1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (c) 2023, Microsoft Corporation. 4 * 5 * Author: 6 * Saurabh Sengar <ssengar@microsoft.com> 7 */ 8 9 #include <asm/apic.h> 10 #include <asm/boot.h> 11 #include <asm/desc.h> 12 #include <asm/i8259.h> 13 #include <asm/mshyperv.h> 14 #include <asm/realmode.h> 15 16 extern struct boot_params boot_params; 17 static struct real_mode_header hv_vtl_real_mode_header; 18 19 void __init hv_vtl_init_platform(void) 20 { 21 pr_info("Linux runs in Hyper-V Virtual Trust Level\n"); 22 23 x86_init.irqs.pre_vector_init = x86_init_noop; 24 x86_init.timers.timer_init = x86_init_noop; 25 26 x86_platform.get_wallclock = get_rtc_noop; 27 x86_platform.set_wallclock = set_rtc_noop; 28 x86_platform.get_nmi_reason = hv_get_nmi_reason; 29 30 x86_platform.legacy.i8042 = X86_LEGACY_I8042_PLATFORM_ABSENT; 31 x86_platform.legacy.rtc = 0; 32 x86_platform.legacy.warm_reset = 0; 33 x86_platform.legacy.reserve_bios_regions = 0; 34 x86_platform.legacy.devices.pnpbios = 0; 35 } 36 37 static inline u64 hv_vtl_system_desc_base(struct ldttss_desc *desc) 38 { 39 return ((u64)desc->base3 << 32) | ((u64)desc->base2 << 24) | 40 (desc->base1 << 16) | desc->base0; 41 } 42 43 static inline u32 hv_vtl_system_desc_limit(struct ldttss_desc *desc) 44 { 45 return ((u32)desc->limit1 << 16) | (u32)desc->limit0; 46 } 47 48 typedef void (*secondary_startup_64_fn)(void*, void*); 49 static void hv_vtl_ap_entry(void) 50 { 51 ((secondary_startup_64_fn)secondary_startup_64)(&boot_params, &boot_params); 52 } 53 54 static int hv_vtl_bringup_vcpu(u32 target_vp_index, u64 eip_ignored) 55 { 56 u64 status; 57 int ret = 0; 58 struct hv_enable_vp_vtl *input; 59 unsigned long irq_flags; 60 61 struct desc_ptr gdt_ptr; 62 struct desc_ptr idt_ptr; 63 64 struct ldttss_desc *tss; 65 struct ldttss_desc *ldt; 66 struct desc_struct *gdt; 67 68 u64 rsp = current->thread.sp; 69 u64 rip = (u64)&hv_vtl_ap_entry; 70 71 native_store_gdt(&gdt_ptr); 72 store_idt(&idt_ptr); 73 74 gdt = (struct desc_struct *)((void *)(gdt_ptr.address)); 75 tss = (struct ldttss_desc *)(gdt + GDT_ENTRY_TSS); 76 ldt = (struct ldttss_desc *)(gdt + GDT_ENTRY_LDT); 77 78 local_irq_save(irq_flags); 79 80 input = *this_cpu_ptr(hyperv_pcpu_input_arg); 81 memset(input, 0, sizeof(*input)); 82 83 input->partition_id = HV_PARTITION_ID_SELF; 84 input->vp_index = target_vp_index; 85 input->target_vtl.target_vtl = HV_VTL_MGMT; 86 87 /* 88 * The x86_64 Linux kernel follows the 16-bit -> 32-bit -> 64-bit 89 * mode transition sequence after waking up an AP with SIPI whose 90 * vector points to the 16-bit AP startup trampoline code. Here in 91 * VTL2, we can't perform that sequence as the AP has to start in 92 * the 64-bit mode. 93 * 94 * To make this happen, we tell the hypervisor to load a valid 64-bit 95 * context (most of which is just magic numbers from the CPU manual) 96 * so that AP jumps right to the 64-bit entry of the kernel, and the 97 * control registers are loaded with values that let the AP fetch the 98 * code and data and carry on with work it gets assigned. 99 */ 100 101 input->vp_context.rip = rip; 102 input->vp_context.rsp = rsp; 103 input->vp_context.rflags = 0x0000000000000002; 104 input->vp_context.efer = __rdmsr(MSR_EFER); 105 input->vp_context.cr0 = native_read_cr0(); 106 input->vp_context.cr3 = __native_read_cr3(); 107 input->vp_context.cr4 = native_read_cr4(); 108 input->vp_context.msr_cr_pat = __rdmsr(MSR_IA32_CR_PAT); 109 input->vp_context.idtr.limit = idt_ptr.size; 110 input->vp_context.idtr.base = idt_ptr.address; 111 input->vp_context.gdtr.limit = gdt_ptr.size; 112 input->vp_context.gdtr.base = gdt_ptr.address; 113 114 /* Non-system desc (64bit), long, code, present */ 115 input->vp_context.cs.selector = __KERNEL_CS; 116 input->vp_context.cs.base = 0; 117 input->vp_context.cs.limit = 0xffffffff; 118 input->vp_context.cs.attributes = 0xa09b; 119 /* Non-system desc (64bit), data, present, granularity, default */ 120 input->vp_context.ss.selector = __KERNEL_DS; 121 input->vp_context.ss.base = 0; 122 input->vp_context.ss.limit = 0xffffffff; 123 input->vp_context.ss.attributes = 0xc093; 124 125 /* System desc (128bit), present, LDT */ 126 input->vp_context.ldtr.selector = GDT_ENTRY_LDT * 8; 127 input->vp_context.ldtr.base = hv_vtl_system_desc_base(ldt); 128 input->vp_context.ldtr.limit = hv_vtl_system_desc_limit(ldt); 129 input->vp_context.ldtr.attributes = 0x82; 130 131 /* System desc (128bit), present, TSS, 0x8b - busy, 0x89 -- default */ 132 input->vp_context.tr.selector = GDT_ENTRY_TSS * 8; 133 input->vp_context.tr.base = hv_vtl_system_desc_base(tss); 134 input->vp_context.tr.limit = hv_vtl_system_desc_limit(tss); 135 input->vp_context.tr.attributes = 0x8b; 136 137 status = hv_do_hypercall(HVCALL_ENABLE_VP_VTL, input, NULL); 138 139 if (!hv_result_success(status) && 140 hv_result(status) != HV_STATUS_VTL_ALREADY_ENABLED) { 141 pr_err("HVCALL_ENABLE_VP_VTL failed for VP : %d ! [Err: %#llx\n]", 142 target_vp_index, status); 143 ret = -EINVAL; 144 goto free_lock; 145 } 146 147 status = hv_do_hypercall(HVCALL_START_VP, input, NULL); 148 149 if (!hv_result_success(status)) { 150 pr_err("HVCALL_START_VP failed for VP : %d ! [Err: %#llx]\n", 151 target_vp_index, status); 152 ret = -EINVAL; 153 } 154 155 free_lock: 156 local_irq_restore(irq_flags); 157 158 return ret; 159 } 160 161 static int hv_vtl_apicid_to_vp_id(u32 apic_id) 162 { 163 u64 control; 164 u64 status; 165 unsigned long irq_flags; 166 struct hv_get_vp_from_apic_id_in *input; 167 u32 *output, ret; 168 169 local_irq_save(irq_flags); 170 171 input = *this_cpu_ptr(hyperv_pcpu_input_arg); 172 memset(input, 0, sizeof(*input)); 173 input->partition_id = HV_PARTITION_ID_SELF; 174 input->apic_ids[0] = apic_id; 175 176 output = (u32 *)input; 177 178 control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_ID_FROM_APIC_ID; 179 status = hv_do_hypercall(control, input, output); 180 ret = output[0]; 181 182 local_irq_restore(irq_flags); 183 184 if (!hv_result_success(status)) { 185 pr_err("failed to get vp id from apic id %d, status %#llx\n", 186 apic_id, status); 187 return -EINVAL; 188 } 189 190 return ret; 191 } 192 193 static int hv_vtl_wakeup_secondary_cpu(int apicid, unsigned long start_eip) 194 { 195 int vp_id; 196 197 pr_debug("Bringing up CPU with APIC ID %d in VTL2...\n", apicid); 198 vp_id = hv_vtl_apicid_to_vp_id(apicid); 199 200 if (vp_id < 0) { 201 pr_err("Couldn't find CPU with APIC ID %d\n", apicid); 202 return -EINVAL; 203 } 204 if (vp_id > ms_hyperv.max_vp_index) { 205 pr_err("Invalid CPU id %d for APIC ID %d\n", vp_id, apicid); 206 return -EINVAL; 207 } 208 209 return hv_vtl_bringup_vcpu(vp_id, start_eip); 210 } 211 212 static int __init hv_vtl_early_init(void) 213 { 214 /* 215 * `boot_cpu_has` returns the runtime feature support, 216 * and here is the earliest it can be used. 217 */ 218 if (cpu_feature_enabled(X86_FEATURE_XSAVE)) 219 panic("XSAVE has to be disabled as it is not supported by this module.\n" 220 "Please add 'noxsave' to the kernel command line.\n"); 221 222 real_mode_header = &hv_vtl_real_mode_header; 223 apic->wakeup_secondary_cpu_64 = hv_vtl_wakeup_secondary_cpu; 224 225 return 0; 226 } 227 early_initcall(hv_vtl_early_init); 228