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From:   "Jason A. Donenfeld" <Jason@zx2c4.com>
To:     linux-kernel@vger.kernel.org, linux-edac@vger.kernel.org,
        x86@kernel.org, arnd@arndb.de, srinivas.pandruvada@linux.intel.com,
        bberg@redhat.com, bp@suse.de
Cc:     "Jason A. Donenfeld" <Jason@zx2c4.com>
Subject: [PATCH 3/3] x86/mce/therm_throt: allow disabling the thermal vector altogether
Date:   Tue,  7 Apr 2020 00:33:45 -0600
Message-Id: <20200407063345.4484-3-Jason@zx2c4.com>
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The thermal IRQ handler uses 1.21% CPU on my system when it's hot from
compiling things. Indeed looking at /proc/interrupts reveals quite a lot
of events coming in. Beyond logging them, the existing drivers on the
system don't appear to do very much that I'm interested in. So, add a
way to disable this entirely so that I can regain precious CPU cycles.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/x86/Kconfig                | 4 ++++
 arch/x86/kernel/cpu/mce/intel.c | 3 ++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 39e7444353af..3125a11932f2 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1157,7 +1157,11 @@ config X86_MCE_INJECT
 
 config X86_THERMAL_VECTOR
 	def_bool y
+	prompt "Machine check thermal vector"
 	depends on X86_MCE_INTEL
+	---help---
+	  Provide support for capturing thermal events, logging them, and
+	  passing them off to other drivers.
 
 config X86_MCE_THERMAL_VERBOSE
 	bool "Verbose logging for thermal events"
diff --git a/arch/x86/kernel/cpu/mce/intel.c b/arch/x86/kernel/cpu/mce/intel.c
index f996ffb887bc..d14f1922fb49 100644
--- a/arch/x86/kernel/cpu/mce/intel.c
+++ b/arch/x86/kernel/cpu/mce/intel.c
@@ -511,7 +511,8 @@ static void intel_ppin_init(struct cpuinfo_x86 *c)
 
 void mce_intel_feature_init(struct cpuinfo_x86 *c)
 {
-	intel_init_thermal(c);
+	if (IS_ENABLED(CONFIG_X86_THERMAL_VECTOR))
+		intel_init_thermal(c);
 	intel_init_cmci();
 	intel_init_lmce();
 	intel_ppin_init(c);
-- 
2.26.0