// SPDX-License-Identifier: GPL-2.0-only /* * X86 specific Hyper-V initialization code. * * Copyright (C) 2016, Microsoft, Inc. * * Author : K. Y. Srinivasan */ #define pr_fmt(fmt) "Hyper-V: " fmt #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include 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 (!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. */ rdmsrl(MSR_AMD64_SEV_ES_GHCB, ghcb_gpa); /* Mask out vTOM bit. ioremap_cache() maps decrypted */ ghcb_gpa &= ~ms_hyperv.shared_gpa_boundary; ghcb_va = (void *)ioremap_cache(ghcb_gpa, HV_HYP_PAGE_SIZE); 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. */ 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); /* * 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; 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) { 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()]; 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) iounmap(*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); } #if IS_ENABLED(CONFIG_HYPERV_VTL_MODE) static u8 __init get_vtl(void) { u64 control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_REGISTERS; struct hv_get_vp_registers_input *input; struct hv_get_vp_registers_output *output; unsigned long flags; u64 ret; local_irq_save(flags); input = *this_cpu_ptr(hyperv_pcpu_input_arg); output = (struct hv_get_vp_registers_output *)input; memset(input, 0, struct_size(input, element, 1)); input->header.partitionid = HV_PARTITION_ID_SELF; input->header.vpindex = HV_VP_INDEX_SELF; input->header.inputvtl = 0; input->element[0].name0 = HV_X64_REGISTER_VSM_VP_STATUS; ret = hv_do_hypercall(control, input, output); if (hv_result_success(ret)) { ret = output->as64.low & HV_X64_VTL_MASK; } else { pr_err("Failed to get VTL(error: %lld) exiting...\n", ret); BUG(); } local_irq_restore(flags); return ret; } #else static inline u8 get_vtl(void) { return 0; } #endif /* * 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 = kcalloc(num_possible_cpus(), sizeof(*hv_vp_assist_page), GFP_KERNEL); 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); wrmsrl(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, 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); hv_remap_tsc_clocksource(); } else { hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg); wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); } skip_hypercall_pg_init: /* * 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("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); 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); /* 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: wrmsrl(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 */ wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0); hv_ivm_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; /* 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; rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); return hypercall_msr.enable; } EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);