned int cpu)1152 void 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 }
1160 EXPORT_SYMBOL_GPL(arch_haltpoll_disable);
1161 #endif
1162