xref: /openbmc/linux/arch/x86/hyperv/hv_init.c (revision b58c6630)
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 <linux/version.h>
19 #include <linux/vmalloc.h>
20 #include <linux/mm.h>
21 #include <linux/hyperv.h>
22 #include <linux/slab.h>
23 #include <linux/kernel.h>
24 #include <linux/cpuhotplug.h>
25 #include <linux/syscore_ops.h>
26 #include <clocksource/hyperv_timer.h>
27 
28 void *hv_hypercall_pg;
29 EXPORT_SYMBOL_GPL(hv_hypercall_pg);
30 
31 /* Storage to save the hypercall page temporarily for hibernation */
32 static void *hv_hypercall_pg_saved;
33 
34 u32 *hv_vp_index;
35 EXPORT_SYMBOL_GPL(hv_vp_index);
36 
37 struct hv_vp_assist_page **hv_vp_assist_page;
38 EXPORT_SYMBOL_GPL(hv_vp_assist_page);
39 
40 void  __percpu **hyperv_pcpu_input_arg;
41 EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg);
42 
43 u32 hv_max_vp_index;
44 EXPORT_SYMBOL_GPL(hv_max_vp_index);
45 
46 void *hv_alloc_hyperv_page(void)
47 {
48 	BUILD_BUG_ON(PAGE_SIZE != HV_HYP_PAGE_SIZE);
49 
50 	return (void *)__get_free_page(GFP_KERNEL);
51 }
52 EXPORT_SYMBOL_GPL(hv_alloc_hyperv_page);
53 
54 void *hv_alloc_hyperv_zeroed_page(void)
55 {
56         BUILD_BUG_ON(PAGE_SIZE != HV_HYP_PAGE_SIZE);
57 
58         return (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
59 }
60 EXPORT_SYMBOL_GPL(hv_alloc_hyperv_zeroed_page);
61 
62 void hv_free_hyperv_page(unsigned long addr)
63 {
64 	free_page(addr);
65 }
66 EXPORT_SYMBOL_GPL(hv_free_hyperv_page);
67 
68 static int hv_cpu_init(unsigned int cpu)
69 {
70 	u64 msr_vp_index;
71 	struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
72 	void **input_arg;
73 	struct page *pg;
74 
75 	input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
76 	pg = alloc_page(GFP_KERNEL);
77 	if (unlikely(!pg))
78 		return -ENOMEM;
79 	*input_arg = page_address(pg);
80 
81 	hv_get_vp_index(msr_vp_index);
82 
83 	hv_vp_index[smp_processor_id()] = msr_vp_index;
84 
85 	if (msr_vp_index > hv_max_vp_index)
86 		hv_max_vp_index = msr_vp_index;
87 
88 	if (!hv_vp_assist_page)
89 		return 0;
90 
91 	/*
92 	 * The VP ASSIST PAGE is an "overlay" page (see Hyper-V TLFS's Section
93 	 * 5.2.1 "GPA Overlay Pages"). Here it must be zeroed out to make sure
94 	 * we always write the EOI MSR in hv_apic_eoi_write() *after* the
95 	 * EOI optimization is disabled in hv_cpu_die(), otherwise a CPU may
96 	 * not be stopped in the case of CPU offlining and the VM will hang.
97 	 */
98 	if (!*hvp) {
99 		*hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL | __GFP_ZERO,
100 				 PAGE_KERNEL);
101 	}
102 
103 	if (*hvp) {
104 		u64 val;
105 
106 		val = vmalloc_to_pfn(*hvp);
107 		val = (val << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT) |
108 			HV_X64_MSR_VP_ASSIST_PAGE_ENABLE;
109 
110 		wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, val);
111 	}
112 
113 	return 0;
114 }
115 
116 static void (*hv_reenlightenment_cb)(void);
117 
118 static void hv_reenlightenment_notify(struct work_struct *dummy)
119 {
120 	struct hv_tsc_emulation_status emu_status;
121 
122 	rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
123 
124 	/* Don't issue the callback if TSC accesses are not emulated */
125 	if (hv_reenlightenment_cb && emu_status.inprogress)
126 		hv_reenlightenment_cb();
127 }
128 static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify);
129 
130 void hyperv_stop_tsc_emulation(void)
131 {
132 	u64 freq;
133 	struct hv_tsc_emulation_status emu_status;
134 
135 	rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
136 	emu_status.inprogress = 0;
137 	wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
138 
139 	rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);
140 	tsc_khz = div64_u64(freq, 1000);
141 }
142 EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation);
143 
144 static inline bool hv_reenlightenment_available(void)
145 {
146 	/*
147 	 * Check for required features and priviliges to make TSC frequency
148 	 * change notifications work.
149 	 */
150 	return ms_hyperv.features & HV_X64_ACCESS_FREQUENCY_MSRS &&
151 		ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE &&
152 		ms_hyperv.features & HV_X64_ACCESS_REENLIGHTENMENT;
153 }
154 
155 __visible void __irq_entry hyperv_reenlightenment_intr(struct pt_regs *regs)
156 {
157 	entering_ack_irq();
158 
159 	inc_irq_stat(irq_hv_reenlightenment_count);
160 
161 	schedule_delayed_work(&hv_reenlightenment_work, HZ/10);
162 
163 	exiting_irq();
164 }
165 
166 void set_hv_tscchange_cb(void (*cb)(void))
167 {
168 	struct hv_reenlightenment_control re_ctrl = {
169 		.vector = HYPERV_REENLIGHTENMENT_VECTOR,
170 		.enabled = 1,
171 		.target_vp = hv_vp_index[smp_processor_id()]
172 	};
173 	struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1};
174 
175 	if (!hv_reenlightenment_available()) {
176 		pr_warn("Hyper-V: reenlightenment support is unavailable\n");
177 		return;
178 	}
179 
180 	hv_reenlightenment_cb = cb;
181 
182 	/* Make sure callback is registered before we write to MSRs */
183 	wmb();
184 
185 	wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
186 	wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl));
187 }
188 EXPORT_SYMBOL_GPL(set_hv_tscchange_cb);
189 
190 void clear_hv_tscchange_cb(void)
191 {
192 	struct hv_reenlightenment_control re_ctrl;
193 
194 	if (!hv_reenlightenment_available())
195 		return;
196 
197 	rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
198 	re_ctrl.enabled = 0;
199 	wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
200 
201 	hv_reenlightenment_cb = NULL;
202 }
203 EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb);
204 
205 static int hv_cpu_die(unsigned int cpu)
206 {
207 	struct hv_reenlightenment_control re_ctrl;
208 	unsigned int new_cpu;
209 	unsigned long flags;
210 	void **input_arg;
211 	void *input_pg = NULL;
212 
213 	local_irq_save(flags);
214 	input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
215 	input_pg = *input_arg;
216 	*input_arg = NULL;
217 	local_irq_restore(flags);
218 	free_page((unsigned long)input_pg);
219 
220 	if (hv_vp_assist_page && hv_vp_assist_page[cpu])
221 		wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0);
222 
223 	if (hv_reenlightenment_cb == NULL)
224 		return 0;
225 
226 	rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
227 	if (re_ctrl.target_vp == hv_vp_index[cpu]) {
228 		/* Reassign to some other online CPU */
229 		new_cpu = cpumask_any_but(cpu_online_mask, cpu);
230 
231 		re_ctrl.target_vp = hv_vp_index[new_cpu];
232 		wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
233 	}
234 
235 	return 0;
236 }
237 
238 static int __init hv_pci_init(void)
239 {
240 	int gen2vm = efi_enabled(EFI_BOOT);
241 
242 	/*
243 	 * For Generation-2 VM, we exit from pci_arch_init() by returning 0.
244 	 * The purpose is to suppress the harmless warning:
245 	 * "PCI: Fatal: No config space access function found"
246 	 */
247 	if (gen2vm)
248 		return 0;
249 
250 	/* For Generation-1 VM, we'll proceed in pci_arch_init().  */
251 	return 1;
252 }
253 
254 static int hv_suspend(void)
255 {
256 	union hv_x64_msr_hypercall_contents hypercall_msr;
257 
258 	/*
259 	 * Reset the hypercall page as it is going to be invalidated
260 	 * accross hibernation. Setting hv_hypercall_pg to NULL ensures
261 	 * that any subsequent hypercall operation fails safely instead of
262 	 * crashing due to an access of an invalid page. The hypercall page
263 	 * pointer is restored on resume.
264 	 */
265 	hv_hypercall_pg_saved = hv_hypercall_pg;
266 	hv_hypercall_pg = NULL;
267 
268 	/* Disable the hypercall page in the hypervisor */
269 	rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
270 	hypercall_msr.enable = 0;
271 	wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
272 
273 	return 0;
274 }
275 
276 static void hv_resume(void)
277 {
278 	union hv_x64_msr_hypercall_contents hypercall_msr;
279 
280 	/* Re-enable the hypercall page */
281 	rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
282 	hypercall_msr.enable = 1;
283 	hypercall_msr.guest_physical_address =
284 		vmalloc_to_pfn(hv_hypercall_pg_saved);
285 	wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
286 
287 	hv_hypercall_pg = hv_hypercall_pg_saved;
288 	hv_hypercall_pg_saved = NULL;
289 }
290 
291 static struct syscore_ops hv_syscore_ops = {
292 	.suspend	= hv_suspend,
293 	.resume		= hv_resume,
294 };
295 
296 /*
297  * This function is to be invoked early in the boot sequence after the
298  * hypervisor has been detected.
299  *
300  * 1. Setup the hypercall page.
301  * 2. Register Hyper-V specific clocksource.
302  * 3. Setup Hyper-V specific APIC entry points.
303  */
304 void __init hyperv_init(void)
305 {
306 	u64 guest_id, required_msrs;
307 	union hv_x64_msr_hypercall_contents hypercall_msr;
308 	int cpuhp, i;
309 
310 	if (x86_hyper_type != X86_HYPER_MS_HYPERV)
311 		return;
312 
313 	/* Absolutely required MSRs */
314 	required_msrs = HV_X64_MSR_HYPERCALL_AVAILABLE |
315 		HV_X64_MSR_VP_INDEX_AVAILABLE;
316 
317 	if ((ms_hyperv.features & required_msrs) != required_msrs)
318 		return;
319 
320 	/*
321 	 * Allocate the per-CPU state for the hypercall input arg.
322 	 * If this allocation fails, we will not be able to setup
323 	 * (per-CPU) hypercall input page and thus this failure is
324 	 * fatal on Hyper-V.
325 	 */
326 	hyperv_pcpu_input_arg = alloc_percpu(void  *);
327 
328 	BUG_ON(hyperv_pcpu_input_arg == NULL);
329 
330 	/* Allocate percpu VP index */
331 	hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
332 				    GFP_KERNEL);
333 	if (!hv_vp_index)
334 		return;
335 
336 	for (i = 0; i < num_possible_cpus(); i++)
337 		hv_vp_index[i] = VP_INVAL;
338 
339 	hv_vp_assist_page = kcalloc(num_possible_cpus(),
340 				    sizeof(*hv_vp_assist_page), GFP_KERNEL);
341 	if (!hv_vp_assist_page) {
342 		ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
343 		goto free_vp_index;
344 	}
345 
346 	cpuhp = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online",
347 				  hv_cpu_init, hv_cpu_die);
348 	if (cpuhp < 0)
349 		goto free_vp_assist_page;
350 
351 	/*
352 	 * Setup the hypercall page and enable hypercalls.
353 	 * 1. Register the guest ID
354 	 * 2. Enable the hypercall and register the hypercall page
355 	 */
356 	guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
357 	wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
358 
359 	hv_hypercall_pg  = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_RX);
360 	if (hv_hypercall_pg == NULL) {
361 		wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
362 		goto remove_cpuhp_state;
363 	}
364 
365 	rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
366 	hypercall_msr.enable = 1;
367 	hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
368 	wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
369 
370 	/*
371 	 * Ignore any errors in setting up stimer clockevents
372 	 * as we can run with the LAPIC timer as a fallback.
373 	 */
374 	(void)hv_stimer_alloc();
375 
376 	hv_apic_init();
377 
378 	x86_init.pci.arch_init = hv_pci_init;
379 
380 	register_syscore_ops(&hv_syscore_ops);
381 
382 	return;
383 
384 remove_cpuhp_state:
385 	cpuhp_remove_state(cpuhp);
386 free_vp_assist_page:
387 	kfree(hv_vp_assist_page);
388 	hv_vp_assist_page = NULL;
389 free_vp_index:
390 	kfree(hv_vp_index);
391 	hv_vp_index = NULL;
392 }
393 
394 /*
395  * This routine is called before kexec/kdump, it does the required cleanup.
396  */
397 void hyperv_cleanup(void)
398 {
399 	union hv_x64_msr_hypercall_contents hypercall_msr;
400 
401 	unregister_syscore_ops(&hv_syscore_ops);
402 
403 	/* Reset our OS id */
404 	wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
405 
406 	/*
407 	 * Reset hypercall page reference before reset the page,
408 	 * let hypercall operations fail safely rather than
409 	 * panic the kernel for using invalid hypercall page
410 	 */
411 	hv_hypercall_pg = NULL;
412 
413 	/* Reset the hypercall page */
414 	hypercall_msr.as_uint64 = 0;
415 	wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
416 
417 	/* Reset the TSC page */
418 	hypercall_msr.as_uint64 = 0;
419 	wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
420 }
421 EXPORT_SYMBOL_GPL(hyperv_cleanup);
422 
423 void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die)
424 {
425 	static bool panic_reported;
426 	u64 guest_id;
427 
428 	if (in_die && !panic_on_oops)
429 		return;
430 
431 	/*
432 	 * We prefer to report panic on 'die' chain as we have proper
433 	 * registers to report, but if we miss it (e.g. on BUG()) we need
434 	 * to report it on 'panic'.
435 	 */
436 	if (panic_reported)
437 		return;
438 	panic_reported = true;
439 
440 	rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
441 
442 	wrmsrl(HV_X64_MSR_CRASH_P0, err);
443 	wrmsrl(HV_X64_MSR_CRASH_P1, guest_id);
444 	wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip);
445 	wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax);
446 	wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp);
447 
448 	/*
449 	 * Let Hyper-V know there is crash data available
450 	 */
451 	wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
452 }
453 EXPORT_SYMBOL_GPL(hyperv_report_panic);
454 
455 /**
456  * hyperv_report_panic_msg - report panic message to Hyper-V
457  * @pa: physical address of the panic page containing the message
458  * @size: size of the message in the page
459  */
460 void hyperv_report_panic_msg(phys_addr_t pa, size_t size)
461 {
462 	/*
463 	 * P3 to contain the physical address of the panic page & P4 to
464 	 * contain the size of the panic data in that page. Rest of the
465 	 * registers are no-op when the NOTIFY_MSG flag is set.
466 	 */
467 	wrmsrl(HV_X64_MSR_CRASH_P0, 0);
468 	wrmsrl(HV_X64_MSR_CRASH_P1, 0);
469 	wrmsrl(HV_X64_MSR_CRASH_P2, 0);
470 	wrmsrl(HV_X64_MSR_CRASH_P3, pa);
471 	wrmsrl(HV_X64_MSR_CRASH_P4, size);
472 
473 	/*
474 	 * Let Hyper-V know there is crash data available along with
475 	 * the panic message.
476 	 */
477 	wrmsrl(HV_X64_MSR_CRASH_CTL,
478 	       (HV_CRASH_CTL_CRASH_NOTIFY | HV_CRASH_CTL_CRASH_NOTIFY_MSG));
479 }
480 EXPORT_SYMBOL_GPL(hyperv_report_panic_msg);
481 
482 bool hv_is_hyperv_initialized(void)
483 {
484 	union hv_x64_msr_hypercall_contents hypercall_msr;
485 
486 	/*
487 	 * Ensure that we're really on Hyper-V, and not a KVM or Xen
488 	 * emulation of Hyper-V
489 	 */
490 	if (x86_hyper_type != X86_HYPER_MS_HYPERV)
491 		return false;
492 
493 	/*
494 	 * Verify that earlier initialization succeeded by checking
495 	 * that the hypercall page is setup
496 	 */
497 	hypercall_msr.as_uint64 = 0;
498 	rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
499 
500 	return hypercall_msr.enable;
501 }
502 EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);
503 
504 bool hv_is_hibernation_supported(void)
505 {
506 	return acpi_sleep_state_supported(ACPI_STATE_S4);
507 }
508 EXPORT_SYMBOL_GPL(hv_is_hibernation_supported);
509