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Message-ID: <d29fa7b13e9179f3d7aae6b2113822c41080a898.camel@linux.ibm.com>
Subject: Re: [PATCH 3/3] vfio/pci: Enable VFIO_PCI_MMAP for s390
From: Niklas Schnelle <schnelle@linux.ibm.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
        Heiko Carstens
 <hca@linux.ibm.com>, Vasily Gorbik <gor@linux.ibm.com>,
        Alexander Gordeev
 <agordeev@linux.ibm.com>,
        Christian Borntraeger
 <borntraeger@linux.ibm.com>,
        Sven Schnelle <svens@linux.ibm.com>,
        Alex
 Williamson <alex.williamson@redhat.com>,
        Gerd Bayer <gbayer@linux.ibm.com>,
        Matthew Rosato <mjrosato@linux.ibm.com>, linux-s390@vger.kernel.org,
        linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Date: Thu, 23 May 2024 10:24:30 +0200
In-Reply-To: <20240522232025.GH69273@ziepe.ca>
References: <20240521-vfio_pci_mmap-v1-0-2f6315e0054e@linux.ibm.com>
	 <20240521-vfio_pci_mmap-v1-3-2f6315e0054e@linux.ibm.com>
	 <20240522232025.GH69273@ziepe.ca>
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On Wed, 2024-05-22 at 20:20 -0300, Jason Gunthorpe wrote:
> On Tue, May 21, 2024 at 02:14:59PM +0200, Niklas Schnelle wrote:
> > With the introduction of memory I/O (MIO) instructions enbaled in commit
> > 71ba41c9b1d9 ("s390/pci: provide support for MIO instructions") s390
> > gained support for direct user-space access to mapped PCI resources.
> > Even without those however user-space can access mapped PCI resources
> > via the s390 specific MMIO syscalls. Thus VFIO_PCI_MMAP can be enabled
> > on all s390 systems with native PCI allowing vfio-pci user-space
> > applications direct access to mapped resources.
> >=20
> > Link: https://lore.kernel.org/all/c5ba134a1d4f4465b5956027e6a4ea6f6beff=
969.camel@linux.ibm.com/
> > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
> > ---
> >  drivers/vfio/pci/Kconfig | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >=20
> > diff --git a/drivers/vfio/pci/Kconfig b/drivers/vfio/pci/Kconfig
> > index 15821a2d77d2..814aa0941d61 100644
> > --- a/drivers/vfio/pci/Kconfig
> > +++ b/drivers/vfio/pci/Kconfig
> > @@ -8,7 +8,7 @@ config VFIO_PCI_CORE
> >  	select IRQ_BYPASS_MANAGER
> >=20=20
> >  config VFIO_PCI_MMAP
> > -	def_bool y if !S390
> > +	def_bool y
> >  	depends on VFIO_PCI_CORE
>=20
> Should we just purge this kconfig entirely? It is never meaningfully n no=
w?
>=20
> Jason

Makes sense to me. Will change this for v2. I'll also add a Suggested-
by for you if that's okay, should probably have been in this version
already.

Thanks,
Niklas