1 /*
2 * X86 specific Hyper-V initialization code.
3 *
4 * Copyright (C) 2016, Microsoft, Inc.
5 *
6 * Author : K. Y. Srinivasan <kys@microsoft.com>
7 *
8 * This program is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 as published
10 * by the Free Software Foundation.
11 *
12 * This program is distributed in the hope that it will be useful, but
13 * WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
15 * NON INFRINGEMENT. See the GNU General Public License for more
16 * details.
17 *
18 */
19
20 #include <linux/efi.h>
21 #include <linux/types.h>
22 #include <asm/apic.h>
23 #include <asm/desc.h>
24 #include <asm/hypervisor.h>
25 #include <asm/hyperv-tlfs.h>
26 #include <asm/mshyperv.h>
27 #include <linux/version.h>
28 #include <linux/vmalloc.h>
29 #include <linux/mm.h>
30 #include <linux/clockchips.h>
31 #include <linux/hyperv.h>
32 #include <linux/slab.h>
33 #include <linux/kernel.h>
34 #include <linux/cpuhotplug.h>
35
36 #ifdef CONFIG_HYPERV_TSCPAGE
37
38 static struct ms_hyperv_tsc_page *tsc_pg;
39
hv_get_tsc_page(void)40 struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
41 {
42 return tsc_pg;
43 }
44 EXPORT_SYMBOL_GPL(hv_get_tsc_page);
45
read_hv_clock_tsc(struct clocksource * arg)46 static u64 read_hv_clock_tsc(struct clocksource *arg)
47 {
48 u64 current_tick = hv_read_tsc_page(tsc_pg);
49
50 if (current_tick == U64_MAX)
51 rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
52
53 return current_tick;
54 }
55
56 static struct clocksource hyperv_cs_tsc = {
57 .name = "hyperv_clocksource_tsc_page",
58 .rating = 400,
59 .read = read_hv_clock_tsc,
60 .mask = CLOCKSOURCE_MASK(64),
61 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
62 };
63 #endif
64
read_hv_clock_msr(struct clocksource * arg)65 static u64 read_hv_clock_msr(struct clocksource *arg)
66 {
67 u64 current_tick;
68 /*
69 * Read the partition counter to get the current tick count. This count
70 * is set to 0 when the partition is created and is incremented in
71 * 100 nanosecond units.
72 */
73 rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
74 return current_tick;
75 }
76
77 static struct clocksource hyperv_cs_msr = {
78 .name = "hyperv_clocksource_msr",
79 .rating = 400,
80 .read = read_hv_clock_msr,
81 .mask = CLOCKSOURCE_MASK(64),
82 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
83 };
84
85 void *hv_hypercall_pg;
86 EXPORT_SYMBOL_GPL(hv_hypercall_pg);
87 struct clocksource *hyperv_cs;
88 EXPORT_SYMBOL_GPL(hyperv_cs);
89
90 u32 *hv_vp_index;
91 EXPORT_SYMBOL_GPL(hv_vp_index);
92
93 struct hv_vp_assist_page **hv_vp_assist_page;
94 EXPORT_SYMBOL_GPL(hv_vp_assist_page);
95
96 void __percpu **hyperv_pcpu_input_arg;
97 EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg);
98
99 u32 hv_max_vp_index;
100
hv_cpu_init(unsigned int cpu)101 static int hv_cpu_init(unsigned int cpu)
102 {
103 u64 msr_vp_index;
104 struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
105 void **input_arg;
106 struct page *pg;
107
108 input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
109 pg = alloc_page(GFP_KERNEL);
110 if (unlikely(!pg))
111 return -ENOMEM;
112 *input_arg = page_address(pg);
113
114 hv_get_vp_index(msr_vp_index);
115
116 hv_vp_index[smp_processor_id()] = msr_vp_index;
117
118 if (msr_vp_index > hv_max_vp_index)
119 hv_max_vp_index = msr_vp_index;
120
121 if (!hv_vp_assist_page)
122 return 0;
123
124 if (!*hvp)
125 *hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
126
127 if (*hvp) {
128 u64 val;
129
130 val = vmalloc_to_pfn(*hvp);
131 val = (val << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT) |
132 HV_X64_MSR_VP_ASSIST_PAGE_ENABLE;
133
134 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, val);
135 }
136
137 return 0;
138 }
139
140 static void (*hv_reenlightenment_cb)(void);
141
hv_reenlightenment_notify(struct work_struct * dummy)142 static void hv_reenlightenment_notify(struct work_struct *dummy)
143 {
144 struct hv_tsc_emulation_status emu_status;
145
146 rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
147
148 /* Don't issue the callback if TSC accesses are not emulated */
149 if (hv_reenlightenment_cb && emu_status.inprogress)
150 hv_reenlightenment_cb();
151 }
152 static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify);
153
hyperv_stop_tsc_emulation(void)154 void hyperv_stop_tsc_emulation(void)
155 {
156 u64 freq;
157 struct hv_tsc_emulation_status emu_status;
158
159 rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
160 emu_status.inprogress = 0;
161 wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
162
163 rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);
164 tsc_khz = div64_u64(freq, 1000);
165 }
166 EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation);
167
hv_reenlightenment_available(void)168 static inline bool hv_reenlightenment_available(void)
169 {
170 /*
171 * Check for required features and priviliges to make TSC frequency
172 * change notifications work.
173 */
174 return ms_hyperv.features & HV_X64_ACCESS_FREQUENCY_MSRS &&
175 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE &&
176 ms_hyperv.features & HV_X64_ACCESS_REENLIGHTENMENT;
177 }
178
hyperv_reenlightenment_intr(struct pt_regs * regs)179 __visible void __irq_entry hyperv_reenlightenment_intr(struct pt_regs *regs)
180 {
181 entering_ack_irq();
182
183 inc_irq_stat(irq_hv_reenlightenment_count);
184
185 schedule_delayed_work(&hv_reenlightenment_work, HZ/10);
186
187 exiting_irq();
188 }
189
set_hv_tscchange_cb(void (* cb)(void))190 void set_hv_tscchange_cb(void (*cb)(void))
191 {
192 struct hv_reenlightenment_control re_ctrl = {
193 .vector = HYPERV_REENLIGHTENMENT_VECTOR,
194 .enabled = 1,
195 .target_vp = hv_vp_index[smp_processor_id()]
196 };
197 struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1};
198
199 if (!hv_reenlightenment_available()) {
200 pr_warn("Hyper-V: reenlightenment support is unavailable\n");
201 return;
202 }
203
204 hv_reenlightenment_cb = cb;
205
206 /* Make sure callback is registered before we write to MSRs */
207 wmb();
208
209 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
210 wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl));
211 }
212 EXPORT_SYMBOL_GPL(set_hv_tscchange_cb);
213
clear_hv_tscchange_cb(void)214 void clear_hv_tscchange_cb(void)
215 {
216 struct hv_reenlightenment_control re_ctrl;
217
218 if (!hv_reenlightenment_available())
219 return;
220
221 rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
222 re_ctrl.enabled = 0;
223 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
224
225 hv_reenlightenment_cb = NULL;
226 }
227 EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb);
228
hv_cpu_die(unsigned int cpu)229 static int hv_cpu_die(unsigned int cpu)
230 {
231 struct hv_reenlightenment_control re_ctrl;
232 unsigned int new_cpu;
233 unsigned long flags;
234 void **input_arg;
235 void *input_pg = NULL;
236
237 local_irq_save(flags);
238 input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
239 input_pg = *input_arg;
240 *input_arg = NULL;
241 local_irq_restore(flags);
242 free_page((unsigned long)input_pg);
243
244 if (hv_vp_assist_page && hv_vp_assist_page[cpu])
245 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0);
246
247 if (hv_reenlightenment_cb == NULL)
248 return 0;
249
250 rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
251 if (re_ctrl.target_vp == hv_vp_index[cpu]) {
252 /* Reassign to some other online CPU */
253 new_cpu = cpumask_any_but(cpu_online_mask, cpu);
254
255 re_ctrl.target_vp = hv_vp_index[new_cpu];
256 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
257 }
258
259 return 0;
260 }
261
hv_pci_init(void)262 static int __init hv_pci_init(void)
263 {
264 int gen2vm = efi_enabled(EFI_BOOT);
265
266 /*
267 * For Generation-2 VM, we exit from pci_arch_init() by returning 0.
268 * The purpose is to suppress the harmless warning:
269 * "PCI: Fatal: No config space access function found"
270 */
271 if (gen2vm)
272 return 0;
273
274 /* For Generation-1 VM, we'll proceed in pci_arch_init(). */
275 return 1;
276 }
277
278 /*
279 * This function is to be invoked early in the boot sequence after the
280 * hypervisor has been detected.
281 *
282 * 1. Setup the hypercall page.
283 * 2. Register Hyper-V specific clocksource.
284 * 3. Setup Hyper-V specific APIC entry points.
285 */
hyperv_init(void)286 void __init hyperv_init(void)
287 {
288 u64 guest_id, required_msrs;
289 union hv_x64_msr_hypercall_contents hypercall_msr;
290 int cpuhp, i;
291
292 if (x86_hyper_type != X86_HYPER_MS_HYPERV)
293 return;
294
295 /* Absolutely required MSRs */
296 required_msrs = HV_X64_MSR_HYPERCALL_AVAILABLE |
297 HV_X64_MSR_VP_INDEX_AVAILABLE;
298
299 if ((ms_hyperv.features & required_msrs) != required_msrs)
300 return;
301
302 /*
303 * Allocate the per-CPU state for the hypercall input arg.
304 * If this allocation fails, we will not be able to setup
305 * (per-CPU) hypercall input page and thus this failure is
306 * fatal on Hyper-V.
307 */
308 hyperv_pcpu_input_arg = alloc_percpu(void *);
309
310 BUG_ON(hyperv_pcpu_input_arg == NULL);
311
312 /* Allocate percpu VP index */
313 hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
314 GFP_KERNEL);
315 if (!hv_vp_index)
316 return;
317
318 for (i = 0; i < num_possible_cpus(); i++)
319 hv_vp_index[i] = VP_INVAL;
320
321 hv_vp_assist_page = kcalloc(num_possible_cpus(),
322 sizeof(*hv_vp_assist_page), GFP_KERNEL);
323 if (!hv_vp_assist_page) {
324 ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
325 goto free_vp_index;
326 }
327
328 cpuhp = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online",
329 hv_cpu_init, hv_cpu_die);
330 if (cpuhp < 0)
331 goto free_vp_assist_page;
332
333 /*
334 * Setup the hypercall page and enable hypercalls.
335 * 1. Register the guest ID
336 * 2. Enable the hypercall and register the hypercall page
337 */
338 guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
339 wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
340
341 hv_hypercall_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_RX);
342 if (hv_hypercall_pg == NULL) {
343 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
344 goto remove_cpuhp_state;
345 }
346
347 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
348 hypercall_msr.enable = 1;
349 hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
350 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
351
352 hv_apic_init();
353
354 x86_init.pci.arch_init = hv_pci_init;
355
356 /*
357 * Register Hyper-V specific clocksource.
358 */
359 #ifdef CONFIG_HYPERV_TSCPAGE
360 if (ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE) {
361 union hv_x64_msr_hypercall_contents tsc_msr;
362
363 tsc_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
364 if (!tsc_pg)
365 goto register_msr_cs;
366
367 hyperv_cs = &hyperv_cs_tsc;
368
369 rdmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
370
371 tsc_msr.enable = 1;
372 tsc_msr.guest_physical_address = vmalloc_to_pfn(tsc_pg);
373
374 wrmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
375
376 hyperv_cs_tsc.archdata.vclock_mode = VCLOCK_HVCLOCK;
377
378 clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
379 return;
380 }
381 register_msr_cs:
382 #endif
383 /*
384 * For 32 bit guests just use the MSR based mechanism for reading
385 * the partition counter.
386 */
387
388 hyperv_cs = &hyperv_cs_msr;
389 if (ms_hyperv.features & HV_MSR_TIME_REF_COUNT_AVAILABLE)
390 clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
391
392 return;
393
394 remove_cpuhp_state:
395 cpuhp_remove_state(cpuhp);
396 free_vp_assist_page:
397 kfree(hv_vp_assist_page);
398 hv_vp_assist_page = NULL;
399 free_vp_index:
400 kfree(hv_vp_index);
401 hv_vp_index = NULL;
402 }
403
404 /*
405 * This routine is called before kexec/kdump, it does the required cleanup.
406 */
hyperv_cleanup(void)407 void hyperv_cleanup(void)
408 {
409 union hv_x64_msr_hypercall_contents hypercall_msr;
410
411 /* Reset our OS id */
412 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
413
414 /*
415 * Reset hypercall page reference before reset the page,
416 * let hypercall operations fail safely rather than
417 * panic the kernel for using invalid hypercall page
418 */
419 hv_hypercall_pg = NULL;
420
421 /* Reset the hypercall page */
422 hypercall_msr.as_uint64 = 0;
423 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
424
425 /* Reset the TSC page */
426 hypercall_msr.as_uint64 = 0;
427 wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
428 }
429 EXPORT_SYMBOL_GPL(hyperv_cleanup);
430
hyperv_report_panic(struct pt_regs * regs,long err,bool in_die)431 void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die)
432 {
433 static bool panic_reported;
434 u64 guest_id;
435
436 if (in_die && !panic_on_oops)
437 return;
438
439 /*
440 * We prefer to report panic on 'die' chain as we have proper
441 * registers to report, but if we miss it (e.g. on BUG()) we need
442 * to report it on 'panic'.
443 */
444 if (panic_reported)
445 return;
446 panic_reported = true;
447
448 rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
449
450 wrmsrl(HV_X64_MSR_CRASH_P0, err);
451 wrmsrl(HV_X64_MSR_CRASH_P1, guest_id);
452 wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip);
453 wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax);
454 wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp);
455
456 /*
457 * Let Hyper-V know there is crash data available
458 */
459 wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
460 }
461 EXPORT_SYMBOL_GPL(hyperv_report_panic);
462
463 /**
464 * hyperv_report_panic_msg - report panic message to Hyper-V
465 * @pa: physical address of the panic page containing the message
466 * @size: size of the message in the page
467 */
hyperv_report_panic_msg(phys_addr_t pa,size_t size)468 void hyperv_report_panic_msg(phys_addr_t pa, size_t size)
469 {
470 /*
471 * P3 to contain the physical address of the panic page & P4 to
472 * contain the size of the panic data in that page. Rest of the
473 * registers are no-op when the NOTIFY_MSG flag is set.
474 */
475 wrmsrl(HV_X64_MSR_CRASH_P0, 0);
476 wrmsrl(HV_X64_MSR_CRASH_P1, 0);
477 wrmsrl(HV_X64_MSR_CRASH_P2, 0);
478 wrmsrl(HV_X64_MSR_CRASH_P3, pa);
479 wrmsrl(HV_X64_MSR_CRASH_P4, size);
480
481 /*
482 * Let Hyper-V know there is crash data available along with
483 * the panic message.
484 */
485 wrmsrl(HV_X64_MSR_CRASH_CTL,
486 (HV_CRASH_CTL_CRASH_NOTIFY | HV_CRASH_CTL_CRASH_NOTIFY_MSG));
487 }
488 EXPORT_SYMBOL_GPL(hyperv_report_panic_msg);
489
hv_is_hyperv_initialized(void)490 bool hv_is_hyperv_initialized(void)
491 {
492 union hv_x64_msr_hypercall_contents hypercall_msr;
493
494 /*
495 * Ensure that we're really on Hyper-V, and not a KVM or Xen
496 * emulation of Hyper-V
497 */
498 if (x86_hyper_type != X86_HYPER_MS_HYPERV)
499 return false;
500
501 /*
502 * Verify that earlier initialization succeeded by checking
503 * that the hypercall page is setup
504 */
505 hypercall_msr.as_uint64 = 0;
506 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
507
508 return hypercall_msr.enable;
509 }
510 EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);
511