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 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, int cpu, 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 struct task_struct *idle = idle_thread_get(cpu); 83 u64 rsp = (unsigned long)idle->thread.sp; 84 85 u64 rip = (u64)&hv_vtl_ap_entry; 86 87 native_store_gdt(&gdt_ptr); 88 store_idt(&idt_ptr); 89 90 gdt = (struct desc_struct *)((void *)(gdt_ptr.address)); 91 tss = (struct ldttss_desc *)(gdt + GDT_ENTRY_TSS); 92 ldt = (struct ldttss_desc *)(gdt + GDT_ENTRY_LDT); 93 94 local_irq_save(irq_flags); 95 96 input = *this_cpu_ptr(hyperv_pcpu_input_arg); 97 memset(input, 0, sizeof(*input)); 98 99 input->partition_id = HV_PARTITION_ID_SELF; 100 input->vp_index = target_vp_index; 101 input->target_vtl.target_vtl = HV_VTL_MGMT; 102 103 /* 104 * The x86_64 Linux kernel follows the 16-bit -> 32-bit -> 64-bit 105 * mode transition sequence after waking up an AP with SIPI whose 106 * vector points to the 16-bit AP startup trampoline code. Here in 107 * VTL2, we can't perform that sequence as the AP has to start in 108 * the 64-bit mode. 109 * 110 * To make this happen, we tell the hypervisor to load a valid 64-bit 111 * context (most of which is just magic numbers from the CPU manual) 112 * so that AP jumps right to the 64-bit entry of the kernel, and the 113 * control registers are loaded with values that let the AP fetch the 114 * code and data and carry on with work it gets assigned. 115 */ 116 117 input->vp_context.rip = rip; 118 input->vp_context.rsp = rsp; 119 input->vp_context.rflags = 0x0000000000000002; 120 input->vp_context.efer = __rdmsr(MSR_EFER); 121 input->vp_context.cr0 = native_read_cr0(); 122 input->vp_context.cr3 = __native_read_cr3(); 123 input->vp_context.cr4 = native_read_cr4(); 124 input->vp_context.msr_cr_pat = __rdmsr(MSR_IA32_CR_PAT); 125 input->vp_context.idtr.limit = idt_ptr.size; 126 input->vp_context.idtr.base = idt_ptr.address; 127 input->vp_context.gdtr.limit = gdt_ptr.size; 128 input->vp_context.gdtr.base = gdt_ptr.address; 129 130 /* Non-system desc (64bit), long, code, present */ 131 input->vp_context.cs.selector = __KERNEL_CS; 132 input->vp_context.cs.base = 0; 133 input->vp_context.cs.limit = 0xffffffff; 134 input->vp_context.cs.attributes = 0xa09b; 135 /* Non-system desc (64bit), data, present, granularity, default */ 136 input->vp_context.ss.selector = __KERNEL_DS; 137 input->vp_context.ss.base = 0; 138 input->vp_context.ss.limit = 0xffffffff; 139 input->vp_context.ss.attributes = 0xc093; 140 141 /* System desc (128bit), present, LDT */ 142 input->vp_context.ldtr.selector = GDT_ENTRY_LDT * 8; 143 input->vp_context.ldtr.base = hv_vtl_system_desc_base(ldt); 144 input->vp_context.ldtr.limit = hv_vtl_system_desc_limit(ldt); 145 input->vp_context.ldtr.attributes = 0x82; 146 147 /* System desc (128bit), present, TSS, 0x8b - busy, 0x89 -- default */ 148 input->vp_context.tr.selector = GDT_ENTRY_TSS * 8; 149 input->vp_context.tr.base = hv_vtl_system_desc_base(tss); 150 input->vp_context.tr.limit = hv_vtl_system_desc_limit(tss); 151 input->vp_context.tr.attributes = 0x8b; 152 153 status = hv_do_hypercall(HVCALL_ENABLE_VP_VTL, input, NULL); 154 155 if (!hv_result_success(status) && 156 hv_result(status) != HV_STATUS_VTL_ALREADY_ENABLED) { 157 pr_err("HVCALL_ENABLE_VP_VTL failed for VP : %d ! [Err: %#llx\n]", 158 target_vp_index, status); 159 ret = -EINVAL; 160 goto free_lock; 161 } 162 163 status = hv_do_hypercall(HVCALL_START_VP, input, NULL); 164 165 if (!hv_result_success(status)) { 166 pr_err("HVCALL_START_VP failed for VP : %d ! [Err: %#llx]\n", 167 target_vp_index, status); 168 ret = -EINVAL; 169 } 170 171 free_lock: 172 local_irq_restore(irq_flags); 173 174 return ret; 175 } 176 177 static int hv_vtl_apicid_to_vp_id(u32 apic_id) 178 { 179 u64 control; 180 u64 status; 181 unsigned long irq_flags; 182 struct hv_get_vp_from_apic_id_in *input; 183 u32 *output, ret; 184 185 local_irq_save(irq_flags); 186 187 input = *this_cpu_ptr(hyperv_pcpu_input_arg); 188 memset(input, 0, sizeof(*input)); 189 input->partition_id = HV_PARTITION_ID_SELF; 190 input->apic_ids[0] = apic_id; 191 192 output = (u32 *)input; 193 194 control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_ID_FROM_APIC_ID; 195 status = hv_do_hypercall(control, input, output); 196 ret = output[0]; 197 198 local_irq_restore(irq_flags); 199 200 if (!hv_result_success(status)) { 201 pr_err("failed to get vp id from apic id %d, status %#llx\n", 202 apic_id, status); 203 return -EINVAL; 204 } 205 206 return ret; 207 } 208 209 static int hv_vtl_wakeup_secondary_cpu(u32 apicid, unsigned long start_eip) 210 { 211 int vp_id, cpu; 212 213 /* Find the logical CPU for the APIC ID */ 214 for_each_present_cpu(cpu) { 215 if (arch_match_cpu_phys_id(cpu, apicid)) 216 break; 217 } 218 if (cpu >= nr_cpu_ids) 219 return -EINVAL; 220 221 pr_debug("Bringing up CPU with APIC ID %d in VTL2...\n", apicid); 222 vp_id = hv_vtl_apicid_to_vp_id(apicid); 223 224 if (vp_id < 0) { 225 pr_err("Couldn't find CPU with APIC ID %d\n", apicid); 226 return -EINVAL; 227 } 228 if (vp_id > ms_hyperv.max_vp_index) { 229 pr_err("Invalid CPU id %d for APIC ID %d\n", vp_id, apicid); 230 return -EINVAL; 231 } 232 233 return hv_vtl_bringup_vcpu(vp_id, cpu, start_eip); 234 } 235 236 int __init hv_vtl_early_init(void) 237 { 238 /* 239 * `boot_cpu_has` returns the runtime feature support, 240 * and here is the earliest it can be used. 241 */ 242 if (cpu_feature_enabled(X86_FEATURE_XSAVE)) 243 panic("XSAVE has to be disabled as it is not supported by this module.\n" 244 "Please add 'noxsave' to the kernel command line.\n"); 245 246 real_mode_header = &hv_vtl_real_mode_header; 247 apic_update_callback(wakeup_secondary_cpu_64, hv_vtl_wakeup_secondary_cpu); 248 249 return 0; 250 } 251