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<6e478a9e-2051-c0cd-b6fd-624ff5ef0f53@redhat.com> <20201020135439.GH6219@nvidia.com> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: BL1PR13CA0185.namprd13.prod.outlook.com (2603:10b6:208:2be::10) 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 BL1PR13CA0185.namprd13.prod.outlook.com (2603:10b6:208:2be::10) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3499.10 via Frontend Transport; Tue, 20 Oct 2020 14:05:05 +0000 Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1kUsG8-002wfN-Dg; Tue, 20 Oct 2020 11:05:04 -0300 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1603202665; bh=MEW8D0/o+7K7YrbY2tkFoHb2jEAToYpLgb9CmfJwM8U=; 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; b=FbYIu8qNblFZjUMLRuiQnmCWTtOg848La+o8HZNiO+ygsBLHJJm5erGRFU1sGWnZx HSwWs9g6znlJl0ftqhoNwEQLunhwZhmMpO1IxuYAg9rwf6GbDcZe7fZ1Ym3sWNVZfX BVyJKpNdnH98fCKeLaZLkwpr4xPwLvUjrAmm+9f0xh7a5+DxYheLXGW4U69RrG/wlj ZoEWmqmhE6NFRNBNWmWctgxmM0Qvcv4G4a3W/Eg2Tzi/9lZTqg9oFWea3qk6PGbZ+a zH7FMEPgcW2lGGXGRGNqId5igPrBdwG5Pm+MpD8fQvwX+DDNPCTdL+LOhS24J3ZPNQ Fre/bdLakRYww== Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, Oct 20, 2020 at 02:00:31PM +0000, Liu, Yi L wrote: > > From: Jason Gunthorpe > > Sent: Tuesday, October 20, 2020 9:55 PM > > > > On Tue, Oct 20, 2020 at 09:40:14AM +0000, Liu, Yi L wrote: > > > > > > See previous discussion with Kevin. If I understand correctly, you expect a > > shared > > > > L2 table if vDPA and VFIO device are using the same PASID. > > > > > > L2 table sharing is not mandatory. The mapping is the same, but no need to > > > assume L2 tables are shared. Especially for VFIO/vDPA devices. Even within > > > a passthru framework, like VFIO, if the attributes of backend IOMMU are not > > > the same, the L2 page table are not shared, but the mapping is the same. > > > > I think not being able to share the PASID shows exactly why this VFIO > > centric approach is bad. > > no, I didn't say PASID is not sharable. My point is sharing L2 page table is > not mandatory. IMHO a PASID should be 1:1 with a page table, what does it even mean to share a PASID but have different page tables? Jason