linux-kernel - Re: [PATCH 1/4] vfio: selftests: Add support for passing vf

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Message-ID: <aQzWnS63x81EhTWy@google.com>
Date: Thu, 6 Nov 2025 17:10:53 +0000
From: David Matlack <dmatlack@...gle.com>
To: Raghavendra Rao Ananta <rananta@...gle.com>
Cc: Alex Williamson <alex@...zbot.org>,
	Alex Williamson <alex.williamson@...hat.com>,
	Josh Hilke <jrhilke@...gle.com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] vfio: selftests: Add support for passing vf_token in
 device init

On 2025-11-06 10:06 PM, Raghavendra Rao Ananta wrote:
> On Thu, Nov 6, 2025 at 5:44 AM David Matlack <dmatlack@...gle.com> wrote:
> >
> > On 2025-11-04 12:35 AM, Raghavendra Rao Ananta wrote:
> >
> > > diff --git a/tools/testing/selftests/vfio/lib/libvfio.mk b/tools/testing/selftests/vfio/lib/libvfio.mk
> > > index 5d11c3a89a28e..2dc85c41ffb4b 100644
> > > --- a/tools/testing/selftests/vfio/lib/libvfio.mk
> > > +++ b/tools/testing/selftests/vfio/lib/libvfio.mk
> > > @@ -18,7 +18,9 @@ $(shell mkdir -p $(LIBVFIO_O_DIRS))
> > >
> > >  CFLAGS += -I$(VFIO_DIR)/lib/include
> > >
> > > +LDLIBS += -luuid
> >
> > I wonder if we really need this dependency. VFIO and IOMMUFD just expect
> > a 16 byte character array. That is easy enough to represent. The other
> > part we use is uuid_parse(), but I don't know if selftests need to do
> > that validation. We can let VFIO and IOMMUFD validate the UUID as they
> > see fit and return an error if they aren't happy with it. i.e. We do not
> > need to duplicate validation in the test.
> 
> Unfortunately, VFIO interface accepts UUID in multiple formats. For
> VFIO_DEVICE_FEATURE and VFIO_DEVICE_BIND_IOMMUFD it accepts a
> 'u8[16]', but for VFIO_GROUP_GET_DEVICE_FD, we must present it as a
> string. Is there an issue with the inclusion of an external library (I
> think I've seen others in tools/ use it).

Ack. In that case, depending on libuuid SGTM.

I mistakenly thought VFIO always took the UUID as a string and
uuid_parse() was just being used to sanity check the format. Thanks for
clarifying.