1 /* SPDX-License-Identifier: GPL-2.0 */
2
3 #include <linux/entry-common.h>
4 #include <linux/kvm_types.h>
5 #include <linux/hrtimer_rearm.h>
6 #include <asm/fred.h>
7 #include <asm/desc.h>
8
9 #if IS_ENABLED(CONFIG_KVM_INTEL)
10 /*
11 * On VMX, NMIs and IRQs (as configured by KVM) are acknowledged by hardware as
12 * part of the VM-Exit, i.e. the event itself is consumed as part the VM-Exit.
13 * x86_entry_from_kvm() is invoked by KVM to effectively forward NMIs and IRQs
14 * to the kernel for servicing. On SVM, a.k.a. AMD, the NMI/IRQ VM-Exit is
15 * purely a signal that an NMI/IRQ is pending, i.e. the event that triggered
16 * the VM-Exit is held pending until it's unblocked in the host.
17 */
x86_entry_from_kvm(unsigned int event_type,unsigned int vector)18 noinstr void x86_entry_from_kvm(unsigned int event_type, unsigned int vector)
19 {
20 if (event_type == EVENT_TYPE_EXTINT) {
21 #ifdef CONFIG_X86_64
22 /*
23 * Use FRED dispatch, even when running IDT. The dispatch
24 * tables are kept in sync between FRED and IDT, and the FRED
25 * dispatch works well with CFI.
26 */
27 fred_entry_from_kvm(event_type, vector);
28 #else
29 idt_entry_from_kvm(vector);
30 #endif
31 /*
32 * Strictly speaking, only the NMI path requires noinstr.
33 */
34 instrumentation_begin();
35 /*
36 * KVM/VMX will dispatch from IRQ-disabled but for a context
37 * that will have IRQs-enabled. This confuses the entry code
38 * and it will not have reprogrammed the timer. Do so now.
39 */
40 hrtimer_rearm_deferred();
41 instrumentation_end();
42
43 return;
44 }
45
46 WARN_ON_ONCE(event_type != EVENT_TYPE_NMI);
47
48 #ifdef CONFIG_X86_64
49 if (cpu_feature_enabled(X86_FEATURE_FRED))
50 return fred_entry_from_kvm(event_type, vector);
51 #endif
52
53 /*
54 * Notably, we must use IDT dispatch for NMI when running in IDT mode.
55 * The FRED NMI context is significantly different and will not work
56 * right (specifically FRED fixed the NMI recursion issue).
57 */
58 idt_entry_from_kvm(vector);
59 }
60 EXPORT_SYMBOL_FOR_KVM(x86_entry_from_kvm);
61 #endif
62