Commit | Line | Data |
---|---|---|
0cf1bfd2 MT |
1 | /* |
2 | * KVM paravirt_ops implementation | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation; either version 2 of the License, or | |
7 | * (at your option) any later version. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * along with this program; if not, write to the Free Software | |
16 | * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. | |
17 | * | |
18 | * Copyright (C) 2007, Red Hat, Inc., Ingo Molnar <mingo@redhat.com> | |
19 | * Copyright IBM Corporation, 2007 | |
20 | * Authors: Anthony Liguori <aliguori@us.ibm.com> | |
21 | */ | |
22 | ||
56dd9470 | 23 | #include <linux/context_tracking.h> |
0cf1bfd2 MT |
24 | #include <linux/module.h> |
25 | #include <linux/kernel.h> | |
26 | #include <linux/kvm_para.h> | |
27 | #include <linux/cpu.h> | |
28 | #include <linux/mm.h> | |
1da8a77b | 29 | #include <linux/highmem.h> |
096d14a3 | 30 | #include <linux/hardirq.h> |
fd10cde9 GN |
31 | #include <linux/notifier.h> |
32 | #include <linux/reboot.h> | |
631bc487 GN |
33 | #include <linux/hash.h> |
34 | #include <linux/sched.h> | |
35 | #include <linux/slab.h> | |
36 | #include <linux/kprobes.h> | |
92b75202 | 37 | #include <linux/debugfs.h> |
9919e39a | 38 | #include <linux/nmi.h> |
a90ede7b | 39 | #include <asm/timer.h> |
fd10cde9 | 40 | #include <asm/cpu.h> |
631bc487 GN |
41 | #include <asm/traps.h> |
42 | #include <asm/desc.h> | |
6c047cd9 | 43 | #include <asm/tlbflush.h> |
e0875921 | 44 | #include <asm/idle.h> |
ab9cf499 MT |
45 | #include <asm/apic.h> |
46 | #include <asm/apicdef.h> | |
fc73373b | 47 | #include <asm/hypervisor.h> |
3dc4f7cf | 48 | #include <asm/kvm_guest.h> |
096d14a3 | 49 | |
fd10cde9 GN |
50 | static int kvmapf = 1; |
51 | ||
52 | static int parse_no_kvmapf(char *arg) | |
53 | { | |
54 | kvmapf = 0; | |
55 | return 0; | |
56 | } | |
57 | ||
58 | early_param("no-kvmapf", parse_no_kvmapf); | |
59 | ||
d910f5c1 GC |
60 | static int steal_acc = 1; |
61 | static int 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 | ||
3dc4f7cf MT |
69 | static int kvmclock_vsyscall = 1; |
70 | static int parse_no_kvmclock_vsyscall(char *arg) | |
71 | { | |
72 | kvmclock_vsyscall = 0; | |
73 | return 0; | |
74 | } | |
75 | ||
76 | early_param("no-kvmclock-vsyscall", parse_no_kvmclock_vsyscall); | |
77 | ||
fd10cde9 | 78 | static DEFINE_PER_CPU(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64); |
d910f5c1 GC |
79 | static DEFINE_PER_CPU(struct kvm_steal_time, steal_time) __aligned(64); |
80 | static int has_steal_clock = 0; | |
096d14a3 | 81 | |
0cf1bfd2 MT |
82 | /* |
83 | * No need for any "IO delay" on KVM | |
84 | */ | |
85 | static void kvm_io_delay(void) | |
86 | { | |
87 | } | |
88 | ||
631bc487 GN |
89 | #define KVM_TASK_SLEEP_HASHBITS 8 |
90 | #define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS) | |
91 | ||
92 | struct kvm_task_sleep_node { | |
93 | struct hlist_node link; | |
94 | wait_queue_head_t wq; | |
95 | u32 token; | |
96 | int cpu; | |
6c047cd9 | 97 | bool halted; |
631bc487 GN |
98 | }; |
99 | ||
100 | static struct kvm_task_sleep_head { | |
101 | spinlock_t lock; | |
102 | struct hlist_head list; | |
103 | } async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE]; | |
104 | ||
105 | static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b, | |
106 | u32 token) | |
107 | { | |
108 | struct hlist_node *p; | |
109 | ||
110 | hlist_for_each(p, &b->list) { | |
111 | struct kvm_task_sleep_node *n = | |
112 | hlist_entry(p, typeof(*n), link); | |
113 | if (n->token == token) | |
114 | return n; | |
115 | } | |
116 | ||
117 | return NULL; | |
118 | } | |
119 | ||
120 | void kvm_async_pf_task_wait(u32 token) | |
121 | { | |
122 | u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS); | |
123 | struct kvm_task_sleep_head *b = &async_pf_sleepers[key]; | |
124 | struct kvm_task_sleep_node n, *e; | |
125 | DEFINE_WAIT(wait); | |
126 | ||
9b132fbe LZ |
127 | rcu_irq_enter(); |
128 | ||
631bc487 GN |
129 | spin_lock(&b->lock); |
130 | e = _find_apf_task(b, token); | |
131 | if (e) { | |
132 | /* dummy entry exist -> wake up was delivered ahead of PF */ | |
133 | hlist_del(&e->link); | |
134 | kfree(e); | |
135 | spin_unlock(&b->lock); | |
9b132fbe LZ |
136 | |
137 | rcu_irq_exit(); | |
631bc487 GN |
138 | return; |
139 | } | |
140 | ||
141 | n.token = token; | |
142 | n.cpu = smp_processor_id(); | |
859f8450 | 143 | n.halted = is_idle_task(current) || preempt_count() > 1; |
631bc487 GN |
144 | init_waitqueue_head(&n.wq); |
145 | hlist_add_head(&n.link, &b->list); | |
146 | spin_unlock(&b->lock); | |
147 | ||
148 | for (;;) { | |
6c047cd9 GN |
149 | if (!n.halted) |
150 | prepare_to_wait(&n.wq, &wait, TASK_UNINTERRUPTIBLE); | |
631bc487 GN |
151 | if (hlist_unhashed(&n.link)) |
152 | break; | |
6c047cd9 GN |
153 | |
154 | if (!n.halted) { | |
155 | local_irq_enable(); | |
156 | schedule(); | |
157 | local_irq_disable(); | |
158 | } else { | |
159 | /* | |
160 | * We cannot reschedule. So halt. | |
161 | */ | |
9b132fbe | 162 | rcu_irq_exit(); |
6c047cd9 | 163 | native_safe_halt(); |
9b132fbe | 164 | rcu_irq_enter(); |
6c047cd9 GN |
165 | local_irq_disable(); |
166 | } | |
631bc487 | 167 | } |
6c047cd9 GN |
168 | if (!n.halted) |
169 | finish_wait(&n.wq, &wait); | |
631bc487 | 170 | |
9b132fbe | 171 | rcu_irq_exit(); |
631bc487 GN |
172 | return; |
173 | } | |
174 | EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait); | |
175 | ||
176 | static void apf_task_wake_one(struct kvm_task_sleep_node *n) | |
177 | { | |
178 | hlist_del_init(&n->link); | |
6c047cd9 GN |
179 | if (n->halted) |
180 | smp_send_reschedule(n->cpu); | |
181 | else if (waitqueue_active(&n->wq)) | |
631bc487 GN |
182 | wake_up(&n->wq); |
183 | } | |
184 | ||
185 | static void apf_task_wake_all(void) | |
186 | { | |
187 | int i; | |
188 | ||
189 | for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) { | |
190 | struct hlist_node *p, *next; | |
191 | struct kvm_task_sleep_head *b = &async_pf_sleepers[i]; | |
192 | spin_lock(&b->lock); | |
193 | hlist_for_each_safe(p, next, &b->list) { | |
194 | struct kvm_task_sleep_node *n = | |
195 | hlist_entry(p, typeof(*n), link); | |
196 | if (n->cpu == smp_processor_id()) | |
197 | apf_task_wake_one(n); | |
198 | } | |
199 | spin_unlock(&b->lock); | |
200 | } | |
201 | } | |
202 | ||
203 | void kvm_async_pf_task_wake(u32 token) | |
204 | { | |
205 | u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS); | |
206 | struct kvm_task_sleep_head *b = &async_pf_sleepers[key]; | |
207 | struct kvm_task_sleep_node *n; | |
208 | ||
209 | if (token == ~0) { | |
210 | apf_task_wake_all(); | |
211 | return; | |
212 | } | |
213 | ||
214 | again: | |
215 | spin_lock(&b->lock); | |
216 | n = _find_apf_task(b, token); | |
217 | if (!n) { | |
218 | /* | |
219 | * async PF was not yet handled. | |
220 | * Add dummy entry for the token. | |
221 | */ | |
62c49cc9 | 222 | n = kzalloc(sizeof(*n), GFP_ATOMIC); |
631bc487 GN |
223 | if (!n) { |
224 | /* | |
225 | * Allocation failed! Busy wait while other cpu | |
226 | * handles async PF. | |
227 | */ | |
228 | spin_unlock(&b->lock); | |
229 | cpu_relax(); | |
230 | goto again; | |
231 | } | |
232 | n->token = token; | |
233 | n->cpu = smp_processor_id(); | |
234 | init_waitqueue_head(&n->wq); | |
235 | hlist_add_head(&n->link, &b->list); | |
236 | } else | |
237 | apf_task_wake_one(n); | |
238 | spin_unlock(&b->lock); | |
239 | return; | |
240 | } | |
241 | EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake); | |
242 | ||
243 | u32 kvm_read_and_reset_pf_reason(void) | |
244 | { | |
245 | u32 reason = 0; | |
246 | ||
89cbc767 CL |
247 | if (__this_cpu_read(apf_reason.enabled)) { |
248 | reason = __this_cpu_read(apf_reason.reason); | |
249 | __this_cpu_write(apf_reason.reason, 0); | |
631bc487 GN |
250 | } |
251 | ||
252 | return reason; | |
253 | } | |
254 | EXPORT_SYMBOL_GPL(kvm_read_and_reset_pf_reason); | |
9326638c | 255 | NOKPROBE_SYMBOL(kvm_read_and_reset_pf_reason); |
631bc487 | 256 | |
9326638c | 257 | dotraplinkage void |
631bc487 GN |
258 | do_async_page_fault(struct pt_regs *regs, unsigned long error_code) |
259 | { | |
6c1e0256 FW |
260 | enum ctx_state prev_state; |
261 | ||
631bc487 GN |
262 | switch (kvm_read_and_reset_pf_reason()) { |
263 | default: | |
65a7f03f | 264 | trace_do_page_fault(regs, error_code); |
631bc487 GN |
265 | break; |
266 | case KVM_PV_REASON_PAGE_NOT_PRESENT: | |
267 | /* page is swapped out by the host. */ | |
6c1e0256 | 268 | prev_state = exception_enter(); |
c5e015d4 | 269 | exit_idle(); |
631bc487 | 270 | kvm_async_pf_task_wait((u32)read_cr2()); |
6c1e0256 | 271 | exception_exit(prev_state); |
631bc487 GN |
272 | break; |
273 | case KVM_PV_REASON_PAGE_READY: | |
e0875921 GN |
274 | rcu_irq_enter(); |
275 | exit_idle(); | |
631bc487 | 276 | kvm_async_pf_task_wake((u32)read_cr2()); |
e0875921 | 277 | rcu_irq_exit(); |
631bc487 GN |
278 | break; |
279 | } | |
280 | } | |
9326638c | 281 | NOKPROBE_SYMBOL(do_async_page_fault); |
631bc487 | 282 | |
d3ac8815 | 283 | static void __init paravirt_ops_setup(void) |
0cf1bfd2 MT |
284 | { |
285 | pv_info.name = "KVM"; | |
29fa6825 AL |
286 | |
287 | /* | |
288 | * KVM isn't paravirt in the sense of paravirt_enabled. A KVM | |
289 | * guest kernel works like a bare metal kernel with additional | |
290 | * features, and paravirt_enabled is about features that are | |
291 | * missing. | |
292 | */ | |
293 | pv_info.paravirt_enabled = 0; | |
0cf1bfd2 MT |
294 | |
295 | if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY)) | |
296 | pv_cpu_ops.io_delay = kvm_io_delay; | |
297 | ||
a90ede7b MT |
298 | #ifdef CONFIG_X86_IO_APIC |
299 | no_timer_check = 1; | |
300 | #endif | |
0cf1bfd2 MT |
301 | } |
302 | ||
d910f5c1 GC |
303 | static void kvm_register_steal_time(void) |
304 | { | |
305 | int cpu = smp_processor_id(); | |
306 | struct kvm_steal_time *st = &per_cpu(steal_time, cpu); | |
307 | ||
308 | if (!has_steal_clock) | |
309 | return; | |
310 | ||
311 | memset(st, 0, sizeof(*st)); | |
312 | ||
5dfd486c | 313 | wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED)); |
136867f5 SK |
314 | pr_info("kvm-stealtime: cpu %d, msr %llx\n", |
315 | cpu, (unsigned long long) slow_virt_to_phys(st)); | |
d910f5c1 GC |
316 | } |
317 | ||
ab9cf499 MT |
318 | static DEFINE_PER_CPU(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED; |
319 | ||
320 | static void kvm_guest_apic_eoi_write(u32 reg, u32 val) | |
321 | { | |
322 | /** | |
323 | * This relies on __test_and_clear_bit to modify the memory | |
324 | * in a way that is atomic with respect to the local CPU. | |
325 | * The hypervisor only accesses this memory from the local CPU so | |
326 | * there's no need for lock or memory barriers. | |
327 | * An optimization barrier is implied in apic write. | |
328 | */ | |
89cbc767 | 329 | if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi))) |
ab9cf499 | 330 | return; |
90536664 | 331 | apic_write(APIC_EOI, APIC_EOI_ACK); |
ab9cf499 MT |
332 | } |
333 | ||
148f9bb8 | 334 | void kvm_guest_cpu_init(void) |
fd10cde9 GN |
335 | { |
336 | if (!kvm_para_available()) | |
337 | return; | |
338 | ||
339 | if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF) && kvmapf) { | |
89cbc767 | 340 | u64 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason)); |
fd10cde9 | 341 | |
6adba527 GN |
342 | #ifdef CONFIG_PREEMPT |
343 | pa |= KVM_ASYNC_PF_SEND_ALWAYS; | |
344 | #endif | |
fd10cde9 | 345 | wrmsrl(MSR_KVM_ASYNC_PF_EN, pa | KVM_ASYNC_PF_ENABLED); |
89cbc767 | 346 | __this_cpu_write(apf_reason.enabled, 1); |
fd10cde9 GN |
347 | printk(KERN_INFO"KVM setup async PF for cpu %d\n", |
348 | smp_processor_id()); | |
349 | } | |
d910f5c1 | 350 | |
ab9cf499 MT |
351 | if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) { |
352 | unsigned long pa; | |
353 | /* Size alignment is implied but just to make it explicit. */ | |
354 | BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4); | |
89cbc767 CL |
355 | __this_cpu_write(kvm_apic_eoi, 0); |
356 | pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi)) | |
5dfd486c | 357 | | KVM_MSR_ENABLED; |
ab9cf499 MT |
358 | wrmsrl(MSR_KVM_PV_EOI_EN, pa); |
359 | } | |
360 | ||
d910f5c1 GC |
361 | if (has_steal_clock) |
362 | kvm_register_steal_time(); | |
fd10cde9 GN |
363 | } |
364 | ||
ab9cf499 | 365 | static void kvm_pv_disable_apf(void) |
fd10cde9 | 366 | { |
89cbc767 | 367 | if (!__this_cpu_read(apf_reason.enabled)) |
fd10cde9 GN |
368 | return; |
369 | ||
370 | wrmsrl(MSR_KVM_ASYNC_PF_EN, 0); | |
89cbc767 | 371 | __this_cpu_write(apf_reason.enabled, 0); |
fd10cde9 GN |
372 | |
373 | printk(KERN_INFO"Unregister pv shared memory for cpu %d\n", | |
374 | smp_processor_id()); | |
375 | } | |
376 | ||
ab9cf499 MT |
377 | static void kvm_pv_guest_cpu_reboot(void *unused) |
378 | { | |
379 | /* | |
380 | * We disable PV EOI before we load a new kernel by kexec, | |
381 | * since MSR_KVM_PV_EOI_EN stores a pointer into old kernel's memory. | |
382 | * New kernel can re-enable when it boots. | |
383 | */ | |
384 | if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) | |
385 | wrmsrl(MSR_KVM_PV_EOI_EN, 0); | |
386 | kvm_pv_disable_apf(); | |
8fbe6a54 | 387 | kvm_disable_steal_time(); |
ab9cf499 MT |
388 | } |
389 | ||
fd10cde9 GN |
390 | static int kvm_pv_reboot_notify(struct notifier_block *nb, |
391 | unsigned long code, void *unused) | |
392 | { | |
393 | if (code == SYS_RESTART) | |
ab9cf499 | 394 | on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1); |
fd10cde9 GN |
395 | return NOTIFY_DONE; |
396 | } | |
397 | ||
398 | static struct notifier_block kvm_pv_reboot_nb = { | |
399 | .notifier_call = kvm_pv_reboot_notify, | |
400 | }; | |
401 | ||
d910f5c1 GC |
402 | static u64 kvm_steal_clock(int cpu) |
403 | { | |
404 | u64 steal; | |
405 | struct kvm_steal_time *src; | |
406 | int version; | |
407 | ||
408 | src = &per_cpu(steal_time, cpu); | |
409 | do { | |
410 | version = src->version; | |
411 | rmb(); | |
412 | steal = src->steal; | |
413 | rmb(); | |
414 | } while ((version & 1) || (version != src->version)); | |
415 | ||
416 | return steal; | |
417 | } | |
418 | ||
419 | void kvm_disable_steal_time(void) | |
420 | { | |
421 | if (!has_steal_clock) | |
422 | return; | |
423 | ||
424 | wrmsr(MSR_KVM_STEAL_TIME, 0, 0); | |
425 | } | |
426 | ||
ca3f1017 GN |
427 | #ifdef CONFIG_SMP |
428 | static void __init kvm_smp_prepare_boot_cpu(void) | |
429 | { | |
fd10cde9 | 430 | kvm_guest_cpu_init(); |
ca3f1017 | 431 | native_smp_prepare_boot_cpu(); |
92b75202 | 432 | kvm_spinlock_init(); |
ca3f1017 | 433 | } |
fd10cde9 | 434 | |
148f9bb8 | 435 | static void kvm_guest_cpu_online(void *dummy) |
fd10cde9 GN |
436 | { |
437 | kvm_guest_cpu_init(); | |
438 | } | |
439 | ||
440 | static void kvm_guest_cpu_offline(void *dummy) | |
441 | { | |
d910f5c1 | 442 | kvm_disable_steal_time(); |
ab9cf499 MT |
443 | if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) |
444 | wrmsrl(MSR_KVM_PV_EOI_EN, 0); | |
445 | kvm_pv_disable_apf(); | |
631bc487 | 446 | apf_task_wake_all(); |
fd10cde9 GN |
447 | } |
448 | ||
148f9bb8 PG |
449 | static int kvm_cpu_notify(struct notifier_block *self, unsigned long action, |
450 | void *hcpu) | |
fd10cde9 GN |
451 | { |
452 | int cpu = (unsigned long)hcpu; | |
453 | switch (action) { | |
454 | case CPU_ONLINE: | |
455 | case CPU_DOWN_FAILED: | |
456 | case CPU_ONLINE_FROZEN: | |
457 | smp_call_function_single(cpu, kvm_guest_cpu_online, NULL, 0); | |
458 | break; | |
459 | case CPU_DOWN_PREPARE: | |
460 | case CPU_DOWN_PREPARE_FROZEN: | |
461 | smp_call_function_single(cpu, kvm_guest_cpu_offline, NULL, 1); | |
462 | break; | |
463 | default: | |
464 | break; | |
465 | } | |
466 | return NOTIFY_OK; | |
467 | } | |
468 | ||
148f9bb8 | 469 | static struct notifier_block kvm_cpu_notifier = { |
fd10cde9 GN |
470 | .notifier_call = kvm_cpu_notify, |
471 | }; | |
ca3f1017 GN |
472 | #endif |
473 | ||
631bc487 GN |
474 | static void __init kvm_apf_trap_init(void) |
475 | { | |
25c74b10 | 476 | set_intr_gate(14, async_page_fault); |
631bc487 GN |
477 | } |
478 | ||
0cf1bfd2 MT |
479 | void __init kvm_guest_init(void) |
480 | { | |
631bc487 GN |
481 | int i; |
482 | ||
0cf1bfd2 MT |
483 | if (!kvm_para_available()) |
484 | return; | |
485 | ||
486 | paravirt_ops_setup(); | |
fd10cde9 | 487 | register_reboot_notifier(&kvm_pv_reboot_nb); |
631bc487 GN |
488 | for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) |
489 | spin_lock_init(&async_pf_sleepers[i].lock); | |
490 | if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF)) | |
491 | x86_init.irqs.trap_init = kvm_apf_trap_init; | |
492 | ||
d910f5c1 GC |
493 | if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) { |
494 | has_steal_clock = 1; | |
495 | pv_time_ops.steal_clock = kvm_steal_clock; | |
496 | } | |
497 | ||
90536664 MT |
498 | if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) |
499 | apic_set_eoi_write(kvm_guest_apic_eoi_write); | |
ab9cf499 | 500 | |
3dc4f7cf MT |
501 | if (kvmclock_vsyscall) |
502 | kvm_setup_vsyscall_timeinfo(); | |
503 | ||
ca3f1017 GN |
504 | #ifdef CONFIG_SMP |
505 | smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu; | |
fd10cde9 GN |
506 | register_cpu_notifier(&kvm_cpu_notifier); |
507 | #else | |
508 | kvm_guest_cpu_init(); | |
ca3f1017 | 509 | #endif |
9919e39a UO |
510 | |
511 | /* | |
512 | * Hard lockup detection is enabled by default. Disable it, as guests | |
513 | * can get false positives too easily, for example if the host is | |
514 | * overcommitted. | |
515 | */ | |
692297d8 | 516 | hardlockup_detector_disable(); |
0cf1bfd2 | 517 | } |
d910f5c1 | 518 | |
1c300a40 PB |
519 | static noinline uint32_t __kvm_cpuid_base(void) |
520 | { | |
521 | if (boot_cpu_data.cpuid_level < 0) | |
522 | return 0; /* So we don't blow up on old processors */ | |
523 | ||
524 | if (cpu_has_hypervisor) | |
525 | return hypervisor_cpuid_base("KVMKVMKVM\0\0\0", 0); | |
526 | ||
527 | return 0; | |
528 | } | |
529 | ||
530 | static inline uint32_t kvm_cpuid_base(void) | |
531 | { | |
532 | static int kvm_cpuid_base = -1; | |
533 | ||
534 | if (kvm_cpuid_base == -1) | |
535 | kvm_cpuid_base = __kvm_cpuid_base(); | |
536 | ||
537 | return kvm_cpuid_base; | |
538 | } | |
539 | ||
540 | bool kvm_para_available(void) | |
541 | { | |
542 | return kvm_cpuid_base() != 0; | |
543 | } | |
544 | EXPORT_SYMBOL_GPL(kvm_para_available); | |
545 | ||
77f01bdf PB |
546 | unsigned int kvm_arch_para_features(void) |
547 | { | |
548 | return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES); | |
549 | } | |
550 | ||
9df56f19 | 551 | static uint32_t __init kvm_detect(void) |
fc73373b | 552 | { |
9df56f19 | 553 | return kvm_cpuid_base(); |
fc73373b PB |
554 | } |
555 | ||
556 | const struct hypervisor_x86 x86_hyper_kvm __refconst = { | |
557 | .name = "KVM", | |
558 | .detect = kvm_detect, | |
4cca6ea0 | 559 | .x2apic_available = kvm_para_available, |
fc73373b PB |
560 | }; |
561 | EXPORT_SYMBOL_GPL(x86_hyper_kvm); | |
562 | ||
d910f5c1 GC |
563 | static __init int activate_jump_labels(void) |
564 | { | |
565 | if (has_steal_clock) { | |
c5905afb | 566 | static_key_slow_inc(¶virt_steal_enabled); |
d910f5c1 | 567 | if (steal_acc) |
c5905afb | 568 | static_key_slow_inc(¶virt_steal_rq_enabled); |
d910f5c1 GC |
569 | } |
570 | ||
571 | return 0; | |
572 | } | |
573 | arch_initcall(activate_jump_labels); | |
92b75202 SV |
574 | |
575 | #ifdef CONFIG_PARAVIRT_SPINLOCKS | |
576 | ||
577 | /* Kick a cpu by its apicid. Used to wake up a halted vcpu */ | |
36bd6213 | 578 | static void kvm_kick_cpu(int cpu) |
92b75202 SV |
579 | { |
580 | int apicid; | |
581 | unsigned long flags = 0; | |
582 | ||
583 | apicid = per_cpu(x86_cpu_to_apicid, cpu); | |
584 | kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid); | |
585 | } | |
586 | ||
587 | enum kvm_contention_stat { | |
588 | TAKEN_SLOW, | |
589 | TAKEN_SLOW_PICKUP, | |
590 | RELEASED_SLOW, | |
591 | RELEASED_SLOW_KICKED, | |
592 | NR_CONTENTION_STATS | |
593 | }; | |
594 | ||
595 | #ifdef CONFIG_KVM_DEBUG_FS | |
596 | #define HISTO_BUCKETS 30 | |
597 | ||
598 | static struct kvm_spinlock_stats | |
599 | { | |
600 | u32 contention_stats[NR_CONTENTION_STATS]; | |
601 | u32 histo_spin_blocked[HISTO_BUCKETS+1]; | |
602 | u64 time_blocked; | |
603 | } spinlock_stats; | |
604 | ||
605 | static u8 zero_stats; | |
606 | ||
607 | static inline void check_zero(void) | |
608 | { | |
609 | u8 ret; | |
610 | u8 old; | |
611 | ||
d6abfdb2 | 612 | old = READ_ONCE(zero_stats); |
92b75202 SV |
613 | if (unlikely(old)) { |
614 | ret = cmpxchg(&zero_stats, old, 0); | |
615 | /* This ensures only one fellow resets the stat */ | |
616 | if (ret == old) | |
617 | memset(&spinlock_stats, 0, sizeof(spinlock_stats)); | |
618 | } | |
619 | } | |
620 | ||
621 | static inline void add_stats(enum kvm_contention_stat var, u32 val) | |
622 | { | |
623 | check_zero(); | |
624 | spinlock_stats.contention_stats[var] += val; | |
625 | } | |
626 | ||
627 | ||
628 | static inline u64 spin_time_start(void) | |
629 | { | |
630 | return sched_clock(); | |
631 | } | |
632 | ||
633 | static void __spin_time_accum(u64 delta, u32 *array) | |
634 | { | |
635 | unsigned index; | |
636 | ||
637 | index = ilog2(delta); | |
638 | check_zero(); | |
639 | ||
640 | if (index < HISTO_BUCKETS) | |
641 | array[index]++; | |
642 | else | |
643 | array[HISTO_BUCKETS]++; | |
644 | } | |
645 | ||
646 | static inline void spin_time_accum_blocked(u64 start) | |
647 | { | |
648 | u32 delta; | |
649 | ||
650 | delta = sched_clock() - start; | |
651 | __spin_time_accum(delta, spinlock_stats.histo_spin_blocked); | |
652 | spinlock_stats.time_blocked += delta; | |
653 | } | |
654 | ||
655 | static struct dentry *d_spin_debug; | |
656 | static struct dentry *d_kvm_debug; | |
657 | ||
658 | struct dentry *kvm_init_debugfs(void) | |
659 | { | |
d780a312 | 660 | d_kvm_debug = debugfs_create_dir("kvm-guest", NULL); |
92b75202 SV |
661 | if (!d_kvm_debug) |
662 | printk(KERN_WARNING "Could not create 'kvm' debugfs directory\n"); | |
663 | ||
664 | return d_kvm_debug; | |
665 | } | |
666 | ||
667 | static int __init kvm_spinlock_debugfs(void) | |
668 | { | |
669 | struct dentry *d_kvm; | |
670 | ||
671 | d_kvm = kvm_init_debugfs(); | |
672 | if (d_kvm == NULL) | |
673 | return -ENOMEM; | |
674 | ||
675 | d_spin_debug = debugfs_create_dir("spinlocks", d_kvm); | |
676 | ||
677 | debugfs_create_u8("zero_stats", 0644, d_spin_debug, &zero_stats); | |
678 | ||
679 | debugfs_create_u32("taken_slow", 0444, d_spin_debug, | |
680 | &spinlock_stats.contention_stats[TAKEN_SLOW]); | |
681 | debugfs_create_u32("taken_slow_pickup", 0444, d_spin_debug, | |
682 | &spinlock_stats.contention_stats[TAKEN_SLOW_PICKUP]); | |
683 | ||
684 | debugfs_create_u32("released_slow", 0444, d_spin_debug, | |
685 | &spinlock_stats.contention_stats[RELEASED_SLOW]); | |
686 | debugfs_create_u32("released_slow_kicked", 0444, d_spin_debug, | |
687 | &spinlock_stats.contention_stats[RELEASED_SLOW_KICKED]); | |
688 | ||
689 | debugfs_create_u64("time_blocked", 0444, d_spin_debug, | |
690 | &spinlock_stats.time_blocked); | |
691 | ||
692 | debugfs_create_u32_array("histo_blocked", 0444, d_spin_debug, | |
693 | spinlock_stats.histo_spin_blocked, HISTO_BUCKETS + 1); | |
694 | ||
695 | return 0; | |
696 | } | |
697 | fs_initcall(kvm_spinlock_debugfs); | |
698 | #else /* !CONFIG_KVM_DEBUG_FS */ | |
699 | static inline void add_stats(enum kvm_contention_stat var, u32 val) | |
700 | { | |
701 | } | |
702 | ||
703 | static inline u64 spin_time_start(void) | |
704 | { | |
705 | return 0; | |
706 | } | |
707 | ||
708 | static inline void spin_time_accum_blocked(u64 start) | |
709 | { | |
710 | } | |
711 | #endif /* CONFIG_KVM_DEBUG_FS */ | |
712 | ||
713 | struct kvm_lock_waiting { | |
714 | struct arch_spinlock *lock; | |
715 | __ticket_t want; | |
716 | }; | |
717 | ||
718 | /* cpus 'waiting' on a spinlock to become available */ | |
719 | static cpumask_t waiting_cpus; | |
720 | ||
721 | /* Track spinlock on which a cpu is waiting */ | |
722 | static DEFINE_PER_CPU(struct kvm_lock_waiting, klock_waiting); | |
723 | ||
dd41f818 | 724 | __visible void kvm_lock_spinning(struct arch_spinlock *lock, __ticket_t want) |
92b75202 SV |
725 | { |
726 | struct kvm_lock_waiting *w; | |
727 | int cpu; | |
728 | u64 start; | |
729 | unsigned long flags; | |
d6abfdb2 | 730 | __ticket_t head; |
92b75202 SV |
731 | |
732 | if (in_nmi()) | |
733 | return; | |
734 | ||
89cbc767 | 735 | w = this_cpu_ptr(&klock_waiting); |
92b75202 SV |
736 | cpu = smp_processor_id(); |
737 | start = spin_time_start(); | |
738 | ||
739 | /* | |
740 | * Make sure an interrupt handler can't upset things in a | |
741 | * partially setup state. | |
742 | */ | |
743 | local_irq_save(flags); | |
744 | ||
745 | /* | |
746 | * The ordering protocol on this is that the "lock" pointer | |
747 | * may only be set non-NULL if the "want" ticket is correct. | |
748 | * If we're updating "want", we must first clear "lock". | |
749 | */ | |
750 | w->lock = NULL; | |
751 | smp_wmb(); | |
752 | w->want = want; | |
753 | smp_wmb(); | |
754 | w->lock = lock; | |
755 | ||
756 | add_stats(TAKEN_SLOW, 1); | |
757 | ||
758 | /* | |
759 | * This uses set_bit, which is atomic but we should not rely on its | |
760 | * reordering gurantees. So barrier is needed after this call. | |
761 | */ | |
762 | cpumask_set_cpu(cpu, &waiting_cpus); | |
763 | ||
764 | barrier(); | |
765 | ||
766 | /* | |
767 | * Mark entry to slowpath before doing the pickup test to make | |
768 | * sure we don't deadlock with an unlocker. | |
769 | */ | |
770 | __ticket_enter_slowpath(lock); | |
771 | ||
d6abfdb2 R |
772 | /* make sure enter_slowpath, which is atomic does not cross the read */ |
773 | smp_mb__after_atomic(); | |
774 | ||
92b75202 SV |
775 | /* |
776 | * check again make sure it didn't become free while | |
777 | * we weren't looking. | |
778 | */ | |
d6abfdb2 R |
779 | head = READ_ONCE(lock->tickets.head); |
780 | if (__tickets_equal(head, want)) { | |
92b75202 SV |
781 | add_stats(TAKEN_SLOW_PICKUP, 1); |
782 | goto out; | |
783 | } | |
784 | ||
785 | /* | |
786 | * halt until it's our turn and kicked. Note that we do safe halt | |
787 | * for irq enabled case to avoid hang when lock info is overwritten | |
788 | * in irq spinlock slowpath and no spurious interrupt occur to save us. | |
789 | */ | |
790 | if (arch_irqs_disabled_flags(flags)) | |
791 | halt(); | |
792 | else | |
793 | safe_halt(); | |
794 | ||
795 | out: | |
796 | cpumask_clear_cpu(cpu, &waiting_cpus); | |
797 | w->lock = NULL; | |
798 | local_irq_restore(flags); | |
799 | spin_time_accum_blocked(start); | |
800 | } | |
801 | PV_CALLEE_SAVE_REGS_THUNK(kvm_lock_spinning); | |
802 | ||
803 | /* Kick vcpu waiting on @lock->head to reach value @ticket */ | |
804 | static void kvm_unlock_kick(struct arch_spinlock *lock, __ticket_t ticket) | |
805 | { | |
806 | int cpu; | |
807 | ||
808 | add_stats(RELEASED_SLOW, 1); | |
809 | for_each_cpu(cpu, &waiting_cpus) { | |
810 | const struct kvm_lock_waiting *w = &per_cpu(klock_waiting, cpu); | |
d6abfdb2 R |
811 | if (READ_ONCE(w->lock) == lock && |
812 | READ_ONCE(w->want) == ticket) { | |
92b75202 SV |
813 | add_stats(RELEASED_SLOW_KICKED, 1); |
814 | kvm_kick_cpu(cpu); | |
815 | break; | |
816 | } | |
817 | } | |
818 | } | |
819 | ||
820 | /* | |
821 | * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present. | |
822 | */ | |
823 | void __init kvm_spinlock_init(void) | |
824 | { | |
825 | if (!kvm_para_available()) | |
826 | return; | |
827 | /* Does host kernel support KVM_FEATURE_PV_UNHALT? */ | |
828 | if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT)) | |
829 | return; | |
830 | ||
3dbef3e3 R |
831 | pv_lock_ops.lock_spinning = PV_CALLEE_SAVE(kvm_lock_spinning); |
832 | pv_lock_ops.unlock_kick = kvm_unlock_kick; | |
833 | } | |
834 | ||
835 | static __init int kvm_spinlock_init_jump(void) | |
836 | { | |
837 | if (!kvm_para_available()) | |
838 | return 0; | |
839 | if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT)) | |
840 | return 0; | |
92b75202 SV |
841 | |
842 | static_key_slow_inc(¶virt_ticketlocks_enabled); | |
3dbef3e3 | 843 | printk(KERN_INFO "KVM setup paravirtual spinlock\n"); |
92b75202 | 844 | |
3dbef3e3 | 845 | return 0; |
92b75202 | 846 | } |
3dbef3e3 R |
847 | early_initcall(kvm_spinlock_init_jump); |
848 | ||
92b75202 | 849 | #endif /* CONFIG_PARAVIRT_SPINLOCKS */ |