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_platform.realmode_reserve = x86_init_noop; 24 x86_platform.realmode_init = x86_init_noop; 25 x86_init.irqs.pre_vector_init = x86_init_noop; 26 x86_init.timers.timer_init = x86_init_noop; 27 28 /* Avoid searching for BIOS MP tables */ 29 x86_init.mpparse.find_smp_config = x86_init_noop; 30 x86_init.mpparse.get_smp_config = x86_init_uint_noop; 31 32 x86_platform.get_wallclock = get_rtc_noop; 33 x86_platform.set_wallclock = set_rtc_noop; 34 x86_platform.get_nmi_reason = hv_get_nmi_reason; 35 36 x86_platform.legacy.i8042 = X86_LEGACY_I8042_PLATFORM_ABSENT; 37 x86_platform.legacy.rtc = 0; 38 x86_platform.legacy.warm_reset = 0; 39 x86_platform.legacy.reserve_bios_regions = 0; 40 x86_platform.legacy.devices.pnpbios = 0; 41 } 42 43 static inline u64 hv_vtl_system_desc_base(struct ldttss_desc *desc) 44 { 45 return ((u64)desc->base3 << 32) | ((u64)desc->base2 << 24) | 46 (desc->base1 << 16) | desc->base0; 47 } 48 49 static inline u32 hv_vtl_system_desc_limit(struct ldttss_desc *desc) 50 { 51 return ((u32)desc->limit1 << 16) | (u32)desc->limit0; 52 } 53 54 typedef void (*secondary_startup_64_fn)(void*, void*); 55 static void hv_vtl_ap_entry(void) 56 { 57 ((secondary_startup_64_fn)secondary_startup_64)(&boot_params, &boot_params); 58 } 59 60 static int hv_vtl_bringup_vcpu(u32 target_vp_index, u64 eip_ignored) 61 { 62 u64 status; 63 int ret = 0; 64 struct hv_enable_vp_vtl *input; 65 unsigned long irq_flags; 66 67 struct desc_ptr gdt_ptr; 68 struct desc_ptr idt_ptr; 69 70 struct ldttss_desc *tss; 71 struct ldttss_desc *ldt; 72 struct desc_struct *gdt; 73 74 u64 rsp = current->thread.sp; 75 u64 rip = (u64)&hv_vtl_ap_entry; 76 77 native_store_gdt(&gdt_ptr); 78 store_idt(&idt_ptr); 79 80 gdt = (struct desc_struct *)((void *)(gdt_ptr.address)); 81 tss = (struct ldttss_desc *)(gdt + GDT_ENTRY_TSS); 82 ldt = (struct ldttss_desc *)(gdt + GDT_ENTRY_LDT); 83 84 local_irq_save(irq_flags); 85 86 input = *this_cpu_ptr(hyperv_pcpu_input_arg); 87 memset(input, 0, sizeof(*input)); 88 89 input->partition_id = HV_PARTITION_ID_SELF; 90 input->vp_index = target_vp_index; 91 input->target_vtl.target_vtl = HV_VTL_MGMT; 92 93 /* 94 * The x86_64 Linux kernel follows the 16-bit -> 32-bit -> 64-bit 95 * mode transition sequence after waking up an AP with SIPI whose 96 * vector points to the 16-bit AP startup trampoline code. Here in 97 * VTL2, we can't perform that sequence as the AP has to start in 98 * the 64-bit mode. 99 * 100 * To make this happen, we tell the hypervisor to load a valid 64-bit 101 * context (most of which is just magic numbers from the CPU manual) 102 * so that AP jumps right to the 64-bit entry of the kernel, and the 103 * control registers are loaded with values that let the AP fetch the 104 * code and data and carry on with work it gets assigned. 105 */ 106 107 input->vp_context.rip = rip; 108 input->vp_context.rsp = rsp; 109 input->vp_context.rflags = 0x0000000000000002; 110 input->vp_context.efer = __rdmsr(MSR_EFER); 111 input->vp_context.cr0 = native_read_cr0(); 112 input->vp_context.cr3 = __native_read_cr3(); 113 input->vp_context.cr4 = native_read_cr4(); 114 input->vp_context.msr_cr_pat = __rdmsr(MSR_IA32_CR_PAT); 115 input->vp_context.idtr.limit = idt_ptr.size; 116 input->vp_context.idtr.base = idt_ptr.address; 117 input->vp_context.gdtr.limit = gdt_ptr.size; 118 input->vp_context.gdtr.base = gdt_ptr.address; 119 120 /* Non-system desc (64bit), long, code, present */ 121 input->vp_context.cs.selector = __KERNEL_CS; 122 input->vp_context.cs.base = 0; 123 input->vp_context.cs.limit = 0xffffffff; 124 input->vp_context.cs.attributes = 0xa09b; 125 /* Non-system desc (64bit), data, present, granularity, default */ 126 input->vp_context.ss.selector = __KERNEL_DS; 127 input->vp_context.ss.base = 0; 128 input->vp_context.ss.limit = 0xffffffff; 129 input->vp_context.ss.attributes = 0xc093; 130 131 /* System desc (128bit), present, LDT */ 132 input->vp_context.ldtr.selector = GDT_ENTRY_LDT * 8; 133 input->vp_context.ldtr.base = hv_vtl_system_desc_base(ldt); 134 input->vp_context.ldtr.limit = hv_vtl_system_desc_limit(ldt); 135 input->vp_context.ldtr.attributes = 0x82; 136 137 /* System desc (128bit), present, TSS, 0x8b - busy, 0x89 -- default */ 138 input->vp_context.tr.selector = GDT_ENTRY_TSS * 8; 139 input->vp_context.tr.base = hv_vtl_system_desc_base(tss); 140 input->vp_context.tr.limit = hv_vtl_system_desc_limit(tss); 141 input->vp_context.tr.attributes = 0x8b; 142 143 status = hv_do_hypercall(HVCALL_ENABLE_VP_VTL, input, NULL); 144 145 if (!hv_result_success(status) && 146 hv_result(status) != HV_STATUS_VTL_ALREADY_ENABLED) { 147 pr_err("HVCALL_ENABLE_VP_VTL failed for VP : %d ! [Err: %#llx\n]", 148 target_vp_index, status); 149 ret = -EINVAL; 150 goto free_lock; 151 } 152 153 status = hv_do_hypercall(HVCALL_START_VP, input, NULL); 154 155 if (!hv_result_success(status)) { 156 pr_err("HVCALL_START_VP failed for VP : %d ! [Err: %#llx]\n", 157 target_vp_index, status); 158 ret = -EINVAL; 159 } 160 161 free_lock: 162 local_irq_restore(irq_flags); 163 164 return ret; 165 } 166 167 static int hv_vtl_apicid_to_vp_id(u32 apic_id) 168 { 169 u64 control; 170 u64 status; 171 unsigned long irq_flags; 172 struct hv_get_vp_from_apic_id_in *input; 173 u32 *output, ret; 174 175 local_irq_save(irq_flags); 176 177 input = *this_cpu_ptr(hyperv_pcpu_input_arg); 178 memset(input, 0, sizeof(*input)); 179 input->partition_id = HV_PARTITION_ID_SELF; 180 input->apic_ids[0] = apic_id; 181 182 output = (u32 *)input; 183 184 control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_ID_FROM_APIC_ID; 185 status = hv_do_hypercall(control, input, output); 186 ret = output[0]; 187 188 local_irq_restore(irq_flags); 189 190 if (!hv_result_success(status)) { 191 pr_err("failed to get vp id from apic id %d, status %#llx\n", 192 apic_id, status); 193 return -EINVAL; 194 } 195 196 return ret; 197 } 198 199 static int hv_vtl_wakeup_secondary_cpu(int apicid, unsigned long start_eip) 200 { 201 int vp_id; 202 203 pr_debug("Bringing up CPU with APIC ID %d in VTL2...\n", apicid); 204 vp_id = hv_vtl_apicid_to_vp_id(apicid); 205 206 if (vp_id < 0) { 207 pr_err("Couldn't find CPU with APIC ID %d\n", apicid); 208 return -EINVAL; 209 } 210 if (vp_id > ms_hyperv.max_vp_index) { 211 pr_err("Invalid CPU id %d for APIC ID %d\n", vp_id, apicid); 212 return -EINVAL; 213 } 214 215 return hv_vtl_bringup_vcpu(vp_id, start_eip); 216 } 217 218 static int __init hv_vtl_early_init(void) 219 { 220 /* 221 * `boot_cpu_has` returns the runtime feature support, 222 * and here is the earliest it can be used. 223 */ 224 if (cpu_feature_enabled(X86_FEATURE_XSAVE)) 225 panic("XSAVE has to be disabled as it is not supported by this module.\n" 226 "Please add 'noxsave' to the kernel command line.\n"); 227 228 real_mode_header = &hv_vtl_real_mode_header; 229 apic_update_callback(wakeup_secondary_cpu_64, hv_vtl_wakeup_secondary_cpu); 230 231 return 0; 232 } 233 early_initcall(hv_vtl_early_init); 234