From: David Gibson <david@gibson.dropbear.id.au>
To: Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: kvm@vger.kernel.org, Alistair Popple <alistair@popple.id.au>,
linuxppc-dev@lists.ozlabs.org, kvm-ppc@vger.kernel.org,
Alex Williamson <alex.williamson@redhat.com>,
Reza Arbab <arbab@linux.ibm.com>
Subject: Re: [PATCH kernel 2/3] vfio_pci: Allow regions to add own capabilities
Date: Thu, 8 Nov 2018 18:16:23 +1100 [thread overview]
Message-ID: <20181108071623.GA26872@umbus.fritz.box> (raw)
In-Reply-To: <72022e34-6cf0-3946-8049-ba3d998097f3@ozlabs.ru>
[-- Attachment #1: Type: text/plain, Size: 1618 bytes --]
On Thu, Nov 08, 2018 at 05:48:58PM +1100, Alexey Kardashevskiy wrote:
>
>
> On 08/11/2018 17:21, David Gibson wrote:
> > On Mon, Oct 15, 2018 at 08:42:32PM +1100, Alexey Kardashevskiy wrote:
> >> VFIO regions already support region capabilities with a limited set of
> >> fields. However the subdriver might have to report to the userspace
> >> additional bits.
> >>
> >> This adds an add_capability() hook to vfio_pci_regops.
> >>
> >> This is aiming Witherspoon POWER9 machines which have multiple
> >> interconnected NVIDIA V100 GPUs with coherent RAM; each GPU's RAM
> >> is mapped to a system bus and to each of GPU internal system bus and
> >> the GPUs use this for DMA routing as DMA trafic can go via any
> >> of many NVLink2 (GPU-GPU or GPU-CPU) or even stay local within a
> >> GPU.
> >
> > This description doesn't really make clear how per-region capabilities
> > are relevant to these devices.
>
>
> I am confused. This patch just adds a hook, and the device specifics are
> explained in the next patch where they are used...
Well, my point is the last paragraph of the commit message appears to
be a rationale for this change in terms of what's needed for the GPU
devices. But how those described properties of the GPU mean that
region capabilites are useful / necessary isn't made clear. If it's
not meant to be a rationale, I'm not sure what it's doing there at
all.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
next prev parent reply other threads:[~2018-11-08 12:07 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-15 9:42 [PATCH kernel 0/3] vfio/spapr_tce: Reworks for NVIDIA V100 + P9 passthrough (part 3) Alexey Kardashevskiy
2018-10-15 9:42 ` [PATCH kernel 1/3] vfio_pci: Allow mapping extra regions Alexey Kardashevskiy
2018-11-08 6:04 ` David Gibson
2018-10-15 9:42 ` [PATCH kernel 2/3] vfio_pci: Allow regions to add own capabilities Alexey Kardashevskiy
2018-11-08 6:21 ` David Gibson
2018-11-08 6:48 ` Alexey Kardashevskiy
2018-11-08 7:16 ` David Gibson [this message]
2018-10-15 9:42 ` [PATCH kernel 3/3] vfio_pci: Add NVIDIA GV100GL [Tesla V100 SXM2] [10de:1db1] subdriver Alexey Kardashevskiy
2018-10-16 19:08 ` Alex Williamson
2018-10-17 1:19 ` Alexey Kardashevskiy
2018-10-17 21:52 ` Alex Williamson
2018-10-17 23:42 ` Piotr Jaroszyński
2018-10-18 0:31 ` Alexey Kardashevskiy
2018-10-18 16:55 ` Alex Williamson
2018-10-18 17:37 ` Piotr Jaroszynski
2018-10-18 18:05 ` Alex Williamson
2018-10-18 18:40 ` Piotr Jaroszynski
2018-10-19 6:25 ` Christoph Hellwig
2018-10-19 0:53 ` Alexey Kardashevskiy
2018-11-12 1:08 ` David Gibson
2018-11-12 2:36 ` Alexey Kardashevskiy
2018-11-12 4:23 ` David Gibson
2018-11-12 4:56 ` Alexey Kardashevskiy
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=20181108071623.GA26872@umbus.fritz.box \
--to=david@gibson.dropbear.id.au \
--cc=aik@ozlabs.ru \
--cc=alex.williamson@redhat.com \
--cc=alistair@popple.id.au \
--cc=arbab@linux.ibm.com \
--cc=kvm-ppc@vger.kernel.org \
--cc=kvm@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
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;
as well as URLs for NNTP newsgroup(s).