1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * X86 specific Hyper-V initialization code. 4 * 5 * Copyright (C) 2016, Microsoft, Inc. 6 * 7 * Author : K. Y. Srinivasan <kys@microsoft.com> 8 */ 9 10 #include <linux/efi.h> 11 #include <linux/types.h> 12 #include <asm/apic.h> 13 #include <asm/desc.h> 14 #include <asm/hypervisor.h> 15 #include <asm/hyperv-tlfs.h> 16 #include <asm/mshyperv.h> 17 #include <linux/version.h> 18 #include <linux/vmalloc.h> 19 #include <linux/mm.h> 20 #include <linux/hyperv.h> 21 #include <linux/slab.h> 22 #include <linux/cpuhotplug.h> 23 #include <clocksource/hyperv_timer.h> 24 25 void *hv_hypercall_pg; 26 EXPORT_SYMBOL_GPL(hv_hypercall_pg); 27 28 u32 *hv_vp_index; 29 EXPORT_SYMBOL_GPL(hv_vp_index); 30 31 struct hv_vp_assist_page **hv_vp_assist_page; 32 EXPORT_SYMBOL_GPL(hv_vp_assist_page); 33 34 void __percpu **hyperv_pcpu_input_arg; 35 EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg); 36 37 u32 hv_max_vp_index; 38 EXPORT_SYMBOL_GPL(hv_max_vp_index); 39 40 void *hv_alloc_hyperv_page(void) 41 { 42 BUILD_BUG_ON(PAGE_SIZE != HV_HYP_PAGE_SIZE); 43 44 return (void *)__get_free_page(GFP_KERNEL); 45 } 46 EXPORT_SYMBOL_GPL(hv_alloc_hyperv_page); 47 48 void hv_free_hyperv_page(unsigned long addr) 49 { 50 free_page(addr); 51 } 52 EXPORT_SYMBOL_GPL(hv_free_hyperv_page); 53 54 static int hv_cpu_init(unsigned int cpu) 55 { 56 u64 msr_vp_index; 57 struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()]; 58 void **input_arg; 59 struct page *pg; 60 61 input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg); 62 pg = alloc_page(GFP_KERNEL); 63 if (unlikely(!pg)) 64 return -ENOMEM; 65 *input_arg = page_address(pg); 66 67 hv_get_vp_index(msr_vp_index); 68 69 hv_vp_index[smp_processor_id()] = msr_vp_index; 70 71 if (msr_vp_index > hv_max_vp_index) 72 hv_max_vp_index = msr_vp_index; 73 74 if (!hv_vp_assist_page) 75 return 0; 76 77 /* 78 * The VP ASSIST PAGE is an "overlay" page (see Hyper-V TLFS's Section 79 * 5.2.1 "GPA Overlay Pages"). Here it must be zeroed out to make sure 80 * we always write the EOI MSR in hv_apic_eoi_write() *after* the 81 * EOI optimization is disabled in hv_cpu_die(), otherwise a CPU may 82 * not be stopped in the case of CPU offlining and the VM will hang. 83 */ 84 if (!*hvp) { 85 *hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL | __GFP_ZERO, 86 PAGE_KERNEL); 87 } 88 89 if (*hvp) { 90 u64 val; 91 92 val = vmalloc_to_pfn(*hvp); 93 val = (val << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT) | 94 HV_X64_MSR_VP_ASSIST_PAGE_ENABLE; 95 96 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, val); 97 } 98 99 return 0; 100 } 101 102 static void (*hv_reenlightenment_cb)(void); 103 104 static void hv_reenlightenment_notify(struct work_struct *dummy) 105 { 106 struct hv_tsc_emulation_status emu_status; 107 108 rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status); 109 110 /* Don't issue the callback if TSC accesses are not emulated */ 111 if (hv_reenlightenment_cb && emu_status.inprogress) 112 hv_reenlightenment_cb(); 113 } 114 static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify); 115 116 void hyperv_stop_tsc_emulation(void) 117 { 118 u64 freq; 119 struct hv_tsc_emulation_status emu_status; 120 121 rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status); 122 emu_status.inprogress = 0; 123 wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status); 124 125 rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq); 126 tsc_khz = div64_u64(freq, 1000); 127 } 128 EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation); 129 130 static inline bool hv_reenlightenment_available(void) 131 { 132 /* 133 * Check for required features and priviliges to make TSC frequency 134 * change notifications work. 135 */ 136 return ms_hyperv.features & HV_X64_ACCESS_FREQUENCY_MSRS && 137 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE && 138 ms_hyperv.features & HV_X64_ACCESS_REENLIGHTENMENT; 139 } 140 141 __visible void __irq_entry hyperv_reenlightenment_intr(struct pt_regs *regs) 142 { 143 entering_ack_irq(); 144 145 inc_irq_stat(irq_hv_reenlightenment_count); 146 147 schedule_delayed_work(&hv_reenlightenment_work, HZ/10); 148 149 exiting_irq(); 150 } 151 152 void set_hv_tscchange_cb(void (*cb)(void)) 153 { 154 struct hv_reenlightenment_control re_ctrl = { 155 .vector = HYPERV_REENLIGHTENMENT_VECTOR, 156 .enabled = 1, 157 .target_vp = hv_vp_index[smp_processor_id()] 158 }; 159 struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1}; 160 161 if (!hv_reenlightenment_available()) { 162 pr_warn("Hyper-V: reenlightenment support is unavailable\n"); 163 return; 164 } 165 166 hv_reenlightenment_cb = cb; 167 168 /* Make sure callback is registered before we write to MSRs */ 169 wmb(); 170 171 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl)); 172 wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl)); 173 } 174 EXPORT_SYMBOL_GPL(set_hv_tscchange_cb); 175 176 void clear_hv_tscchange_cb(void) 177 { 178 struct hv_reenlightenment_control re_ctrl; 179 180 if (!hv_reenlightenment_available()) 181 return; 182 183 rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl); 184 re_ctrl.enabled = 0; 185 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl); 186 187 hv_reenlightenment_cb = NULL; 188 } 189 EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb); 190 191 static int hv_cpu_die(unsigned int cpu) 192 { 193 struct hv_reenlightenment_control re_ctrl; 194 unsigned int new_cpu; 195 unsigned long flags; 196 void **input_arg; 197 void *input_pg = NULL; 198 199 local_irq_save(flags); 200 input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg); 201 input_pg = *input_arg; 202 *input_arg = NULL; 203 local_irq_restore(flags); 204 free_page((unsigned long)input_pg); 205 206 if (hv_vp_assist_page && hv_vp_assist_page[cpu]) 207 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0); 208 209 if (hv_reenlightenment_cb == NULL) 210 return 0; 211 212 rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl)); 213 if (re_ctrl.target_vp == hv_vp_index[cpu]) { 214 /* Reassign to some other online CPU */ 215 new_cpu = cpumask_any_but(cpu_online_mask, cpu); 216 217 re_ctrl.target_vp = hv_vp_index[new_cpu]; 218 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl)); 219 } 220 221 return 0; 222 } 223 224 static int __init hv_pci_init(void) 225 { 226 int gen2vm = efi_enabled(EFI_BOOT); 227 228 /* 229 * For Generation-2 VM, we exit from pci_arch_init() by returning 0. 230 * The purpose is to suppress the harmless warning: 231 * "PCI: Fatal: No config space access function found" 232 */ 233 if (gen2vm) 234 return 0; 235 236 /* For Generation-1 VM, we'll proceed in pci_arch_init(). */ 237 return 1; 238 } 239 240 /* 241 * This function is to be invoked early in the boot sequence after the 242 * hypervisor has been detected. 243 * 244 * 1. Setup the hypercall page. 245 * 2. Register Hyper-V specific clocksource. 246 * 3. Setup Hyper-V specific APIC entry points. 247 */ 248 void __init hyperv_init(void) 249 { 250 u64 guest_id, required_msrs; 251 union hv_x64_msr_hypercall_contents hypercall_msr; 252 int cpuhp, i; 253 254 if (x86_hyper_type != X86_HYPER_MS_HYPERV) 255 return; 256 257 /* Absolutely required MSRs */ 258 required_msrs = HV_X64_MSR_HYPERCALL_AVAILABLE | 259 HV_X64_MSR_VP_INDEX_AVAILABLE; 260 261 if ((ms_hyperv.features & required_msrs) != required_msrs) 262 return; 263 264 /* 265 * Allocate the per-CPU state for the hypercall input arg. 266 * If this allocation fails, we will not be able to setup 267 * (per-CPU) hypercall input page and thus this failure is 268 * fatal on Hyper-V. 269 */ 270 hyperv_pcpu_input_arg = alloc_percpu(void *); 271 272 BUG_ON(hyperv_pcpu_input_arg == NULL); 273 274 /* Allocate percpu VP index */ 275 hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index), 276 GFP_KERNEL); 277 if (!hv_vp_index) 278 return; 279 280 for (i = 0; i < num_possible_cpus(); i++) 281 hv_vp_index[i] = VP_INVAL; 282 283 hv_vp_assist_page = kcalloc(num_possible_cpus(), 284 sizeof(*hv_vp_assist_page), GFP_KERNEL); 285 if (!hv_vp_assist_page) { 286 ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED; 287 goto free_vp_index; 288 } 289 290 cpuhp = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online", 291 hv_cpu_init, hv_cpu_die); 292 if (cpuhp < 0) 293 goto free_vp_assist_page; 294 295 /* 296 * Setup the hypercall page and enable hypercalls. 297 * 1. Register the guest ID 298 * 2. Enable the hypercall and register the hypercall page 299 */ 300 guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0); 301 wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id); 302 303 hv_hypercall_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_RX); 304 if (hv_hypercall_pg == NULL) { 305 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0); 306 goto remove_cpuhp_state; 307 } 308 309 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 310 hypercall_msr.enable = 1; 311 hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg); 312 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 313 314 hv_apic_init(); 315 316 x86_init.pci.arch_init = hv_pci_init; 317 318 return; 319 320 remove_cpuhp_state: 321 cpuhp_remove_state(cpuhp); 322 free_vp_assist_page: 323 kfree(hv_vp_assist_page); 324 hv_vp_assist_page = NULL; 325 free_vp_index: 326 kfree(hv_vp_index); 327 hv_vp_index = NULL; 328 } 329 330 /* 331 * This routine is called before kexec/kdump, it does the required cleanup. 332 */ 333 void hyperv_cleanup(void) 334 { 335 union hv_x64_msr_hypercall_contents hypercall_msr; 336 337 /* Reset our OS id */ 338 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0); 339 340 /* 341 * Reset hypercall page reference before reset the page, 342 * let hypercall operations fail safely rather than 343 * panic the kernel for using invalid hypercall page 344 */ 345 hv_hypercall_pg = NULL; 346 347 /* Reset the hypercall page */ 348 hypercall_msr.as_uint64 = 0; 349 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 350 351 /* Reset the TSC page */ 352 hypercall_msr.as_uint64 = 0; 353 wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64); 354 } 355 EXPORT_SYMBOL_GPL(hyperv_cleanup); 356 357 void hyperv_report_panic(struct pt_regs *regs, long err) 358 { 359 static bool panic_reported; 360 u64 guest_id; 361 362 /* 363 * We prefer to report panic on 'die' chain as we have proper 364 * registers to report, but if we miss it (e.g. on BUG()) we need 365 * to report it on 'panic'. 366 */ 367 if (panic_reported) 368 return; 369 panic_reported = true; 370 371 rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id); 372 373 wrmsrl(HV_X64_MSR_CRASH_P0, err); 374 wrmsrl(HV_X64_MSR_CRASH_P1, guest_id); 375 wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip); 376 wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax); 377 wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp); 378 379 /* 380 * Let Hyper-V know there is crash data available 381 */ 382 wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY); 383 } 384 EXPORT_SYMBOL_GPL(hyperv_report_panic); 385 386 /** 387 * hyperv_report_panic_msg - report panic message to Hyper-V 388 * @pa: physical address of the panic page containing the message 389 * @size: size of the message in the page 390 */ 391 void hyperv_report_panic_msg(phys_addr_t pa, size_t size) 392 { 393 /* 394 * P3 to contain the physical address of the panic page & P4 to 395 * contain the size of the panic data in that page. Rest of the 396 * registers are no-op when the NOTIFY_MSG flag is set. 397 */ 398 wrmsrl(HV_X64_MSR_CRASH_P0, 0); 399 wrmsrl(HV_X64_MSR_CRASH_P1, 0); 400 wrmsrl(HV_X64_MSR_CRASH_P2, 0); 401 wrmsrl(HV_X64_MSR_CRASH_P3, pa); 402 wrmsrl(HV_X64_MSR_CRASH_P4, size); 403 404 /* 405 * Let Hyper-V know there is crash data available along with 406 * the panic message. 407 */ 408 wrmsrl(HV_X64_MSR_CRASH_CTL, 409 (HV_CRASH_CTL_CRASH_NOTIFY | HV_CRASH_CTL_CRASH_NOTIFY_MSG)); 410 } 411 EXPORT_SYMBOL_GPL(hyperv_report_panic_msg); 412 413 bool hv_is_hyperv_initialized(void) 414 { 415 union hv_x64_msr_hypercall_contents hypercall_msr; 416 417 /* 418 * Ensure that we're really on Hyper-V, and not a KVM or Xen 419 * emulation of Hyper-V 420 */ 421 if (x86_hyper_type != X86_HYPER_MS_HYPERV) 422 return false; 423 424 /* 425 * Verify that earlier initialization succeeded by checking 426 * that the hypercall page is setup 427 */ 428 hypercall_msr.as_uint64 = 0; 429 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 430 431 return hypercall_msr.enable; 432 } 433 EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized); 434