[PATCH v7 04/10] x86/nmi: Extend the registration interface to include the... | linux-trace-kernel

[PATCH v7 04/10] x86/nmi: Extend the registration interface to include the NMI-source vector

From: Sohil Mehta <hidden>
Date: 2025-06-12 21:50:30
Also in: kvm, linux-edac, linux-perf-users, linux-pm, lkml
Subsystem: acpi, acpi apei, edac-core, edac-igen6, hewlett packard enterprise ilo nmi watchdog driver, hyper-v/azure core and drivers, ipmi subsystem, performance events subsystem, the rest, watchdog device drivers, x86 architecture (32-bit and 64-bit), x86 mce infrastructure, x86 platform uv hpe superdome flex · Maintainers: "Rafael J. Wysocki", Borislav Petkov, Tony Luck, Craig Lamparter, "K. Y. Srinivasan", Haiyang Zhang, Wei Liu, Dexuan Cui, Long Li, Corey Minyard, Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo, Namhyung Kim, Linus Torvalds, Wim Van Sebroeck, Guenter Roeck, Thomas Gleixner, Dave Hansen, Steve Wahl

To prepare for NMI-source reporting, add a source vector argument to the
NMI handler registration interface. Later, this will be used to
register NMI handlers with a unique source vector that can be used to
identify the originator of the NMI.

Vector 0 is reserved by the hardware for situations when a source vector
is not used while generating an NMI or the originator could not be
reliably identified. Registering an NMI handler with vector 0 is
equivalent to not using NMI-source reporting.

For now, just extend the interface with no source information (vector 0)
for all the handlers. No functional change intended.

Originally-by: Jacob Pan [off-list ref]
Signed-off-by: Sohil Mehta <redacted>
Reviewed-by: Xin Li (Intel) <xin@zytor.com>
---
v7: Use an enum for defining source vectors (DaveH).
    Use NMIS_NO_SOURCE instead of zero (DaveH).
    Add review tag (Xin).

v6: No change.

v5: Split the patch into two parts. This one only extends the interface.
---
 arch/x86/events/amd/ibs.c         |  2 +-
 arch/x86/events/core.c            |  2 +-
 arch/x86/include/asm/nmi.h        | 16 +++++++++++++++-
 arch/x86/kernel/apic/hw_nmi.c     |  3 +--
 arch/x86/kernel/cpu/mce/inject.c  |  2 +-
 arch/x86/kernel/cpu/mshyperv.c    |  2 +-
 arch/x86/kernel/kgdb.c            |  6 ++----
 arch/x86/kernel/nmi_selftest.c    |  6 +++---
 arch/x86/kernel/smp.c             |  4 ++--
 arch/x86/platform/uv/uv_nmi.c     |  4 ++--
 drivers/acpi/apei/ghes.c          |  2 +-
 drivers/char/ipmi/ipmi_watchdog.c |  3 +--
 drivers/edac/igen6_edac.c         |  3 +--
 drivers/watchdog/hpwdt.c          |  6 +++---
 14 files changed, 35 insertions(+), 26 deletions(-)

diff --git a/arch/x86/events/amd/ibs.c b/arch/x86/events/amd/ibs.c
index 112f43b23ebf..6f8f0d663f2f 100644
--- a/arch/x86/events/amd/ibs.c
+++ b/arch/x86/events/amd/ibs.c

@@ -1485,7 +1485,7 @@ static __init int perf_event_ibs_init(void)
 	if (ret)
 		goto err_op;
 
-	ret = register_nmi_handler(NMI_LOCAL, perf_ibs_nmi_handler, 0, "perf_ibs");
+	ret = register_nmi_handler(NMI_LOCAL, perf_ibs_nmi_handler, 0, "perf_ibs", NMIS_NO_SOURCE);
 	if (ret)
 		goto err_nmi;

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 7610f26dfbd9..ec59837d10d1 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c

@@ -2129,7 +2129,7 @@ static int __init init_hw_perf_events(void)
 		x86_pmu.config_mask = X86_RAW_EVENT_MASK;
 
 	perf_events_lapic_init();
-	register_nmi_handler(NMI_LOCAL, perf_event_nmi_handler, 0, "PMI");
+	register_nmi_handler(NMI_LOCAL, perf_event_nmi_handler, 0, "PMI", NMIS_NO_SOURCE);
 
 	unconstrained = (struct event_constraint)
 		__EVENT_CONSTRAINT(0, x86_pmu.cntr_mask64,

diff --git a/arch/x86/include/asm/nmi.h b/arch/x86/include/asm/nmi.h
index 79d88d12c8fb..42820c4f59b9 100644
--- a/arch/x86/include/asm/nmi.h
+++ b/arch/x86/include/asm/nmi.h

@@ -48,12 +48,24 @@ enum {
 
 typedef int (*nmi_handler_t)(unsigned int, struct pt_regs *);
 
+/**
+ * enum nmi_source_vectors - NMI-source vectors are used to identify the
+ * origin of an NMI and to route the NMI directly to the appropriate
+ * handler.
+ *
+ * @NMIS_NO_SOURCE:        Reserved for undefined or unidentified sources.
+ */
+enum nmi_source_vectors {
+	NMIS_NO_SOURCE		= 0,
+};
+
 struct nmiaction {
 	struct list_head	list;
 	nmi_handler_t		handler;
 	u64			max_duration;
 	unsigned long		flags;
 	const char		*name;
+	enum nmi_source_vectors	source_vector;
 };
 
 /**

@@ -62,6 +74,7 @@ struct nmiaction {
  * @fn:   The NMI handler
  * @fg:   Flags associated with the NMI handler
  * @n:    Name of the NMI handler
+ * @src:  NMI-source vector for the NMI handler
  * @init: Optional __init* attributes for struct nmiaction
  *
  * Adds the provided handler to the list of handlers for the specified

@@ -75,13 +88,14 @@ struct nmiaction {
  *
  * Return: 0 on success, or an error code on failure.
  */
-#define register_nmi_handler(t, fn, fg, n, init...)	\
+#define register_nmi_handler(t, fn, fg, n, src, init...)\
 ({							\
 	static struct nmiaction init fn##_na = {	\
 		.list = LIST_HEAD_INIT(fn##_na.list),	\
 		.handler = (fn),			\
 		.name = (n),				\
 		.flags = (fg),				\
+		.source_vector = (src),			\
 	};						\
 	__register_nmi_handler((t), &fn##_na);		\
 })

diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c
index 45af535c44a0..d09e771723ed 100644
--- a/arch/x86/kernel/apic/hw_nmi.c
+++ b/arch/x86/kernel/apic/hw_nmi.c

@@ -53,8 +53,7 @@ NOKPROBE_SYMBOL(nmi_cpu_backtrace_handler);
 
 static int __init register_nmi_cpu_backtrace_handler(void)
 {
-	register_nmi_handler(NMI_LOCAL, nmi_cpu_backtrace_handler,
-				0, "arch_bt");
+	register_nmi_handler(NMI_LOCAL, nmi_cpu_backtrace_handler, 0, "arch_bt", NMIS_NO_SOURCE);
 	return 0;
 }
 early_initcall(register_nmi_cpu_backtrace_handler);

diff --git a/arch/x86/kernel/cpu/mce/inject.c b/arch/x86/kernel/cpu/mce/inject.c
index d02c4f556cd0..ba70ef8a1964 100644
--- a/arch/x86/kernel/cpu/mce/inject.c
+++ b/arch/x86/kernel/cpu/mce/inject.c

@@ -775,7 +775,7 @@ static int __init inject_init(void)
 
 	debugfs_init();
 
-	register_nmi_handler(NMI_LOCAL, mce_raise_notify, 0, "mce_notify");
+	register_nmi_handler(NMI_LOCAL, mce_raise_notify, 0, "mce_notify", NMIS_NO_SOURCE);
 	mce_register_injector_chain(&inject_nb);
 
 	setup_inj_struct(&i_mce);

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index c78f860419d6..c093f7baab6a 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c

@@ -550,7 +550,7 @@ static void __init ms_hyperv_init_platform(void)
 	}
 
 	register_nmi_handler(NMI_UNKNOWN, hv_nmi_unknown, NMI_FLAG_FIRST,
-			     "hv_nmi_unknown");
+			     "hv_nmi_unknown", NMIS_NO_SOURCE);
 #endif
 
 #ifdef CONFIG_X86_IO_APIC

diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 102641fd2172..ae28fdeefc7f 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c

@@ -602,13 +602,11 @@ int kgdb_arch_init(void)
 	if (retval)
 		goto out;
 
-	retval = register_nmi_handler(NMI_LOCAL, kgdb_nmi_handler,
-					0, "kgdb");
+	retval = register_nmi_handler(NMI_LOCAL, kgdb_nmi_handler, 0, "kgdb", NMIS_NO_SOURCE);
 	if (retval)
 		goto out1;
 
-	retval = register_nmi_handler(NMI_UNKNOWN, kgdb_nmi_handler,
-					0, "kgdb");
+	retval = register_nmi_handler(NMI_UNKNOWN, kgdb_nmi_handler, 0, "kgdb", NMIS_NO_SOURCE);
 
 	if (retval)
 		goto out2;

diff --git a/arch/x86/kernel/nmi_selftest.c b/arch/x86/kernel/nmi_selftest.c
index a010e9d062bf..c4fffa868160 100644
--- a/arch/x86/kernel/nmi_selftest.c
+++ b/arch/x86/kernel/nmi_selftest.c

@@ -41,7 +41,7 @@ static void __init init_nmi_testsuite(void)
 {
 	/* trap all the unknown NMIs we may generate */
 	register_nmi_handler(NMI_UNKNOWN, nmi_unk_cb, 0, "nmi_selftest_unk",
-			__initdata);
+			     NMIS_NO_SOURCE, __initdata);
 }
 
 static void __init cleanup_nmi_testsuite(void)

@@ -63,8 +63,8 @@ static void __init test_nmi_ipi(struct cpumask *mask)
 {
 	unsigned long timeout;
 
-	if (register_nmi_handler(NMI_LOCAL, test_nmi_ipi_callback,
-				 NMI_FLAG_FIRST, "nmi_selftest", __initdata)) {
+	if (register_nmi_handler(NMI_LOCAL, test_nmi_ipi_callback, NMI_FLAG_FIRST,
+				 "nmi_selftest", NMIS_NO_SOURCE, __initdata)) {
 		nmi_fail = FAILURE;
 		return;
 	}

diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c
index 18266cc3d98c..c9435730dfb0 100644
--- a/arch/x86/kernel/smp.c
+++ b/arch/x86/kernel/smp.c

@@ -142,8 +142,8 @@ DEFINE_IDTENTRY_SYSVEC(sysvec_reboot)
 
 static int register_stop_handler(void)
 {
-	return register_nmi_handler(NMI_LOCAL, smp_stop_nmi_callback,
-				    NMI_FLAG_FIRST, "smp_stop");
+	return register_nmi_handler(NMI_LOCAL, smp_stop_nmi_callback, NMI_FLAG_FIRST,
+				    "smp_stop", NMIS_NO_SOURCE);
 }
 
 static void native_stop_other_cpus(int wait)

diff --git a/arch/x86/platform/uv/uv_nmi.c b/arch/x86/platform/uv/uv_nmi.c
index 5c50e550ab63..5af368710f69 100644
--- a/arch/x86/platform/uv/uv_nmi.c
+++ b/arch/x86/platform/uv/uv_nmi.c

@@ -1029,10 +1029,10 @@ static int uv_handle_nmi_ping(unsigned int reason, struct pt_regs *regs)
 
 static void uv_register_nmi_notifier(void)
 {
-	if (register_nmi_handler(NMI_UNKNOWN, uv_handle_nmi, 0, "uv"))
+	if (register_nmi_handler(NMI_UNKNOWN, uv_handle_nmi, 0, "uv", NMIS_NO_SOURCE))
 		pr_warn("UV: NMI handler failed to register\n");
 
-	if (register_nmi_handler(NMI_LOCAL, uv_handle_nmi_ping, 0, "uvping"))
+	if (register_nmi_handler(NMI_LOCAL, uv_handle_nmi_ping, 0, "uvping", NMIS_NO_SOURCE))
 		pr_warn("UV: PING NMI handler failed to register\n");
 }

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index f0584ccad451..5e8632f34769 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c

@@ -1421,7 +1421,7 @@ static void ghes_nmi_add(struct ghes *ghes)
 {
 	mutex_lock(&ghes_list_mutex);
 	if (list_empty(&ghes_nmi))
-		register_nmi_handler(NMI_LOCAL, ghes_notify_nmi, 0, "ghes");
+		register_nmi_handler(NMI_LOCAL, ghes_notify_nmi, 0, "ghes", NMIS_NO_SOURCE);
 	list_add_rcu(&ghes->list, &ghes_nmi);
 	mutex_unlock(&ghes_list_mutex);
 }

diff --git a/drivers/char/ipmi/ipmi_watchdog.c b/drivers/char/ipmi/ipmi_watchdog.c
index ab759b492fdd..944caef3dd31 100644
--- a/drivers/char/ipmi/ipmi_watchdog.c
+++ b/drivers/char/ipmi/ipmi_watchdog.c

@@ -1227,8 +1227,7 @@ static void check_parms(void)
 		}
 	}
 	if (do_nmi && !nmi_handler_registered) {
-		rv = register_nmi_handler(NMI_UNKNOWN, ipmi_nmi, 0,
-						"ipmi");
+		rv = register_nmi_handler(NMI_UNKNOWN, ipmi_nmi, 0, "ipmi", NMIS_NO_SOURCE);
 		if (rv) {
 			pr_warn("Can't register nmi handler\n");
 			return;

diff --git a/drivers/edac/igen6_edac.c b/drivers/edac/igen6_edac.c
index 1930dc00c791..9c7913e5bd3e 100644
--- a/drivers/edac/igen6_edac.c
+++ b/drivers/edac/igen6_edac.c

@@ -1419,8 +1419,7 @@ static int register_err_handler(void)
 		return 0;
 	}
 
-	rc = register_nmi_handler(NMI_SERR, ecclog_nmi_handler,
-				  0, IGEN6_NMI_NAME);
+	rc = register_nmi_handler(NMI_SERR, ecclog_nmi_handler, 0, IGEN6_NMI_NAME, NMIS_NO_SOURCE);
 	if (rc) {
 		igen6_printk(KERN_ERR, "Failed to register NMI handler\n");
 		return rc;

diff --git a/drivers/watchdog/hpwdt.c b/drivers/watchdog/hpwdt.c
index ae30e394d176..90ae59a09270 100644
--- a/drivers/watchdog/hpwdt.c
+++ b/drivers/watchdog/hpwdt.c

@@ -242,13 +242,13 @@ static int hpwdt_init_nmi_decoding(struct pci_dev *dev)
 	/*
 	 * Only one function can register for NMI_UNKNOWN
 	 */
-	retval = register_nmi_handler(NMI_UNKNOWN, hpwdt_pretimeout, 0, "hpwdt");
+	retval = register_nmi_handler(NMI_UNKNOWN, hpwdt_pretimeout, 0, "hpwdt", NMIS_NO_SOURCE);
 	if (retval)
 		goto error;
-	retval = register_nmi_handler(NMI_SERR, hpwdt_pretimeout, 0, "hpwdt");
+	retval = register_nmi_handler(NMI_SERR, hpwdt_pretimeout, 0, "hpwdt", NMIS_NO_SOURCE);
 	if (retval)
 		goto error1;
-	retval = register_nmi_handler(NMI_IO_CHECK, hpwdt_pretimeout, 0, "hpwdt");
+	retval = register_nmi_handler(NMI_IO_CHECK, hpwdt_pretimeout, 0, "hpwdt", NMIS_NO_SOURCE);
 	if (retval)
 		goto error2;

-- 
2.43.0

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