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Message-ID: <662c3db180909_b6e02942e@dwillia2-mobl3.amr.corp.intel.com.notmuch>
Date: Fri, 26 Apr 2024 16:50:09 -0700
From: Dan Williams <dan.j.williams@...el.com>
To: Ira Weiny <ira.weiny@...el.com>, Dave Jiang <dave.jiang@...el.com>, "Dan
Williams" <dan.j.williams@...el.com>, Jonathan Cameron
<jonathan.cameron@...wei.com>, Smita Koralahalli
<Smita.KoralahalliChannabasappa@....com>, Shiju Jose <shiju.jose@...wei.com>
CC: Dan Carpenter <dan.carpenter@...aro.org>, Yazen Ghannam
<yazen.ghannam@....com>, Davidlohr Bueso <dave@...olabs.net>, "Alison
Schofield" <alison.schofield@...el.com>, Vishal Verma
<vishal.l.verma@...el.com>, Ard Biesheuvel <ardb@...nel.org>,
<linux-efi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-cxl@...r.kernel.org>, Ira Weiny <ira.weiny@...el.com>, "Rafael J.
Wysocki" <rafael@...nel.org>, Tony Luck <tony.luck@...el.com>, "Borislav
Petkov" <bp@...en8.de>
Subject: Re: [PATCH v3 1/2] acpi/ghes: Process CXL Component Events
Ira Weiny wrote:
> BIOS can configure memory devices as firmware first. This will send CXL
> events to the firmware instead of the OS. The firmware can then inform
> the OS of these events via UEFI.
>
> UEFI v2.10 section N.2.14 defines a Common Platform Error Record (CPER)
> format for CXL Component Events. The format is mostly the same as the
> CXL Common Event Record Format. The difference lies in the use of a
> GUID as the CPER Section Type which matches the UUID defined in CXL 3.1
> Table 8-43.
>
> Currently a configuration such as this will trace a non standard event
> in the log omitting useful details of the event. In addition the CXL
> sub-system contains additional region and HPA information useful to the
> user.[0]
>
> The CXL code is required to be called from process context as it needs
> to take a device lock. The GHES code may be in interrupt context. This
> complicated the use of a callback. Dan Williams suggested the use of
> work items as an atomic way of switching between the callback execution
> and a default handler.[1]
>
> The use of a kfifo simplifies queue processing by providing lock free
> fifo operations. cxl_cper_kfifo_get() allows easier management of the
> kfifo between the ghes and cxl modules.
>
> CXL 3.1 Table 8-127 requires a device to have a queue depth of 1 for
> each of the four event logs. A combined queue depth of 32 is chosen to
> provide room for 8 entries of each log type.
>
> Add GHES support to detect CXL CPER records. Add the ability for the
> CXL sub-system to register a work queue to process the events.
>
> This patch adds back the functionality which was removed to fix the
> report by Dan Carpenter[2].
>
> [0]
> Link: https://lore.kernel.org/all/cover.1711598777.git.alison.schofield@intel.com/
> [1]
> Link: https://lore.kernel.org/all/65d111eb87115_6c745294ac@dwillia2-xfh.jf.intel.com.notmuch/
> [2]
> Link: https://lore.kernel.org/all/b963c490-2c13-4b79-bbe7-34c6568423c7@moroto.mountain/
Like I mentioned last time, perhaps Dave can reformat these lines on
applying to:
Link: http://lore.kernel.org/r/cover.1711598777.git.alison.schofield@intel.com [0]
Link: http://lore.kernel.org/r/65d111eb87115_6c745294ac@dwillia2-xfh.jf.intel.com.notmuch [1]
Link: http://lore.kernel.org/r/b963c490-2c13-4b79-bbe7-34c6568423c7@moroto.mountain [2]
Other than that, this looks good to me:
Reviewed-by: Dan Williams <dan.j.williams@...el.com>
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