1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (c) 2023, Microsoft Corporation.
6 * Saurabh Sengar <ssengar@microsoft.com>
12 #include <asm/i8259.h>
13 #include <asm/mshyperv.h>
14 #include <asm/realmode.h>
16 extern struct boot_params boot_params;
17 static struct real_mode_header hv_vtl_real_mode_header;
19 void __init hv_vtl_init_platform(void)
21 pr_info("Linux runs in Hyper-V Virtual Trust Level\n");
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;
28 x86_platform.get_wallclock = get_rtc_noop;
29 x86_platform.set_wallclock = set_rtc_noop;
30 x86_platform.get_nmi_reason = hv_get_nmi_reason;
32 x86_platform.legacy.i8042 = X86_LEGACY_I8042_PLATFORM_ABSENT;
33 x86_platform.legacy.rtc = 0;
34 x86_platform.legacy.warm_reset = 0;
35 x86_platform.legacy.reserve_bios_regions = 0;
36 x86_platform.legacy.devices.pnpbios = 0;
39 static inline u64 hv_vtl_system_desc_base(struct ldttss_desc *desc)
41 return ((u64)desc->base3 << 32) | ((u64)desc->base2 << 24) |
42 (desc->base1 << 16) | desc->base0;
45 static inline u32 hv_vtl_system_desc_limit(struct ldttss_desc *desc)
47 return ((u32)desc->limit1 << 16) | (u32)desc->limit0;
50 typedef void (*secondary_startup_64_fn)(void*, void*);
51 static void hv_vtl_ap_entry(void)
53 ((secondary_startup_64_fn)secondary_startup_64)(&boot_params, &boot_params);
56 static int hv_vtl_bringup_vcpu(u32 target_vp_index, u64 eip_ignored)
60 struct hv_enable_vp_vtl *input;
61 unsigned long irq_flags;
63 struct desc_ptr gdt_ptr;
64 struct desc_ptr idt_ptr;
66 struct ldttss_desc *tss;
67 struct ldttss_desc *ldt;
68 struct desc_struct *gdt;
70 u64 rsp = current->thread.sp;
71 u64 rip = (u64)&hv_vtl_ap_entry;
73 native_store_gdt(&gdt_ptr);
76 gdt = (struct desc_struct *)((void *)(gdt_ptr.address));
77 tss = (struct ldttss_desc *)(gdt + GDT_ENTRY_TSS);
78 ldt = (struct ldttss_desc *)(gdt + GDT_ENTRY_LDT);
80 local_irq_save(irq_flags);
82 input = *this_cpu_ptr(hyperv_pcpu_input_arg);
83 memset(input, 0, sizeof(*input));
85 input->partition_id = HV_PARTITION_ID_SELF;
86 input->vp_index = target_vp_index;
87 input->target_vtl.target_vtl = HV_VTL_MGMT;
90 * The x86_64 Linux kernel follows the 16-bit -> 32-bit -> 64-bit
91 * mode transition sequence after waking up an AP with SIPI whose
92 * vector points to the 16-bit AP startup trampoline code. Here in
93 * VTL2, we can't perform that sequence as the AP has to start in
96 * To make this happen, we tell the hypervisor to load a valid 64-bit
97 * context (most of which is just magic numbers from the CPU manual)
98 * so that AP jumps right to the 64-bit entry of the kernel, and the
99 * control registers are loaded with values that let the AP fetch the
100 * code and data and carry on with work it gets assigned.
103 input->vp_context.rip = rip;
104 input->vp_context.rsp = rsp;
105 input->vp_context.rflags = 0x0000000000000002;
106 input->vp_context.efer = __rdmsr(MSR_EFER);
107 input->vp_context.cr0 = native_read_cr0();
108 input->vp_context.cr3 = __native_read_cr3();
109 input->vp_context.cr4 = native_read_cr4();
110 input->vp_context.msr_cr_pat = __rdmsr(MSR_IA32_CR_PAT);
111 input->vp_context.idtr.limit = idt_ptr.size;
112 input->vp_context.idtr.base = idt_ptr.address;
113 input->vp_context.gdtr.limit = gdt_ptr.size;
114 input->vp_context.gdtr.base = gdt_ptr.address;
116 /* Non-system desc (64bit), long, code, present */
117 input->vp_context.cs.selector = __KERNEL_CS;
118 input->vp_context.cs.base = 0;
119 input->vp_context.cs.limit = 0xffffffff;
120 input->vp_context.cs.attributes = 0xa09b;
121 /* Non-system desc (64bit), data, present, granularity, default */
122 input->vp_context.ss.selector = __KERNEL_DS;
123 input->vp_context.ss.base = 0;
124 input->vp_context.ss.limit = 0xffffffff;
125 input->vp_context.ss.attributes = 0xc093;
127 /* System desc (128bit), present, LDT */
128 input->vp_context.ldtr.selector = GDT_ENTRY_LDT * 8;
129 input->vp_context.ldtr.base = hv_vtl_system_desc_base(ldt);
130 input->vp_context.ldtr.limit = hv_vtl_system_desc_limit(ldt);
131 input->vp_context.ldtr.attributes = 0x82;
133 /* System desc (128bit), present, TSS, 0x8b - busy, 0x89 -- default */
134 input->vp_context.tr.selector = GDT_ENTRY_TSS * 8;
135 input->vp_context.tr.base = hv_vtl_system_desc_base(tss);
136 input->vp_context.tr.limit = hv_vtl_system_desc_limit(tss);
137 input->vp_context.tr.attributes = 0x8b;
139 status = hv_do_hypercall(HVCALL_ENABLE_VP_VTL, input, NULL);
141 if (!hv_result_success(status) &&
142 hv_result(status) != HV_STATUS_VTL_ALREADY_ENABLED) {
143 pr_err("HVCALL_ENABLE_VP_VTL failed for VP : %d ! [Err: %#llx\n]",
144 target_vp_index, status);
149 status = hv_do_hypercall(HVCALL_START_VP, input, NULL);
151 if (!hv_result_success(status)) {
152 pr_err("HVCALL_START_VP failed for VP : %d ! [Err: %#llx]\n",
153 target_vp_index, status);
158 local_irq_restore(irq_flags);
163 static int hv_vtl_apicid_to_vp_id(u32 apic_id)
167 unsigned long irq_flags;
168 struct hv_get_vp_from_apic_id_in *input;
171 local_irq_save(irq_flags);
173 input = *this_cpu_ptr(hyperv_pcpu_input_arg);
174 memset(input, 0, sizeof(*input));
175 input->partition_id = HV_PARTITION_ID_SELF;
176 input->apic_ids[0] = apic_id;
178 output = (u32 *)input;
180 control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_ID_FROM_APIC_ID;
181 status = hv_do_hypercall(control, input, output);
184 local_irq_restore(irq_flags);
186 if (!hv_result_success(status)) {
187 pr_err("failed to get vp id from apic id %d, status %#llx\n",
195 static int hv_vtl_wakeup_secondary_cpu(int apicid, unsigned long start_eip)
199 pr_debug("Bringing up CPU with APIC ID %d in VTL2...\n", apicid);
200 vp_id = hv_vtl_apicid_to_vp_id(apicid);
203 pr_err("Couldn't find CPU with APIC ID %d\n", apicid);
206 if (vp_id > ms_hyperv.max_vp_index) {
207 pr_err("Invalid CPU id %d for APIC ID %d\n", vp_id, apicid);
211 return hv_vtl_bringup_vcpu(vp_id, start_eip);
214 static int __init hv_vtl_early_init(void)
217 * `boot_cpu_has` returns the runtime feature support,
218 * and here is the earliest it can be used.
220 if (cpu_feature_enabled(X86_FEATURE_XSAVE))
221 panic("XSAVE has to be disabled as it is not supported by this module.\n"
222 "Please add 'noxsave' to the kernel command line.\n");
224 real_mode_header = &hv_vtl_real_mode_header;
225 apic->wakeup_secondary_cpu_64 = hv_vtl_wakeup_secondary_cpu;
229 early_initcall(hv_vtl_early_init);