From: Michael Ellerman <mpe@ellerman•id.au>
To: Tyrel Datwyler <tyreld@linux•ibm.com>
Cc: linuxppc-dev@lists•ozlabs.org, linux-kernel@vger•kernel.org
Subject: Re: [PATCH] powerpc/pseries: Add shutdown() to vio_driver and vio_bus
Date: Tue, 20 Apr 2021 13:42:37 +1000 [thread overview]
Message-ID: <87mtttd3ki.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <59bd8028-cb1a-fdf6-74ce-68e868e4f486@linux.ibm.com>
Tyrel Datwyler <tyreld@linux•ibm.com> writes:
> On 4/17/21 5:30 AM, Michael Ellerman wrote:
>> Tyrel Datwyler <tyreld@linux•ibm.com> writes:
>>> On 4/1/21 5:13 PM, Tyrel Datwyler wrote:
>>>> Currently, neither the vio_bus or vio_driver structures provide support
>>>> for a shutdown() routine.
>>>>
>>>> Add support for shutdown() by allowing drivers to provide a
>>>> implementation via function pointer in their vio_driver struct and
>>>> provide a proper implementation in the driver template for the vio_bus
>>>> that calls a vio drivers shutdown() if defined.
>>>>
>>>> In the case that no shutdown() is defined by a vio driver and a kexec is
>>>> in progress we implement a big hammer that calls remove() to ensure no
>>>> further DMA for the devices is possible.
>>>>
>>>> Signed-off-by: Tyrel Datwyler <tyreld@linux•ibm.com>
>>>> ---
>>>
>>> Ping... any comments, problems with this approach?
>>
>> The kexec part seems like a bit of a hack.
>>
>> It also doesn't help for kdump, when none of the shutdown code is run.
>
> If I understand correctly for kdump we have a reserved memory space where the
> kdump kernel is loaded, but for kexec the memory region isn't reserved ahead of
> time meaning we can try and load the kernel over potential memory used for DMA
> by the current kernel.
That's correct.
>> How many drivers do we have? Can we just implement a proper shutdown for
>> them?
>
> Well that is the end goal. I just don't currently have the bandwidth to do each
> driver myself with a proper shutdown sequence, and thought this was a launching
> off point to at least introduce the shutdown callback to the VIO bus.
Fair enough.
> Off the top of my head we have 3 storage drivers, 2 network drivers, vtpm, vmc,
> pseries_rng, nx, nx842, hvcs, hvc_vio.
>
> I can drop the kexec_in_progress hammer and just have each driver call remove()
> themselves in their shutdown function. Leave it to each maintainer to decide if
> remove() is enough or if there is a more lightweight quiesce sequence they
> choose to implement.
That's OK, you've convinced me. I'll take it as-is.
Eventually it would be good for drivers to implement shutdown in the
optimal way for their device, but that can be done incrementally.
cheers
next prev parent reply other threads:[~2021-04-20 3:43 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-02 0:13 [PATCH] powerpc/pseries: Add shutdown() to vio_driver and vio_bus Tyrel Datwyler
2021-04-16 18:46 ` Tyrel Datwyler
2021-04-17 12:30 ` Michael Ellerman
2021-04-19 18:30 ` Tyrel Datwyler
2021-04-20 3:42 ` Michael Ellerman [this message]
2021-04-21 13:08 ` Michael Ellerman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87mtttd3ki.fsf@mpe.ellerman.id.au \
--to=mpe@ellerman$(echo .)id.au \
--cc=linux-kernel@vger$(echo .)kernel.org \
--cc=linuxppc-dev@lists$(echo .)ozlabs.org \
--cc=tyreld@linux$(echo .)ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox