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 static bool __init hv_vtl_msi_ext_dest_id(void) 20 { 21 return true; 22 } 23 24 void __init hv_vtl_init_platform(void) 25 { 26 pr_info("Linux runs in Hyper-V Virtual Trust Level\n"); 27 28 x86_platform.realmode_reserve = x86_init_noop; 29 x86_platform.realmode_init = x86_init_noop; 30 x86_init.irqs.pre_vector_init = x86_init_noop; 31 x86_init.timers.timer_init = x86_init_noop; 32 33 /* Avoid searching for BIOS MP tables */ 34 x86_init.mpparse.find_mptable = x86_init_noop; 35 x86_init.mpparse.early_parse_smp_cfg = x86_init_noop; 36 x86_init.mpparse.parse_smp_cfg = x86_init_noop; 37 38 x86_platform.get_wallclock = get_rtc_noop; 39 x86_platform.set_wallclock = set_rtc_noop; 40 x86_platform.get_nmi_reason = hv_get_nmi_reason; 41 42 x86_platform.legacy.i8042 = X86_LEGACY_I8042_PLATFORM_ABSENT; 43 x86_platform.legacy.rtc = 0; 44 x86_platform.legacy.warm_reset = 0; 45 x86_platform.legacy.reserve_bios_regions = 0; 46 x86_platform.legacy.devices.pnpbios = 0; 47 48 x86_init.hyper.msi_ext_dest_id = hv_vtl_msi_ext_dest_id; 49 } 50 51 static inline u64 hv_vtl_system_desc_base(struct ldttss_desc *desc) 52 { 53 return ((u64)desc->base3 << 32) | ((u64)desc->base2 << 24) | 54 (desc->base1 << 16) | desc->base0; 55 } 56 57 static inline u32 hv_vtl_system_desc_limit(struct ldttss_desc *desc) 58 { 59 return ((u32)desc->limit1 << 16) | (u32)desc->limit0; 60 } 61 62 typedef void (*secondary_startup_64_fn)(void*, void*); 63 static void hv_vtl_ap_entry(void) 64 { 65 ((secondary_startup_64_fn)secondary_startup_64)(&boot_params, &boot_params); 66 } 67 68 static int hv_vtl_bringup_vcpu(u32 target_vp_index, u64 eip_ignored) 69 { 70 u64 status; 71 int ret = 0; 72 struct hv_enable_vp_vtl *input; 73 unsigned long irq_flags; 74 75 struct desc_ptr gdt_ptr; 76 struct desc_ptr idt_ptr; 77 78 struct ldttss_desc *tss; 79 struct ldttss_desc *ldt; 80 struct desc_struct *gdt; 81 82 u64 rsp = current->thread.sp; 83 u64 rip = (u64)&hv_vtl_ap_entry; 84 85 native_store_gdt(&gdt_ptr); 86 store_idt(&idt_ptr); 87 88 gdt = (struct desc_struct *)((void *)(gdt_ptr.address)); 89 tss = (struct ldttss_desc *)(gdt + GDT_ENTRY_TSS); 90 ldt = (struct ldttss_desc *)(gdt + GDT_ENTRY_LDT); 91 92 local_irq_save(irq_flags); 93 94 input = *this_cpu_ptr(hyperv_pcpu_input_arg); 95 memset(input, 0, sizeof(*input)); 96 97 input->partition_id = HV_PARTITION_ID_SELF; 98 input->vp_index = target_vp_index; 99 input->target_vtl.target_vtl = HV_VTL_MGMT; 100 101 /* 102 * The x86_64 Linux kernel follows the 16-bit -> 32-bit -> 64-bit 103 * mode transition sequence after waking up an AP with SIPI whose 104 * vector points to the 16-bit AP startup trampoline code. Here in 105 * VTL2, we can't perform that sequence as the AP has to start in 106 * the 64-bit mode. 107 * 108 * To make this happen, we tell the hypervisor to load a valid 64-bit 109 * context (most of which is just magic numbers from the CPU manual) 110 * so that AP jumps right to the 64-bit entry of the kernel, and the 111 * control registers are loaded with values that let the AP fetch the 112 * code and data and carry on with work it gets assigned. 113 */ 114 115 input->vp_context.rip = rip; 116 input->vp_context.rsp = rsp; 117 input->vp_context.rflags = 0x0000000000000002; 118 input->vp_context.efer = __rdmsr(MSR_EFER); 119 input->vp_context.cr0 = native_read_cr0(); 120 input->vp_context.cr3 = __native_read_cr3(); 121 input->vp_context.cr4 = native_read_cr4(); 122 input->vp_context.msr_cr_pat = __rdmsr(MSR_IA32_CR_PAT); 123 input->vp_context.idtr.limit = idt_ptr.size; 124 input->vp_context.idtr.base = idt_ptr.address; 125 input->vp_context.gdtr.limit = gdt_ptr.size; 126 input->vp_context.gdtr.base = gdt_ptr.address; 127 128 /* Non-system desc (64bit), long, code, present */ 129 input->vp_context.cs.selector = __KERNEL_CS; 130 input->vp_context.cs.base = 0; 131 input->vp_context.cs.limit = 0xffffffff; 132 input->vp_context.cs.attributes = 0xa09b; 133 /* Non-system desc (64bit), data, present, granularity, default */ 134 input->vp_context.ss.selector = __KERNEL_DS; 135 input->vp_context.ss.base = 0; 136 input->vp_context.ss.limit = 0xffffffff; 137 input->vp_context.ss.attributes = 0xc093; 138 139 /* System desc (128bit), present, LDT */ 140 input->vp_context.ldtr.selector = GDT_ENTRY_LDT * 8; 141 input->vp_context.ldtr.base = hv_vtl_system_desc_base(ldt); 142 input->vp_context.ldtr.limit = hv_vtl_system_desc_limit(ldt); 143 input->vp_context.ldtr.attributes = 0x82; 144 145 /* System desc (128bit), present, TSS, 0x8b - busy, 0x89 -- default */ 146 input->vp_context.tr.selector = GDT_ENTRY_TSS * 8; 147 input->vp_context.tr.base = hv_vtl_system_desc_base(tss); 148 input->vp_context.tr.limit = hv_vtl_system_desc_limit(tss); 149 input->vp_context.tr.attributes = 0x8b; 150 151 status = hv_do_hypercall(HVCALL_ENABLE_VP_VTL, input, NULL); 152 153 if (!hv_result_success(status) && 154 hv_result(status) != HV_STATUS_VTL_ALREADY_ENABLED) { 155 pr_err("HVCALL_ENABLE_VP_VTL failed for VP : %d ! [Err: %#llx\n]", 156 target_vp_index, status); 157 ret = -EINVAL; 158 goto free_lock; 159 } 160 161 status = hv_do_hypercall(HVCALL_START_VP, input, NULL); 162 163 if (!hv_result_success(status)) { 164 pr_err("HVCALL_START_VP failed for VP : %d ! [Err: %#llx]\n", 165 target_vp_index, status); 166 ret = -EINVAL; 167 } 168 169 free_lock: 170 local_irq_restore(irq_flags); 171 172 return ret; 173 } 174 175 static int hv_vtl_apicid_to_vp_id(u32 apic_id) 176 { 177 u64 control; 178 u64 status; 179 unsigned long irq_flags; 180 struct hv_get_vp_from_apic_id_in *input; 181 u32 *output, ret; 182 183 local_irq_save(irq_flags); 184 185 input = *this_cpu_ptr(hyperv_pcpu_input_arg); 186 memset(input, 0, sizeof(*input)); 187 input->partition_id = HV_PARTITION_ID_SELF; 188 input->apic_ids[0] = apic_id; 189 190 output = (u32 *)input; 191 192 control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_ID_FROM_APIC_ID; 193 status = hv_do_hypercall(control, input, output); 194 ret = output[0]; 195 196 local_irq_restore(irq_flags); 197 198 if (!hv_result_success(status)) { 199 pr_err("failed to get vp id from apic id %d, status %#llx\n", 200 apic_id, status); 201 return -EINVAL; 202 } 203 204 return ret; 205 } 206 207 static int hv_vtl_wakeup_secondary_cpu(u32 apicid, unsigned long start_eip) 208 { 209 int vp_id; 210 211 pr_debug("Bringing up CPU with APIC ID %d in VTL2...\n", apicid); 212 vp_id = hv_vtl_apicid_to_vp_id(apicid); 213 214 if (vp_id < 0) { 215 pr_err("Couldn't find CPU with APIC ID %d\n", apicid); 216 return -EINVAL; 217 } 218 if (vp_id > ms_hyperv.max_vp_index) { 219 pr_err("Invalid CPU id %d for APIC ID %d\n", vp_id, apicid); 220 return -EINVAL; 221 } 222 223 return hv_vtl_bringup_vcpu(vp_id, start_eip); 224 } 225 226 int __init hv_vtl_early_init(void) 227 { 228 /* 229 * `boot_cpu_has` returns the runtime feature support, 230 * and here is the earliest it can be used. 231 */ 232 if (cpu_feature_enabled(X86_FEATURE_XSAVE)) 233 panic("XSAVE has to be disabled as it is not supported by this module.\n" 234 "Please add 'noxsave' to the kernel command line.\n"); 235 236 real_mode_header = &hv_vtl_real_mode_header; 237 apic_update_callback(wakeup_secondary_cpu_64, hv_vtl_wakeup_secondary_cpu); 238 239 return 0; 240 } 241