linux-kernel - [PATCH v5 9/9] x86/nmi: Include NMI-source information in tracepoint and debug prints

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250507012145.2998143-10-sohil.mehta@intel.com>
Date: Tue,  6 May 2025 18:21:45 -0700
From: Sohil Mehta <sohil.mehta@...el.com>
To: x86@...nel.org,
	linux-kernel@...r.kernel.org
Cc: Xin Li <xin@...or.com>,
	"H . Peter Anvin" <hpa@...or.com>,
	Andy Lutomirski <luto@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Sean Christopherson <seanjc@...gle.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Kan Liang <kan.liang@...ux.intel.com>,
	Tony Luck <tony.luck@...el.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Vitaly Kuznetsov <vkuznets@...hat.com>,
	"Rafael J . Wysocki" <rafael@...nel.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Zhang Rui <rui.zhang@...el.com>,
	Lukasz Luba <lukasz.luba@....com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Sohil Mehta <sohil.mehta@...el.com>,
	Brian Gerst <brgerst@...il.com>,
	Andrew Cooper <andrew.cooper3@...rix.com>,
	"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
	Jacob Pan <jacob.pan@...ux.microsoft.com>,
	Andi Kleen <ak@...ux.intel.com>,
	Kai Huang <kai.huang@...el.com>,
	Nikolay Borisov <nik.borisov@...e.com>,
	linux-perf-users@...r.kernel.org,
	linux-edac@...r.kernel.org,
	kvm@...r.kernel.org,
	linux-pm@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org
Subject: [PATCH v5 9/9] x86/nmi: Include NMI-source information in tracepoint and debug prints

The NMI-source bitmap is the most critical information provided by the
NMI-source reporting feature. It can help identify issues when multiple
NMIs occur simultaneously or if certain NMI handlers consistently
misbehave. It is also very useful in debugging unknown NMIs since it can
pinpoint the exact source that caused the NMI.

Add the source bitmap to the nmi_handler() tracepoint. Also, print the
bitmap along with the "Unknown NMI" kernel log message.

Signed-off-by: Sohil Mehta <sohil.mehta@...el.com>
---
v5: New patch
---
 arch/x86/kernel/nmi.c      |  5 ++++-
 include/trace/events/nmi.h | 13 ++++++++-----
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 183e3e717326..b9ece0b63ca7 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -202,7 +202,7 @@ static int nmi_handle(unsigned int type, struct pt_regs *regs)
 		thishandled = a->handler(type, regs);
 		handled += thishandled;
 		delta = sched_clock() - delta;
-		trace_nmi_handler(a->handler, (int)delta, thishandled);
+		trace_nmi_handler(a->handler, (int)delta, thishandled, source_bitmap);
 
 		nmi_check_duration(a, delta);
 	}
@@ -387,6 +387,9 @@ unknown_nmi_error(unsigned char reason, struct pt_regs *regs)
 	pr_emerg_ratelimited("Uhhuh. NMI received for unknown reason %02x on CPU %d.\n",
 			     reason, smp_processor_id());
 
+	if (cpu_feature_enabled(X86_FEATURE_NMI_SOURCE))
+		pr_emerg_ratelimited("NMI-source bitmap is 0x%lx\n", fred_event_data(regs));
+
 	if (unknown_nmi_panic || panic_on_unrecovered_nmi)
 		nmi_panic(regs, "NMI: Not continuing");
 
diff --git a/include/trace/events/nmi.h b/include/trace/events/nmi.h
index 18e0411398ba..6e4a1ff70a44 100644
--- a/include/trace/events/nmi.h
+++ b/include/trace/events/nmi.h
@@ -10,29 +10,32 @@
 
 TRACE_EVENT(nmi_handler,
 
-	TP_PROTO(void *handler, s64 delta_ns, int handled),
+	TP_PROTO(void *handler, s64 delta_ns, int handled, unsigned long source_bitmap),
 
-	TP_ARGS(handler, delta_ns, handled),
+	TP_ARGS(handler, delta_ns, handled, source_bitmap),
 
 	TP_STRUCT__entry(
 		__field(	void *,		handler	)
 		__field(	s64,		delta_ns)
 		__field(	int,		handled	)
+		__field(	unsigned long,	source_bitmap)
 	),
 
 	TP_fast_assign(
 		__entry->handler = handler;
 		__entry->delta_ns = delta_ns;
 		__entry->handled = handled;
+		__entry->source_bitmap = source_bitmap;
 	),
 
-	TP_printk("%ps() delta_ns: %lld handled: %d",
+	TP_printk("%ps() delta_ns: %lld handled: %d source_bitmap: 0x%lx",
 		__entry->handler,
 		__entry->delta_ns,
-		__entry->handled)
+		__entry->handled,
+		__entry->source_bitmap)
 );
 
 #endif /* _TRACE_NMI_H */
 
-/* This part ust be outside protection */
+/* This part must be outside protection */
 #include <trace/define_trace.h>
-- 
2.43.0