// SPDX-License-Identifier: GPL-2.0-only
/*
 * X86 specific Hyper-V initialization code.
 *
 * Copyright (C) 2016, Microsoft, Inc.
 *
 * Author : K. Y. Srinivasan <kys@microsoft.com>
 */

#define pr_fmt(fmt)  "Hyper-V: " fmt

#include <linux/efi.h>
#include <linux/types.h>
#include <linux/bitfield.h>
#include <linux/io.h>
#include <asm/apic.h>
#include <asm/desc.h>
#include <asm/e820/api.h>
#include <asm/sev.h>
#include <asm/hypervisor.h>
#include <hyperv/hvhdk.h>
#include <asm/mshyperv.h>
#include <asm/msr.h>
#include <asm/idtentry.h>
#include <asm/set_memory.h>
#include <linux/kexec.h>
#include <linux/version.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/cpuhotplug.h>
#include <linux/syscore_ops.h>
#include <clocksource/hyperv_timer.h>
#include <linux/highmem.h>
#include <linux/export.h>

void *hv_hypercall_pg;

#ifdef CONFIG_X86_64
static u64 __hv_hyperfail(u64 control, u64 param1, u64 param2)
{
        return U64_MAX;
}

DEFINE_STATIC_CALL(__hv_hypercall, __hv_hyperfail);

u64 hv_std_hypercall(u64 control, u64 param1, u64 param2)
{
        u64 hv_status;

        register u64 __r8 asm("r8") = param2;
        asm volatile ("call " STATIC_CALL_TRAMP_STR(__hv_hypercall)
                      : "=a" (hv_status), ASM_CALL_CONSTRAINT,
                        "+c" (control), "+d" (param1), "+r" (__r8)
                      : : "cc", "memory", "r9", "r10", "r11");

        return hv_status;
}

typedef u64 (*hv_hypercall_f)(u64 control, u64 param1, u64 param2);

static inline void hv_set_hypercall_pg(void *ptr)
{
        hv_hypercall_pg = ptr;

        if (!ptr)
                ptr = &__hv_hyperfail;
        static_call_update(__hv_hypercall, (hv_hypercall_f)ptr);
}
#else
static inline void hv_set_hypercall_pg(void *ptr)
{
        hv_hypercall_pg = ptr;
}
EXPORT_SYMBOL_GPL(hv_hypercall_pg);
#endif

union hv_ghcb * __percpu *hv_ghcb_pg;

/* Storage to save the hypercall page temporarily for hibernation */
static void *hv_hypercall_pg_saved;

struct hv_vp_assist_page **hv_vp_assist_page;
EXPORT_SYMBOL_GPL(hv_vp_assist_page);

static int hyperv_init_ghcb(void)
{
        u64 ghcb_gpa;
        void *ghcb_va;
        void **ghcb_base;

        if (!ms_hyperv.paravisor_present || !hv_isolation_type_snp())
                return 0;

        if (!hv_ghcb_pg)
                return -EINVAL;

        /*
         * GHCB page is allocated by paravisor. The address
         * returned by MSR_AMD64_SEV_ES_GHCB is above shared
         * memory boundary and map it here.
         */
        rdmsrq(MSR_AMD64_SEV_ES_GHCB, ghcb_gpa);

        /* Mask out vTOM bit and map as decrypted */
        ghcb_gpa &= ~ms_hyperv.shared_gpa_boundary;
        ghcb_va = memremap(ghcb_gpa, HV_HYP_PAGE_SIZE, MEMREMAP_WB | MEMREMAP_DEC);
        if (!ghcb_va)
                return -ENOMEM;

        ghcb_base = (void **)this_cpu_ptr(hv_ghcb_pg);
        *ghcb_base = ghcb_va;

        return 0;
}

static int hv_cpu_init(unsigned int cpu)
{
        union hv_vp_assist_msr_contents msr = { 0 };
        struct hv_vp_assist_page **hvp;
        int ret;

        ret = hv_common_cpu_init(cpu);
        if (ret)
                return ret;

        if (!hv_vp_assist_page)
                return 0;

        hvp = &hv_vp_assist_page[cpu];
        if (hv_root_partition()) {
                /*
                 * For root partition we get the hypervisor provided VP assist
                 * page, instead of allocating a new page.
                 */
                rdmsrq(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
                *hvp = memremap(msr.pfn << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT,
                                PAGE_SIZE, MEMREMAP_WB);
        } else {
                /*
                 * The VP assist page is an "overlay" page (see Hyper-V TLFS's
                 * Section 5.2.1 "GPA Overlay Pages"). Here it must be zeroed
                 * out to make sure we always write the EOI MSR in
                 * hv_apic_eoi_write() *after* the EOI optimization is disabled
                 * in hv_cpu_die(), otherwise a CPU may not be stopped in the
                 * case of CPU offlining and the VM will hang.
                 */
                if (!*hvp) {
                        *hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL | __GFP_ZERO);

                        /*
                         * Hyper-V should never specify a VM that is a Confidential
                         * VM and also running in the root partition. Root partition
                         * is blocked to run in Confidential VM. So only decrypt assist
                         * page in non-root partition here.
                         */
                        if (*hvp && !ms_hyperv.paravisor_present && hv_isolation_type_snp()) {
                                WARN_ON_ONCE(set_memory_decrypted((unsigned long)(*hvp), 1));
                                memset(*hvp, 0, PAGE_SIZE);
                        }
                }

                if (*hvp)
                        msr.pfn = vmalloc_to_pfn(*hvp);

        }
        if (!WARN_ON(!(*hvp))) {
                msr.enable = 1;
                wrmsrq(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
        }

        /* Allow Hyper-V stimer vector to be injected from Hypervisor. */
        if (ms_hyperv.misc_features & HV_STIMER_DIRECT_MODE_AVAILABLE)
                apic_update_vector(cpu, HYPERV_STIMER0_VECTOR, true);

        return hyperv_init_ghcb();
}

static void (*hv_reenlightenment_cb)(void);

static void hv_reenlightenment_notify(struct work_struct *dummy)
{
        struct hv_tsc_emulation_status emu_status;

        rdmsrq(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);

        /* Don't issue the callback if TSC accesses are not emulated */
        if (hv_reenlightenment_cb && emu_status.inprogress)
                hv_reenlightenment_cb();
}
static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify);

void hyperv_stop_tsc_emulation(void)
{
        u64 freq;
        struct hv_tsc_emulation_status emu_status;

        rdmsrq(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
        emu_status.inprogress = 0;
        wrmsrq(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);

        rdmsrq(HV_X64_MSR_TSC_FREQUENCY, freq);
        tsc_khz = div64_u64(freq, 1000);
}
EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation);

static inline bool hv_reenlightenment_available(void)
{
        /*
         * Check for required features and privileges to make TSC frequency
         * change notifications work.
         */
        return ms_hyperv.features & HV_ACCESS_FREQUENCY_MSRS &&
                ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE &&
                ms_hyperv.features & HV_ACCESS_REENLIGHTENMENT;
}

DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_reenlightenment)
{
        apic_eoi();
        inc_irq_stat(irq_hv_reenlightenment_count);
        schedule_delayed_work(&hv_reenlightenment_work, HZ/10);
}

void set_hv_tscchange_cb(void (*cb)(void))
{
        struct hv_reenlightenment_control re_ctrl = {
                .vector = HYPERV_REENLIGHTENMENT_VECTOR,
                .enabled = 1,
        };
        struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1};

        if (!hv_reenlightenment_available()) {
                pr_warn("reenlightenment support is unavailable\n");
                return;
        }

        if (!hv_vp_index)
                return;

        hv_reenlightenment_cb = cb;

        /* Make sure callback is registered before we write to MSRs */
        wmb();

        re_ctrl.target_vp = hv_vp_index[get_cpu()];

        wrmsrq(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
        wrmsrq(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl));

        put_cpu();
}
EXPORT_SYMBOL_GPL(set_hv_tscchange_cb);

void clear_hv_tscchange_cb(void)
{
        struct hv_reenlightenment_control re_ctrl;

        if (!hv_reenlightenment_available())
                return;

        rdmsrq(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
        re_ctrl.enabled = 0;
        wrmsrq(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);

        hv_reenlightenment_cb = NULL;
}
EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb);

static int hv_cpu_die(unsigned int cpu)
{
        struct hv_reenlightenment_control re_ctrl;
        unsigned int new_cpu;
        void **ghcb_va;

        if (hv_ghcb_pg) {
                ghcb_va = (void **)this_cpu_ptr(hv_ghcb_pg);
                if (*ghcb_va)
                        memunmap(*ghcb_va);
                *ghcb_va = NULL;
        }

        if (ms_hyperv.misc_features & HV_STIMER_DIRECT_MODE_AVAILABLE)
                apic_update_vector(cpu, HYPERV_STIMER0_VECTOR, false);

        hv_common_cpu_die(cpu);

        if (hv_vp_assist_page && hv_vp_assist_page[cpu]) {
                union hv_vp_assist_msr_contents msr = { 0 };
                if (hv_root_partition()) {
                        /*
                         * For root partition the VP assist page is mapped to
                         * hypervisor provided page, and thus we unmap the
                         * page here and nullify it, so that in future we have
                         * correct page address mapped in hv_cpu_init.
                         */
                        memunmap(hv_vp_assist_page[cpu]);
                        hv_vp_assist_page[cpu] = NULL;
                        rdmsrq(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
                        msr.enable = 0;
                }
                wrmsrq(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
        }

        if (hv_reenlightenment_cb == NULL)
                return 0;

        rdmsrq(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
        if (re_ctrl.target_vp == hv_vp_index[cpu]) {
                /*
                 * Reassign reenlightenment notifications to some other online
                 * CPU or just disable the feature if there are no online CPUs
                 * left (happens on hibernation).
                 */
                new_cpu = cpumask_any_but(cpu_online_mask, cpu);

                if (new_cpu < nr_cpu_ids)
                        re_ctrl.target_vp = hv_vp_index[new_cpu];
                else
                        re_ctrl.enabled = 0;

                wrmsrq(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
        }

        return 0;
}

static int __init hv_pci_init(void)
{
        bool gen2vm = efi_enabled(EFI_BOOT);

        /*
         * A Generation-2 VM doesn't support legacy PCI/PCIe, so both
         * raw_pci_ops and raw_pci_ext_ops are NULL, and pci_subsys_init() ->
         * pcibios_init() doesn't call pcibios_resource_survey() ->
         * e820__reserve_resources_late(); as a result, any emulated persistent
         * memory of E820_TYPE_PRAM (12) via the kernel parameter
         * memmap=nn[KMG]!ss is not added into iomem_resource and hence can't be
         * detected by register_e820_pmem(). Fix this by directly calling
         * e820__reserve_resources_late() here: e820__reserve_resources_late()
         * depends on e820__reserve_resources(), which has been called earlier
         * from setup_arch(). Note: e820__reserve_resources_late() also adds
         * any memory of E820_TYPE_PMEM (7) into iomem_resource, and
         * acpi_nfit_register_region() -> acpi_nfit_insert_resource() ->
         * region_intersects() returns REGION_INTERSECTS, so the memory of
         * E820_TYPE_PMEM won't get added twice.
         *
         * We return 0 here so that pci_arch_init() won't print the warning:
         * "PCI: Fatal: No config space access function found"
         */
        if (gen2vm) {
                e820__reserve_resources_late();
                return 0;
        }

        /* For Generation-1 VM, we'll proceed in pci_arch_init().  */
        return 1;
}

static int hv_suspend(void *data)
{
        union hv_x64_msr_hypercall_contents hypercall_msr;
        int ret;

        if (hv_root_partition())
                return -EPERM;

        /*
         * Reset the hypercall page as it is going to be invalidated
         * across hibernation. Setting hv_hypercall_pg to NULL ensures
         * that any subsequent hypercall operation fails safely instead of
         * crashing due to an access of an invalid page. The hypercall page
         * pointer is restored on resume.
         */
        hv_hypercall_pg_saved = hv_hypercall_pg;
        hv_set_hypercall_pg(NULL);

        /* Disable the hypercall page in the hypervisor */
        rdmsrq(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
        hypercall_msr.enable = 0;
        wrmsrq(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);

        ret = hv_cpu_die(0);
        return ret;
}

static void hv_resume(void *data)
{
        union hv_x64_msr_hypercall_contents hypercall_msr;
        int ret;

        ret = hv_cpu_init(0);
        WARN_ON(ret);

        /* Re-enable the hypercall page */
        rdmsrq(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
        hypercall_msr.enable = 1;
        hypercall_msr.guest_physical_address =
                vmalloc_to_pfn(hv_hypercall_pg_saved);
        wrmsrq(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);

        hv_set_hypercall_pg(hv_hypercall_pg_saved);
        hv_hypercall_pg_saved = NULL;

        /*
         * Reenlightenment notifications are disabled by hv_cpu_die(0),
         * reenable them here if hv_reenlightenment_cb was previously set.
         */
        if (hv_reenlightenment_cb)
                set_hv_tscchange_cb(hv_reenlightenment_cb);
}

/* Note: when the ops are called, only CPU0 is online and IRQs are disabled. */
static const struct syscore_ops hv_syscore_ops = {
        .suspend        = hv_suspend,
        .resume         = hv_resume,
};

static struct syscore hv_syscore = {
        .ops = &hv_syscore_ops,
};

static void (* __initdata old_setup_percpu_clockev)(void);

static void __init hv_stimer_setup_percpu_clockev(void)
{
        /*
         * Ignore any errors in setting up stimer clockevents
         * as we can run with the LAPIC timer as a fallback.
         */
        (void)hv_stimer_alloc(false);

        /*
         * Still register the LAPIC timer, because the direct-mode STIMER is
         * not supported by old versions of Hyper-V. This also allows users
         * to switch to LAPIC timer via /sys, if they want to.
         */
        if (old_setup_percpu_clockev)
                old_setup_percpu_clockev();
}

/*
 * This function is to be invoked early in the boot sequence after the
 * hypervisor has been detected.
 *
 * 1. Setup the hypercall page.
 * 2. Register Hyper-V specific clocksource.
 * 3. Setup Hyper-V specific APIC entry points.
 */
void __init hyperv_init(void)
{
        u64 guest_id;
        union hv_x64_msr_hypercall_contents hypercall_msr;
        int cpuhp;

        if (x86_hyper_type != X86_HYPER_MS_HYPERV)
                return;

        if (hv_common_init())
                return;

        /*
         * The VP assist page is useless to a TDX guest: the only use we
         * would have for it is lazy EOI, which can not be used with TDX.
         */
        if (hv_isolation_type_tdx())
                hv_vp_assist_page = NULL;
        else
                hv_vp_assist_page = kzalloc_objs(*hv_vp_assist_page, nr_cpu_ids);
        if (!hv_vp_assist_page) {
                ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;

                if (!hv_isolation_type_tdx())
                        goto common_free;
        }

        if (ms_hyperv.paravisor_present && hv_isolation_type_snp()) {
                /* Negotiate GHCB Version. */
                if (!hv_ghcb_negotiate_protocol())
                        hv_ghcb_terminate(SEV_TERM_SET_GEN,
                                          GHCB_SEV_ES_PROT_UNSUPPORTED);

                hv_ghcb_pg = alloc_percpu(union hv_ghcb *);
                if (!hv_ghcb_pg)
                        goto free_vp_assist_page;
        }

        cpuhp = cpuhp_setup_state(CPUHP_AP_HYPERV_ONLINE, "x86/hyperv_init:online",
                                  hv_cpu_init, hv_cpu_die);
        if (cpuhp < 0)
                goto free_ghcb_page;

        /*
         * Setup the hypercall page and enable hypercalls.
         * 1. Register the guest ID
         * 2. Enable the hypercall and register the hypercall page
         *
         * A TDX VM with no paravisor only uses TDX GHCI rather than hv_hypercall_pg:
         * when the hypercall input is a page, such a VM must pass a decrypted
         * page to Hyper-V, e.g. hv_post_message() uses the per-CPU page
         * hyperv_pcpu_input_arg, which is decrypted if no paravisor is present.
         *
         * A TDX VM with the paravisor uses hv_hypercall_pg for most hypercalls,
         * which are handled by the paravisor and the VM must use an encrypted
         * input page: in such a VM, the hyperv_pcpu_input_arg is encrypted and
         * used in the hypercalls, e.g. see hv_mark_gpa_visibility() and
         * hv_arch_irq_unmask(). Such a VM uses TDX GHCI for two hypercalls:
         * 1. HVCALL_SIGNAL_EVENT: see vmbus_set_event() and _hv_do_fast_hypercall8().
         * 2. HVCALL_POST_MESSAGE: the input page must be a decrypted page, i.e.
         * hv_post_message() in such a VM can't use the encrypted hyperv_pcpu_input_arg;
         * instead, hv_post_message() uses the post_msg_page, which is decrypted
         * in such a VM and is only used in such a VM.
         */
        guest_id = hv_generate_guest_id(LINUX_VERSION_CODE);
        wrmsrq(HV_X64_MSR_GUEST_OS_ID, guest_id);

        /* With the paravisor, the VM must also write the ID via GHCB/GHCI */
        hv_ivm_msr_write(HV_X64_MSR_GUEST_OS_ID, guest_id);

        /* A TDX VM with no paravisor only uses TDX GHCI rather than hv_hypercall_pg */
        if (hv_isolation_type_tdx() && !ms_hyperv.paravisor_present)
                goto skip_hypercall_pg_init;

        hv_hypercall_pg = __vmalloc_node_range(PAGE_SIZE, 1, MODULES_VADDR,
                        MODULES_END, GFP_KERNEL, PAGE_KERNEL_ROX,
                        VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
                        __builtin_return_address(0));
        if (hv_hypercall_pg == NULL)
                goto clean_guest_os_id;

        rdmsrq(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
        hypercall_msr.enable = 1;

        if (hv_root_partition()) {
                struct page *pg;
                void *src;

                /*
                 * For the root partition, the hypervisor will set up its
                 * hypercall page. The hypervisor guarantees it will not show
                 * up in the root's address space. The root can't change the
                 * location of the hypercall page.
                 *
                 * Order is important here. We must enable the hypercall page
                 * so it is populated with code, then copy the code to an
                 * executable page.
                 */
                wrmsrq(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);

                pg = vmalloc_to_page(hv_hypercall_pg);
                src = memremap(hypercall_msr.guest_physical_address << PAGE_SHIFT, PAGE_SIZE,
                                MEMREMAP_WB);
                BUG_ON(!src);
                memcpy_to_page(pg, 0, src, HV_HYP_PAGE_SIZE);
                memunmap(src);

                hv_remap_tsc_clocksource();
                hv_sleep_notifiers_register();
        } else {
                hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
                wrmsrq(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
        }

        hv_set_hypercall_pg(hv_hypercall_pg);

        if (hv_root_partition())        /* after set hypercall pg */
                hv_root_crash_init();

skip_hypercall_pg_init:
        /*
         * hyperv_init() is called before LAPIC is initialized: see
         * apic_intr_mode_init() -> x86_platform.apic_post_init() and
         * apic_bsp_setup() -> setup_local_APIC(). The direct-mode STIMER
         * depends on LAPIC, so hv_stimer_alloc() should be called from
         * x86_init.timers.setup_percpu_clockev.
         */
        old_setup_percpu_clockev = x86_init.timers.setup_percpu_clockev;
        x86_init.timers.setup_percpu_clockev = hv_stimer_setup_percpu_clockev;

        hv_apic_init();

        x86_init.pci.arch_init = hv_pci_init;

        register_syscore(&hv_syscore);

        if (ms_hyperv.priv_high & HV_ACCESS_PARTITION_ID)
                hv_get_partition_id();

#ifdef CONFIG_PCI_MSI
        /*
         * If we're running as root, we want to create our own PCI MSI domain.
         * We can't set this in hv_pci_init because that would be too late.
         */
        if (hv_root_partition())
                x86_init.irqs.create_pci_msi_domain = hv_create_pci_msi_domain;
#endif

        /* Query the VMs extended capability once, so that it can be cached. */
        hv_query_ext_cap(0);

        /* Find the VTL */
        ms_hyperv.vtl = get_vtl();

        if (ms_hyperv.vtl > 0) /* non default VTL */
                hv_vtl_early_init();

        return;

clean_guest_os_id:
        wrmsrq(HV_X64_MSR_GUEST_OS_ID, 0);
        hv_ivm_msr_write(HV_X64_MSR_GUEST_OS_ID, 0);
        cpuhp_remove_state(CPUHP_AP_HYPERV_ONLINE);
free_ghcb_page:
        free_percpu(hv_ghcb_pg);
free_vp_assist_page:
        kfree(hv_vp_assist_page);
        hv_vp_assist_page = NULL;
common_free:
        hv_common_free();
}

/*
 * This routine is called before kexec/kdump, it does the required cleanup.
 */
void hyperv_cleanup(void)
{
        union hv_x64_msr_hypercall_contents hypercall_msr;
        union hv_reference_tsc_msr tsc_msr;

        /* Reset our OS id */
        wrmsrq(HV_X64_MSR_GUEST_OS_ID, 0);
        hv_ivm_msr_write(HV_X64_MSR_GUEST_OS_ID, 0);

        /*
         * Reset hv_hypercall_pg before resetting it in the hypervisor.
         * hv_set_hypercall_pg(NULL) is not used because at this point in the
         * panic path other CPUs have been stopped, causing static_call_update()
         * to hang. So resetting hv_hypercall_pg to cause hypercalls to fail
         * cleanly is only operative on 32-bit builds. But this is OK as it is
         * just a preventative measure to ease detecting a hypercall being made
         * after this point, which shouldn't be happening anyway.
         */
        hv_hypercall_pg = NULL;

        /* Reset the hypercall page */
        hypercall_msr.as_uint64 = hv_get_msr(HV_X64_MSR_HYPERCALL);
        hypercall_msr.enable = 0;
        hv_set_msr(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);

        /* Reset the TSC page */
        tsc_msr.as_uint64 = hv_get_msr(HV_X64_MSR_REFERENCE_TSC);
        tsc_msr.enable = 0;
        hv_set_msr(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
}

void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die)
{
        static bool panic_reported;
        u64 guest_id;

        if (in_die && !panic_on_oops)
                return;

        /*
         * We prefer to report panic on 'die' chain as we have proper
         * registers to report, but if we miss it (e.g. on BUG()) we need
         * to report it on 'panic'.
         */
        if (panic_reported)
                return;
        panic_reported = true;

        rdmsrq(HV_X64_MSR_GUEST_OS_ID, guest_id);

        wrmsrq(HV_X64_MSR_CRASH_P0, err);
        wrmsrq(HV_X64_MSR_CRASH_P1, guest_id);
        wrmsrq(HV_X64_MSR_CRASH_P2, regs->ip);
        wrmsrq(HV_X64_MSR_CRASH_P3, regs->ax);
        wrmsrq(HV_X64_MSR_CRASH_P4, regs->sp);

        /*
         * Let Hyper-V know there is crash data available
         */
        wrmsrq(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
}
EXPORT_SYMBOL_GPL(hyperv_report_panic);

bool hv_is_hyperv_initialized(void)
{
        union hv_x64_msr_hypercall_contents hypercall_msr;

        /*
         * Ensure that we're really on Hyper-V, and not a KVM or Xen
         * emulation of Hyper-V
         */
        if (x86_hyper_type != X86_HYPER_MS_HYPERV)
                return false;

        /* A TDX VM with no paravisor uses TDX GHCI call rather than hv_hypercall_pg */
        if (hv_isolation_type_tdx() && !ms_hyperv.paravisor_present)
                return true;
        /*
         * Verify that earlier initialization succeeded by checking
         * that the hypercall page is setup
         */
        hypercall_msr.as_uint64 = 0;
        rdmsrq(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);

        return hypercall_msr.enable;
}
EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);

int hv_apicid_to_vp_index(u32 apic_id)
{
        u64 control;
        u64 status;
        unsigned long irq_flags;
        struct hv_get_vp_from_apic_id_in *input;
        u32 *output, ret;

        local_irq_save(irq_flags);

        input = *this_cpu_ptr(hyperv_pcpu_input_arg);
        memset(input, 0, sizeof(*input));
        input->partition_id = HV_PARTITION_ID_SELF;
        input->apic_ids[0] = apic_id;

        output = *this_cpu_ptr(hyperv_pcpu_output_arg);

        control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_INDEX_FROM_APIC_ID;
        status = hv_do_hypercall(control, input, output);
        ret = output[0];

        local_irq_restore(irq_flags);

        if (!hv_result_success(status)) {
                pr_err("failed to get vp index from apic id %d, status %#llx\n",
                       apic_id, status);
                return -EINVAL;
        }

        return ret;
}
EXPORT_SYMBOL_GPL(hv_apicid_to_vp_index);