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 static bool __init hv_vtl_msi_ext_dest_id(void)
24 void __init hv_vtl_init_platform(void)
26 pr_info("Linux runs in Hyper-V Virtual Trust Level\n");
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;
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;
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;
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;
48 x86_init.hyper.msi_ext_dest_id = hv_vtl_msi_ext_dest_id;
51 static inline u64 hv_vtl_system_desc_base(struct ldttss_desc *desc)
53 return ((u64)desc->base3 << 32) | ((u64)desc->base2 << 24) |
54 (desc->base1 << 16) | desc->base0;
57 static inline u32 hv_vtl_system_desc_limit(struct ldttss_desc *desc)
59 return ((u32)desc->limit1 << 16) | (u32)desc->limit0;
62 typedef void (*secondary_startup_64_fn)(void*, void*);
63 static void hv_vtl_ap_entry(void)
65 ((secondary_startup_64_fn)secondary_startup_64)(&boot_params, &boot_params);
68 static int hv_vtl_bringup_vcpu(u32 target_vp_index, u64 eip_ignored)
72 struct hv_enable_vp_vtl *input;
73 unsigned long irq_flags;
75 struct desc_ptr gdt_ptr;
76 struct desc_ptr idt_ptr;
78 struct ldttss_desc *tss;
79 struct ldttss_desc *ldt;
80 struct desc_struct *gdt;
82 u64 rsp = current->thread.sp;
83 u64 rip = (u64)&hv_vtl_ap_entry;
85 native_store_gdt(&gdt_ptr);
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);
92 local_irq_save(irq_flags);
94 input = *this_cpu_ptr(hyperv_pcpu_input_arg);
95 memset(input, 0, sizeof(*input));
97 input->partition_id = HV_PARTITION_ID_SELF;
98 input->vp_index = target_vp_index;
99 input->target_vtl.target_vtl = HV_VTL_MGMT;
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
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.
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;
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;
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;
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;
151 status = hv_do_hypercall(HVCALL_ENABLE_VP_VTL, input, NULL);
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);
161 status = hv_do_hypercall(HVCALL_START_VP, input, NULL);
163 if (!hv_result_success(status)) {
164 pr_err("HVCALL_START_VP failed for VP : %d ! [Err: %#llx]\n",
165 target_vp_index, status);
170 local_irq_restore(irq_flags);
175 static int hv_vtl_apicid_to_vp_id(u32 apic_id)
179 unsigned long irq_flags;
180 struct hv_get_vp_from_apic_id_in *input;
183 local_irq_save(irq_flags);
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;
190 output = (u32 *)input;
192 control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_ID_FROM_APIC_ID;
193 status = hv_do_hypercall(control, input, output);
196 local_irq_restore(irq_flags);
198 if (!hv_result_success(status)) {
199 pr_err("failed to get vp id from apic id %d, status %#llx\n",
207 static int hv_vtl_wakeup_secondary_cpu(u32 apicid, unsigned long start_eip)
211 pr_debug("Bringing up CPU with APIC ID %d in VTL2...\n", apicid);
212 vp_id = hv_vtl_apicid_to_vp_id(apicid);
215 pr_err("Couldn't find CPU with APIC ID %d\n", apicid);
218 if (vp_id > ms_hyperv.max_vp_index) {
219 pr_err("Invalid CPU id %d for APIC ID %d\n", vp_id, apicid);
223 return hv_vtl_bringup_vcpu(vp_id, start_eip);
226 int __init hv_vtl_early_init(void)
229 * `boot_cpu_has` returns the runtime feature support,
230 * and here is the earliest it can be used.
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");
236 real_mode_header = &hv_vtl_real_mode_header;
237 apic_update_callback(wakeup_secondary_cpu_64, hv_vtl_wakeup_secondary_cpu);