From: Jason Gunthorpe <jgg@nvidia.com>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: ankita@nvidia.com, aniketa@nvidia.com, cjia@nvidia.com,
kwankhede@nvidia.com, targupta@nvidia.com, vsethi@nvidia.com,
acurrid@nvidia.com, apopple@nvidia.com, jhubbard@nvidia.com,
danw@nvidia.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 1/1] vfio/nvgpu: Add vfio pci variant module for grace hopper
Date: Mon, 26 Jun 2023 13:23:07 -0300 [thread overview]
Message-ID: <ZJm7a1BpeLmQQ5Mj@nvidia.com> (raw)
In-Reply-To: <20230626100629.3c318922.alex.williamson@redhat.com>
On Mon, Jun 26, 2023 at 10:06:29AM -0600, Alex Williamson wrote:
> On Fri, 23 Jun 2023 10:26:05 -0300
> Jason Gunthorpe <jgg@nvidia.com> wrote:
>
> > On Wed, Jun 21, 2023 at 08:07:20PM -0700, ankita@nvidia.com wrote:
> > > + if (caps.size) {
> > > + info.flags |= VFIO_REGION_INFO_FLAG_CAPS;
> > > + if (info.argsz < sizeof(info) + caps.size) {
> > > + info.argsz = sizeof(info) + caps.size;
> > > + info.cap_offset = 0;
> >
> > Shouldn't this be an error if we can't fit the caps into the response?
> > Silently discarding the caps seems wrong..
>
> It's required for backwards compatibility. If a userspace doesn't
> support the info ioctl capabilities chain, it gets the basic
> information successfully, while an enlightened userspace makes use of
> the flags to know that a capability chain is available but unreported
> due to an insufficient buffer size, with the required size being
> provided in the return structure.
Hum, maybe this part should be pushed into the cap helpers..
Jason
next prev parent reply other threads:[~2023-06-26 16:24 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-22 3:07 [PATCH v4 1/1] vfio/nvgpu: Add vfio pci variant module for grace hopper ankita
2023-06-23 6:27 ` Cédric Le Goater
2023-06-23 11:47 ` Jason Gunthorpe
2023-06-23 13:04 ` Cédric Le Goater
2023-06-23 13:07 ` Jason Gunthorpe
2023-06-23 15:07 ` Cédric Le Goater
2023-06-23 16:38 ` Jason Gunthorpe
2023-06-23 13:26 ` Jason Gunthorpe
2023-06-26 16:06 ` Alex Williamson
2023-06-26 16:23 ` Jason Gunthorpe [this message]
2023-06-28 19:00 ` Ankit Agrawal
2023-06-26 16:01 ` Alex Williamson
2023-07-05 18:37 ` Ankit Agrawal
2023-07-05 22:16 ` Alex Williamson
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