From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794421403; b=M/ZMdck0jRK06p3wo64QLNgItJdUQb51X79ZKdusd7fD31cLieobWD8KOeEsl4Qqy1I/ 4TflcHvAWGDgRVUqUQobCbY57WwosN2Z4vGWvYxY87A+BMQblNzA8TTAPMJuAv/nByBbL zDf0LEYn35EhN/pLa5IAlMWz1sNFihZZbP7xs3lWhwROB1QbLNv3KXA7hbNVC/fRlVzkb pkv8E4QPJFSp3WxI7kko7hhp1/WCVRgUCyHGXUFkWVJ7Czecca6h2WHq2n0HrPYRhwYHl +E5y6sBrvKnaa04Xf2DawTSL8cf62TvxjY7vS5eAOFOMD1iFMSeuI4Y15WHQPsQAh2w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794421403; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=UwJB1YWyj9pDO/W8xyKSxCNsv5DxN1vL9s38Rnbi8Ww=; b=vCNFfvfyQ0zRgl6Ats6CQUONrEIoeqbFAFJZOtLHh1zWIERJwh9MHSUhYWGw29ncwb3x tbIl41eekkzwfZOpU9XAua2bzVBdmG3/HVJDvIoRTqBfyZsN9zRLpCpPgSYk9lSssQfHg wIHaJGaDOYtPUBBHugc2dik87KShYrjbB6Hopvu80i0PCuprHEsi3f7dPM5iyg1c719yi J/ifQ8/tAKY7GSmVWIONJ/OZYIb8vSbu1ZqGNPbS/aGniFU/VmH5YW0Z/atGStUzA1Haf 7eEeu3WaLsKLd5MaJTbL/RH7ImfyxUdYO4nQSWNxwXphcyybnG21Ipy0vhw2fG2aKWQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=ObfD8RnZ; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 22A5C606A336 for ; Wed, 11 Nov 2026 18:23:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=ObfD8RnZ Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3704D1F00A05; Wed, 11 Nov 2026 18:23:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794421402; bh=UwJB1YWyj9pDO/W8xyKSxCNsv5DxN1vL9s38Rnbi8Ww=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ObfD8RnZckfiCoRcIm/0jQlFRRW9YePJJ42uOLLo2xxfHj/b8YGDlPYTCYTZNGQbA 9HnqRzL/dxDy+bbOm2LsVlChNDGrRVWwtUuKw7xqapAfiNBAsG0w+6ymoqleJ/+iJ5 H/qcOcmS9/0+RdAcV+EA/sVB8e5lt6cSrN0Nz3UsI1MiaDB1fvke889MbrImAt9Tyh Eeolj447U0sTiQOx6UjDisgN3rP+jGu6EPEZjg6yA2uCb3Yy0uJbgfyJNY5FgugnKV rbQK4nXKJuOma4vGFVAF6jIKxTYpVOmv4zDDA7ZRVUdbncl8UcAOKv9wiGhGMO210j 49B/HWZNU73xw== From: Sasha Levin To: stable@vger.kernel.org Cc: Ricardo Neri , Guenter Roeck , Sasha Levin Subject: [PATCH 6.12.y] hwmon: (coretemp) Return -ENODATA for invalid temperature readings Date: Wed, 11 Nov 2026 13:23:21 -0500 Message-ID: <20261111182303.3834607-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107052352-failed-6.12-f63aaa529cbc@kernel.org> References: <20261107052352-failed-6.12-f63aaa529cbc@kernel.org> X-Mailing-List: stable@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: Ricardo Neri [ Upstream commit f63aaa529cbc73146ff0d52235e5479042285cae ] IA32_THERM_STATUS and IA32_PACKAGE_THERM_STATUS have a valid bit, bit 31. The Intel SDM documents it only for the former, but the package register implements it too: x86_pkg_temp_thermal has required it since commit f1a18a105660 ("Thermal: CPU Package temperature thermal"). This driver checked the bit for both registers as well, until commit bf6ea084ebb5 ("hwmon: (coretemp) Do not return -EAGAIN for low temperatures") made it ignore the bit because some CPUs clear it while the temperature is too low to be measured. Since then, temp%d_input reports such a reading as a real temperature. Userspace cannot tell it apart from a genuinely low one. Fail the read with -ENODATA while the CPU reports the reading as invalid. On a CPU that clears the bit, reading temp%d_input now fails where it used to return a low value. sensors(1) shows N/A in its place. Cc: stable@vger.kernel.org Suggested-by: Guenter Roeck Link: https://lore.kernel.org/all/46f9f319-de71-412f-a424-6cb801478456@roeck-us.net/ Signed-off-by: Ricardo Neri Link: https://patch.msgid.link/20261006-coretemp-enodata-v2-1-64e788acc7dc@linux.intel.com Signed-off-by: Guenter Roeck [ sashal: adapted the validity check to use eax from rdmsr_on_cpu() instead of val.l from rdmsrq_on_cpu() ] Signed-off-by: Sasha Levin --- Documentation/hwmon/coretemp.rst | 3 +++ drivers/hwmon/coretemp.c | 21 +++++++++++++++------ 2 files changed, 18 insertions(+), 6 deletions(-) diff --git a/Documentation/hwmon/coretemp.rst b/Documentation/hwmon/coretemp.rst index c609329e3bc45..6089bee1159f1 100644 --- a/Documentation/hwmon/coretemp.rst +++ b/Documentation/hwmon/coretemp.rst @@ -47,6 +47,9 @@ All Sysfs entries are named with their core_id (represented here by 'X'). ================= ======================================================== tempX_input Core temperature (in millidegrees Celsius). + Reading fails with -ENODATA while the CPU reports the + temperature as invalid. Some CPUs do this when the + temperature is too low to be measured. tempX_max All cooling devices should be turned on (on Core2). tempX_crit Maximum junction temperature (in millidegrees Celsius). tempX_crit_alarm Set when Out-of-spec bit is set, never clears. diff --git a/drivers/hwmon/coretemp.c b/drivers/hwmon/coretemp.c index 8de1c781ac7a8..cc81b849c09ef 100644 --- a/drivers/hwmon/coretemp.c +++ b/drivers/hwmon/coretemp.c @@ -61,6 +61,8 @@ enum coretemp_attr_index { /* * Per-Core Temperature Data + * @temp_valid: Whether the CPU reported @temp as valid. @temp is not + * reported when this is false. * @tjmax: The static tjmax value when tjmax cannot be retrieved from * IA32_TEMPERATURE_TARGET MSR. * @last_updated: The time when the current temperature value was updated @@ -73,6 +75,7 @@ enum coretemp_attr_index { */ struct temp_data { int temp; + bool temp_valid; int tjmax; unsigned long last_updated; unsigned int cpu; @@ -397,7 +400,8 @@ static ssize_t show_temp(struct device *dev, { u32 eax, edx; struct temp_data *tdata = container_of(devattr, struct temp_data, sd_attrs[ATTR_TEMP]); - int tjmax; + int tjmax, temp; + bool valid; mutex_lock(&tdata->update_lock); @@ -406,17 +410,22 @@ static ssize_t show_temp(struct device *dev, if (time_after(jiffies, tdata->last_updated + HZ)) { rdmsr_on_cpu(tdata->cpu, tdata->status_reg, &eax, &edx); /* - * Ignore the valid bit. In all observed cases the register - * value is either low or zero if the valid bit is 0. - * Return it instead of reporting an error which doesn't - * really help at all. + * Bit 31 indicates whether the reading is valid. Some CPUs + * clear it while the temperature is too low to be measured. + * Such a reading is not a temperature. Do not report it. */ + tdata->temp_valid = (eax >> 31) & 1; tdata->temp = tjmax - ((eax >> 16) & 0xff) * 1000; tdata->last_updated = jiffies; } + valid = tdata->temp_valid; + temp = tdata->temp; mutex_unlock(&tdata->update_lock); - return sprintf(buf, "%d\n", tdata->temp); + + if (!valid) + return -ENODATA; + return sprintf(buf, "%d\n", temp); } static int create_core_attrs(struct temp_data *tdata, struct device *dev) -- 2.53.0