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
hv_vtl_msi_ext_dest_id(void)20 static bool __init hv_vtl_msi_ext_dest_id(void)
21 {
22 return true;
23 }
24
hv_vtl_init_platform(void)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
hv_vtl_system_desc_base(struct ldttss_desc * desc)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
hv_vtl_system_desc_limit(struct ldttss_desc * desc)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*);
hv_vtl_ap_entry(void)63 static void hv_vtl_ap_entry(void)
64 {
65 ((secondary_startup_64_fn)secondary_startup_64)(&boot_params, &boot_params);
66 }
67
hv_vtl_bringup_vcpu(u32 target_vp_index,int cpu,u64 eip_ignored)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
hv_vtl_apicid_to_vp_id(u32 apic_id)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
hv_vtl_wakeup_secondary_cpu(u32 apicid,unsigned long start_eip)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
hv_vtl_early_init(void)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