1 // SPDX-License-Identifier: GPL-2.0-only
3 * X86 specific Hyper-V initialization code.
5 * Copyright (C) 2016, Microsoft, Inc.
7 * Author : K. Y. Srinivasan <kys@microsoft.com>
10 #include <linux/efi.h>
11 #include <linux/types.h>
12 #include <linux/bitfield.h>
16 #include <asm/hypervisor.h>
17 #include <asm/hyperv-tlfs.h>
18 #include <asm/mshyperv.h>
19 #include <asm/idtentry.h>
20 #include <linux/kexec.h>
21 #include <linux/version.h>
22 #include <linux/vmalloc.h>
24 #include <linux/hyperv.h>
25 #include <linux/slab.h>
26 #include <linux/kernel.h>
27 #include <linux/cpuhotplug.h>
28 #include <linux/syscore_ops.h>
29 #include <clocksource/hyperv_timer.h>
30 #include <linux/highmem.h>
32 int hyperv_init_cpuhp;
33 u64 hv_current_partition_id = ~0ull;
34 EXPORT_SYMBOL_GPL(hv_current_partition_id);
36 void *hv_hypercall_pg;
37 EXPORT_SYMBOL_GPL(hv_hypercall_pg);
39 /* Storage to save the hypercall page temporarily for hibernation */
40 static void *hv_hypercall_pg_saved;
42 struct hv_vp_assist_page **hv_vp_assist_page;
43 EXPORT_SYMBOL_GPL(hv_vp_assist_page);
45 static int hv_cpu_init(unsigned int cpu)
47 union hv_vp_assist_msr_contents msr = { 0 };
48 struct hv_vp_assist_page **hvp = &hv_vp_assist_page[cpu];
51 ret = hv_common_cpu_init(cpu);
55 if (!hv_vp_assist_page)
58 if (hv_root_partition) {
60 * For root partition we get the hypervisor provided VP assist
61 * page, instead of allocating a new page.
63 rdmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
64 *hvp = memremap(msr.pfn << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT,
65 PAGE_SIZE, MEMREMAP_WB);
68 * The VP assist page is an "overlay" page (see Hyper-V TLFS's
69 * Section 5.2.1 "GPA Overlay Pages"). Here it must be zeroed
70 * out to make sure we always write the EOI MSR in
71 * hv_apic_eoi_write() *after* the EOI optimization is disabled
72 * in hv_cpu_die(), otherwise a CPU may not be stopped in the
73 * case of CPU offlining and the VM will hang.
76 *hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL | __GFP_ZERO);
78 msr.pfn = vmalloc_to_pfn(*hvp);
81 if (!WARN_ON(!(*hvp))) {
83 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
89 static void (*hv_reenlightenment_cb)(void);
91 static void hv_reenlightenment_notify(struct work_struct *dummy)
93 struct hv_tsc_emulation_status emu_status;
95 rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
97 /* Don't issue the callback if TSC accesses are not emulated */
98 if (hv_reenlightenment_cb && emu_status.inprogress)
99 hv_reenlightenment_cb();
101 static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify);
103 void hyperv_stop_tsc_emulation(void)
106 struct hv_tsc_emulation_status emu_status;
108 rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
109 emu_status.inprogress = 0;
110 wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
112 rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);
113 tsc_khz = div64_u64(freq, 1000);
115 EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation);
117 static inline bool hv_reenlightenment_available(void)
120 * Check for required features and privileges to make TSC frequency
121 * change notifications work.
123 return ms_hyperv.features & HV_ACCESS_FREQUENCY_MSRS &&
124 ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE &&
125 ms_hyperv.features & HV_ACCESS_REENLIGHTENMENT;
128 DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_reenlightenment)
131 inc_irq_stat(irq_hv_reenlightenment_count);
132 schedule_delayed_work(&hv_reenlightenment_work, HZ/10);
135 void set_hv_tscchange_cb(void (*cb)(void))
137 struct hv_reenlightenment_control re_ctrl = {
138 .vector = HYPERV_REENLIGHTENMENT_VECTOR,
141 struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1};
143 if (!hv_reenlightenment_available()) {
144 pr_warn("Hyper-V: reenlightenment support is unavailable\n");
151 hv_reenlightenment_cb = cb;
153 /* Make sure callback is registered before we write to MSRs */
156 re_ctrl.target_vp = hv_vp_index[get_cpu()];
158 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
159 wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl));
163 EXPORT_SYMBOL_GPL(set_hv_tscchange_cb);
165 void clear_hv_tscchange_cb(void)
167 struct hv_reenlightenment_control re_ctrl;
169 if (!hv_reenlightenment_available())
172 rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
174 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
176 hv_reenlightenment_cb = NULL;
178 EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb);
180 static int hv_cpu_die(unsigned int cpu)
182 struct hv_reenlightenment_control re_ctrl;
183 unsigned int new_cpu;
185 hv_common_cpu_die(cpu);
187 if (hv_vp_assist_page && hv_vp_assist_page[cpu]) {
188 union hv_vp_assist_msr_contents msr = { 0 };
189 if (hv_root_partition) {
191 * For root partition the VP assist page is mapped to
192 * hypervisor provided page, and thus we unmap the
193 * page here and nullify it, so that in future we have
194 * correct page address mapped in hv_cpu_init.
196 memunmap(hv_vp_assist_page[cpu]);
197 hv_vp_assist_page[cpu] = NULL;
198 rdmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
201 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
204 if (hv_reenlightenment_cb == NULL)
207 rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
208 if (re_ctrl.target_vp == hv_vp_index[cpu]) {
210 * Reassign reenlightenment notifications to some other online
211 * CPU or just disable the feature if there are no online CPUs
212 * left (happens on hibernation).
214 new_cpu = cpumask_any_but(cpu_online_mask, cpu);
216 if (new_cpu < nr_cpu_ids)
217 re_ctrl.target_vp = hv_vp_index[new_cpu];
221 wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
227 static int __init hv_pci_init(void)
229 int gen2vm = efi_enabled(EFI_BOOT);
232 * For Generation-2 VM, we exit from pci_arch_init() by returning 0.
233 * The purpose is to suppress the harmless warning:
234 * "PCI: Fatal: No config space access function found"
239 /* For Generation-1 VM, we'll proceed in pci_arch_init(). */
243 static int hv_suspend(void)
245 union hv_x64_msr_hypercall_contents hypercall_msr;
248 if (hv_root_partition)
252 * Reset the hypercall page as it is going to be invalidated
253 * across hibernation. Setting hv_hypercall_pg to NULL ensures
254 * that any subsequent hypercall operation fails safely instead of
255 * crashing due to an access of an invalid page. The hypercall page
256 * pointer is restored on resume.
258 hv_hypercall_pg_saved = hv_hypercall_pg;
259 hv_hypercall_pg = NULL;
261 /* Disable the hypercall page in the hypervisor */
262 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
263 hypercall_msr.enable = 0;
264 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
270 static void hv_resume(void)
272 union hv_x64_msr_hypercall_contents hypercall_msr;
275 ret = hv_cpu_init(0);
278 /* Re-enable the hypercall page */
279 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
280 hypercall_msr.enable = 1;
281 hypercall_msr.guest_physical_address =
282 vmalloc_to_pfn(hv_hypercall_pg_saved);
283 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
285 hv_hypercall_pg = hv_hypercall_pg_saved;
286 hv_hypercall_pg_saved = NULL;
289 * Reenlightenment notifications are disabled by hv_cpu_die(0),
290 * reenable them here if hv_reenlightenment_cb was previously set.
292 if (hv_reenlightenment_cb)
293 set_hv_tscchange_cb(hv_reenlightenment_cb);
296 /* Note: when the ops are called, only CPU0 is online and IRQs are disabled. */
297 static struct syscore_ops hv_syscore_ops = {
298 .suspend = hv_suspend,
302 static void (* __initdata old_setup_percpu_clockev)(void);
304 static void __init hv_stimer_setup_percpu_clockev(void)
307 * Ignore any errors in setting up stimer clockevents
308 * as we can run with the LAPIC timer as a fallback.
310 (void)hv_stimer_alloc(false);
313 * Still register the LAPIC timer, because the direct-mode STIMER is
314 * not supported by old versions of Hyper-V. This also allows users
315 * to switch to LAPIC timer via /sys, if they want to.
317 if (old_setup_percpu_clockev)
318 old_setup_percpu_clockev();
321 static void __init hv_get_partition_id(void)
323 struct hv_get_partition_id *output_page;
327 local_irq_save(flags);
328 output_page = *this_cpu_ptr(hyperv_pcpu_output_arg);
329 status = hv_do_hypercall(HVCALL_GET_PARTITION_ID, NULL, output_page);
330 if (!hv_result_success(status)) {
331 /* No point in proceeding if this failed */
332 pr_err("Failed to get partition ID: %lld\n", status);
335 hv_current_partition_id = output_page->partition_id;
336 local_irq_restore(flags);
340 * This function is to be invoked early in the boot sequence after the
341 * hypervisor has been detected.
343 * 1. Setup the hypercall page.
344 * 2. Register Hyper-V specific clocksource.
345 * 3. Setup Hyper-V specific APIC entry points.
347 void __init hyperv_init(void)
350 union hv_x64_msr_hypercall_contents hypercall_msr;
353 if (x86_hyper_type != X86_HYPER_MS_HYPERV)
356 if (hv_common_init())
359 hv_vp_assist_page = kcalloc(num_possible_cpus(),
360 sizeof(*hv_vp_assist_page), GFP_KERNEL);
361 if (!hv_vp_assist_page) {
362 ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
366 cpuhp = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online",
367 hv_cpu_init, hv_cpu_die);
369 goto free_vp_assist_page;
372 * Setup the hypercall page and enable hypercalls.
373 * 1. Register the guest ID
374 * 2. Enable the hypercall and register the hypercall page
376 guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
377 wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
379 hv_hypercall_pg = __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START,
380 VMALLOC_END, GFP_KERNEL, PAGE_KERNEL_ROX,
381 VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
382 __builtin_return_address(0));
383 if (hv_hypercall_pg == NULL) {
384 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
385 goto remove_cpuhp_state;
388 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
389 hypercall_msr.enable = 1;
391 if (hv_root_partition) {
396 * For the root partition, the hypervisor will set up its
397 * hypercall page. The hypervisor guarantees it will not show
398 * up in the root's address space. The root can't change the
399 * location of the hypercall page.
401 * Order is important here. We must enable the hypercall page
402 * so it is populated with code, then copy the code to an
405 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
407 pg = vmalloc_to_page(hv_hypercall_pg);
409 src = memremap(hypercall_msr.guest_physical_address << PAGE_SHIFT, PAGE_SIZE,
411 BUG_ON(!(src && dst));
412 memcpy(dst, src, HV_HYP_PAGE_SIZE);
416 hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
417 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
421 * hyperv_init() is called before LAPIC is initialized: see
422 * apic_intr_mode_init() -> x86_platform.apic_post_init() and
423 * apic_bsp_setup() -> setup_local_APIC(). The direct-mode STIMER
424 * depends on LAPIC, so hv_stimer_alloc() should be called from
425 * x86_init.timers.setup_percpu_clockev.
427 old_setup_percpu_clockev = x86_init.timers.setup_percpu_clockev;
428 x86_init.timers.setup_percpu_clockev = hv_stimer_setup_percpu_clockev;
432 x86_init.pci.arch_init = hv_pci_init;
434 register_syscore_ops(&hv_syscore_ops);
436 hyperv_init_cpuhp = cpuhp;
438 if (cpuid_ebx(HYPERV_CPUID_FEATURES) & HV_ACCESS_PARTITION_ID)
439 hv_get_partition_id();
441 BUG_ON(hv_root_partition && hv_current_partition_id == ~0ull);
443 #ifdef CONFIG_PCI_MSI
445 * If we're running as root, we want to create our own PCI MSI domain.
446 * We can't set this in hv_pci_init because that would be too late.
448 if (hv_root_partition)
449 x86_init.irqs.create_pci_msi_domain = hv_create_pci_msi_domain;
452 /* Query the VMs extended capability once, so that it can be cached. */
457 cpuhp_remove_state(cpuhp);
459 kfree(hv_vp_assist_page);
460 hv_vp_assist_page = NULL;
466 * This routine is called before kexec/kdump, it does the required cleanup.
468 void hyperv_cleanup(void)
470 union hv_x64_msr_hypercall_contents hypercall_msr;
472 /* Reset our OS id */
473 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
476 * Reset hypercall page reference before reset the page,
477 * let hypercall operations fail safely rather than
478 * panic the kernel for using invalid hypercall page
480 hv_hypercall_pg = NULL;
482 /* Reset the hypercall page */
483 hypercall_msr.as_uint64 = 0;
484 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
486 /* Reset the TSC page */
487 hypercall_msr.as_uint64 = 0;
488 wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
491 void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die)
493 static bool panic_reported;
496 if (in_die && !panic_on_oops)
500 * We prefer to report panic on 'die' chain as we have proper
501 * registers to report, but if we miss it (e.g. on BUG()) we need
502 * to report it on 'panic'.
506 panic_reported = true;
508 rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
510 wrmsrl(HV_X64_MSR_CRASH_P0, err);
511 wrmsrl(HV_X64_MSR_CRASH_P1, guest_id);
512 wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip);
513 wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax);
514 wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp);
517 * Let Hyper-V know there is crash data available
519 wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
521 EXPORT_SYMBOL_GPL(hyperv_report_panic);
523 bool hv_is_hyperv_initialized(void)
525 union hv_x64_msr_hypercall_contents hypercall_msr;
528 * Ensure that we're really on Hyper-V, and not a KVM or Xen
529 * emulation of Hyper-V
531 if (x86_hyper_type != X86_HYPER_MS_HYPERV)
535 * Verify that earlier initialization succeeded by checking
536 * that the hypercall page is setup
538 hypercall_msr.as_uint64 = 0;
539 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
541 return hypercall_msr.enable;
543 EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);
545 enum hv_isolation_type hv_get_isolation_type(void)
547 if (!(ms_hyperv.priv_high & HV_ISOLATION))
548 return HV_ISOLATION_TYPE_NONE;
549 return FIELD_GET(HV_ISOLATION_TYPE, ms_hyperv.isolation_config_b);
551 EXPORT_SYMBOL_GPL(hv_get_isolation_type);
553 bool hv_is_isolation_supported(void)
555 return hv_get_isolation_type() != HV_ISOLATION_TYPE_NONE;