1 files changed, 19 insertions, 6 deletions

diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index bf250a339655..cec0bfa3bc04 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -33,7 +33,7 @@
 #include <asm/reboot.h>
 #include <asm/cache.h>
 #include <asm/nospec-branch.h>
-#include <asm/sev-es.h>
+#include <asm/sev.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/nmi.h>
@@ -157,7 +157,7 @@ int __register_nmi_handler(unsigned int type, struct nmiaction *action)
 	struct nmi_desc *desc = nmi_to_desc(type);
 	unsigned long flags;
 
-	if (!action->handler)
+	if (WARN_ON_ONCE(!action->handler || !list_empty(&action->list)))
 		return -EINVAL;
 
 	raw_spin_lock_irqsave(&desc->lock, flags);
@@ -177,7 +177,7 @@ int __register_nmi_handler(unsigned int type, struct nmiaction *action)
 		list_add_rcu(&action->list, &desc->head);
 	else
 		list_add_tail_rcu(&action->list, &desc->head);
-	
+
 	raw_spin_unlock_irqrestore(&desc->lock, flags);
 	return 0;
 }
@@ -186,7 +186,7 @@ EXPORT_SYMBOL(__register_nmi_handler);
 void unregister_nmi_handler(unsigned int type, const char *name)
 {
 	struct nmi_desc *desc = nmi_to_desc(type);
-	struct nmiaction *n;
+	struct nmiaction *n, *found = NULL;
 	unsigned long flags;
 
 	raw_spin_lock_irqsave(&desc->lock, flags);
@@ -200,12 +200,16 @@ void unregister_nmi_handler(unsigned int type, const char *name)
 			WARN(in_nmi(),
 				"Trying to free NMI (%s) from NMI context!\n", n->name);
 			list_del_rcu(&n->list);
+			found = n;
 			break;
 		}
 	}
 
 	raw_spin_unlock_irqrestore(&desc->lock, flags);
-	synchronize_rcu();
+	if (found) {
+		synchronize_rcu();
+		INIT_LIST_HEAD(&found->list);
+	}
 }
 EXPORT_SYMBOL_GPL(unregister_nmi_handler);
 
@@ -292,7 +296,6 @@ unknown_nmi_error(unsigned char reason, struct pt_regs *regs)
 	pr_emerg("Uhhuh. NMI received for unknown reason %02x on CPU %d.\n",
 		 reason, smp_processor_id());
 
-	pr_emerg("Do you have a strange power saving mode enabled?\n");
 	if (unknown_nmi_panic || panic_on_unrecovered_nmi)
 		nmi_panic(regs, "NMI: Not continuing");
 
@@ -524,6 +527,16 @@ nmi_restart:
 		mds_user_clear_cpu_buffers();
 }
 
+#if defined(CONFIG_X86_64) && IS_ENABLED(CONFIG_KVM_INTEL)
+DEFINE_IDTENTRY_RAW(exc_nmi_noist)
+{
+	exc_nmi(regs);
+}
+#endif
+#if IS_MODULE(CONFIG_KVM_INTEL)
+EXPORT_SYMBOL_GPL(asm_exc_nmi_noist);
+#endif
+
 void stop_nmi(void)
 {
 	ignore_nmis++;