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Thu, 3 Jun 2021 05:52:58 +0000 From: "Tian, Kevin" To: Jason Gunthorpe , "Alex Williamson (alex.williamson@redhat.com)" , Cornelia Huck , Kirti Wankhede CC: "Jiang, Dave" , "alex.williamson@redhat.com" , "kwankhede@nvidia.com" , "tglx@linutronix.de" , "vkoul@kernel.org" , "Raj, Ashok" , "Dey, Megha" , "Pan, Jacob jun" , "Liu, Yi L" , "Lu, Baolu" , "Kumar, Sanjay K" , "Luck, Tony" , "Williams, Dan J" , "eric.auger@redhat.com" , "pbonzini@redhat.com" , "dmaengine@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" Subject: RE: [PATCH v6 00/20] Add VFIO mediated device support and DEV-MSI support for the idxd driver Thread-Topic: [PATCH v6 00/20] Add VFIO mediated device support and DEV-MSI support for the idxd driver Thread-Index: AQHXTqAZRXZQVBJp50eOXR3CymY0rKrxt7OAgA82YYCAAH+rgIAAHwJQgAALZACAAD0zgA== Date: Thu, 3 Jun 2021 05:52:58 +0000 Message-ID: References: <162164243591.261970.3439987543338120797.stgit@djiang5-desk3.ch.intel.com> <20210523232219.GG1002214@nvidia.com> <86cde154-37c7-c00d-b0c6-06b15b50dbf7@intel.com> <20210602231747.GK1002214@nvidia.com> <20210603014932.GN1002214@nvidia.com> In-Reply-To: <20210603014932.GN1002214@nvidia.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: dlp-version: 11.5.1.3 dlp-product: dlpe-windows dlp-reaction: no-action authentication-results: nvidia.com; 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charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: MWHPR11MB1886.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: edd88873-8885-4706-3877-08d92653d774 X-MS-Exchange-CrossTenant-originalarrivaltime: 03 Jun 2021 05:52:58.7545 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: XaLAh1I15Ig5iSATFtXNcVtUox25EcrLDUUE+9vai5c+VGN3bS3aDwaKRfQ8X2P3hlcU3elkNcEajELWDMGszw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR11MB1662 X-OriginatorOrg: intel.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > From: Jason Gunthorpe > Sent: Thursday, June 3, 2021 9:50 AM >=20 > On Thu, Jun 03, 2021 at 01:11:37AM +0000, Tian, Kevin wrote: >=20 > > Jason, can you clarify your attitude on mdev guid stuff? Are you > > completely against it or case-by-case? If the former, this is a big > > decision thus it's better to have consensus with Alex/Kirti. If the > > latter, would like to hear your criteria for when it can be used > > and when not... >=20 > I dislike it generally, but it exists so . I know others feel > more strongly about it being un-kernely and the wrong way to use sysfs. >=20 > Here I was remarking how the example in the cover letter made the mdev > part seem totally pointless. If it is pointless then don't do it. Is your point about that as long as a mdev requires pre-config through driver specific sysfs then it doesn't make sense to use mdev guid interface anymore? The value of mdev guid interface is providing a vendor-agnostic interface for mdev life-cycle management which allows one- enable-fit-all in upper management stack. Requiring vendor specific pre-config does blur the boundary here. Alex/Kirt/Cornelia, what about your opinion here? It's better=20 we can have an consensus on when and where the existing mdev sysfs could be used, as this will affect every new mdev implementation from now on. >=20 > Remember we have stripped away the actual special need to use > mdev. You don't *have* to use mdev anymore to use vfio. That is a > significant ideology change even from a few months ago. >=20 Yes, "don't have to" but if there is value of doing so it's not necessary to blocking it? One point in my mind is that if we should minimize vendor-specific contracts for user to manage mdev or subdevice... Thanks Kevin