linux-kernel - Re: [PATCH v8 10/13] hwmon: peci: Add cputemp driver

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] [day] [month] [year] [list]

Message-ID: <35aff70623a156ebe39106db26a443659de2ef79.camel@intel.com>
Date:   Tue, 21 Mar 2023 09:08:16 +0000
From:   "Winiarska, Iwona" <iwona.winiarska@...el.com>
To:     "fercerpav@...il.com" <fercerpav@...il.com>
CC:     "corbet@....net" <corbet@....net>,
        "jae.hyun.yoo@...ux.intel.com" <jae.hyun.yoo@...ux.intel.com>,
        "billy_tsai@...eedtech.com" <billy_tsai@...eedtech.com>,
        "linux-hwmon@...r.kernel.org" <linux-hwmon@...r.kernel.org>,
        "Hansen, Dave" <dave.hansen@...el.com>,
        "Luck, Tony" <tony.luck@...el.com>,
        "andrew@...id.au" <andrew@...id.au>,
        "jdelvare@...e.com" <jdelvare@...e.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "olof@...om.net" <olof@...om.net>,
        "rdunlap@...radead.org" <rdunlap@...radead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-aspeed@...ts.ozlabs.org" <linux-aspeed@...ts.ozlabs.org>,
        "linux@...ck-us.net" <linux@...ck-us.net>,
        "Weiss, Zev" <zweiss@...inix.com>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "openbmc@...ts.ozlabs.org" <openbmc@...ts.ozlabs.org>,
        "arnd@...db.de" <arnd@...db.de>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "bp@...en8.de" <bp@...en8.de>,
        "pierre-louis.bossart@...ux.intel.com" 
        <pierre-louis.bossart@...ux.intel.com>,
        "andriy.shevchenko@...ux.intel.com" 
        <andriy.shevchenko@...ux.intel.com>,
        "Williams, Dan J" <dan.j.williams@...el.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v8 10/13] hwmon: peci: Add cputemp driver

On Mon, 2023-03-20 at 14:45 +0300, Paul Fertser wrote:
> Hello,
> 
> We are seeing wrong DTS temperatures on at least "Intel(R) Xeon(R)
> Bronze 3204 CPU @ 1.90GHz" and most probably other Skylake Xeon CPUs
> are also affected, see inline.
> 
> On Tue, Feb 08, 2022 at 04:36:36PM +0100, Iwona Winiarska wrote:
> > Add peci-cputemp driver for Digital Thermal Sensor (DTS) thermal
> > readings of the processor package and processor cores that are
> > accessible via the PECI interface.
> ...
> > +static const struct cpu_info cpu_hsx = {
> > +       .reg            = &resolved_cores_reg_hsx,
> > +       .min_peci_revision = 0x33,
> > +       .thermal_margin_to_millidegree =
> > &dts_eight_dot_eight_to_millidegree,
> > +};
> > +
> > +static const struct cpu_info cpu_icx = {
> > +       .reg            = &resolved_cores_reg_icx,
> > +       .min_peci_revision = 0x40,
> > +       .thermal_margin_to_millidegree = &dts_ten_dot_six_to_millidegree,
> > +};
> ...
> > +       {
> > +               .name = "peci_cpu.cputemp.skx",
> > +               .driver_data = (kernel_ulong_t)&cpu_hsx,
> > +       },
> 
> With this configuration we get this data:
> 
> /sys/bus/peci/devices/0-30/peci_cpu.cputemp.skx.48/hwmon/hwmon15# grep .
> temp[123]_{label,input}
> temp1_label:Die
> temp2_label:DTS
> temp3_label:Tcontrol
> temp1_input:30938
> temp2_input:67735
> temp3_input:80000
> 
> On the host system "sensors" report
> 
> Package id 0:  +31.C (high = +80.C, crit = +90.C)
> 
> So I conclude Die temperature as retrieved over PECI is correct while
> DTS is mis-calculated. The old downstream code in OpenBMC was using
> ten_dot_six_to_millidegree() function for conversion, and that was
> providing expected results. And indeed if we reverse the calculation
> here we get 80000 - ((80000-67735) * 256 / 64) = 30940 which matches
> expectations.
> 

Hi!

Thanks for the report.

It was changed between v2 and v3 after a report about negative temperature on
pre-ICX platforms:
https://lore.kernel.org/lkml/6891496eabcc6f9cacec4fea505fb757ea9c11fc.camel@intel.com/

Unfortunately, I'm not able to test this on Cascade Lake X (or any other pre-ICX
platform).
I just sent a patch that changes SKX to use S10.6 format:
https://lore.kernel.org/lkml/20230321090410.866766-1-iwona.winiarska@intel.com/

Thanks
-Iwona