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-rw-r--r--arch/x86/hyperv/hv_init.c650
1 files changed, 650 insertions, 0 deletions
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
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index 000000000..c18e5c764
--- /dev/null
+++ b/arch/x86/hyperv/hv_init.c
@@ -0,0 +1,650 @@
+// 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>
+ */
+
+#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/ibt.h>
+#include <asm/hypervisor.h>
+#include <asm/hyperv-tlfs.h>
+#include <asm/mshyperv.h>
+#include <asm/idtentry.h>
+#include <linux/kexec.h>
+#include <linux/version.h>
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
+#include <linux/hyperv.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/swiotlb.h>
+
+int hyperv_init_cpuhp;
+u64 hv_current_partition_id = ~0ull;
+EXPORT_SYMBOL_GPL(hv_current_partition_id);
+
+void *hv_hypercall_pg;
+EXPORT_SYMBOL_GPL(hv_hypercall_pg);
+
+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 (!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.
+ */
+ rdmsrl(MSR_AMD64_SEV_ES_GHCB, ghcb_gpa);
+ ghcb_va = memremap(ghcb_gpa, HV_HYP_PAGE_SIZE, MEMREMAP_WB);
+ 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 = &hv_vp_assist_page[cpu];
+ int ret;
+
+ ret = hv_common_cpu_init(cpu);
+ if (ret)
+ return ret;
+
+ if (!hv_vp_assist_page)
+ return 0;
+
+ if (hv_root_partition) {
+ /*
+ * For root partition we get the hypervisor provided VP assist
+ * page, instead of allocating a new page.
+ */
+ rdmsrl(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);
+ if (*hvp)
+ msr.pfn = vmalloc_to_pfn(*hvp);
+
+ }
+ if (!WARN_ON(!(*hvp))) {
+ msr.enable = 1;
+ wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
+ }
+
+ 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;
+
+ rdmsrl(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;
+
+ rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
+ emu_status.inprogress = 0;
+ wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
+
+ rdmsrl(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)
+{
+ ack_APIC_irq();
+ 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("Hyper-V: 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()];
+
+ wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
+ wrmsrl(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;
+
+ rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
+ re_ctrl.enabled = 0;
+ wrmsrl(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;
+ }
+
+ 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;
+ rdmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
+ msr.enable = 0;
+ }
+ wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
+ }
+
+ if (hv_reenlightenment_cb == NULL)
+ return 0;
+
+ rdmsrl(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;
+
+ wrmsrl(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)
+{
+ 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_hypercall_pg = NULL;
+
+ /* Disable the hypercall page in the hypervisor */
+ rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
+ hypercall_msr.enable = 0;
+ wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
+
+ ret = hv_cpu_die(0);
+ return ret;
+}
+
+static void hv_resume(void)
+{
+ union hv_x64_msr_hypercall_contents hypercall_msr;
+ int ret;
+
+ ret = hv_cpu_init(0);
+ WARN_ON(ret);
+
+ /* Re-enable the hypercall page */
+ rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
+ hypercall_msr.enable = 1;
+ hypercall_msr.guest_physical_address =
+ vmalloc_to_pfn(hv_hypercall_pg_saved);
+ wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
+
+ hv_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 struct syscore_ops hv_syscore_ops = {
+ .suspend = hv_suspend,
+ .resume = hv_resume,
+};
+
+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();
+}
+
+static void __init hv_get_partition_id(void)
+{
+ struct hv_get_partition_id *output_page;
+ u64 status;
+ unsigned long flags;
+
+ local_irq_save(flags);
+ output_page = *this_cpu_ptr(hyperv_pcpu_output_arg);
+ status = hv_do_hypercall(HVCALL_GET_PARTITION_ID, NULL, output_page);
+ if (!hv_result_success(status)) {
+ /* No point in proceeding if this failed */
+ pr_err("Failed to get partition ID: %lld\n", status);
+ BUG();
+ }
+ hv_current_partition_id = output_page->partition_id;
+ local_irq_restore(flags);
+}
+
+/*
+ * 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;
+
+ hv_vp_assist_page = kcalloc(num_possible_cpus(),
+ sizeof(*hv_vp_assist_page), GFP_KERNEL);
+ if (!hv_vp_assist_page) {
+ ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
+ goto common_free;
+ }
+
+ if (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_ONLINE_DYN, "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
+ */
+ guest_id = hv_generate_guest_id(LINUX_VERSION_CODE);
+ wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
+
+ /* Hyper-V requires to write guest os id via ghcb in SNP IVM. */
+ hv_ghcb_msr_write(HV_X64_MSR_GUEST_OS_ID, guest_id);
+
+ hv_hypercall_pg = __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START,
+ VMALLOC_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;
+
+ rdmsrl(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.
+ */
+ wrmsrl(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);
+ } else {
+ hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
+ wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
+ }
+
+ /*
+ * Some versions of Hyper-V that provide IBT in guest VMs have a bug
+ * in that there's no ENDBR64 instruction at the entry to the
+ * hypercall page. Because hypercalls are invoked via an indirect call
+ * to the hypercall page, all hypercall attempts fail when IBT is
+ * enabled, and Linux panics. For such buggy versions, disable IBT.
+ *
+ * Fixed versions of Hyper-V always provide ENDBR64 on the hypercall
+ * page, so if future Linux kernel versions enable IBT for 32-bit
+ * builds, additional hypercall page hackery will be required here
+ * to provide an ENDBR32.
+ */
+#ifdef CONFIG_X86_KERNEL_IBT
+ if (cpu_feature_enabled(X86_FEATURE_IBT) &&
+ *(u32 *)hv_hypercall_pg != gen_endbr()) {
+ setup_clear_cpu_cap(X86_FEATURE_IBT);
+ pr_warn("Hyper-V: Disabling IBT because of Hyper-V bug\n");
+ }
+#endif
+
+ /*
+ * 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_ops(&hv_syscore_ops);
+
+ hyperv_init_cpuhp = cpuhp;
+
+ if (cpuid_ebx(HYPERV_CPUID_FEATURES) & HV_ACCESS_PARTITION_ID)
+ hv_get_partition_id();
+
+ BUG_ON(hv_root_partition && hv_current_partition_id == ~0ull);
+
+#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);
+
+#ifdef CONFIG_SWIOTLB
+ /*
+ * Swiotlb bounce buffer needs to be mapped in extra address
+ * space. Map function doesn't work in the early place and so
+ * call swiotlb_update_mem_attributes() here.
+ */
+ if (hv_is_isolation_supported())
+ swiotlb_update_mem_attributes();
+#endif
+
+ return;
+
+clean_guest_os_id:
+ wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
+ hv_ghcb_msr_write(HV_X64_MSR_GUEST_OS_ID, 0);
+ cpuhp_remove_state(cpuhp);
+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 */
+ wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
+ hv_ghcb_msr_write(HV_X64_MSR_GUEST_OS_ID, 0);
+
+ /*
+ * Reset hypercall page reference before reset the page,
+ * let hypercall operations fail safely rather than
+ * panic the kernel for using invalid hypercall page
+ */
+ hv_hypercall_pg = NULL;
+
+ /* Reset the hypercall page */
+ hypercall_msr.as_uint64 = hv_get_register(HV_X64_MSR_HYPERCALL);
+ hypercall_msr.enable = 0;
+ hv_set_register(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
+
+ /* Reset the TSC page */
+ tsc_msr.as_uint64 = hv_get_register(HV_X64_MSR_REFERENCE_TSC);
+ tsc_msr.enable = 0;
+ hv_set_register(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;
+
+ rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
+
+ wrmsrl(HV_X64_MSR_CRASH_P0, err);
+ wrmsrl(HV_X64_MSR_CRASH_P1, guest_id);
+ wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip);
+ wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax);
+ wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp);
+
+ /*
+ * Let Hyper-V know there is crash data available
+ */
+ wrmsrl(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;
+
+ /*
+ * Verify that earlier initialization succeeded by checking
+ * that the hypercall page is setup
+ */
+ hypercall_msr.as_uint64 = 0;
+ rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
+
+ return hypercall_msr.enable;
+}
+EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);