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1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * HyperV  Detection code.
4  *
5  * Copyright (C) 2010, Novell, Inc.
6  * Author : K. Y. Srinivasan <ksrinivasan@novell.com>
7  */
8 
9 #include <linux/types.h>
10 #include <linux/time.h>
11 #include <linux/clocksource.h>
12 #include <linux/init.h>
13 #include <linux/export.h>
14 #include <linux/hardirq.h>
15 #include <linux/efi.h>
16 #include <linux/interrupt.h>
17 #include <linux/irq.h>
18 #include <linux/kexec.h>
19 #include <linux/i8253.h>
20 #include <linux/random.h>
21 #include <asm/processor.h>
22 #include <asm/hypervisor.h>
23 #include <asm/hyperv-tlfs.h>
24 #include <asm/mshyperv.h>
25 #include <asm/desc.h>
26 #include <asm/idtentry.h>
27 #include <asm/irq_regs.h>
28 #include <asm/i8259.h>
29 #include <asm/apic.h>
30 #include <asm/timer.h>
31 #include <asm/reboot.h>
32 #include <asm/nmi.h>
33 #include <clocksource/hyperv_timer.h>
34 
35 struct ms_hyperv_info ms_hyperv;
36 EXPORT_SYMBOL_GPL(ms_hyperv);
37 
38 #if IS_ENABLED(CONFIG_HYPERV)
39 static void (*vmbus_handler)(void);
40 static void (*hv_stimer0_handler)(void);
41 static void (*hv_kexec_handler)(void);
42 static void (*hv_crash_handler)(struct pt_regs *regs);
43 
DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_callback)44 DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_callback)
45 {
46 	struct pt_regs *old_regs = set_irq_regs(regs);
47 
48 	inc_irq_stat(irq_hv_callback_count);
49 	if (vmbus_handler)
50 		vmbus_handler();
51 
52 	if (ms_hyperv.hints & HV_DEPRECATING_AEOI_RECOMMENDED)
53 		ack_APIC_irq();
54 
55 	set_irq_regs(old_regs);
56 }
57 
hv_setup_vmbus_irq(int irq,void (* handler)(void))58 int hv_setup_vmbus_irq(int irq, void (*handler)(void))
59 {
60 	/*
61 	 * The 'irq' argument is ignored on x86/x64 because a hard-coded
62 	 * interrupt vector is used for Hyper-V interrupts.
63 	 */
64 	vmbus_handler = handler;
65 	return 0;
66 }
67 
hv_remove_vmbus_irq(void)68 void hv_remove_vmbus_irq(void)
69 {
70 	/* We have no way to deallocate the interrupt gate */
71 	vmbus_handler = NULL;
72 }
73 EXPORT_SYMBOL_GPL(hv_setup_vmbus_irq);
74 EXPORT_SYMBOL_GPL(hv_remove_vmbus_irq);
75 
76 /*
77  * Routines to do per-architecture handling of stimer0
78  * interrupts when in Direct Mode
79  */
DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_stimer0)80 DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_stimer0)
81 {
82 	struct pt_regs *old_regs = set_irq_regs(regs);
83 
84 	inc_irq_stat(hyperv_stimer0_count);
85 	if (hv_stimer0_handler)
86 		hv_stimer0_handler();
87 	add_interrupt_randomness(HYPERV_STIMER0_VECTOR);
88 	ack_APIC_irq();
89 
90 	set_irq_regs(old_regs);
91 }
92 
hv_setup_stimer0_irq(int * irq,int * vector,void (* handler)(void))93 int hv_setup_stimer0_irq(int *irq, int *vector, void (*handler)(void))
94 {
95 	*vector = HYPERV_STIMER0_VECTOR;
96 	*irq = -1;   /* Unused on x86/x64 */
97 	hv_stimer0_handler = handler;
98 	return 0;
99 }
100 EXPORT_SYMBOL_GPL(hv_setup_stimer0_irq);
101 
hv_remove_stimer0_irq(int irq)102 void hv_remove_stimer0_irq(int irq)
103 {
104 	/* We have no way to deallocate the interrupt gate */
105 	hv_stimer0_handler = NULL;
106 }
107 EXPORT_SYMBOL_GPL(hv_remove_stimer0_irq);
108 
hv_setup_kexec_handler(void (* handler)(void))109 void hv_setup_kexec_handler(void (*handler)(void))
110 {
111 	hv_kexec_handler = handler;
112 }
113 EXPORT_SYMBOL_GPL(hv_setup_kexec_handler);
114 
hv_remove_kexec_handler(void)115 void hv_remove_kexec_handler(void)
116 {
117 	hv_kexec_handler = NULL;
118 }
119 EXPORT_SYMBOL_GPL(hv_remove_kexec_handler);
120 
hv_setup_crash_handler(void (* handler)(struct pt_regs * regs))121 void hv_setup_crash_handler(void (*handler)(struct pt_regs *regs))
122 {
123 	hv_crash_handler = handler;
124 }
125 EXPORT_SYMBOL_GPL(hv_setup_crash_handler);
126 
hv_remove_crash_handler(void)127 void hv_remove_crash_handler(void)
128 {
129 	hv_crash_handler = NULL;
130 }
131 EXPORT_SYMBOL_GPL(hv_remove_crash_handler);
132 
133 #ifdef CONFIG_KEXEC_CORE
hv_machine_shutdown(void)134 static void hv_machine_shutdown(void)
135 {
136 	if (kexec_in_progress && hv_kexec_handler)
137 		hv_kexec_handler();
138 
139 	/*
140 	 * Call hv_cpu_die() on all the CPUs, otherwise later the hypervisor
141 	 * corrupts the old VP Assist Pages and can crash the kexec kernel.
142 	 */
143 	if (kexec_in_progress && hyperv_init_cpuhp > 0)
144 		cpuhp_remove_state(hyperv_init_cpuhp);
145 
146 	/* The function calls stop_other_cpus(). */
147 	native_machine_shutdown();
148 
149 	/* Disable the hypercall page when there is only 1 active CPU. */
150 	if (kexec_in_progress)
151 		hyperv_cleanup();
152 }
153 
hv_machine_crash_shutdown(struct pt_regs * regs)154 static void hv_machine_crash_shutdown(struct pt_regs *regs)
155 {
156 	if (hv_crash_handler)
157 		hv_crash_handler(regs);
158 
159 	/* The function calls crash_smp_send_stop(). */
160 	native_machine_crash_shutdown(regs);
161 
162 	/* Disable the hypercall page when there is only 1 active CPU. */
163 	hyperv_cleanup();
164 }
165 #endif /* CONFIG_KEXEC_CORE */
166 #endif /* CONFIG_HYPERV */
167 
ms_hyperv_platform(void)168 static uint32_t  __init ms_hyperv_platform(void)
169 {
170 	u32 eax;
171 	u32 hyp_signature[3];
172 
173 	if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
174 		return 0;
175 
176 	cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
177 	      &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);
178 
179 	if (eax >= HYPERV_CPUID_MIN &&
180 	    eax <= HYPERV_CPUID_MAX &&
181 	    !memcmp("Microsoft Hv", hyp_signature, 12))
182 		return HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS;
183 
184 	return 0;
185 }
186 
hv_get_nmi_reason(void)187 static unsigned char hv_get_nmi_reason(void)
188 {
189 	return 0;
190 }
191 
192 #ifdef CONFIG_X86_LOCAL_APIC
193 /*
194  * Prior to WS2016 Debug-VM sends NMIs to all CPUs which makes
195  * it dificult to process CHANNELMSG_UNLOAD in case of crash. Handle
196  * unknown NMI on the first CPU which gets it.
197  */
hv_nmi_unknown(unsigned int val,struct pt_regs * regs)198 static int hv_nmi_unknown(unsigned int val, struct pt_regs *regs)
199 {
200 	static atomic_t nmi_cpu = ATOMIC_INIT(-1);
201 
202 	if (!unknown_nmi_panic)
203 		return NMI_DONE;
204 
205 	if (atomic_cmpxchg(&nmi_cpu, -1, raw_smp_processor_id()) != -1)
206 		return NMI_HANDLED;
207 
208 	return NMI_DONE;
209 }
210 #endif
211 
hv_get_tsc_khz(void)212 static unsigned long hv_get_tsc_khz(void)
213 {
214 	unsigned long freq;
215 
216 	rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);
217 
218 	return freq / 1000;
219 }
220 
221 #if defined(CONFIG_SMP) && IS_ENABLED(CONFIG_HYPERV)
hv_smp_prepare_boot_cpu(void)222 static void __init hv_smp_prepare_boot_cpu(void)
223 {
224 	native_smp_prepare_boot_cpu();
225 #if defined(CONFIG_X86_64) && defined(CONFIG_PARAVIRT_SPINLOCKS)
226 	hv_init_spinlocks();
227 #endif
228 }
229 #endif
230 
ms_hyperv_init_platform(void)231 static void __init ms_hyperv_init_platform(void)
232 {
233 	int hv_host_info_eax;
234 	int hv_host_info_ebx;
235 	int hv_host_info_ecx;
236 	int hv_host_info_edx;
237 
238 #ifdef CONFIG_PARAVIRT
239 	pv_info.name = "Hyper-V";
240 #endif
241 
242 	/*
243 	 * Extract the features and hints
244 	 */
245 	ms_hyperv.features = cpuid_eax(HYPERV_CPUID_FEATURES);
246 	ms_hyperv.misc_features = cpuid_edx(HYPERV_CPUID_FEATURES);
247 	ms_hyperv.hints    = cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);
248 
249 	pr_info("Hyper-V: features 0x%x, hints 0x%x, misc 0x%x\n",
250 		ms_hyperv.features, ms_hyperv.hints, ms_hyperv.misc_features);
251 
252 	ms_hyperv.max_vp_index = cpuid_eax(HYPERV_CPUID_IMPLEMENT_LIMITS);
253 	ms_hyperv.max_lp_index = cpuid_ebx(HYPERV_CPUID_IMPLEMENT_LIMITS);
254 
255 	pr_debug("Hyper-V: max %u virtual processors, %u logical processors\n",
256 		 ms_hyperv.max_vp_index, ms_hyperv.max_lp_index);
257 
258 	/*
259 	 * Extract host information.
260 	 */
261 	if (cpuid_eax(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS) >=
262 	    HYPERV_CPUID_VERSION) {
263 		hv_host_info_eax = cpuid_eax(HYPERV_CPUID_VERSION);
264 		hv_host_info_ebx = cpuid_ebx(HYPERV_CPUID_VERSION);
265 		hv_host_info_ecx = cpuid_ecx(HYPERV_CPUID_VERSION);
266 		hv_host_info_edx = cpuid_edx(HYPERV_CPUID_VERSION);
267 
268 		pr_info("Hyper-V Host Build:%d-%d.%d-%d-%d.%d\n",
269 			hv_host_info_eax, hv_host_info_ebx >> 16,
270 			hv_host_info_ebx & 0xFFFF, hv_host_info_ecx,
271 			hv_host_info_edx >> 24, hv_host_info_edx & 0xFFFFFF);
272 	}
273 
274 	if (ms_hyperv.features & HV_ACCESS_FREQUENCY_MSRS &&
275 	    ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE) {
276 		x86_platform.calibrate_tsc = hv_get_tsc_khz;
277 		x86_platform.calibrate_cpu = hv_get_tsc_khz;
278 	}
279 
280 	if (ms_hyperv.hints & HV_X64_ENLIGHTENED_VMCS_RECOMMENDED) {
281 		ms_hyperv.nested_features =
282 			cpuid_eax(HYPERV_CPUID_NESTED_FEATURES);
283 	}
284 
285 	/*
286 	 * Hyper-V expects to get crash register data or kmsg when
287 	 * crash enlightment is available and system crashes. Set
288 	 * crash_kexec_post_notifiers to be true to make sure that
289 	 * calling crash enlightment interface before running kdump
290 	 * kernel.
291 	 */
292 	if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE)
293 		crash_kexec_post_notifiers = true;
294 
295 #ifdef CONFIG_X86_LOCAL_APIC
296 	if (ms_hyperv.features & HV_ACCESS_FREQUENCY_MSRS &&
297 	    ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE) {
298 		/*
299 		 * Get the APIC frequency.
300 		 */
301 		u64	hv_lapic_frequency;
302 
303 		rdmsrl(HV_X64_MSR_APIC_FREQUENCY, hv_lapic_frequency);
304 		hv_lapic_frequency = div_u64(hv_lapic_frequency, HZ);
305 		lapic_timer_period = hv_lapic_frequency;
306 		pr_info("Hyper-V: LAPIC Timer Frequency: %#x\n",
307 			lapic_timer_period);
308 	}
309 
310 	register_nmi_handler(NMI_UNKNOWN, hv_nmi_unknown, NMI_FLAG_FIRST,
311 			     "hv_nmi_unknown");
312 #endif
313 
314 #ifdef CONFIG_X86_IO_APIC
315 	no_timer_check = 1;
316 #endif
317 
318 #if IS_ENABLED(CONFIG_HYPERV) && defined(CONFIG_KEXEC_CORE)
319 	machine_ops.shutdown = hv_machine_shutdown;
320 	machine_ops.crash_shutdown = hv_machine_crash_shutdown;
321 #endif
322 	if (ms_hyperv.features & HV_ACCESS_TSC_INVARIANT) {
323 		wrmsrl(HV_X64_MSR_TSC_INVARIANT_CONTROL, 0x1);
324 		setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
325 	}
326 
327 	/*
328 	 * Generation 2 instances don't support reading the NMI status from
329 	 * 0x61 port.
330 	 */
331 	if (efi_enabled(EFI_BOOT))
332 		x86_platform.get_nmi_reason = hv_get_nmi_reason;
333 
334 	/*
335 	 * Hyper-V VMs have a PIT emulation quirk such that zeroing the
336 	 * counter register during PIT shutdown restarts the PIT. So it
337 	 * continues to interrupt @18.2 HZ. Setting i8253_clear_counter
338 	 * to false tells pit_shutdown() not to zero the counter so that
339 	 * the PIT really is shutdown. Generation 2 VMs don't have a PIT,
340 	 * and setting this value has no effect.
341 	 */
342 	i8253_clear_counter_on_shutdown = false;
343 
344 #if IS_ENABLED(CONFIG_HYPERV)
345 	/*
346 	 * Setup the hook to get control post apic initialization.
347 	 */
348 	x86_platform.apic_post_init = hyperv_init;
349 	hyperv_setup_mmu_ops();
350 	/* Setup the IDT for hypervisor callback */
351 	alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, asm_sysvec_hyperv_callback);
352 
353 	/* Setup the IDT for reenlightenment notifications */
354 	if (ms_hyperv.features & HV_ACCESS_REENLIGHTENMENT) {
355 		alloc_intr_gate(HYPERV_REENLIGHTENMENT_VECTOR,
356 				asm_sysvec_hyperv_reenlightenment);
357 	}
358 
359 	/* Setup the IDT for stimer0 */
360 	if (ms_hyperv.misc_features & HV_STIMER_DIRECT_MODE_AVAILABLE) {
361 		alloc_intr_gate(HYPERV_STIMER0_VECTOR,
362 				asm_sysvec_hyperv_stimer0);
363 	}
364 
365 # ifdef CONFIG_SMP
366 	smp_ops.smp_prepare_boot_cpu = hv_smp_prepare_boot_cpu;
367 # endif
368 
369 	/*
370 	 * Hyper-V doesn't provide irq remapping for IO-APIC. To enable x2apic,
371 	 * set x2apic destination mode to physcial mode when x2apic is available
372 	 * and Hyper-V IOMMU driver makes sure cpus assigned with IO-APIC irqs
373 	 * have 8-bit APIC id.
374 	 */
375 # ifdef CONFIG_X86_X2APIC
376 	if (x2apic_supported())
377 		x2apic_phys = 1;
378 # endif
379 
380 	/* Register Hyper-V specific clocksource */
381 	hv_init_clocksource();
382 #endif
383 	/*
384 	 * TSC should be marked as unstable only after Hyper-V
385 	 * clocksource has been initialized. This ensures that the
386 	 * stability of the sched_clock is not altered.
387 	 */
388 	if (!(ms_hyperv.features & HV_ACCESS_TSC_INVARIANT))
389 		mark_tsc_unstable("running on Hyper-V");
390 }
391 
392 const __initconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
393 	.name			= "Microsoft Hyper-V",
394 	.detect			= ms_hyperv_platform,
395 	.type			= X86_HYPER_MS_HYPERV,
396 	.init.init_platform	= ms_hyperv_init_platform,
397 };
398