From: Alex Williamson <alex.williamson@redhat.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: David Hildenbrand <david@redhat.com>,
lizhe.67@bytedance.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, muchun.song@linux.dev
Subject: Re: [PATCH v3] vfio/type1: optimize vfio_pin_pages_remote() for huge folio
Date: Wed, 28 May 2025 20:58:02 -0600 [thread overview]
Message-ID: <20250528205802.4afb3a1b.alex.williamson@redhat.com> (raw)
In-Reply-To: <20250529005147.GC192517@ziepe.ca>
On Wed, 28 May 2025 21:51:47 -0300
Jason Gunthorpe <jgg@ziepe.ca> wrote:
> On Wed, May 28, 2025 at 02:09:41PM -0600, Alex Williamson wrote:
>
> > To be fair to libvirt, we'd really like libvirt to make use of iommufd
> > whenever it's available, but without feature parity this would break
> > users.
>
> If people ask there should be no issue with making API functionality
> discoverable with a query command of some kind. Alot of new stuff is
> already discoverable by invoking an ioctl with bogus arguments and
> checking for EOPNOTSUPP/ENOTTY.
>
> But most likely P2P will use the same ioctl as memfd so it will not
> work that way.
>
> So for now libvirt could assume no P2P support in iommufd. A simple
> algorithm would be to look for more than 1 VFIO device. Or add an xml
> "disable P2P" which is a useful thing anyhow.
Hotplug is always a problem if we make assumptions based on device
counts. Thanks,
Alex
next prev parent reply other threads:[~2025-05-29 2:58 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-05-20 7:00 [PATCH v3] vfio/type1: optimize vfio_pin_pages_remote() for huge folio lizhe.67
2025-05-20 14:07 ` Alex Williamson
2025-05-20 16:59 ` Peter Xu
2025-05-20 17:41 ` David Hildenbrand
2025-05-20 21:56 ` Alex Williamson
2025-05-21 3:34 ` lizhe.67
2025-05-20 17:38 ` David Hildenbrand
2025-05-20 22:21 ` Alex Williamson
2025-05-21 6:35 ` David Hildenbrand
2025-05-21 15:40 ` Peter Xu
2025-05-21 16:02 ` David Hildenbrand
2025-05-21 16:55 ` Alex Williamson
2025-05-26 20:19 ` Jason Gunthorpe
2025-05-27 19:52 ` Alex Williamson
2025-05-27 23:46 ` Jason Gunthorpe
2025-05-28 20:09 ` Alex Williamson
2025-05-29 0:51 ` Jason Gunthorpe
2025-05-29 2:58 ` Alex Williamson [this message]
2025-05-29 4:31 ` lizhe.67
2025-05-21 3:45 ` lizhe.67
2025-05-20 23:37 ` kernel test robot
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