// 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,
};