1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * X86 specific Hyper-V initialization code.
4 *
5 * Copyright (C) 2016, Microsoft, Inc.
6 *
7 * Author : K. Y. Srinivasan <kys@microsoft.com>
8 */
9
10 #include <linux/acpi.h>
11 #include <linux/efi.h>
12 #include <linux/types.h>
13 #include <asm/apic.h>
14 #include <asm/desc.h>
15 #include <asm/hypervisor.h>
16 #include <asm/hyperv-tlfs.h>
17 #include <asm/mshyperv.h>
18 #include <asm/idtentry.h>
19 #include <linux/version.h>
20 #include <linux/vmalloc.h>
21 #include <linux/mm.h>
22 #include <linux/hyperv.h>
23 #include <linux/slab.h>
24 #include <linux/kernel.h>
25 #include <linux/cpuhotplug.h>
26 #include <linux/syscore_ops.h>
27 #include <clocksource/hyperv_timer.h>
28
29 void *hv_hypercall_pg;
30 EXPORT_SYMBOL_GPL(hv_hypercall_pg);
31
32 /* Storage to save the hypercall page temporarily for hibernation */
33 static void *hv_hypercall_pg_saved;
34
35 u32 *hv_vp_index;
36 EXPORT_SYMBOL_GPL(hv_vp_index);
37
38 struct hv_vp_assist_page **hv_vp_assist_page;
39 EXPORT_SYMBOL_GPL(hv_vp_assist_page);
40
41 void __percpu **hyperv_pcpu_input_arg;
42 EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg);
43
44 u32 hv_max_vp_index;
45 EXPORT_SYMBOL_GPL(hv_max_vp_index);
46
hv_alloc_hyperv_page(void)47 void *hv_alloc_hyperv_page(void)
48 {
49 BUILD_BUG_ON(PAGE_SIZE != HV_HYP_PAGE_SIZE);
50
51 return (void *)__get_free_page(GFP_KERNEL);
52 }
53 EXPORT_SYMBOL_GPL(hv_alloc_hyperv_page);
54
hv_alloc_hyperv_zeroed_page(void)55 void *hv_alloc_hyperv_zeroed_page(void)
56 {
57 BUILD_BUG_ON(PAGE_SIZE != HV_HYP_PAGE_SIZE);
58
59 return (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
60 }
61 EXPORT_SYMBOL_GPL(hv_alloc_hyperv_zeroed_page);
62
hv_free_hyperv_page(unsigned long addr)63 void hv_free_hyperv_page(unsigned long addr)
64 {
65 free_page(addr);
66 }
67 EXPORT_SYMBOL_GPL(hv_free_hyperv_page);
68
hv_cpu_init(unsigned int cpu)69 static int hv_cpu_init(unsigned int cpu)
70 {
71 u64 msr_vp_index;
72 struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
73 void **input_arg;
74 struct page *pg;
75
76 input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
77 /* hv_cpu_init() can be called with IRQs disabled from hv_resume() */
78 pg = alloc_page(irqs_disabled() ? GFP_ATOMIC : GFP_KERNEL);
79 if (unlikely(!pg))
80 return -ENOMEM;
81 *input_arg = page_address(pg);
82
83 hv_get_vp_index(msr_vp_index);
84
85 hv_vp_index[smp_processor_id()] = msr_vp_index;
86
87 if (msr_vp_index > hv_max_vp_index)
88 hv_max_vp_index = msr_vp_index;
89
90 if (!hv_vp_assist_page)
91 return 0;
92
93 /*
94 * The VP ASSIST PAGE is an "overlay" page (see Hyper-V TLFS's Section
95 * 5.2.1 "GPA Overlay Pages"). Here it must be zeroed out to make sure
96 * we always write the EOI MSR in hv_apic_eoi_write() *after* the
97 * EOI optimization is disabled in hv_cpu_die(), otherwise a CPU may
98 * not be stopped in the case of CPU offlining and the VM will hang.
99 */
100 if (!*hvp) {
101 *hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL | __GFP_ZERO);
102 }
103
104 if (*hvp) {
105 u64 val;
106
107 val = vmalloc_to_pfn(*hvp);
108 val = (val << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT) |
109 HV_X64_MSR_VP_ASSIST_PAGE_ENABLE;
110
111 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, val);
112 }
113
114 return 0;
115 }
116
117 static void (*hv_reenlightenment_cb)(void);
118
hv_reenlightenment_notify(struct work_struct * dummy)119 static void hv_reenlightenment_notify(struct work_struct *dummy)
120 {
121 struct hv_tsc_emulation_status emu_status;
122
123 rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
124
125 /* Don't issue the callback if TSC accesses are not emulated */
126 if (hv_reenlightenment_cb && emu_status.inprogress)
127 hv_reenlightenment_cb();
128 }
129 static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify);
130
hyperv_stop_tsc_emulation(void)131 void hyperv_stop_tsc_emulation(void)
132 {
133 u64 freq;
134 struct hv_tsc_emulation_status emu_status;
135
136 rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
137 emu_status.inprogress = 0;
138 wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
139
140 rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);
141 tsc_khz = div64_u64(freq, 1000);
142 }
143 EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation);
144
hv_reenlightenment_available(void)145 static inline bool hv_reenlightenment_available(void)
146 {
147 /*
148 * Check for required features and priviliges to make TSC frequency
149 * change notifications work.
150 */
151 return ms_hyperv.features & HV_ACCESS_FREQUENCY_MSRS &&
152 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE &&
153 ms_hyperv.features & HV_ACCESS_REENLIGHTENMENT;
154 }
155
DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_reenlightenment)156 DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_reenlightenment)
157 {
158 ack_APIC_irq();
159 inc_irq_stat(irq_hv_reenlightenment_count);
160 schedule_delayed_work(&hv_reenlightenment_work, HZ/10);
161 }
162
set_hv_tscchange_cb(void (* cb)(void))163 void set_hv_tscchange_cb(void (*cb)(void))
164 {
165 struct hv_reenlightenment_control re_ctrl = {
166 .vector = HYPERV_REENLIGHTENMENT_VECTOR,
167 .enabled = 1,
168 .target_vp = hv_vp_index[smp_processor_id()]
169 };
170 struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1};
171
172 if (!hv_reenlightenment_available()) {
173 pr_warn("Hyper-V: reenlightenment support is unavailable\n");
174 return;
175 }
176
177 hv_reenlightenment_cb = cb;
178
179 /* Make sure callback is registered before we write to MSRs */
180 wmb();
181
182 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
183 wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl));
184 }
185 EXPORT_SYMBOL_GPL(set_hv_tscchange_cb);
186
clear_hv_tscchange_cb(void)187 void clear_hv_tscchange_cb(void)
188 {
189 struct hv_reenlightenment_control re_ctrl;
190
191 if (!hv_reenlightenment_available())
192 return;
193
194 rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
195 re_ctrl.enabled = 0;
196 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
197
198 hv_reenlightenment_cb = NULL;
199 }
200 EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb);
201
hv_cpu_die(unsigned int cpu)202 static int hv_cpu_die(unsigned int cpu)
203 {
204 struct hv_reenlightenment_control re_ctrl;
205 unsigned int new_cpu;
206 unsigned long flags;
207 void **input_arg;
208 void *input_pg = NULL;
209
210 local_irq_save(flags);
211 input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
212 input_pg = *input_arg;
213 *input_arg = NULL;
214 local_irq_restore(flags);
215 free_page((unsigned long)input_pg);
216
217 if (hv_vp_assist_page && hv_vp_assist_page[cpu])
218 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0);
219
220 if (hv_reenlightenment_cb == NULL)
221 return 0;
222
223 rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
224 if (re_ctrl.target_vp == hv_vp_index[cpu]) {
225 /*
226 * Reassign reenlightenment notifications to some other online
227 * CPU or just disable the feature if there are no online CPUs
228 * left (happens on hibernation).
229 */
230 new_cpu = cpumask_any_but(cpu_online_mask, cpu);
231
232 if (new_cpu < nr_cpu_ids)
233 re_ctrl.target_vp = hv_vp_index[new_cpu];
234 else
235 re_ctrl.enabled = 0;
236
237 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
238 }
239
240 return 0;
241 }
242
hv_pci_init(void)243 static int __init hv_pci_init(void)
244 {
245 int gen2vm = efi_enabled(EFI_BOOT);
246
247 /*
248 * For Generation-2 VM, we exit from pci_arch_init() by returning 0.
249 * The purpose is to suppress the harmless warning:
250 * "PCI: Fatal: No config space access function found"
251 */
252 if (gen2vm)
253 return 0;
254
255 /* For Generation-1 VM, we'll proceed in pci_arch_init(). */
256 return 1;
257 }
258
hv_suspend(void)259 static int hv_suspend(void)
260 {
261 union hv_x64_msr_hypercall_contents hypercall_msr;
262 int ret;
263
264 /*
265 * Reset the hypercall page as it is going to be invalidated
266 * accross hibernation. Setting hv_hypercall_pg to NULL ensures
267 * that any subsequent hypercall operation fails safely instead of
268 * crashing due to an access of an invalid page. The hypercall page
269 * pointer is restored on resume.
270 */
271 hv_hypercall_pg_saved = hv_hypercall_pg;
272 hv_hypercall_pg = NULL;
273
274 /* Disable the hypercall page in the hypervisor */
275 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
276 hypercall_msr.enable = 0;
277 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
278
279 ret = hv_cpu_die(0);
280 return ret;
281 }
282
hv_resume(void)283 static void hv_resume(void)
284 {
285 union hv_x64_msr_hypercall_contents hypercall_msr;
286 int ret;
287
288 ret = hv_cpu_init(0);
289 WARN_ON(ret);
290
291 /* Re-enable the hypercall page */
292 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
293 hypercall_msr.enable = 1;
294 hypercall_msr.guest_physical_address =
295 vmalloc_to_pfn(hv_hypercall_pg_saved);
296 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
297
298 hv_hypercall_pg = hv_hypercall_pg_saved;
299 hv_hypercall_pg_saved = NULL;
300
301 /*
302 * Reenlightenment notifications are disabled by hv_cpu_die(0),
303 * reenable them here if hv_reenlightenment_cb was previously set.
304 */
305 if (hv_reenlightenment_cb)
306 set_hv_tscchange_cb(hv_reenlightenment_cb);
307 }
308
309 /* Note: when the ops are called, only CPU0 is online and IRQs are disabled. */
310 static struct syscore_ops hv_syscore_ops = {
311 .suspend = hv_suspend,
312 .resume = hv_resume,
313 };
314
315 /*
316 * This function is to be invoked early in the boot sequence after the
317 * hypervisor has been detected.
318 *
319 * 1. Setup the hypercall page.
320 * 2. Register Hyper-V specific clocksource.
321 * 3. Setup Hyper-V specific APIC entry points.
322 */
hyperv_init(void)323 void __init hyperv_init(void)
324 {
325 u64 guest_id, required_msrs;
326 union hv_x64_msr_hypercall_contents hypercall_msr;
327 int cpuhp, i;
328
329 if (x86_hyper_type != X86_HYPER_MS_HYPERV)
330 return;
331
332 /* Absolutely required MSRs */
333 required_msrs = HV_MSR_HYPERCALL_AVAILABLE |
334 HV_MSR_VP_INDEX_AVAILABLE;
335
336 if ((ms_hyperv.features & required_msrs) != required_msrs)
337 return;
338
339 /*
340 * Allocate the per-CPU state for the hypercall input arg.
341 * If this allocation fails, we will not be able to setup
342 * (per-CPU) hypercall input page and thus this failure is
343 * fatal on Hyper-V.
344 */
345 hyperv_pcpu_input_arg = alloc_percpu(void *);
346
347 BUG_ON(hyperv_pcpu_input_arg == NULL);
348
349 /* Allocate percpu VP index */
350 hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
351 GFP_KERNEL);
352 if (!hv_vp_index)
353 return;
354
355 for (i = 0; i < num_possible_cpus(); i++)
356 hv_vp_index[i] = VP_INVAL;
357
358 hv_vp_assist_page = kcalloc(num_possible_cpus(),
359 sizeof(*hv_vp_assist_page), GFP_KERNEL);
360 if (!hv_vp_assist_page) {
361 ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
362 goto free_vp_index;
363 }
364
365 cpuhp = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online",
366 hv_cpu_init, hv_cpu_die);
367 if (cpuhp < 0)
368 goto free_vp_assist_page;
369
370 /*
371 * Setup the hypercall page and enable hypercalls.
372 * 1. Register the guest ID
373 * 2. Enable the hypercall and register the hypercall page
374 */
375 guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
376 wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
377
378 hv_hypercall_pg = __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START,
379 VMALLOC_END, GFP_KERNEL, PAGE_KERNEL_ROX,
380 VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
381 __builtin_return_address(0));
382 if (hv_hypercall_pg == NULL) {
383 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
384 goto remove_cpuhp_state;
385 }
386
387 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
388 hypercall_msr.enable = 1;
389 hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
390 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
391
392 /*
393 * Ignore any errors in setting up stimer clockevents
394 * as we can run with the LAPIC timer as a fallback.
395 */
396 (void)hv_stimer_alloc();
397
398 hv_apic_init();
399
400 x86_init.pci.arch_init = hv_pci_init;
401
402 register_syscore_ops(&hv_syscore_ops);
403
404 return;
405
406 remove_cpuhp_state:
407 cpuhp_remove_state(cpuhp);
408 free_vp_assist_page:
409 kfree(hv_vp_assist_page);
410 hv_vp_assist_page = NULL;
411 free_vp_index:
412 kfree(hv_vp_index);
413 hv_vp_index = NULL;
414 }
415
416 /*
417 * This routine is called before kexec/kdump, it does the required cleanup.
418 */
hyperv_cleanup(void)419 void hyperv_cleanup(void)
420 {
421 union hv_x64_msr_hypercall_contents hypercall_msr;
422
423 unregister_syscore_ops(&hv_syscore_ops);
424
425 /* Reset our OS id */
426 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
427
428 /*
429 * Reset hypercall page reference before reset the page,
430 * let hypercall operations fail safely rather than
431 * panic the kernel for using invalid hypercall page
432 */
433 hv_hypercall_pg = NULL;
434
435 /* Reset the hypercall page */
436 hypercall_msr.as_uint64 = 0;
437 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
438
439 /* Reset the TSC page */
440 hypercall_msr.as_uint64 = 0;
441 wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
442 }
443 EXPORT_SYMBOL_GPL(hyperv_cleanup);
444
hyperv_report_panic(struct pt_regs * regs,long err,bool in_die)445 void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die)
446 {
447 static bool panic_reported;
448 u64 guest_id;
449
450 if (in_die && !panic_on_oops)
451 return;
452
453 /*
454 * We prefer to report panic on 'die' chain as we have proper
455 * registers to report, but if we miss it (e.g. on BUG()) we need
456 * to report it on 'panic'.
457 */
458 if (panic_reported)
459 return;
460 panic_reported = true;
461
462 rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
463
464 wrmsrl(HV_X64_MSR_CRASH_P0, err);
465 wrmsrl(HV_X64_MSR_CRASH_P1, guest_id);
466 wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip);
467 wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax);
468 wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp);
469
470 /*
471 * Let Hyper-V know there is crash data available
472 */
473 wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
474 }
475 EXPORT_SYMBOL_GPL(hyperv_report_panic);
476
477 /**
478 * hyperv_report_panic_msg - report panic message to Hyper-V
479 * @pa: physical address of the panic page containing the message
480 * @size: size of the message in the page
481 */
hyperv_report_panic_msg(phys_addr_t pa,size_t size)482 void hyperv_report_panic_msg(phys_addr_t pa, size_t size)
483 {
484 /*
485 * P3 to contain the physical address of the panic page & P4 to
486 * contain the size of the panic data in that page. Rest of the
487 * registers are no-op when the NOTIFY_MSG flag is set.
488 */
489 wrmsrl(HV_X64_MSR_CRASH_P0, 0);
490 wrmsrl(HV_X64_MSR_CRASH_P1, 0);
491 wrmsrl(HV_X64_MSR_CRASH_P2, 0);
492 wrmsrl(HV_X64_MSR_CRASH_P3, pa);
493 wrmsrl(HV_X64_MSR_CRASH_P4, size);
494
495 /*
496 * Let Hyper-V know there is crash data available along with
497 * the panic message.
498 */
499 wrmsrl(HV_X64_MSR_CRASH_CTL,
500 (HV_CRASH_CTL_CRASH_NOTIFY | HV_CRASH_CTL_CRASH_NOTIFY_MSG));
501 }
502 EXPORT_SYMBOL_GPL(hyperv_report_panic_msg);
503
hv_is_hyperv_initialized(void)504 bool hv_is_hyperv_initialized(void)
505 {
506 union hv_x64_msr_hypercall_contents hypercall_msr;
507
508 /*
509 * Ensure that we're really on Hyper-V, and not a KVM or Xen
510 * emulation of Hyper-V
511 */
512 if (x86_hyper_type != X86_HYPER_MS_HYPERV)
513 return false;
514
515 /*
516 * Verify that earlier initialization succeeded by checking
517 * that the hypercall page is setup
518 */
519 hypercall_msr.as_uint64 = 0;
520 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
521
522 return hypercall_msr.enable;
523 }
524 EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);
525
hv_is_hibernation_supported(void)526 bool hv_is_hibernation_supported(void)
527 {
528 return acpi_sleep_state_supported(ACPI_STATE_S4);
529 }
530 EXPORT_SYMBOL_GPL(hv_is_hibernation_supported);
531
