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Subject: Re: [PATCH v17 0/5] FPGA Image Load (previously Security Manager)
To:     Xu Yilun <yilun.xu@intel.com>
Cc:     Russ Weight <russell.h.weight@intel.com>, mdf@kernel.org,
        linux-fpga@vger.kernel.org, linux-kernel@vger.kernel.org,
        lgoncalv@redhat.com, hao.wu@intel.com, matthew.gerlach@intel.com
References: <20210929230025.68961-1-russell.h.weight@intel.com>
 <20211009080859.GA85181@yilunxu-OptiPlex-7050>
 <450ed897-f726-9671-26b7-2a24bb046e89@redhat.com>
 <20211011014154.GA82360@yilunxu-OptiPlex-7050>
From:   Tom Rix <trix@redhat.com>
Message-ID: <79350773-3629-2734-21c0-0314a762e722@redhat.com>
Date:   Mon, 11 Oct 2021 05:35:03 -0700
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On 10/10/21 6:41 PM, Xu Yilun wrote:
> On Sat, Oct 09, 2021 at 05:11:20AM -0700, Tom Rix wrote:
>> On 10/9/21 1:08 AM, Xu Yilun wrote:
>>> On Wed, Sep 29, 2021 at 04:00:20PM -0700, Russ Weight wrote:
>>>> The FPGA Image Load framework provides an API to upload image
>>>> files to an FPGA device. Image files are self-describing. They could
>>>> contain FPGA images, BMC images, Root Entry Hashes, or other device
>>>> specific files. It is up to the lower-level device driver and the
>>>> target device to authenticate and disposition the file data.
>>> I've reconsider the FPGA persistent image update again, and think we
>>> may include it in FPGA manager framework.
>>>
>>> Sorry I raised this topic again when it is already at patch v17, but now
>>> I need to consider more seriously than before.
>>>
>>> We have consensus the FPGA persistent image update is just like a normal
>>> firmware update which finally writes the nvmem like flash or eeprom,
>>> while the current FPGA manager deals with the active FPGA region update
>>> and re-activation. Could we just expand the FPGA manager and let it handle
>>> the nvmem update as well? Many FPGA cards have nvmem and downloaders
>>> supports updating both FPGA region and nvmem.
>>>
>>> According to the patchset, the basic workflow of the 2 update types are
>>> quite similar, get the data, prepare for the HW, write and complete.
>>> They are already implemented in FPGA manager. We've discussed some
>>> differences like threading or canceling the update, which are
>>> not provided by FPGA manager but they may also nice to have for FPGA
>>> region update. An FPGA region update may also last for a long time??
>>> So I think having 2 sets of similar frameworks in FPGA is unnecessary.
>>>
>>> My quick mind is that we add some flags in struct fpga_mgr & struct
>>> fpga_image_info to indicate the HW capability (support FPGA region
>>> update or nvmem update or both) of the download engine and the provided
>>> image type. Then the low-level driver knows how to download if it
>>> supports both image types.
>>>
>>> An char device could be added for each fpga manager dev, providing the
>>> user APIs for nvmem update. We may not use the char dev for FPGA region
>>> update cause it changes the system HW devices and needs device hotplug
>>> in FPGA region. We'd better leave it to FPGA region class, this is
>>> another topic.
>>>
>>> More discussion is appreciated.
>> I also think fpga_mgr could be extended.
>>
>> In this patchset,
>>
>> https://lore.kernel.org/linux-fpga/20210625195849.837976-1-trix@redhat.com/
>>
>> A second, similar set of write ops was added to fpga_manger_ops,
>>
>> new bit/flag was added to fpga_image_info
>>
>> The intent was for dfl to add their specific ops to cover what is done in
>> this patchset.
> I think we don't have to add 2 ops for reconfig & reimage in framework,
> the 2 processes are almost the same.
>
> Just add the _REIMAGE (or something else, NVMEM?) flag for
> fpga_image_info, and low level drivers handle it as they do for other
> flags.
>
> How do you think?

A single set is fine.

A difficult part of is the length of  time to do the write. The existing 
write should be improved to use a worker thread.

Tom

>
> Thanks,
> Yilun
>
>> Any other driver would do similar.
>>
>> Is this close to what you are thinking ?
>>
>> Tom
>>
>>> Thanks,
>>> Yilun
>>>