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/mtrr.h>
41 #include <asm/tlb.h>
42 #include <asm/cpuidle_haltpoll.h>
43 #include <asm/ptrace.h>
44 #include <asm/reboot.h>
45 #include <asm/svm.h>
46 #include <asm/e820/api.h>
47 
48 DEFINE_STATIC_KEY_FALSE_RO(kvm_async_pf_enabled);
49 
50 static int kvmapf = 1;
51 
parse_no_kvmapf(char * arg)52 static int __init parse_no_kvmapf(char *arg)
53 {
54         kvmapf = 0;
55         return 0;
56 }
57 
58 early_param("no-kvmapf", parse_no_kvmapf);
59 
60 static int steal_acc = 1;
parse_no_stealacc(char * arg)61 static int __init parse_no_stealacc(char *arg)
62 {
63         steal_acc = 0;
64         return 0;
65 }
66 
67 early_param("no-steal-acc", parse_no_stealacc);
68 
69 static DEFINE_PER_CPU_READ_MOSTLY(bool, async_pf_enabled);
70 static DEFINE_PER_CPU_DECRYPTED(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
71 DEFINE_PER_CPU_DECRYPTED(struct kvm_steal_time, steal_time) __aligned(64) __visible;
72 static int has_steal_clock = 0;
73 
74 static int has_guest_poll = 0;
75 /*
76  * No need for any "IO delay" on KVM
77  */
kvm_io_delay(void)78 static void kvm_io_delay(void)
79 {
80 }
81 
82 #define KVM_TASK_SLEEP_HASHBITS 8
83 #define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS)
84 
85 struct kvm_task_sleep_node {
86 	struct hlist_node link;
87 	struct swait_queue_head wq;
88 	u32 token;
89 	int cpu;
90 };
91 
92 static struct kvm_task_sleep_head {
93 	raw_spinlock_t lock;
94 	struct hlist_head list;
95 } async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];
96 
_find_apf_task(struct kvm_task_sleep_head * b,u32 token)97 static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b,
98 						  u32 token)
99 {
100 	struct hlist_node *p;
101 
102 	hlist_for_each(p, &b->list) {
103 		struct kvm_task_sleep_node *n =
104 			hlist_entry(p, typeof(*n), link);
105 		if (n->token == token)
106 			return n;
107 	}
108 
109 	return NULL;
110 }
111 
kvm_async_pf_queue_task(u32 token,struct kvm_task_sleep_node * n)112 static bool kvm_async_pf_queue_task(u32 token, struct kvm_task_sleep_node *n)
113 {
114 	u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
115 	struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
116 	struct kvm_task_sleep_node *e;
117 
118 	raw_spin_lock(&b->lock);
119 	e = _find_apf_task(b, token);
120 	if (e) {
121 		/* dummy entry exist -> wake up was delivered ahead of PF */
122 		hlist_del(&e->link);
123 		raw_spin_unlock(&b->lock);
124 		kfree(e);
125 		return false;
126 	}
127 
128 	n->token = token;
129 	n->cpu = smp_processor_id();
130 	init_swait_queue_head(&n->wq);
131 	hlist_add_head(&n->link, &b->list);
132 	raw_spin_unlock(&b->lock);
133 	return true;
134 }
135 
136 /*
137  * kvm_async_pf_task_wait_schedule - Wait for pagefault to be handled
138  * @token:	Token to identify the sleep node entry
139  *
140  * Invoked from the async pagefault handling code or from the VM exit page
141  * fault handler. In both cases RCU is watching.
142  */
kvm_async_pf_task_wait_schedule(u32 token)143 void kvm_async_pf_task_wait_schedule(u32 token)
144 {
145 	struct kvm_task_sleep_node n;
146 	DECLARE_SWAITQUEUE(wait);
147 
148 	lockdep_assert_irqs_disabled();
149 
150 	if (!kvm_async_pf_queue_task(token, &n))
151 		return;
152 
153 	for (;;) {
154 		prepare_to_swait_exclusive(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
155 		if (hlist_unhashed(&n.link))
156 			break;
157 
158 		local_irq_enable();
159 		schedule();
160 		local_irq_disable();
161 	}
162 	finish_swait(&n.wq, &wait);
163 }
164 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait_schedule);
165 
apf_task_wake_one(struct kvm_task_sleep_node * n)166 static void apf_task_wake_one(struct kvm_task_sleep_node *n)
167 {
168 	hlist_del_init(&n->link);
169 	if (swq_has_sleeper(&n->wq))
170 		swake_up_one(&n->wq);
171 }
172 
apf_task_wake_all(void)173 static void apf_task_wake_all(void)
174 {
175 	int i;
176 
177 	for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
178 		struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
179 		struct kvm_task_sleep_node *n;
180 		struct hlist_node *p, *next;
181 
182 		raw_spin_lock(&b->lock);
183 		hlist_for_each_safe(p, next, &b->list) {
184 			n = hlist_entry(p, typeof(*n), link);
185 			if (n->cpu == smp_processor_id())
186 				apf_task_wake_one(n);
187 		}
188 		raw_spin_unlock(&b->lock);
189 	}
190 }
191 
kvm_async_pf_task_wake(u32 token)192 void kvm_async_pf_task_wake(u32 token)
193 {
194 	u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
195 	struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
196 	struct kvm_task_sleep_node *n, *dummy = NULL;
197 
198 	if (token == ~0) {
199 		apf_task_wake_all();
200 		return;
201 	}
202 
203 again:
204 	raw_spin_lock(&b->lock);
205 	n = _find_apf_task(b, token);
206 	if (!n) {
207 		/*
208 		 * Async #PF not yet handled, add a dummy entry for the token.
209 		 * Allocating the token must be down outside of the raw lock
210 		 * as the allocator is preemptible on PREEMPT_RT kernels.
211 		 */
212 		if (!dummy) {
213 			raw_spin_unlock(&b->lock);
214 			dummy = kzalloc(sizeof(*dummy), GFP_ATOMIC);
215 
216 			/*
217 			 * Continue looping on allocation failure, eventually
218 			 * the async #PF will be handled and allocating a new
219 			 * node will be unnecessary.
220 			 */
221 			if (!dummy)
222 				cpu_relax();
223 
224 			/*
225 			 * Recheck for async #PF completion before enqueueing
226 			 * the dummy token to avoid duplicate list entries.
227 			 */
228 			goto again;
229 		}
230 		dummy->token = token;
231 		dummy->cpu = smp_processor_id();
232 		init_swait_queue_head(&dummy->wq);
233 		hlist_add_head(&dummy->link, &b->list);
234 		dummy = NULL;
235 	} else {
236 		apf_task_wake_one(n);
237 	}
238 	raw_spin_unlock(&b->lock);
239 
240 	/* A dummy token might be allocated and ultimately not used.  */
241 	kfree(dummy);
242 }
243 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
244 
kvm_read_and_reset_apf_flags(void)245 noinstr u32 kvm_read_and_reset_apf_flags(void)
246 {
247 	u32 flags = 0;
248 
249 	if (__this_cpu_read(async_pf_enabled)) {
250 		flags = __this_cpu_read(apf_reason.flags);
251 		__this_cpu_write(apf_reason.flags, 0);
252 	}
253 
254 	return flags;
255 }
256 EXPORT_SYMBOL_GPL(kvm_read_and_reset_apf_flags);
257 
__kvm_handle_async_pf(struct pt_regs * regs,u32 token)258 noinstr bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token)
259 {
260 	u32 flags = kvm_read_and_reset_apf_flags();
261 	irqentry_state_t state;
262 
263 	if (!flags)
264 		return false;
265 
266 	state = irqentry_enter(regs);
267 	instrumentation_begin();
268 
269 	/*
270 	 * If the host managed to inject an async #PF into an interrupt
271 	 * disabled region, then die hard as this is not going to end well
272 	 * and the host side is seriously broken.
273 	 */
274 	if (unlikely(!(regs->flags & X86_EFLAGS_IF)))
275 		panic("Host injected async #PF in interrupt disabled region\n");
276 
277 	if (flags & KVM_PV_REASON_PAGE_NOT_PRESENT) {
278 		if (unlikely(!(user_mode(regs))))
279 			panic("Host injected async #PF in kernel mode\n");
280 		/* Page is swapped out by the host. */
281 		kvm_async_pf_task_wait_schedule(token);
282 	} else {
283 		WARN_ONCE(1, "Unexpected async PF flags: %x\n", flags);
284 	}
285 
286 	instrumentation_end();
287 	irqentry_exit(regs, state);
288 	return true;
289 }
290 
DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt)291 DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt)
292 {
293 	struct pt_regs *old_regs = set_irq_regs(regs);
294 	u32 token;
295 
296 	apic_eoi();
297 
298 	inc_irq_stat(irq_hv_callback_count);
299 
300 	if (__this_cpu_read(async_pf_enabled)) {
301 		token = __this_cpu_read(apf_reason.token);
302 		kvm_async_pf_task_wake(token);
303 		__this_cpu_write(apf_reason.token, 0);
304 		wrmsrl(MSR_KVM_ASYNC_PF_ACK, 1);
305 	}
306 
307 	set_irq_regs(old_regs);
308 }
309 
paravirt_ops_setup(void)310 static void __init paravirt_ops_setup(void)
311 {
312 	pv_info.name = "KVM";
313 
314 	if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
315 		pv_ops.cpu.io_delay = kvm_io_delay;
316 
317 #ifdef CONFIG_X86_IO_APIC
318 	no_timer_check = 1;
319 #endif
320 }
321 
kvm_register_steal_time(void)322 static void kvm_register_steal_time(void)
323 {
324 	int cpu = smp_processor_id();
325 	struct kvm_steal_time *st = &per_cpu(steal_time, cpu);
326 
327 	if (!has_steal_clock)
328 		return;
329 
330 	wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED));
331 	pr_debug("stealtime: cpu %d, msr %llx\n", cpu,
332 		(unsigned long long) slow_virt_to_phys(st));
333 }
334 
335 static DEFINE_PER_CPU_DECRYPTED(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;
336 
kvm_guest_apic_eoi_write(void)337 static notrace __maybe_unused void kvm_guest_apic_eoi_write(void)
338 {
339 	/**
340 	 * This relies on __test_and_clear_bit to modify the memory
341 	 * in a way that is atomic with respect to the local CPU.
342 	 * The hypervisor only accesses this memory from the local CPU so
343 	 * there's no need for lock or memory barriers.
344 	 * An optimization barrier is implied in apic write.
345 	 */
346 	if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi)))
347 		return;
348 	apic_native_eoi();
349 }
350 
kvm_guest_cpu_init(void)351 static void kvm_guest_cpu_init(void)
352 {
353 	if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
354 		u64 pa;
355 
356 		WARN_ON_ONCE(!static_branch_likely(&kvm_async_pf_enabled));
357 
358 		pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason));
359 		pa |= KVM_ASYNC_PF_ENABLED | KVM_ASYNC_PF_DELIVERY_AS_INT;
360 
361 		if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_VMEXIT))
362 			pa |= KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT;
363 
364 		wrmsrl(MSR_KVM_ASYNC_PF_INT, HYPERVISOR_CALLBACK_VECTOR);
365 
366 		wrmsrl(MSR_KVM_ASYNC_PF_EN, pa);
367 		__this_cpu_write(async_pf_enabled, true);
368 		pr_debug("setup async PF for cpu %d\n", smp_processor_id());
369 	}
370 
371 	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
372 		unsigned long pa;
373 
374 		/* Size alignment is implied but just to make it explicit. */
375 		BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4);
376 		__this_cpu_write(kvm_apic_eoi, 0);
377 		pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi))
378 			| KVM_MSR_ENABLED;
379 		wrmsrl(MSR_KVM_PV_EOI_EN, pa);
380 	}
381 
382 	if (has_steal_clock)
383 		kvm_register_steal_time();
384 }
385 
kvm_pv_disable_apf(void)386 static void kvm_pv_disable_apf(void)
387 {
388 	if (!__this_cpu_read(async_pf_enabled))
389 		return;
390 
391 	wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
392 	__this_cpu_write(async_pf_enabled, false);
393 
394 	pr_debug("disable async PF for cpu %d\n", smp_processor_id());
395 }
396 
kvm_disable_steal_time(void)397 static void kvm_disable_steal_time(void)
398 {
399 	if (!has_steal_clock)
400 		return;
401 
402 	wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
403 }
404 
kvm_steal_clock(int cpu)405 static u64 kvm_steal_clock(int cpu)
406 {
407 	u64 steal;
408 	struct kvm_steal_time *src;
409 	int version;
410 
411 	src = &per_cpu(steal_time, cpu);
412 	do {
413 		version = src->version;
414 		virt_rmb();
415 		steal = src->steal;
416 		virt_rmb();
417 	} while ((version & 1) || (version != src->version));
418 
419 	return steal;
420 }
421 
__set_percpu_decrypted(void * ptr,unsigned long size)422 static inline void __set_percpu_decrypted(void *ptr, unsigned long size)
423 {
424 	early_set_memory_decrypted((unsigned long) ptr, size);
425 }
426 
427 /*
428  * Iterate through all possible CPUs and map the memory region pointed
429  * by apf_reason, steal_time and kvm_apic_eoi as decrypted at once.
430  *
431  * Note: we iterate through all possible CPUs to ensure that CPUs
432  * hotplugged will have their per-cpu variable already mapped as
433  * decrypted.
434  */
sev_map_percpu_data(void)435 static void __init sev_map_percpu_data(void)
436 {
437 	int cpu;
438 
439 	if (cc_vendor != CC_VENDOR_AMD ||
440 	    !cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
441 		return;
442 
443 	for_each_possible_cpu(cpu) {
444 		__set_percpu_decrypted(&per_cpu(apf_reason, cpu), sizeof(apf_reason));
445 		__set_percpu_decrypted(&per_cpu(steal_time, cpu), sizeof(steal_time));
446 		__set_percpu_decrypted(&per_cpu(kvm_apic_eoi, cpu), sizeof(kvm_apic_eoi));
447 	}
448 }
449 
kvm_guest_cpu_offline(bool shutdown)450 static void kvm_guest_cpu_offline(bool shutdown)
451 {
452 	kvm_disable_steal_time();
453 	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
454 		wrmsrl(MSR_KVM_PV_EOI_EN, 0);
455 	if (kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL))
456 		wrmsrl(MSR_KVM_MIGRATION_CONTROL, 0);
457 	kvm_pv_disable_apf();
458 	if (!shutdown)
459 		apf_task_wake_all();
460 	kvmclock_disable();
461 }
462 
kvm_cpu_online(unsigned int cpu)463 static int kvm_cpu_online(unsigned int cpu)
464 {
465 	unsigned long flags;
466 
467 	local_irq_save(flags);
468 	kvm_guest_cpu_init();
469 	local_irq_restore(flags);
470 	return 0;
471 }
472 
473 #ifdef CONFIG_SMP
474 
475 static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask);
476 
pv_tlb_flush_supported(void)477 static bool pv_tlb_flush_supported(void)
478 {
479 	return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) &&
480 		!kvm_para_has_hint(KVM_HINTS_REALTIME) &&
481 		kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) &&
482 		!boot_cpu_has(X86_FEATURE_MWAIT) &&
483 		(num_possible_cpus() != 1));
484 }
485 
pv_ipi_supported(void)486 static bool pv_ipi_supported(void)
487 {
488 	return (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI) &&
489 	       (num_possible_cpus() != 1));
490 }
491 
pv_sched_yield_supported(void)492 static bool pv_sched_yield_supported(void)
493 {
494 	return (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) &&
495 		!kvm_para_has_hint(KVM_HINTS_REALTIME) &&
496 	    kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) &&
497 	    !boot_cpu_has(X86_FEATURE_MWAIT) &&
498 	    (num_possible_cpus() != 1));
499 }
500 
501 #define KVM_IPI_CLUSTER_SIZE	(2 * BITS_PER_LONG)
502 
__send_ipi_mask(const struct cpumask * mask,int vector)503 static void __send_ipi_mask(const struct cpumask *mask, int vector)
504 {
505 	unsigned long flags;
506 	int cpu, min = 0, max = 0;
507 #ifdef CONFIG_X86_64
508 	__uint128_t ipi_bitmap = 0;
509 #else
510 	u64 ipi_bitmap = 0;
511 #endif
512 	u32 apic_id, icr;
513 	long ret;
514 
515 	if (cpumask_empty(mask))
516 		return;
517 
518 	local_irq_save(flags);
519 
520 	switch (vector) {
521 	default:
522 		icr = APIC_DM_FIXED | vector;
523 		break;
524 	case NMI_VECTOR:
525 		icr = APIC_DM_NMI;
526 		break;
527 	}
528 
529 	for_each_cpu(cpu, mask) {
530 		apic_id = per_cpu(x86_cpu_to_apicid, cpu);
531 		if (!ipi_bitmap) {
532 			min = max = apic_id;
533 		} else if (apic_id < min && max - apic_id < KVM_IPI_CLUSTER_SIZE) {
534 			ipi_bitmap <<= min - apic_id;
535 			min = apic_id;
536 		} else if (apic_id > min && apic_id < min + KVM_IPI_CLUSTER_SIZE) {
537 			max = apic_id < max ? max : apic_id;
538 		} else {
539 			ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
540 				(unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
541 			WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld",
542 				  ret);
543 			min = max = apic_id;
544 			ipi_bitmap = 0;
545 		}
546 		__set_bit(apic_id - min, (unsigned long *)&ipi_bitmap);
547 	}
548 
549 	if (ipi_bitmap) {
550 		ret = kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap,
551 			(unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr);
552 		WARN_ONCE(ret < 0, "kvm-guest: failed to send PV IPI: %ld",
553 			  ret);
554 	}
555 
556 	local_irq_restore(flags);
557 }
558 
kvm_send_ipi_mask(const struct cpumask * mask,int vector)559 static void kvm_send_ipi_mask(const struct cpumask *mask, int vector)
560 {
561 	__send_ipi_mask(mask, vector);
562 }
563 
kvm_send_ipi_mask_allbutself(const struct cpumask * mask,int vector)564 static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
565 {
566 	unsigned int this_cpu = smp_processor_id();
567 	struct cpumask *new_mask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
568 	const struct cpumask *local_mask;
569 
570 	cpumask_copy(new_mask, mask);
571 	cpumask_clear_cpu(this_cpu, new_mask);
572 	local_mask = new_mask;
573 	__send_ipi_mask(local_mask, vector);
574 }
575 
setup_efi_kvm_sev_migration(void)576 static int __init setup_efi_kvm_sev_migration(void)
577 {
578 	efi_char16_t efi_sev_live_migration_enabled[] = L"SevLiveMigrationEnabled";
579 	efi_guid_t efi_variable_guid = AMD_SEV_MEM_ENCRYPT_GUID;
580 	efi_status_t status;
581 	unsigned long size;
582 	bool enabled;
583 
584 	if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) ||
585 	    !kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL))
586 		return 0;
587 
588 	if (!efi_enabled(EFI_BOOT))
589 		return 0;
590 
591 	if (!efi_enabled(EFI_RUNTIME_SERVICES)) {
592 		pr_info("%s : EFI runtime services are not enabled\n", __func__);
593 		return 0;
594 	}
595 
596 	size = sizeof(enabled);
597 
598 	/* Get variable contents into buffer */
599 	status = efi.get_variable(efi_sev_live_migration_enabled,
600 				  &efi_variable_guid, NULL, &size, &enabled);
601 
602 	if (status == EFI_NOT_FOUND) {
603 		pr_info("%s : EFI live migration variable not found\n", __func__);
604 		return 0;
605 	}
606 
607 	if (status != EFI_SUCCESS) {
608 		pr_info("%s : EFI variable retrieval failed\n", __func__);
609 		return 0;
610 	}
611 
612 	if (enabled == 0) {
613 		pr_info("%s: live migration disabled in EFI\n", __func__);
614 		return 0;
615 	}
616 
617 	pr_info("%s : live migration enabled in EFI\n", __func__);
618 	wrmsrl(MSR_KVM_MIGRATION_CONTROL, KVM_MIGRATION_READY);
619 
620 	return 1;
621 }
622 
623 late_initcall(setup_efi_kvm_sev_migration);
624 
625 /*
626  * Set the IPI entry points
627  */
kvm_setup_pv_ipi(void)628 static __init void kvm_setup_pv_ipi(void)
629 {
630 	apic_update_callback(send_IPI_mask, kvm_send_ipi_mask);
631 	apic_update_callback(send_IPI_mask_allbutself, kvm_send_ipi_mask_allbutself);
632 	pr_info("setup PV IPIs\n");
633 }
634 
kvm_smp_send_call_func_ipi(const struct cpumask * mask)635 static void kvm_smp_send_call_func_ipi(const struct cpumask *mask)
636 {
637 	int cpu;
638 
639 	native_send_call_func_ipi(mask);
640 
641 	/* Make sure other vCPUs get a chance to run if they need to. */
642 	for_each_cpu(cpu, mask) {
643 		if (!idle_cpu(cpu) && vcpu_is_preempted(cpu)) {
644 			kvm_hypercall1(KVM_HC_SCHED_YIELD, per_cpu(x86_cpu_to_apicid, cpu));
645 			break;
646 		}
647 	}
648 }
649 
kvm_flush_tlb_multi(const struct cpumask * cpumask,const struct flush_tlb_info * info)650 static void kvm_flush_tlb_multi(const struct cpumask *cpumask,
651 			const struct flush_tlb_info *info)
652 {
653 	u8 state;
654 	int cpu;
655 	struct kvm_steal_time *src;
656 	struct cpumask *flushmask = this_cpu_cpumask_var_ptr(__pv_cpu_mask);
657 
658 	cpumask_copy(flushmask, cpumask);
659 	/*
660 	 * We have to call flush only on online vCPUs. And
661 	 * queue flush_on_enter for pre-empted vCPUs
662 	 */
663 	for_each_cpu(cpu, flushmask) {
664 		/*
665 		 * The local vCPU is never preempted, so we do not explicitly
666 		 * skip check for local vCPU - it will never be cleared from
667 		 * flushmask.
668 		 */
669 		src = &per_cpu(steal_time, cpu);
670 		state = READ_ONCE(src->preempted);
671 		if ((state & KVM_VCPU_PREEMPTED)) {
672 			if (try_cmpxchg(&src->preempted, &state,
673 					state | KVM_VCPU_FLUSH_TLB))
674 				__cpumask_clear_cpu(cpu, flushmask);
675 		}
676 	}
677 
678 	native_flush_tlb_multi(flushmask, info);
679 }
680 
kvm_alloc_cpumask(void)681 static __init int kvm_alloc_cpumask(void)
682 {
683 	int cpu;
684 
685 	if (!kvm_para_available() || nopv)
686 		return 0;
687 
688 	if (pv_tlb_flush_supported() || pv_ipi_supported())
689 		for_each_possible_cpu(cpu) {
690 			zalloc_cpumask_var_node(per_cpu_ptr(&__pv_cpu_mask, cpu),
691 				GFP_KERNEL, cpu_to_node(cpu));
692 		}
693 
694 	return 0;
695 }
696 arch_initcall(kvm_alloc_cpumask);
697 
kvm_smp_prepare_boot_cpu(void)698 static void __init kvm_smp_prepare_boot_cpu(void)
699 {
700 	/*
701 	 * Map the per-cpu variables as decrypted before kvm_guest_cpu_init()
702 	 * shares the guest physical address with the hypervisor.
703 	 */
704 	sev_map_percpu_data();
705 
706 	kvm_guest_cpu_init();
707 	native_smp_prepare_boot_cpu();
708 	kvm_spinlock_init();
709 }
710 
kvm_cpu_down_prepare(unsigned int cpu)711 static int kvm_cpu_down_prepare(unsigned int cpu)
712 {
713 	unsigned long flags;
714 
715 	local_irq_save(flags);
716 	kvm_guest_cpu_offline(false);
717 	local_irq_restore(flags);
718 	return 0;
719 }
720 
721 #endif
722 
kvm_suspend(void)723 static int kvm_suspend(void)
724 {
725 	u64 val = 0;
726 
727 	kvm_guest_cpu_offline(false);
728 
729 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
730 	if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
731 		rdmsrl(MSR_KVM_POLL_CONTROL, val);
732 	has_guest_poll = !(val & 1);
733 #endif
734 	return 0;
735 }
736 
kvm_resume(void)737 static void kvm_resume(void)
738 {
739 	kvm_cpu_online(raw_smp_processor_id());
740 
741 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
742 	if (kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL) && has_guest_poll)
743 		wrmsrl(MSR_KVM_POLL_CONTROL, 0);
744 #endif
745 }
746 
747 static struct syscore_ops kvm_syscore_ops = {
748 	.suspend	= kvm_suspend,
749 	.resume		= kvm_resume,
750 };
751 
kvm_pv_guest_cpu_reboot(void * unused)752 static void kvm_pv_guest_cpu_reboot(void *unused)
753 {
754 	kvm_guest_cpu_offline(true);
755 }
756 
kvm_pv_reboot_notify(struct notifier_block * nb,unsigned long code,void * unused)757 static int kvm_pv_reboot_notify(struct notifier_block *nb,
758 				unsigned long code, void *unused)
759 {
760 	if (code == SYS_RESTART)
761 		on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
762 	return NOTIFY_DONE;
763 }
764 
765 static struct notifier_block kvm_pv_reboot_nb = {
766 	.notifier_call = kvm_pv_reboot_notify,
767 };
768 
769 /*
770  * After a PV feature is registered, the host will keep writing to the
771  * registered memory location. If the guest happens to shutdown, this memory
772  * won't be valid. In cases like kexec, in which you install a new kernel, this
773  * means a random memory location will be kept being written.
774  */
775 #ifdef CONFIG_CRASH_DUMP
kvm_crash_shutdown(struct pt_regs * regs)776 static void kvm_crash_shutdown(struct pt_regs *regs)
777 {
778 	kvm_guest_cpu_offline(true);
779 	native_machine_crash_shutdown(regs);
780 }
781 #endif
782 
783 #if defined(CONFIG_X86_32) || !defined(CONFIG_SMP)
784 bool __kvm_vcpu_is_preempted(long cpu);
785 
__kvm_vcpu_is_preempted(long cpu)786 __visible bool __kvm_vcpu_is_preempted(long cpu)
787 {
788 	struct kvm_steal_time *src = &per_cpu(steal_time, cpu);
789 
790 	return !!(src->preempted & KVM_VCPU_PREEMPTED);
791 }
792 PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted);
793 
794 #else
795 
796 #include <asm/asm-offsets.h>
797 
798 extern bool __raw_callee_save___kvm_vcpu_is_preempted(long);
799 
800 /*
801  * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and
802  * restoring to/from the stack.
803  */
804 #define PV_VCPU_PREEMPTED_ASM						     \
805  "movq   __per_cpu_offset(,%rdi,8), %rax\n\t"				     \
806  "cmpb   $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax)\n\t" \
807  "setne  %al\n\t"
808 
809 DEFINE_ASM_FUNC(__raw_callee_save___kvm_vcpu_is_preempted,
810 		PV_VCPU_PREEMPTED_ASM, .text);
811 #endif
812 
kvm_guest_init(void)813 static void __init kvm_guest_init(void)
814 {
815 	int i;
816 
817 	paravirt_ops_setup();
818 	register_reboot_notifier(&kvm_pv_reboot_nb);
819 	for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
820 		raw_spin_lock_init(&async_pf_sleepers[i].lock);
821 
822 	if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
823 		has_steal_clock = 1;
824 		static_call_update(pv_steal_clock, kvm_steal_clock);
825 
826 		pv_ops.lock.vcpu_is_preempted =
827 			PV_CALLEE_SAVE(__kvm_vcpu_is_preempted);
828 	}
829 
830 	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
831 		apic_update_callback(eoi, kvm_guest_apic_eoi_write);
832 
833 	if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) {
834 		static_branch_enable(&kvm_async_pf_enabled);
835 		sysvec_install(HYPERVISOR_CALLBACK_VECTOR, sysvec_kvm_asyncpf_interrupt);
836 	}
837 
838 #ifdef CONFIG_SMP
839 	if (pv_tlb_flush_supported()) {
840 		pv_ops.mmu.flush_tlb_multi = kvm_flush_tlb_multi;
841 		pr_info("KVM setup pv remote TLB flush\n");
842 	}
843 
844 	smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
845 	if (pv_sched_yield_supported()) {
846 		smp_ops.send_call_func_ipi = kvm_smp_send_call_func_ipi;
847 		pr_info("setup PV sched yield\n");
848 	}
849 	if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online",
850 				      kvm_cpu_online, kvm_cpu_down_prepare) < 0)
851 		pr_err("failed to install cpu hotplug callbacks\n");
852 #else
853 	sev_map_percpu_data();
854 	kvm_guest_cpu_init();
855 #endif
856 
857 #ifdef CONFIG_CRASH_DUMP
858 	machine_ops.crash_shutdown = kvm_crash_shutdown;
859 #endif
860 
861 	register_syscore_ops(&kvm_syscore_ops);
862 
863 	/*
864 	 * Hard lockup detection is enabled by default. Disable it, as guests
865 	 * can get false positives too easily, for example if the host is
866 	 * overcommitted.
867 	 */
868 	hardlockup_detector_disable();
869 }
870 
__kvm_cpuid_base(void)871 static noinline uint32_t __kvm_cpuid_base(void)
872 {
873 	if (boot_cpu_data.cpuid_level < 0)
874 		return 0;	/* So we don't blow up on old processors */
875 
876 	if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
877 		return hypervisor_cpuid_base(KVM_SIGNATURE, 0);
878 
879 	return 0;
880 }
881 
kvm_cpuid_base(void)882 static inline uint32_t kvm_cpuid_base(void)
883 {
884 	static int kvm_cpuid_base = -1;
885 
886 	if (kvm_cpuid_base == -1)
887 		kvm_cpuid_base = __kvm_cpuid_base();
888 
889 	return kvm_cpuid_base;
890 }
891 
kvm_para_available(void)892 bool kvm_para_available(void)
893 {
894 	return kvm_cpuid_base() != 0;
895 }
896 EXPORT_SYMBOL_GPL(kvm_para_available);
897 
kvm_arch_para_features(void)898 unsigned int kvm_arch_para_features(void)
899 {
900 	return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES);
901 }
902 
kvm_arch_para_hints(void)903 unsigned int kvm_arch_para_hints(void)
904 {
905 	return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES);
906 }
907 EXPORT_SYMBOL_GPL(kvm_arch_para_hints);
908 
kvm_detect(void)909 static uint32_t __init kvm_detect(void)
910 {
911 	return kvm_cpuid_base();
912 }
913 
kvm_apic_init(void)914 static void __init kvm_apic_init(void)
915 {
916 #ifdef CONFIG_SMP
917 	if (pv_ipi_supported())
918 		kvm_setup_pv_ipi();
919 #endif
920 }
921 
kvm_msi_ext_dest_id(void)922 static bool __init kvm_msi_ext_dest_id(void)
923 {
924 	return kvm_para_has_feature(KVM_FEATURE_MSI_EXT_DEST_ID);
925 }
926 
kvm_sev_hc_page_enc_status(unsigned long pfn,int npages,bool enc)927 static void kvm_sev_hc_page_enc_status(unsigned long pfn, int npages, bool enc)
928 {
929 	kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, pfn << PAGE_SHIFT, npages,
930 			   KVM_MAP_GPA_RANGE_ENC_STAT(enc) | KVM_MAP_GPA_RANGE_PAGE_SZ_4K);
931 }
932 
kvm_init_platform(void)933 static void __init kvm_init_platform(void)
934 {
935 	if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) &&
936 	    kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) {
937 		unsigned long nr_pages;
938 		int i;
939 
940 		pv_ops.mmu.notify_page_enc_status_changed =
941 			kvm_sev_hc_page_enc_status;
942 
943 		/*
944 		 * Reset the host's shared pages list related to kernel
945 		 * specific page encryption status settings before we load a
946 		 * new kernel by kexec. Reset the page encryption status
947 		 * during early boot instead of just before kexec to avoid SMP
948 		 * races during kvm_pv_guest_cpu_reboot().
949 		 * NOTE: We cannot reset the complete shared pages list
950 		 * here as we need to retain the UEFI/OVMF firmware
951 		 * specific settings.
952 		 */
953 
954 		for (i = 0; i < e820_table->nr_entries; i++) {
955 			struct e820_entry *entry = &e820_table->entries[i];
956 
957 			if (entry->type != E820_TYPE_RAM)
958 				continue;
959 
960 			nr_pages = DIV_ROUND_UP(entry->size, PAGE_SIZE);
961 
962 			kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, entry->addr,
963 				       nr_pages,
964 				       KVM_MAP_GPA_RANGE_ENCRYPTED | KVM_MAP_GPA_RANGE_PAGE_SZ_4K);
965 		}
966 
967 		/*
968 		 * Ensure that _bss_decrypted section is marked as decrypted in the
969 		 * shared pages list.
970 		 */
971 		early_set_mem_enc_dec_hypercall((unsigned long)__start_bss_decrypted,
972 						__end_bss_decrypted - __start_bss_decrypted, 0);
973 
974 		/*
975 		 * If not booted using EFI, enable Live migration support.
976 		 */
977 		if (!efi_enabled(EFI_BOOT))
978 			wrmsrl(MSR_KVM_MIGRATION_CONTROL,
979 			       KVM_MIGRATION_READY);
980 	}
981 	kvmclock_init();
982 	x86_platform.apic_post_init = kvm_apic_init;
983 
984 	/* Set WB as the default cache mode for SEV-SNP and TDX */
985 	guest_force_mtrr_state(NULL, 0, MTRR_TYPE_WRBACK);
986 }
987 
988 #if defined(CONFIG_AMD_MEM_ENCRYPT)
kvm_sev_es_hcall_prepare(struct ghcb * ghcb,struct pt_regs * regs)989 static void kvm_sev_es_hcall_prepare(struct ghcb *ghcb, struct pt_regs *regs)
990 {
991 	/* RAX and CPL are already in the GHCB */
992 	ghcb_set_rbx(ghcb, regs->bx);
993 	ghcb_set_rcx(ghcb, regs->cx);
994 	ghcb_set_rdx(ghcb, regs->dx);
995 	ghcb_set_rsi(ghcb, regs->si);
996 }
997 
kvm_sev_es_hcall_finish(struct ghcb * ghcb,struct pt_regs * regs)998 static bool kvm_sev_es_hcall_finish(struct ghcb *ghcb, struct pt_regs *regs)
999 {
1000 	/* No checking of the return state needed */
1001 	return true;
1002 }
1003 #endif
1004 
1005 const __initconst struct hypervisor_x86 x86_hyper_kvm = {
1006 	.name				= "KVM",
1007 	.detect				= kvm_detect,
1008 	.type				= X86_HYPER_KVM,
1009 	.init.guest_late_init		= kvm_guest_init,
1010 	.init.x2apic_available		= kvm_para_available,
1011 	.init.msi_ext_dest_id		= kvm_msi_ext_dest_id,
1012 	.init.init_platform		= kvm_init_platform,
1013 #if defined(CONFIG_AMD_MEM_ENCRYPT)
1014 	.runtime.sev_es_hcall_prepare	= kvm_sev_es_hcall_prepare,
1015 	.runtime.sev_es_hcall_finish	= kvm_sev_es_hcall_finish,
1016 #endif
1017 };
1018 
activate_jump_labels(void)1019 static __init int activate_jump_labels(void)
1020 {
1021 	if (has_steal_clock) {
1022 		static_key_slow_inc(&paravirt_steal_enabled);
1023 		if (steal_acc)
1024 			static_key_slow_inc(&paravirt_steal_rq_enabled);
1025 	}
1026 
1027 	return 0;
1028 }
1029 arch_initcall(activate_jump_labels);
1030 
1031 #ifdef CONFIG_PARAVIRT_SPINLOCKS
1032 
1033 /* Kick a cpu by its apicid. Used to wake up a halted vcpu */
kvm_kick_cpu(int cpu)1034 static void kvm_kick_cpu(int cpu)
1035 {
1036 	unsigned long flags = 0;
1037 	u32 apicid;
1038 
1039 	apicid = per_cpu(x86_cpu_to_apicid, cpu);
1040 	kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid);
1041 }
1042 
1043 #include <asm/qspinlock.h>
1044 
kvm_wait(u8 * ptr,u8 val)1045 static void kvm_wait(u8 *ptr, u8 val)
1046 {
1047 	if (in_nmi())
1048 		return;
1049 
1050 	/*
1051 	 * halt until it's our turn and kicked. Note that we do safe halt
1052 	 * for irq enabled case to avoid hang when lock info is overwritten
1053 	 * in irq spinlock slowpath and no spurious interrupt occur to save us.
1054 	 */
1055 	if (irqs_disabled()) {
1056 		if (READ_ONCE(*ptr) == val)
1057 			halt();
1058 	} else {
1059 		local_irq_disable();
1060 
1061 		/* safe_halt() will enable IRQ */
1062 		if (READ_ONCE(*ptr) == val)
1063 			safe_halt();
1064 		else
1065 			local_irq_enable();
1066 	}
1067 }
1068 
1069 /*
1070  * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present.
1071  */
kvm_spinlock_init(void)1072 void __init kvm_spinlock_init(void)
1073 {
1074 	/*
1075 	 * In case host doesn't support KVM_FEATURE_PV_UNHALT there is still an
1076 	 * advantage of keeping virt_spin_lock_key enabled: virt_spin_lock() is
1077 	 * preferred over native qspinlock when vCPU is preempted.
1078 	 */
1079 	if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT)) {
1080 		pr_info("PV spinlocks disabled, no host support\n");
1081 		return;
1082 	}
1083 
1084 	/*
1085 	 * Disable PV spinlocks and use native qspinlock when dedicated pCPUs
1086 	 * are available.
1087 	 */
1088 	if (kvm_para_has_hint(KVM_HINTS_REALTIME)) {
1089 		pr_info("PV spinlocks disabled with KVM_HINTS_REALTIME hints\n");
1090 		goto out;
1091 	}
1092 
1093 	if (num_possible_cpus() == 1) {
1094 		pr_info("PV spinlocks disabled, single CPU\n");
1095 		goto out;
1096 	}
1097 
1098 	if (nopvspin) {
1099 		pr_info("PV spinlocks disabled, forced by \"nopvspin\" parameter\n");
1100 		goto out;
1101 	}
1102 
1103 	pr_info("PV spinlocks enabled\n");
1104 
1105 	__pv_init_lock_hash();
1106 	pv_ops.lock.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
1107 	pv_ops.lock.queued_spin_unlock =
1108 		PV_CALLEE_SAVE(__pv_queued_spin_unlock);
1109 	pv_ops.lock.wait = kvm_wait;
1110 	pv_ops.lock.kick = kvm_kick_cpu;
1111 
1112 	/*
1113 	 * When PV spinlock is enabled which is preferred over
1114 	 * virt_spin_lock(), virt_spin_lock_key's value is meaningless.
1115 	 * Just disable it anyway.
1116 	 */
1117 out:
1118 	static_branch_disable(&virt_spin_lock_key);
1119 }
1120 
1121 #endif	/* CONFIG_PARAVIRT_SPINLOCKS */
1122 
1123 #ifdef CONFIG_ARCH_CPUIDLE_HALTPOLL
1124 
kvm_disable_host_haltpoll(void * i)1125 static void kvm_disable_host_haltpoll(void *i)
1126 {
1127 	wrmsrl(MSR_KVM_POLL_CONTROL, 0);
1128 }
1129 
kvm_enable_host_haltpoll(void * i)1130 static void kvm_enable_host_haltpoll(void *i)
1131 {
1132 	wrmsrl(MSR_KVM_POLL_CONTROL, 1);
1133 }
1134 
arch_haltpoll_enable(unsigned int cpu)1135 void arch_haltpoll_enable(unsigned int cpu)
1136 {
1137 	if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL)) {
1138 		pr_err_once("host does not support poll control\n");
1139 		pr_err_once("host upgrade recommended\n");
1140 		return;
1141 	}
1142 
1143 	/* Enable guest halt poll disables host halt poll */
1144 	smp_call_function_single(cpu, kvm_disable_host_haltpoll, NULL, 1);
1145 }
1146 EXPORT_SYMBOL_GPL(arch_haltpoll_enable);
1147 
arch_haltpoll_disable(unsigned int cpu)1148 void arch_haltpoll_disable(unsigned int cpu)
1149 {
1150 	if (!kvm_para_has_feature(KVM_FEATURE_POLL_CONTROL))
1151 		return;
1152 
1153 	/* Disable guest halt poll enables host halt poll */
1154 	smp_call_function_single(cpu, kvm_enable_host_haltpoll, NULL, 1);
1155 }
1156 EXPORT_SYMBOL_GPL(arch_haltpoll_disable);
1157 #endif
1158