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Bae" To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, tglx@kernel.org, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, peterz@infradead.org, david.kaplan@amd.com, chang.seok.bae@intel.com Subject: [PATCH v4 5/9] x86/nmi: Support NMI stop-machine handler Date: Wed, 4 Nov 2026 18:23:18 +0000 Message-ID: <20261104182322.578066-6-chang.seok.bae@intel.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261104182322.578066-1-chang.seok.bae@intel.com> References: <20261104182322.578066-1-chang.seok.bae@intel.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: David Kaplan Call the stop-machine handler from the NMI path in order to support the NMI stop-machine. Signed-off-by: David Kaplan Signed-off-by: Chang S. Bae --- V3 -> V4: Leave a note against coalesced NMI events in theory (Sashiko). --- arch/x86/kernel/nmi.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c index 3c9f60d6ca5a..0d426e5e74ee 100644 --- a/arch/x86/kernel/nmi.c +++ b/arch/x86/kernel/nmi.c @@ -24,6 +24,7 @@ #include #include #include +#include #include #include @@ -382,6 +383,14 @@ static noinstr void default_do_nmi(struct pt_regs *regs) instrumentation_begin(); + /* + * When an NMI stop-machine runs, the rest of the system should be idle, + * so handle the stop-machine NMI first even if other NMIs might get + * coalesced with it. + */ + if (stop_machine_nmi_handler()) + goto out; + if (microcode_nmi_handler_enabled() && microcode_nmi_handler()) goto out; -- 2.53.0