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 #include <../kernel/smpboot.h> 16 17 extern struct boot_params boot_params; 18 static struct real_mode_header hv_vtl_real_mode_header; 19 20 static bool __init hv_vtl_msi_ext_dest_id(void) 21 { 22 return true; 23 } 24 25 void __init hv_vtl_init_platform(void) 26 { 27 pr_info("Linux runs in Hyper-V Virtual Trust Level\n"); 28 29 x86_platform.realmode_reserve = x86_init_noop; 30 x86_platform.realmode_init = x86_init_noop; 31 x86_init.irqs.pre_vector_init = x86_init_noop; 32 x86_init.timers.timer_init = x86_init_noop; 33 34 /* Avoid searching for BIOS MP tables */ 35 x86_init.mpparse.find_mptable = x86_init_noop; 36 x86_init.mpparse.early_parse_smp_cfg = x86_init_noop; 37 x86_init.mpparse.parse_smp_cfg = x86_init_noop; 38 39 x86_platform.get_wallclock = get_rtc_noop; 40 x86_platform.set_wallclock = set_rtc_noop; 41 x86_platform.get_nmi_reason = hv_get_nmi_reason; 42 43 x86_platform.legacy.i8042 = X86_LEGACY_I8042_PLATFORM_ABSENT; 44 x86_platform.legacy.rtc = 0; 45 x86_platform.legacy.warm_reset = 0; 46 x86_platform.legacy.reserve_bios_regions = 0; 47 x86_platform.legacy.devices.pnpbios = 0; 48 49 x86_init.hyper.msi_ext_dest_id = hv_vtl_msi_ext_dest_id; 50 } 51 52 static inline u64 hv_vtl_system_desc_base(struct ldttss_desc *desc) 53 { 54 return ((u64)desc->base3 << 32) | ((u64)desc->base2 << 24) | 55 (desc->base1 << 16) | desc->base0; 56 } 57 58 static inline u32 hv_vtl_system_desc_limit(struct ldttss_desc *desc) 59 { 60 return ((u32)desc->limit1 << 16) | (u32)desc->limit0; 61 } 62 63 typedef void (*secondary_startup_64_fn)(void*, void*); 64 static void hv_vtl_ap_entry(void) 65 { 66 ((secondary_startup_64_fn)secondary_startup_64)(&boot_params, &boot_params); 67 } 68 69 static int hv_vtl_bringup_vcpu(u32 target_vp_index, int cpu, u64 eip_ignored) 70 { 71 u64 status; 72 int ret = 0; 73 struct hv_enable_vp_vtl *input; 74 unsigned long irq_flags; 75 76 struct desc_ptr gdt_ptr; 77 struct desc_ptr idt_ptr; 78 79 struct ldttss_desc *tss; 80 struct ldttss_desc *ldt; 81 struct desc_struct *gdt; 82 83 struct task_struct *idle = idle_thread_get(cpu); 84 u64 rsp = (unsigned long)idle->thread.sp; 85 86 u64 rip = (u64)&hv_vtl_ap_entry; 87 88 native_store_gdt(&gdt_ptr); 89 store_idt(&idt_ptr); 90 91 gdt = (struct desc_struct *)((void *)(gdt_ptr.address)); 92 tss = (struct ldttss_desc *)(gdt + GDT_ENTRY_TSS); 93 ldt = (struct ldttss_desc *)(gdt + GDT_ENTRY_LDT); 94 95 local_irq_save(irq_flags); 96 97 input = *this_cpu_ptr(hyperv_pcpu_input_arg); 98 memset(input, 0, sizeof(*input)); 99 100 input->partition_id = HV_PARTITION_ID_SELF; 101 input->vp_index = target_vp_index; 102 input->target_vtl.target_vtl = HV_VTL_MGMT; 103 104 /* 105 * The x86_64 Linux kernel follows the 16-bit -> 32-bit -> 64-bit 106 * mode transition sequence after waking up an AP with SIPI whose 107 * vector points to the 16-bit AP startup trampoline code. Here in 108 * VTL2, we can't perform that sequence as the AP has to start in 109 * the 64-bit mode. 110 * 111 * To make this happen, we tell the hypervisor to load a valid 64-bit 112 * context (most of which is just magic numbers from the CPU manual) 113 * so that AP jumps right to the 64-bit entry of the kernel, and the 114 * control registers are loaded with values that let the AP fetch the 115 * code and data and carry on with work it gets assigned. 116 */ 117 118 input->vp_context.rip = rip; 119 input->vp_context.rsp = rsp; 120 input->vp_context.rflags = 0x0000000000000002; 121 input->vp_context.efer = __rdmsr(MSR_EFER); 122 input->vp_context.cr0 = native_read_cr0(); 123 input->vp_context.cr3 = __native_read_cr3(); 124 input->vp_context.cr4 = native_read_cr4(); 125 input->vp_context.msr_cr_pat = __rdmsr(MSR_IA32_CR_PAT); 126 input->vp_context.idtr.limit = idt_ptr.size; 127 input->vp_context.idtr.base = idt_ptr.address; 128 input->vp_context.gdtr.limit = gdt_ptr.size; 129 input->vp_context.gdtr.base = gdt_ptr.address; 130 131 /* Non-system desc (64bit), long, code, present */ 132 input->vp_context.cs.selector = __KERNEL_CS; 133 input->vp_context.cs.base = 0; 134 input->vp_context.cs.limit = 0xffffffff; 135 input->vp_context.cs.attributes = 0xa09b; 136 /* Non-system desc (64bit), data, present, granularity, default */ 137 input->vp_context.ss.selector = __KERNEL_DS; 138 input->vp_context.ss.base = 0; 139 input->vp_context.ss.limit = 0xffffffff; 140 input->vp_context.ss.attributes = 0xc093; 141 142 /* System desc (128bit), present, LDT */ 143 input->vp_context.ldtr.selector = GDT_ENTRY_LDT * 8; 144 input->vp_context.ldtr.base = hv_vtl_system_desc_base(ldt); 145 input->vp_context.ldtr.limit = hv_vtl_system_desc_limit(ldt); 146 input->vp_context.ldtr.attributes = 0x82; 147 148 /* System desc (128bit), present, TSS, 0x8b - busy, 0x89 -- default */ 149 input->vp_context.tr.selector = GDT_ENTRY_TSS * 8; 150 input->vp_context.tr.base = hv_vtl_system_desc_base(tss); 151 input->vp_context.tr.limit = hv_vtl_system_desc_limit(tss); 152 input->vp_context.tr.attributes = 0x8b; 153 154 status = hv_do_hypercall(HVCALL_ENABLE_VP_VTL, input, NULL); 155 156 if (!hv_result_success(status) && 157 hv_result(status) != HV_STATUS_VTL_ALREADY_ENABLED) { 158 pr_err("HVCALL_ENABLE_VP_VTL failed for VP : %d ! [Err: %#llx\n]", 159 target_vp_index, status); 160 ret = -EINVAL; 161 goto free_lock; 162 } 163 164 status = hv_do_hypercall(HVCALL_START_VP, input, NULL); 165 166 if (!hv_result_success(status)) { 167 pr_err("HVCALL_START_VP failed for VP : %d ! [Err: %#llx]\n", 168 target_vp_index, status); 169 ret = -EINVAL; 170 } 171 172 free_lock: 173 local_irq_restore(irq_flags); 174 175 return ret; 176 } 177 178 static int hv_vtl_apicid_to_vp_id(u32 apic_id) 179 { 180 u64 control; 181 u64 status; 182 unsigned long irq_flags; 183 struct hv_get_vp_from_apic_id_in *input; 184 u32 *output, ret; 185 186 local_irq_save(irq_flags); 187 188 input = *this_cpu_ptr(hyperv_pcpu_input_arg); 189 memset(input, 0, sizeof(*input)); 190 input->partition_id = HV_PARTITION_ID_SELF; 191 input->apic_ids[0] = apic_id; 192 193 output = (u32 *)input; 194 195 control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_ID_FROM_APIC_ID; 196 status = hv_do_hypercall(control, input, output); 197 ret = output[0]; 198 199 local_irq_restore(irq_flags); 200 201 if (!hv_result_success(status)) { 202 pr_err("failed to get vp id from apic id %d, status %#llx\n", 203 apic_id, status); 204 return -EINVAL; 205 } 206 207 return ret; 208 } 209 210 static int hv_vtl_wakeup_secondary_cpu(u32 apicid, unsigned long start_eip) 211 { 212 int vp_id, cpu; 213 214 /* Find the logical CPU for the APIC ID */ 215 for_each_present_cpu(cpu) { 216 if (arch_match_cpu_phys_id(cpu, apicid)) 217 break; 218 } 219 if (cpu >= nr_cpu_ids) 220 return -EINVAL; 221 222 pr_debug("Bringing up CPU with APIC ID %d in VTL2...\n", apicid); 223 vp_id = hv_vtl_apicid_to_vp_id(apicid); 224 225 if (vp_id < 0) { 226 pr_err("Couldn't find CPU with APIC ID %d\n", apicid); 227 return -EINVAL; 228 } 229 if (vp_id > ms_hyperv.max_vp_index) { 230 pr_err("Invalid CPU id %d for APIC ID %d\n", vp_id, apicid); 231 return -EINVAL; 232 } 233 234 return hv_vtl_bringup_vcpu(vp_id, cpu, start_eip); 235 } 236 237 int __init hv_vtl_early_init(void) 238 { 239 /* 240 * `boot_cpu_has` returns the runtime feature support, 241 * and here is the earliest it can be used. 242 */ 243 if (cpu_feature_enabled(X86_FEATURE_XSAVE)) 244 panic("XSAVE has to be disabled as it is not supported by this module.\n" 245 "Please add 'noxsave' to the kernel command line.\n"); 246 247 real_mode_header = &hv_vtl_real_mode_header; 248 apic_update_callback(wakeup_secondary_cpu_64, hv_vtl_wakeup_secondary_cpu); 249 250 return 0; 251 } 252