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From: Alex Williamson <alex.williamson@redhat.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: kvm@vger.kernel.org, linux-pci@vger.kernel.org,
	linux-kernel@vger.kernel.org, dev@dpdk.org, mtosatti@redhat.com,
	thomas@monjalon.net, bluca@debian.org, jerinjacobk@gmail.com,
	bruce.richardson@intel.com, cohuck@redhat.com
Subject: Re: [RFC PATCH 0/7] vfio/pci: SR-IOV support
Date: Wed, 5 Feb 2020 06:58:36 -0700	[thread overview]
Message-ID: <20200205065836.12308197@x1.home> (raw)
In-Reply-To: <20200205070109.GA18027@infradead.org>

On Tue, 4 Feb 2020 23:01:09 -0800
Christoph Hellwig <hch@infradead.org> wrote:

> On Tue, Feb 04, 2020 at 04:05:34PM -0700, Alex Williamson wrote:
> > We address this in a few ways in this series.  First, we can use a bus
> > notifier and the driver_override facility to make sure VFs are bound
> > to the vfio-pci driver by default.  This should eliminate the chance
> > that a VF is accidentally bound and used by host drivers.  We don't
> > however remove the ability for a host admin to change this override.  
> 
> That is just such a bad idea.  Using VFs in the host is a perfectly
> valid use case that you are breaking.

vfio-pci currently does not allow binding to a PF with VFs enabled and
does not provide an sriov_configure callback, so it's not possible to
have VFs on a vfio-pci bound PF.  Therefore I'm not breaking any
existing use cases.  I'm also not preventing VFs from being used in the
host, I only set a default driver_override value, which can be replaced
if a different driver binding is desired.  So I also don't see that I'm
breaking a usage model here.  I do stand by the idea that VFs sourced
from a user owned PF should not by default be used in the host (ie.
autoprobed on device add).  There's a pci-pf-stub driver that can be
used to create VFs on a PF if no userspace access of the PF is required.
Thanks,

Alex


  reply	other threads:[~2020-02-05 13:58 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-04 23:05 [RFC PATCH 0/7] vfio/pci: SR-IOV support Alex Williamson
2020-02-04 23:05 ` [RFC PATCH 1/7] vfio: Include optional device match in vfio_device_ops callbacks Alex Williamson
2020-02-06 11:14   ` Cornelia Huck
2020-02-06 18:18     ` Alex Williamson
2020-02-07  9:33       ` Cornelia Huck
2020-02-04 23:05 ` [RFC PATCH 2/7] vfio/pci: Implement match ops Alex Williamson
2020-02-04 23:06 ` [RFC PATCH 3/7] vfio/pci: Introduce VF token Alex Williamson
2020-02-05  7:57   ` Liu, Yi L
2020-02-05 14:13     ` Alex Williamson
2020-02-04 23:06 ` [RFC PATCH 4/7] vfio: Introduce VFIO_DEVICE_FEATURE ioctl and first user Alex Williamson
2020-02-04 23:06 ` [RFC PATCH 5/7] vfio/pci: Add sriov_configure support Alex Williamson
2020-02-04 23:06 ` [RFC PATCH 6/7] vfio/pci: Remove dev_fmt definition Alex Williamson
2020-02-06 13:45   ` Cornelia Huck
2020-02-04 23:06 ` [RFC PATCH 7/7] vfio/pci: Cleanup .probe() exit paths Alex Williamson
2020-02-04 23:17 ` [RFC PATCH 0/7] vfio/pci: SR-IOV support Alex Williamson
2020-02-05  7:57   ` Liu, Yi L
2020-02-05 14:18     ` Alex Williamson
2020-02-05  7:01 ` Christoph Hellwig
2020-02-05 13:58   ` Alex Williamson [this message]
2020-02-05  7:57 ` Liu, Yi L
2020-02-05 14:10   ` Alex Williamson
2020-02-11 11:18 ` Jerin Jacob
2020-02-11 13:57   ` [dpdk-dev] " Thomas Monjalon
2020-02-11 17:06   ` Alex Williamson
2020-02-11 18:03     ` Jerin Jacob

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