From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Gibson Subject: Re: [RFC PATCH kernel] vfio-pci: Allow write combining Date: Mon, 16 Oct 2017 17:00:43 +1100 Message-ID: <20171016060043.GC2776@umbus.fritz.box> References: <20171009025000.39435-1-aik@ozlabs.ru> <20171010155515.39a0c5fe@t450s.home> <20171010204256.309715ce@t450s.home> <26fbe3b7-c54b-87a5-799d-22f4f043edd2@ozlabs.ru> <1507736107.25065.222.camel@kernel.crashing.org> <7ad2ee73-80dc-69ef-c98a-63b020f2f48b@ozlabs.ru> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="ZARJHfwaSJQLOEUz" Cc: Benjamin Herrenschmidt , Alex Williamson , kvm@vger.kernel.org, Eric Auger To: Alexey Kardashevskiy Return-path: Received: from ozlabs.org ([103.22.144.67]:41867 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750707AbdJPGHh (ORCPT ); Mon, 16 Oct 2017 02:07:37 -0400 Content-Disposition: inline In-Reply-To: <7ad2ee73-80dc-69ef-c98a-63b020f2f48b@ozlabs.ru> Sender: kvm-owner@vger.kernel.org List-ID: --ZARJHfwaSJQLOEUz Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Oct 16, 2017 at 04:54:08PM +1100, Alexey Kardashevskiy wrote: > On 12/10/17 02:35, Benjamin Herrenschmidt wrote: > > On Wed, 2017-10-11 at 13:56 +1100, Alexey Kardashevskiy wrote: > >> Oopsie. This is because I overlooked it. Others do not use it. So I do= need > >> a file. But in the current scheme where all BARs share one fd - it won= 't > >> work - I simply cannot allow WC on non-prefetchable BARs :-/ > >=20 > > This is an oversight in the design of VFIO-PCI, it should have a way to > > specify write combine, either implicitely via such an arch hook, or > > explicitely via an ioctl prior to mapping the BARs for example. > >=20 > > Alex, what do you reckon is the best approach here ? >=20 > /me wonders if it is yet another issue for the dead issues bucket, just > like the msix mapping one :) Maybe. Alexey, maybe you can make up a list of things that we (me, you, BenH) need to discuss with Alex W at KVM Forum? --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --ZARJHfwaSJQLOEUz Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEdfRlhq5hpmzETofcbDjKyiDZs5IFAlnkSwgACgkQbDjKyiDZ s5LO4A/9G0h1MFdipsooXZZTgFHJRX5zgGK+//s56hao0r6oEz8vkMa+4AFWSvMv IuIl8Amd1H6ZWlYF6yDxsTVYj5A3gMBDHaNBUQ7iIs7t0ZlGodOMep0UUp93XdbM 0RWCS59rcbGmyU4OTwUySdXniqPgTa80OQ+jQCJi6XRdIo7C6vLQoA/jgU2LEb6L sT2YEesTA6F4a6jRuSf2nNg5rYL6Kd/svtnpIh5RAhR42gpb0q3A8s0uU5n+ZXUA I0ZUMbKtG4hwdIyM63/oDE12XayCzv1P9H1VCANV4ji03Dv0gOseHpSzEjmN2SVC rhCppt3TYnrmz3PxrntSzqmVsU2TCilxbvG1pMXh41c4+S2A7RWiMx7uVRhwOe7m OKf74M9y/HVAuvOLm7k1CjKDtxHCCz9RVNxcw7d3OI7Zo/+7VZ3S+KuDk9w+MGrv OL6CMq6tevssgMAltDxv4hhLr9rTQFU0PgCXtBNHEic3zF+nF8qKAgKkyLiwuGg8 lw9jUcLjSxKOEFjf7HwjLEpP2hUyW3D05E0vS0sncM6Uh2ISgXMJ87MPW00q76gu OexGuGxyUHMzy4WCmIWHx+3763AY7OKn2rFK45Y0r+VBekCee8gIrBNMVlp12n2w xgmiios6Ux3R8535/sP4GQEYJ39/MyM386RizZQXu4o18SP87vA= =qhl6 -----END PGP SIGNATURE----- --ZARJHfwaSJQLOEUz--