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Commit | Line | Data |
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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 | ||
23 | #include <linux/module.h> | |
24 | #include <linux/kernel.h> | |
25 | #include <linux/kvm_para.h> | |
26 | #include <linux/cpu.h> | |
27 | #include <linux/mm.h> | |
1da8a77b | 28 | #include <linux/highmem.h> |
096d14a3 | 29 | #include <linux/hardirq.h> |
fd10cde9 GN |
30 | #include <linux/notifier.h> |
31 | #include <linux/reboot.h> | |
631bc487 GN |
32 | #include <linux/hash.h> |
33 | #include <linux/sched.h> | |
34 | #include <linux/slab.h> | |
35 | #include <linux/kprobes.h> | |
a90ede7b | 36 | #include <asm/timer.h> |
fd10cde9 | 37 | #include <asm/cpu.h> |
631bc487 GN |
38 | #include <asm/traps.h> |
39 | #include <asm/desc.h> | |
6c047cd9 | 40 | #include <asm/tlbflush.h> |
e0875921 | 41 | #include <asm/idle.h> |
ab9cf499 MT |
42 | #include <asm/apic.h> |
43 | #include <asm/apicdef.h> | |
fc73373b | 44 | #include <asm/hypervisor.h> |
096d14a3 | 45 | |
fd10cde9 GN |
46 | static int kvmapf = 1; |
47 | ||
48 | static int parse_no_kvmapf(char *arg) | |
49 | { | |
50 | kvmapf = 0; | |
51 | return 0; | |
52 | } | |
53 | ||
54 | early_param("no-kvmapf", parse_no_kvmapf); | |
55 | ||
d910f5c1 GC |
56 | static int steal_acc = 1; |
57 | static int parse_no_stealacc(char *arg) | |
58 | { | |
59 | steal_acc = 0; | |
60 | return 0; | |
61 | } | |
62 | ||
63 | early_param("no-steal-acc", parse_no_stealacc); | |
64 | ||
fd10cde9 | 65 | static DEFINE_PER_CPU(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64); |
d910f5c1 GC |
66 | static DEFINE_PER_CPU(struct kvm_steal_time, steal_time) __aligned(64); |
67 | static int has_steal_clock = 0; | |
096d14a3 | 68 | |
0cf1bfd2 MT |
69 | /* |
70 | * No need for any "IO delay" on KVM | |
71 | */ | |
72 | static void kvm_io_delay(void) | |
73 | { | |
74 | } | |
75 | ||
631bc487 GN |
76 | #define KVM_TASK_SLEEP_HASHBITS 8 |
77 | #define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS) | |
78 | ||
79 | struct kvm_task_sleep_node { | |
80 | struct hlist_node link; | |
81 | wait_queue_head_t wq; | |
82 | u32 token; | |
83 | int cpu; | |
6c047cd9 | 84 | bool halted; |
631bc487 GN |
85 | }; |
86 | ||
87 | static struct kvm_task_sleep_head { | |
88 | spinlock_t lock; | |
89 | struct hlist_head list; | |
90 | } async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE]; | |
91 | ||
92 | static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b, | |
93 | u32 token) | |
94 | { | |
95 | struct hlist_node *p; | |
96 | ||
97 | hlist_for_each(p, &b->list) { | |
98 | struct kvm_task_sleep_node *n = | |
99 | hlist_entry(p, typeof(*n), link); | |
100 | if (n->token == token) | |
101 | return n; | |
102 | } | |
103 | ||
104 | return NULL; | |
105 | } | |
106 | ||
107 | void kvm_async_pf_task_wait(u32 token) | |
108 | { | |
109 | u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS); | |
110 | struct kvm_task_sleep_head *b = &async_pf_sleepers[key]; | |
111 | struct kvm_task_sleep_node n, *e; | |
112 | DEFINE_WAIT(wait); | |
6c047cd9 GN |
113 | int cpu, idle; |
114 | ||
115 | cpu = get_cpu(); | |
116 | idle = idle_cpu(cpu); | |
117 | put_cpu(); | |
631bc487 GN |
118 | |
119 | spin_lock(&b->lock); | |
120 | e = _find_apf_task(b, token); | |
121 | if (e) { | |
122 | /* dummy entry exist -> wake up was delivered ahead of PF */ | |
123 | hlist_del(&e->link); | |
124 | kfree(e); | |
125 | spin_unlock(&b->lock); | |
126 | return; | |
127 | } | |
128 | ||
129 | n.token = token; | |
130 | n.cpu = smp_processor_id(); | |
6c047cd9 | 131 | n.halted = idle || preempt_count() > 1; |
631bc487 GN |
132 | init_waitqueue_head(&n.wq); |
133 | hlist_add_head(&n.link, &b->list); | |
134 | spin_unlock(&b->lock); | |
135 | ||
136 | for (;;) { | |
6c047cd9 GN |
137 | if (!n.halted) |
138 | prepare_to_wait(&n.wq, &wait, TASK_UNINTERRUPTIBLE); | |
631bc487 GN |
139 | if (hlist_unhashed(&n.link)) |
140 | break; | |
6c047cd9 GN |
141 | |
142 | if (!n.halted) { | |
143 | local_irq_enable(); | |
144 | schedule(); | |
145 | local_irq_disable(); | |
146 | } else { | |
147 | /* | |
148 | * We cannot reschedule. So halt. | |
149 | */ | |
150 | native_safe_halt(); | |
151 | local_irq_disable(); | |
152 | } | |
631bc487 | 153 | } |
6c047cd9 GN |
154 | if (!n.halted) |
155 | finish_wait(&n.wq, &wait); | |
631bc487 GN |
156 | |
157 | return; | |
158 | } | |
159 | EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait); | |
160 | ||
161 | static void apf_task_wake_one(struct kvm_task_sleep_node *n) | |
162 | { | |
163 | hlist_del_init(&n->link); | |
6c047cd9 GN |
164 | if (n->halted) |
165 | smp_send_reschedule(n->cpu); | |
166 | else if (waitqueue_active(&n->wq)) | |
631bc487 GN |
167 | wake_up(&n->wq); |
168 | } | |
169 | ||
170 | static void apf_task_wake_all(void) | |
171 | { | |
172 | int i; | |
173 | ||
174 | for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) { | |
175 | struct hlist_node *p, *next; | |
176 | struct kvm_task_sleep_head *b = &async_pf_sleepers[i]; | |
177 | spin_lock(&b->lock); | |
178 | hlist_for_each_safe(p, next, &b->list) { | |
179 | struct kvm_task_sleep_node *n = | |
180 | hlist_entry(p, typeof(*n), link); | |
181 | if (n->cpu == smp_processor_id()) | |
182 | apf_task_wake_one(n); | |
183 | } | |
184 | spin_unlock(&b->lock); | |
185 | } | |
186 | } | |
187 | ||
188 | void kvm_async_pf_task_wake(u32 token) | |
189 | { | |
190 | u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS); | |
191 | struct kvm_task_sleep_head *b = &async_pf_sleepers[key]; | |
192 | struct kvm_task_sleep_node *n; | |
193 | ||
194 | if (token == ~0) { | |
195 | apf_task_wake_all(); | |
196 | return; | |
197 | } | |
198 | ||
199 | again: | |
200 | spin_lock(&b->lock); | |
201 | n = _find_apf_task(b, token); | |
202 | if (!n) { | |
203 | /* | |
204 | * async PF was not yet handled. | |
205 | * Add dummy entry for the token. | |
206 | */ | |
62c49cc9 | 207 | n = kzalloc(sizeof(*n), GFP_ATOMIC); |
631bc487 GN |
208 | if (!n) { |
209 | /* | |
210 | * Allocation failed! Busy wait while other cpu | |
211 | * handles async PF. | |
212 | */ | |
213 | spin_unlock(&b->lock); | |
214 | cpu_relax(); | |
215 | goto again; | |
216 | } | |
217 | n->token = token; | |
218 | n->cpu = smp_processor_id(); | |
219 | init_waitqueue_head(&n->wq); | |
220 | hlist_add_head(&n->link, &b->list); | |
221 | } else | |
222 | apf_task_wake_one(n); | |
223 | spin_unlock(&b->lock); | |
224 | return; | |
225 | } | |
226 | EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake); | |
227 | ||
228 | u32 kvm_read_and_reset_pf_reason(void) | |
229 | { | |
230 | u32 reason = 0; | |
231 | ||
232 | if (__get_cpu_var(apf_reason).enabled) { | |
233 | reason = __get_cpu_var(apf_reason).reason; | |
234 | __get_cpu_var(apf_reason).reason = 0; | |
235 | } | |
236 | ||
237 | return reason; | |
238 | } | |
239 | EXPORT_SYMBOL_GPL(kvm_read_and_reset_pf_reason); | |
240 | ||
241 | dotraplinkage void __kprobes | |
242 | do_async_page_fault(struct pt_regs *regs, unsigned long error_code) | |
243 | { | |
244 | switch (kvm_read_and_reset_pf_reason()) { | |
245 | default: | |
246 | do_page_fault(regs, error_code); | |
247 | break; | |
248 | case KVM_PV_REASON_PAGE_NOT_PRESENT: | |
249 | /* page is swapped out by the host. */ | |
c5e015d4 SL |
250 | rcu_irq_enter(); |
251 | exit_idle(); | |
631bc487 | 252 | kvm_async_pf_task_wait((u32)read_cr2()); |
c5e015d4 | 253 | rcu_irq_exit(); |
631bc487 GN |
254 | break; |
255 | case KVM_PV_REASON_PAGE_READY: | |
e0875921 GN |
256 | rcu_irq_enter(); |
257 | exit_idle(); | |
631bc487 | 258 | kvm_async_pf_task_wake((u32)read_cr2()); |
e0875921 | 259 | rcu_irq_exit(); |
631bc487 GN |
260 | break; |
261 | } | |
262 | } | |
263 | ||
d3ac8815 | 264 | static void __init paravirt_ops_setup(void) |
0cf1bfd2 MT |
265 | { |
266 | pv_info.name = "KVM"; | |
267 | pv_info.paravirt_enabled = 1; | |
268 | ||
269 | if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY)) | |
270 | pv_cpu_ops.io_delay = kvm_io_delay; | |
271 | ||
a90ede7b MT |
272 | #ifdef CONFIG_X86_IO_APIC |
273 | no_timer_check = 1; | |
274 | #endif | |
0cf1bfd2 MT |
275 | } |
276 | ||
d910f5c1 GC |
277 | static void kvm_register_steal_time(void) |
278 | { | |
279 | int cpu = smp_processor_id(); | |
280 | struct kvm_steal_time *st = &per_cpu(steal_time, cpu); | |
281 | ||
282 | if (!has_steal_clock) | |
283 | return; | |
284 | ||
285 | memset(st, 0, sizeof(*st)); | |
286 | ||
287 | wrmsrl(MSR_KVM_STEAL_TIME, (__pa(st) | KVM_MSR_ENABLED)); | |
288 | printk(KERN_INFO "kvm-stealtime: cpu %d, msr %lx\n", | |
289 | cpu, __pa(st)); | |
290 | } | |
291 | ||
ab9cf499 MT |
292 | static DEFINE_PER_CPU(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED; |
293 | ||
294 | static void kvm_guest_apic_eoi_write(u32 reg, u32 val) | |
295 | { | |
296 | /** | |
297 | * This relies on __test_and_clear_bit to modify the memory | |
298 | * in a way that is atomic with respect to the local CPU. | |
299 | * The hypervisor only accesses this memory from the local CPU so | |
300 | * there's no need for lock or memory barriers. | |
301 | * An optimization barrier is implied in apic write. | |
302 | */ | |
303 | if (__test_and_clear_bit(KVM_PV_EOI_BIT, &__get_cpu_var(kvm_apic_eoi))) | |
304 | return; | |
90536664 | 305 | apic_write(APIC_EOI, APIC_EOI_ACK); |
ab9cf499 MT |
306 | } |
307 | ||
fd10cde9 GN |
308 | void __cpuinit kvm_guest_cpu_init(void) |
309 | { | |
310 | if (!kvm_para_available()) | |
311 | return; | |
312 | ||
313 | if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF) && kvmapf) { | |
314 | u64 pa = __pa(&__get_cpu_var(apf_reason)); | |
315 | ||
6adba527 GN |
316 | #ifdef CONFIG_PREEMPT |
317 | pa |= KVM_ASYNC_PF_SEND_ALWAYS; | |
318 | #endif | |
fd10cde9 GN |
319 | wrmsrl(MSR_KVM_ASYNC_PF_EN, pa | KVM_ASYNC_PF_ENABLED); |
320 | __get_cpu_var(apf_reason).enabled = 1; | |
321 | printk(KERN_INFO"KVM setup async PF for cpu %d\n", | |
322 | smp_processor_id()); | |
323 | } | |
d910f5c1 | 324 | |
ab9cf499 MT |
325 | if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) { |
326 | unsigned long pa; | |
327 | /* Size alignment is implied but just to make it explicit. */ | |
328 | BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4); | |
329 | __get_cpu_var(kvm_apic_eoi) = 0; | |
330 | pa = __pa(&__get_cpu_var(kvm_apic_eoi)) | KVM_MSR_ENABLED; | |
331 | wrmsrl(MSR_KVM_PV_EOI_EN, pa); | |
332 | } | |
333 | ||
d910f5c1 GC |
334 | if (has_steal_clock) |
335 | kvm_register_steal_time(); | |
fd10cde9 GN |
336 | } |
337 | ||
ab9cf499 | 338 | static void kvm_pv_disable_apf(void) |
fd10cde9 GN |
339 | { |
340 | if (!__get_cpu_var(apf_reason).enabled) | |
341 | return; | |
342 | ||
343 | wrmsrl(MSR_KVM_ASYNC_PF_EN, 0); | |
344 | __get_cpu_var(apf_reason).enabled = 0; | |
345 | ||
346 | printk(KERN_INFO"Unregister pv shared memory for cpu %d\n", | |
347 | smp_processor_id()); | |
348 | } | |
349 | ||
ab9cf499 MT |
350 | static void kvm_pv_guest_cpu_reboot(void *unused) |
351 | { | |
352 | /* | |
353 | * We disable PV EOI before we load a new kernel by kexec, | |
354 | * since MSR_KVM_PV_EOI_EN stores a pointer into old kernel's memory. | |
355 | * New kernel can re-enable when it boots. | |
356 | */ | |
357 | if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) | |
358 | wrmsrl(MSR_KVM_PV_EOI_EN, 0); | |
359 | kvm_pv_disable_apf(); | |
8fbe6a54 | 360 | kvm_disable_steal_time(); |
ab9cf499 MT |
361 | } |
362 | ||
fd10cde9 GN |
363 | static int kvm_pv_reboot_notify(struct notifier_block *nb, |
364 | unsigned long code, void *unused) | |
365 | { | |
366 | if (code == SYS_RESTART) | |
ab9cf499 | 367 | on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1); |
fd10cde9 GN |
368 | return NOTIFY_DONE; |
369 | } | |
370 | ||
371 | static struct notifier_block kvm_pv_reboot_nb = { | |
372 | .notifier_call = kvm_pv_reboot_notify, | |
373 | }; | |
374 | ||
d910f5c1 GC |
375 | static u64 kvm_steal_clock(int cpu) |
376 | { | |
377 | u64 steal; | |
378 | struct kvm_steal_time *src; | |
379 | int version; | |
380 | ||
381 | src = &per_cpu(steal_time, cpu); | |
382 | do { | |
383 | version = src->version; | |
384 | rmb(); | |
385 | steal = src->steal; | |
386 | rmb(); | |
387 | } while ((version & 1) || (version != src->version)); | |
388 | ||
389 | return steal; | |
390 | } | |
391 | ||
392 | void kvm_disable_steal_time(void) | |
393 | { | |
394 | if (!has_steal_clock) | |
395 | return; | |
396 | ||
397 | wrmsr(MSR_KVM_STEAL_TIME, 0, 0); | |
398 | } | |
399 | ||
ca3f1017 GN |
400 | #ifdef CONFIG_SMP |
401 | static void __init kvm_smp_prepare_boot_cpu(void) | |
402 | { | |
403 | WARN_ON(kvm_register_clock("primary cpu clock")); | |
fd10cde9 | 404 | kvm_guest_cpu_init(); |
ca3f1017 GN |
405 | native_smp_prepare_boot_cpu(); |
406 | } | |
fd10cde9 | 407 | |
775077a0 | 408 | static void __cpuinit kvm_guest_cpu_online(void *dummy) |
fd10cde9 GN |
409 | { |
410 | kvm_guest_cpu_init(); | |
411 | } | |
412 | ||
413 | static void kvm_guest_cpu_offline(void *dummy) | |
414 | { | |
d910f5c1 | 415 | kvm_disable_steal_time(); |
ab9cf499 MT |
416 | if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) |
417 | wrmsrl(MSR_KVM_PV_EOI_EN, 0); | |
418 | kvm_pv_disable_apf(); | |
631bc487 | 419 | apf_task_wake_all(); |
fd10cde9 GN |
420 | } |
421 | ||
422 | static int __cpuinit kvm_cpu_notify(struct notifier_block *self, | |
423 | unsigned long action, void *hcpu) | |
424 | { | |
425 | int cpu = (unsigned long)hcpu; | |
426 | switch (action) { | |
427 | case CPU_ONLINE: | |
428 | case CPU_DOWN_FAILED: | |
429 | case CPU_ONLINE_FROZEN: | |
430 | smp_call_function_single(cpu, kvm_guest_cpu_online, NULL, 0); | |
431 | break; | |
432 | case CPU_DOWN_PREPARE: | |
433 | case CPU_DOWN_PREPARE_FROZEN: | |
434 | smp_call_function_single(cpu, kvm_guest_cpu_offline, NULL, 1); | |
435 | break; | |
436 | default: | |
437 | break; | |
438 | } | |
439 | return NOTIFY_OK; | |
440 | } | |
441 | ||
442 | static struct notifier_block __cpuinitdata kvm_cpu_notifier = { | |
443 | .notifier_call = kvm_cpu_notify, | |
444 | }; | |
ca3f1017 GN |
445 | #endif |
446 | ||
631bc487 GN |
447 | static void __init kvm_apf_trap_init(void) |
448 | { | |
449 | set_intr_gate(14, &async_page_fault); | |
450 | } | |
451 | ||
0cf1bfd2 MT |
452 | void __init kvm_guest_init(void) |
453 | { | |
631bc487 GN |
454 | int i; |
455 | ||
0cf1bfd2 MT |
456 | if (!kvm_para_available()) |
457 | return; | |
458 | ||
459 | paravirt_ops_setup(); | |
fd10cde9 | 460 | register_reboot_notifier(&kvm_pv_reboot_nb); |
631bc487 GN |
461 | for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) |
462 | spin_lock_init(&async_pf_sleepers[i].lock); | |
463 | if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF)) | |
464 | x86_init.irqs.trap_init = kvm_apf_trap_init; | |
465 | ||
d910f5c1 GC |
466 | if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) { |
467 | has_steal_clock = 1; | |
468 | pv_time_ops.steal_clock = kvm_steal_clock; | |
469 | } | |
470 | ||
90536664 MT |
471 | if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) |
472 | apic_set_eoi_write(kvm_guest_apic_eoi_write); | |
ab9cf499 | 473 | |
ca3f1017 GN |
474 | #ifdef CONFIG_SMP |
475 | smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu; | |
fd10cde9 GN |
476 | register_cpu_notifier(&kvm_cpu_notifier); |
477 | #else | |
478 | kvm_guest_cpu_init(); | |
ca3f1017 | 479 | #endif |
0cf1bfd2 | 480 | } |
d910f5c1 | 481 | |
fc73373b PB |
482 | static bool __init kvm_detect(void) |
483 | { | |
484 | if (!kvm_para_available()) | |
485 | return false; | |
486 | return true; | |
487 | } | |
488 | ||
489 | const struct hypervisor_x86 x86_hyper_kvm __refconst = { | |
490 | .name = "KVM", | |
491 | .detect = kvm_detect, | |
492 | }; | |
493 | EXPORT_SYMBOL_GPL(x86_hyper_kvm); | |
494 | ||
d910f5c1 GC |
495 | static __init int activate_jump_labels(void) |
496 | { | |
497 | if (has_steal_clock) { | |
c5905afb | 498 | static_key_slow_inc(¶virt_steal_enabled); |
d910f5c1 | 499 | if (steal_acc) |
c5905afb | 500 | static_key_slow_inc(¶virt_steal_rq_enabled); |
d910f5c1 GC |
501 | } |
502 | ||
503 | return 0; | |
504 | } | |
505 | arch_initcall(activate_jump_labels); |