234 lines
6.7 KiB
C
234 lines
6.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (c) 2023, Microsoft Corporation.
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*
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* Author:
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* Saurabh Sengar <ssengar@microsoft.com>
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*/
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#include <asm/apic.h>
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#include <asm/boot.h>
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#include <asm/desc.h>
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#include <asm/i8259.h>
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#include <asm/mshyperv.h>
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#include <asm/realmode.h>
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extern struct boot_params boot_params;
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static struct real_mode_header hv_vtl_real_mode_header;
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void __init hv_vtl_init_platform(void)
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{
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pr_info("Linux runs in Hyper-V Virtual Trust Level\n");
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x86_platform.realmode_reserve = x86_init_noop;
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x86_platform.realmode_init = x86_init_noop;
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x86_init.irqs.pre_vector_init = x86_init_noop;
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x86_init.timers.timer_init = x86_init_noop;
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/* Avoid searching for BIOS MP tables */
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x86_init.mpparse.find_smp_config = x86_init_noop;
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x86_init.mpparse.get_smp_config = x86_init_uint_noop;
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x86_platform.get_wallclock = get_rtc_noop;
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x86_platform.set_wallclock = set_rtc_noop;
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x86_platform.get_nmi_reason = hv_get_nmi_reason;
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x86_platform.legacy.i8042 = X86_LEGACY_I8042_PLATFORM_ABSENT;
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x86_platform.legacy.rtc = 0;
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x86_platform.legacy.warm_reset = 0;
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x86_platform.legacy.reserve_bios_regions = 0;
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x86_platform.legacy.devices.pnpbios = 0;
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}
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static inline u64 hv_vtl_system_desc_base(struct ldttss_desc *desc)
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{
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return ((u64)desc->base3 << 32) | ((u64)desc->base2 << 24) |
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(desc->base1 << 16) | desc->base0;
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}
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static inline u32 hv_vtl_system_desc_limit(struct ldttss_desc *desc)
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{
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return ((u32)desc->limit1 << 16) | (u32)desc->limit0;
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}
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typedef void (*secondary_startup_64_fn)(void*, void*);
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static void hv_vtl_ap_entry(void)
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{
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((secondary_startup_64_fn)secondary_startup_64)(&boot_params, &boot_params);
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}
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static int hv_vtl_bringup_vcpu(u32 target_vp_index, u64 eip_ignored)
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{
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u64 status;
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int ret = 0;
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struct hv_enable_vp_vtl *input;
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unsigned long irq_flags;
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struct desc_ptr gdt_ptr;
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struct desc_ptr idt_ptr;
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struct ldttss_desc *tss;
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struct ldttss_desc *ldt;
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struct desc_struct *gdt;
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u64 rsp = current->thread.sp;
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u64 rip = (u64)&hv_vtl_ap_entry;
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native_store_gdt(&gdt_ptr);
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store_idt(&idt_ptr);
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gdt = (struct desc_struct *)((void *)(gdt_ptr.address));
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tss = (struct ldttss_desc *)(gdt + GDT_ENTRY_TSS);
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ldt = (struct ldttss_desc *)(gdt + GDT_ENTRY_LDT);
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local_irq_save(irq_flags);
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input = *this_cpu_ptr(hyperv_pcpu_input_arg);
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memset(input, 0, sizeof(*input));
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input->partition_id = HV_PARTITION_ID_SELF;
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input->vp_index = target_vp_index;
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input->target_vtl.target_vtl = HV_VTL_MGMT;
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/*
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* The x86_64 Linux kernel follows the 16-bit -> 32-bit -> 64-bit
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* mode transition sequence after waking up an AP with SIPI whose
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* vector points to the 16-bit AP startup trampoline code. Here in
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* VTL2, we can't perform that sequence as the AP has to start in
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* the 64-bit mode.
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*
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* To make this happen, we tell the hypervisor to load a valid 64-bit
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* context (most of which is just magic numbers from the CPU manual)
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* so that AP jumps right to the 64-bit entry of the kernel, and the
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* control registers are loaded with values that let the AP fetch the
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* code and data and carry on with work it gets assigned.
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*/
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input->vp_context.rip = rip;
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input->vp_context.rsp = rsp;
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input->vp_context.rflags = 0x0000000000000002;
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input->vp_context.efer = __rdmsr(MSR_EFER);
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input->vp_context.cr0 = native_read_cr0();
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input->vp_context.cr3 = __native_read_cr3();
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input->vp_context.cr4 = native_read_cr4();
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input->vp_context.msr_cr_pat = __rdmsr(MSR_IA32_CR_PAT);
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input->vp_context.idtr.limit = idt_ptr.size;
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input->vp_context.idtr.base = idt_ptr.address;
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input->vp_context.gdtr.limit = gdt_ptr.size;
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input->vp_context.gdtr.base = gdt_ptr.address;
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/* Non-system desc (64bit), long, code, present */
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input->vp_context.cs.selector = __KERNEL_CS;
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input->vp_context.cs.base = 0;
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input->vp_context.cs.limit = 0xffffffff;
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input->vp_context.cs.attributes = 0xa09b;
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/* Non-system desc (64bit), data, present, granularity, default */
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input->vp_context.ss.selector = __KERNEL_DS;
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input->vp_context.ss.base = 0;
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input->vp_context.ss.limit = 0xffffffff;
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input->vp_context.ss.attributes = 0xc093;
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/* System desc (128bit), present, LDT */
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input->vp_context.ldtr.selector = GDT_ENTRY_LDT * 8;
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input->vp_context.ldtr.base = hv_vtl_system_desc_base(ldt);
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input->vp_context.ldtr.limit = hv_vtl_system_desc_limit(ldt);
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input->vp_context.ldtr.attributes = 0x82;
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/* System desc (128bit), present, TSS, 0x8b - busy, 0x89 -- default */
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input->vp_context.tr.selector = GDT_ENTRY_TSS * 8;
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input->vp_context.tr.base = hv_vtl_system_desc_base(tss);
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input->vp_context.tr.limit = hv_vtl_system_desc_limit(tss);
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input->vp_context.tr.attributes = 0x8b;
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status = hv_do_hypercall(HVCALL_ENABLE_VP_VTL, input, NULL);
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if (!hv_result_success(status) &&
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hv_result(status) != HV_STATUS_VTL_ALREADY_ENABLED) {
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pr_err("HVCALL_ENABLE_VP_VTL failed for VP : %d ! [Err: %#llx\n]",
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target_vp_index, status);
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ret = -EINVAL;
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goto free_lock;
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}
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status = hv_do_hypercall(HVCALL_START_VP, input, NULL);
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if (!hv_result_success(status)) {
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pr_err("HVCALL_START_VP failed for VP : %d ! [Err: %#llx]\n",
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target_vp_index, status);
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ret = -EINVAL;
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}
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free_lock:
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local_irq_restore(irq_flags);
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return ret;
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}
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static int hv_vtl_apicid_to_vp_id(u32 apic_id)
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{
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u64 control;
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u64 status;
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unsigned long irq_flags;
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struct hv_get_vp_from_apic_id_in *input;
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u32 *output, ret;
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local_irq_save(irq_flags);
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input = *this_cpu_ptr(hyperv_pcpu_input_arg);
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memset(input, 0, sizeof(*input));
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input->partition_id = HV_PARTITION_ID_SELF;
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input->apic_ids[0] = apic_id;
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output = (u32 *)input;
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control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_ID_FROM_APIC_ID;
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status = hv_do_hypercall(control, input, output);
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ret = output[0];
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local_irq_restore(irq_flags);
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if (!hv_result_success(status)) {
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pr_err("failed to get vp id from apic id %d, status %#llx\n",
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apic_id, status);
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return -EINVAL;
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}
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return ret;
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}
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static int hv_vtl_wakeup_secondary_cpu(int apicid, unsigned long start_eip)
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{
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int vp_id;
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pr_debug("Bringing up CPU with APIC ID %d in VTL2...\n", apicid);
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vp_id = hv_vtl_apicid_to_vp_id(apicid);
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if (vp_id < 0) {
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pr_err("Couldn't find CPU with APIC ID %d\n", apicid);
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return -EINVAL;
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}
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if (vp_id > ms_hyperv.max_vp_index) {
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pr_err("Invalid CPU id %d for APIC ID %d\n", vp_id, apicid);
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return -EINVAL;
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}
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return hv_vtl_bringup_vcpu(vp_id, start_eip);
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}
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static int __init hv_vtl_early_init(void)
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{
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/*
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* `boot_cpu_has` returns the runtime feature support,
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* and here is the earliest it can be used.
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*/
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if (cpu_feature_enabled(X86_FEATURE_XSAVE))
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panic("XSAVE has to be disabled as it is not supported by this module.\n"
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"Please add 'noxsave' to the kernel command line.\n");
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real_mode_header = &hv_vtl_real_mode_header;
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apic->wakeup_secondary_cpu_64 = hv_vtl_wakeup_secondary_cpu;
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return 0;
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}
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early_initcall(hv_vtl_early_init);
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