linux-kernel - Re: [PATCH V8 0/5] Intel Platform Monitoring Technology

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Message-ID: <2f17db4b-2988-7f0d-fd0e-9e5b621d24ec@redhat.com>
Date:   Tue, 27 Oct 2020 12:28:04 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     "David E. Box" <david.e.box@...ux.intel.com>, lee.jones@...aro.org,
        dvhart@...radead.org, andy@...radead.org, bhelgaas@...gle.com,
        alexey.budankov@...ux.intel.com
Cc:     linux-kernel@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        linux-pci@...r.kernel.org
Subject: Re: [PATCH V8 0/5] Intel Platform Monitoring Technology

Hi,

On 10/3/20 3:31 AM, David E. Box wrote:
> Intel Platform Monitoring Technology (PMT) is an architecture for
> enumerating and accessing hardware monitoring capabilities on a device.
> With customers increasingly asking for hardware telemetry, engineers not
> only have to figure out how to measure and collect data, but also how to
> deliver it and make it discoverable. The latter may be through some device
> specific method requiring device specific tools to collect the data. This
> in turn requires customers to manage a suite of different tools in order to
> collect the differing assortment of monitoring data on their systems.  Even
> when such information can be provided in kernel drivers, they may require
> constant maintenance to update register mappings as they change with
> firmware updates and new versions of hardware. PMT provides a solution for
> discovering and reading telemetry from a device through a hardware agnostic
> framework that allows for updates to systems without requiring patches to
> the kernel or software tools.
> 
> PMT defines several capabilities to support collecting monitoring data from
> hardware. All are discoverable as separate instances of the PCIE Designated
> Vendor extended capability (DVSEC) with the Intel vendor code. The DVSEC ID
> field uniquely identifies the capability. Each DVSEC also provides a BAR
> offset to a header that defines capability-specific attributes, including
> GUID, feature type, offset and length, as well as configuration settings
> where applicable. The GUID uniquely identifies the register space of any
> monitor data exposed by the capability. The GUID is associated with an XML
> file from the vendor that describes the mapping of the register space along
> with properties of the monitor data. This allows vendors to perform
> firmware updates that can change the mapping (e.g. add new metrics) without
> requiring any changes to drivers or software tools. The new mapping is
> confirmed by an updated GUID, read from the hardware, which software uses
> with a new XML.
> 
> The current capabilities defined by PMT are Telemetry, Watcher, and
> Crashlog.  The Telemetry capability provides access to a continuous block
> of read only data. The Watcher capability provides access to hardware
> sampling and tracing features. Crashlog provides access to device crash
> dumps.  While there is some relationship between capabilities (Watcher can
> be configured to sample from the Telemetry data set) each exists as stand
> alone features with no dependency on any other. The design therefore splits
> them into individual, capability specific drivers. MFD is used to create
> platform devices for each capability so that they may be managed by their
> own driver. The PMT architecture is (for the most part) agnostic to the
> type of device it can collect from. Software can determine which devices
> support a PMT feature by searching through each device node entry in the
> sysfs class folder. It can additionally determine if a particular device
> supports a PMT feature by checking for a PMT class folder in the device
> folder.
> 
> This patch set provides support for the PMT framework, along with support
> for Telemetry on Tiger Lake.

The entire series looks good to me, so you may add my:

Reviewed-by: Hans de Goede <hdegoede@...hat.com>

To the entire series.

Lee, in the discussion about previous versions you indicated that you
would be happy to merge the entire series through the MFD tree.

>From my pov this is ready for merging, so if you can pick up the entire
series and then provide me with an immutable branch to merge into the
pdx86 tree that would be great.

Regards,

Hans