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Tue, 3 Nov 2020 12:43:52 +0000 Date: Tue, 3 Nov 2020 08:43:51 -0400 From: Jason Gunthorpe To: "Tian, Kevin" CC: "Jiang, Dave" , Bjorn Helgaas , "vkoul@kernel.org" , "Dey, Megha" , "maz@kernel.org" , "bhelgaas@google.com" , "tglx@linutronix.de" , "alex.williamson@redhat.com" , "Pan, Jacob jun" , "Raj, Ashok" , "Liu, Yi L" , "Lu, Baolu" , "Kumar, Sanjay K" , "Luck, Tony" , "jing.lin@intel.com" , "Williams, Dan J" , "kwankhede@nvidia.com" , "eric.auger@redhat.com" , "parav@mellanox.com" , "rafael@kernel.org" , "netanelg@mellanox.com" , "shahafs@mellanox.com" , "yan.y.zhao@linux.intel.com" , "pbonzini@redhat.com" , "Ortiz, Samuel" , "Hossain, Mona" , "dmaengine@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-pci@vger.kernel.org" , "kvm@vger.kernel.org" Subject: Re: [PATCH v4 06/17] PCI: add SIOV and IMS capability detection Message-ID: <20201103124351.GM2620339@nvidia.com> References: <20201030195159.GA589138@bjorn-Precision-5520> <71da5f66-e929-bab1-a1c6-a9ac9627a141@intel.com> <20201030224534.GN2620339@nvidia.com> <20201102132158.GA3352700@nvidia.com> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: BL0PR0102CA0005.prod.exchangelabs.com (2603:10b6:207:18::18) To DM6PR12MB3834.namprd12.prod.outlook.com (2603:10b6:5:14a::12) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from mlx.ziepe.ca (156.34.48.30) by BL0PR0102CA0005.prod.exchangelabs.com (2603:10b6:207:18::18) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3499.18 via Frontend Transport; Tue, 3 Nov 2020 12:43:52 +0000 Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1kZvfD-00FtP6-3p; Tue, 03 Nov 2020 08:43:51 -0400 X-LD-Processed: 43083d15-7273-40c1-b7db-39efd9ccc17a,ExtAddr DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1604407444; bh=VITmViDD5s5KksrgEClyFBFCt+4V1E7TiSIsnAbSL/8=; h=ARC-Seal:ARC-Message-Signature:ARC-Authentication-Results:Date: From:To:CC:Subject:Message-ID:References:Content-Type: Content-Disposition:In-Reply-To:X-ClientProxiedBy:MIME-Version: X-MS-Exchange-MessageSentRepresentingType:X-LD-Processed; b=CJNiQ2y7edfB+SutsDr6bjWrEdovPBeRUU+TYSMbKyU3rpm2kTcO2gJGq4G55hcLN X1XQAkhvZLIpUsmaweQiZuakArT9GyU3bcIeIo0BCvItU9i0NPZsunOaJ2jVASXcgH knuCyUTvnXeNSs99s9HIu1xX3+A4TjS4fMy3VQTRrUF9FggSJ9KK06MLD9w9QSAK7T 7Lot1KjIjwyqubbA9Bsoa6wr3SbCb1YMla4nV5VqArfAHzjq7sAw2ZRsQMR+J99PN4 WENrlQaUh1eel+I1f77X+QRZMAli2lYsswoKsCyHDpwhIRlQ+0XlnsVdB7iroAornT AZ3gcTbtZyUdw== Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Tue, Nov 03, 2020 at 02:49:27AM +0000, Tian, Kevin wrote: > > There is a missing hypercall to allow the guest to do this on its own, > > presumably it will someday be fixed so IMS can work in guests. > > Hypercall is VMM specific, while IMS cap provides a VMM-agnostic > interface so any guest driver (if following the spec) can seamlessly > work on all hypervisors. It is a *VMM* issue, not PCI. Adding a PCI cap to describe a VMM issue is architecturally wrong. IMS *can not work* in any hypervsior without some special hypercall. Just block it in the platform code and forget about the PCI cap. Jason