linux-kernel - [PATCH 3/7] x86/nmi: Support stop_machine

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Message-ID: <20260125014224.249901-4-chang.seok.bae@intel.com>
Date: Sun, 25 Jan 2026 01:42:18 +0000
From: "Chang S. Bae" <chang.seok.bae@...el.com>
To: linux-kernel@...r.kernel.org
Cc: x86@...nel.org,
	tglx@...utronix.de,
	mingo@...hat.com,
	bp@...en8.de,
	dave.hansen@...ux.intel.com,
	peterz@...radead.org,
	david.kaplan@....com,
	chang.seok.bae@...el.com
Subject: [PATCH 3/7] x86/nmi: Support stop_machine_nmi() handler

From: David Kaplan <david.kaplan@....com>

Call stop_machine_nmi_handler() from the NMI path when the corresponding
static key is enabled, in order to support stop_machine_nmi().

Signed-off-by: David Kaplan <david.kaplan@....com>
Signed-off-by: Chang S. Bae <chang.seok.bae@...el.com>
---
Update from the original posting:
* Massage the subject and expand changelog a little bit.
---
 arch/x86/kernel/nmi.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 3d239ed12744..4bc4b49f1ea7 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -24,6 +24,7 @@
 #include <linux/export.h>
 #include <linux/atomic.h>
 #include <linux/sched/clock.h>
+#include <linux/stop_machine.h>
 #include <linux/kvm_types.h>
 
 #include <asm/cpu_entry_area.h>
@@ -382,6 +383,9 @@ static noinstr void default_do_nmi(struct pt_regs *regs)
 
 	instrumentation_begin();
 
+	if (stop_machine_nmi_handler_enabled() && stop_machine_nmi_handler())
+		goto out;
+
 	if (microcode_nmi_handler_enabled() && microcode_nmi_handler())
 		goto out;
 
-- 
2.51.0