text: // SPDX-License-Identifier: GPL-2.0-only
  /*
   * HyperV  Detection code.
   *
   * Copyright (C) 2010, Novell, Inc.
   * Author : K. Y. Srinivasan <ksrinivasan@novell.com>
   */
  
  #include <linux/types.h>
  #include <linux/time.h>
  #include <linux/clocksource.h>
  #include <linux/init.h>
  #include <linux/export.h>
  #include <linux/hardirq.h>
  #include <linux/efi.h>
  #include <linux/interrupt.h>
  #include <linux/irq.h>
  #include <linux/kexec.h>
  #include <linux/i8253.h>
  #include <linux/random.h>
  #include <asm/processor.h>
  #include <asm/hypervisor.h>
  #include <asm/hyperv-tlfs.h>
  #include <asm/mshyperv.h>
  #include <asm/desc.h>
  #include <asm/irq_regs.h>
  #include <asm/i8259.h>
  #include <asm/apic.h>
  #include <asm/timer.h>
  #include <asm/reboot.h>
  #include <asm/nmi.h>
  
  struct ms_hyperv_info ms_hyperv;
  EXPORT_SYMBOL_GPL(ms_hyperv);
  
  #if IS_ENABLED(CONFIG_HYPERV)
  static void (*vmbus_handler)(void);
  static void (*hv_stimer0_handler)(void);
  static void (*hv_kexec_handler)(void);
  static void (*hv_crash_handler)(struct pt_regs *regs);
  
  __visible void __irq_entry hyperv_vector_handler(struct pt_regs *regs)
  {
  	struct pt_regs *old_regs = set_irq_regs(regs);
  
  	entering_irq();
  	inc_irq_stat(irq_hv_callback_count);
  	if (vmbus_handler)
  		vmbus_handler();
  
  	if (ms_hyperv.hints & HV_DEPRECATING_AEOI_RECOMMENDED)
  		ack_APIC_irq();
  
  	exiting_irq();
  	set_irq_regs(old_regs);
  }
  
  void hv_setup_vmbus_irq(void (*handler)(void))
  {
  	vmbus_handler = handler;
  }
  
  void hv_remove_vmbus_irq(void)
  {
  	/* We have no way to deallocate the interrupt gate */
  	vmbus_handler = NULL;
  }
  EXPORT_SYMBOL_GPL(hv_setup_vmbus_irq);
  EXPORT_SYMBOL_GPL(hv_remove_vmbus_irq);
  
  /*
   * Routines to do per-architecture handling of stimer0
   * interrupts when in Direct Mode
   */
  
  __visible void __irq_entry hv_stimer0_vector_handler(struct pt_regs *regs)
  {
  	struct pt_regs *old_regs = set_irq_regs(regs);
  
  	entering_irq();
  	inc_irq_stat(hyperv_stimer0_count);
  	if (hv_stimer0_handler)
  		hv_stimer0_handler();
  	add_interrupt_randomness(HYPERV_STIMER0_VECTOR, 0);
  	ack_APIC_irq();
  
  	exiting_irq();
  	set_irq_regs(old_regs);
  }
  
  int hv_setup_stimer0_irq(int *irq, int *vector, void (*handler)(void))
  {
  	*vector = HYPERV_STIMER0_VECTOR;
  	*irq = -1;   /* Unused on x86/x64 */
  	hv_stimer0_handler = handler;
  	return 0;
  }
  EXPORT_SYMBOL_GPL(hv_setup_stimer0_irq);
  
  void hv_remove_stimer0_irq(int irq)
  {
  	/* We have no way to deallocate the interrupt gate */
  	hv_stimer0_handler = NULL;
  }
  EXPORT_SYMBOL_GPL(hv_remove_stimer0_irq);
  
  void hv_setup_kexec_handler(void (*handler)(void))
  {
  	hv_kexec_handler = handler;
  }
  EXPORT_SYMBOL_GPL(hv_setup_kexec_handler);
  
  void hv_remove_kexec_handler(void)
  {
  	hv_kexec_handler = NULL;
  }
  EXPORT_SYMBOL_GPL(hv_remove_kexec_handler);
  
  void hv_setup_crash_handler(void (*handler)(struct pt_regs *regs))
  {
  	hv_crash_handler = handler;
  }
  EXPORT_SYMBOL_GPL(hv_setup_crash_handler);
  
  void hv_remove_crash_handler(void)
  {
  	hv_crash_handler = NULL;
  }
  EXPORT_SYMBOL_GPL(hv_remove_crash_handler);
  
  #ifdef CONFIG_KEXEC_CORE
  static void hv_machine_shutdown(void)
  {
  	if (kexec_in_progress && hv_kexec_handler)
  		hv_kexec_handler();
  	native_machine_shutdown();
  }
  
  static void hv_machine_crash_shutdown(struct pt_regs *regs)
  {
  	if (hv_crash_handler)
  		hv_crash_handler(regs);
  	native_machine_crash_shutdown(regs);
  }
  #endif /* CONFIG_KEXEC_CORE */
  #endif /* CONFIG_HYPERV */
  
  static uint32_t  __init ms_hyperv_platform(void)
  {
  	u32 eax;
  	u32 hyp_signature[3];
  
  	if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
  		return 0;
  
  	cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
  	      &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);
  
  	if (eax >= HYPERV_CPUID_MIN &&
  	    eax <= HYPERV_CPUID_MAX &&
  	    !memcmp("Microsoft Hv", hyp_signature, 12))
  		return HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS;
  
  	return 0;
  }
  
  static unsigned char hv_get_nmi_reason(void)
  {
  	return 0;
  }
  
  #ifdef CONFIG_X86_LOCAL_APIC
  /*
   * Prior to WS2016 Debug-VM sends NMIs to all CPUs which makes
   * it dificult to process CHANNELMSG_UNLOAD in case of crash. Handle
   * unknown NMI on the first CPU which gets it.
   */
  static int hv_nmi_unknown(unsigned int val, struct pt_regs *regs)
  {
  	static atomic_t nmi_cpu = ATOMIC_INIT(-1);
  
  	if (!unknown_nmi_panic)
  		return NMI_DONE;
  
  	if (atomic_cmpxchg(&nmi_cpu, -1, raw_smp_processor_id()) != -1)
  		return NMI_HANDLED;
  
  	return NMI_DONE;
  }
  #endif
  
  static unsigned long hv_get_tsc_khz(void)
  {
  	unsigned long freq;
  
  	rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);
  
  	return freq / 1000;
  }
  
  #if defined(CONFIG_SMP) && IS_ENABLED(CONFIG_HYPERV)
  static void __init hv_smp_prepare_boot_cpu(void)
  {
  	native_smp_prepare_boot_cpu();
  #if defined(CONFIG_X86_64) && defined(CONFIG_PARAVIRT_SPINLOCKS)
  	hv_init_spinlocks();
  #endif
  }
  #endif
  
  static void __init ms_hyperv_init_platform(void)
  {
  	int hv_host_info_eax;
  	int hv_host_info_ebx;
  	int hv_host_info_ecx;
  	int hv_host_info_edx;
  
  	/*
  	 * Extract the features and hints
  	 */
  	ms_hyperv.features = cpuid_eax(HYPERV_CPUID_FEATURES);
  	ms_hyperv.misc_features = cpuid_edx(HYPERV_CPUID_FEATURES);
  	ms_hyperv.hints    = cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);
  
  	pr_info("Hyper-V: features 0x%x, hints 0x%x\n",
  		ms_hyperv.features, ms_hyperv.hints);
  
  	ms_hyperv.max_vp_index = cpuid_eax(HYPERV_CPUID_IMPLEMENT_LIMITS);
  	ms_hyperv.max_lp_index = cpuid_ebx(HYPERV_CPUID_IMPLEMENT_LIMITS);
  
  	pr_debug("Hyper-V: max %u virtual processors, %u logical processors\n",
  		 ms_hyperv.max_vp_index, ms_hyperv.max_lp_index);
  
  	/*
  	 * Extract host information.
  	 */
  	if (cpuid_eax(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS) >=
  	    HYPERV_CPUID_VERSION) {
  		hv_host_info_eax = cpuid_eax(HYPERV_CPUID_VERSION);
  		hv_host_info_ebx = cpuid_ebx(HYPERV_CPUID_VERSION);
  		hv_host_info_ecx = cpuid_ecx(HYPERV_CPUID_VERSION);
  		hv_host_info_edx = cpuid_edx(HYPERV_CPUID_VERSION);
  
  		pr_info("Hyper-V Host Build:%d-%d.%d-%d-%d.%d\n",
  			hv_host_info_eax, hv_host_info_ebx >> 16,
  			hv_host_info_ebx & 0xFFFF, hv_host_info_ecx,
  			hv_host_info_edx >> 24, hv_host_info_edx & 0xFFFFFF);
  	}
  
  	if (ms_hyperv.features & HV_X64_ACCESS_FREQUENCY_MSRS &&
  	    ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE) {
  		x86_platform.calibrate_tsc = hv_get_tsc_khz;
  		x86_platform.calibrate_cpu = hv_get_tsc_khz;
  	}
  
  	if (ms_hyperv.hints & HV_X64_ENLIGHTENED_VMCS_RECOMMENDED) {
  		ms_hyperv.nested_features =
  			cpuid_eax(HYPERV_CPUID_NESTED_FEATURES);
  	}
  
  #ifdef CONFIG_X86_LOCAL_APIC
  	if (ms_hyperv.features & HV_X64_ACCESS_FREQUENCY_MSRS &&
  	    ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE) {
  		/*
  		 * Get the APIC frequency.
  		 */
  		u64	hv_lapic_frequency;
  
  		rdmsrl(HV_X64_MSR_APIC_FREQUENCY, hv_lapic_frequency);
  		hv_lapic_frequency = div_u64(hv_lapic_frequency, HZ);
  		lapic_timer_period = hv_lapic_frequency;
  		pr_info("Hyper-V: LAPIC Timer Frequency: %#x\n",
  			lapic_timer_period);
  	}
  
  	register_nmi_handler(NMI_UNKNOWN, hv_nmi_unknown, NMI_FLAG_FIRST,
  			     "hv_nmi_unknown");
  #endif
  
  #ifdef CONFIG_X86_IO_APIC
  	no_timer_check = 1;
  #endif
  
  #if IS_ENABLED(CONFIG_HYPERV) && defined(CONFIG_KEXEC_CORE)
  	machine_ops.shutdown = hv_machine_shutdown;
  	machine_ops.crash_shutdown = hv_machine_crash_shutdown;
  #endif
  	mark_tsc_unstable("running on Hyper-V");
  
  	/*
  	 * Generation 2 instances don't support reading the NMI status from
  	 * 0x61 port.
  	 */
  	if (efi_enabled(EFI_BOOT))
  		x86_platform.get_nmi_reason = hv_get_nmi_reason;
  
  	/*
  	 * Hyper-V VMs have a PIT emulation quirk such that zeroing the
  	 * counter register during PIT shutdown restarts the PIT. So it
  	 * continues to interrupt @18.2 HZ. Setting i8253_clear_counter
  	 * to false tells pit_shutdown() not to zero the counter so that
  	 * the PIT really is shutdown. Generation 2 VMs don't have a PIT,
  	 * and setting this value has no effect.
  	 */
  	i8253_clear_counter_on_shutdown = false;
  
  #if IS_ENABLED(CONFIG_HYPERV)
  	/*
  	 * Setup the hook to get control post apic initialization.
  	 */
  	x86_platform.apic_post_init = hyperv_init;
  	hyperv_setup_mmu_ops();
  	/* Setup the IDT for hypervisor callback */
  	alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, hyperv_callback_vector);
  
  	/* Setup the IDT for reenlightenment notifications */
  	if (ms_hyperv.features & HV_X64_ACCESS_REENLIGHTENMENT)
  		alloc_intr_gate(HYPERV_REENLIGHTENMENT_VECTOR,
  				hyperv_reenlightenment_vector);
  
  	/* Setup the IDT for stimer0 */
  	if (ms_hyperv.misc_features & HV_STIMER_DIRECT_MODE_AVAILABLE)
  		alloc_intr_gate(HYPERV_STIMER0_VECTOR,
  				hv_stimer0_callback_vector);
  
  # ifdef CONFIG_SMP
  	smp_ops.smp_prepare_boot_cpu = hv_smp_prepare_boot_cpu;
  # endif
  
  	/*
  	 * Hyper-V doesn't provide irq remapping for IO-APIC. To enable x2apic,
  	 * set x2apic destination mode to physcial mode when x2apic is available
  	 * and Hyper-V IOMMU driver makes sure cpus assigned with IO-APIC irqs
  	 * have 8-bit APIC id.
  	 */
  # ifdef CONFIG_X86_X2APIC
  	if (x2apic_supported())
  		x2apic_phys = 1;
  # endif
  
  #endif
  }
  
  const __initconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
  	.name			= "Microsoft Hyper-V",
  	.detect			= ms_hyperv_platform,
  	.type			= X86_HYPER_MS_HYPERV,
  	.init.init_platform	= ms_hyperv_init_platform,
  };
  