From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 41hsJc3HFxzF1P8 for ; Sat, 4 Aug 2018 02:02:56 +1000 (AEST) Date: Fri, 3 Aug 2018 09:02:46 -0700 From: Christoph Hellwig To: Benjamin Herrenschmidt Cc: Christoph Hellwig , "Michael S. Tsirkin" , Will Deacon , Anshuman Khandual , virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, aik@ozlabs.ru, robh@kernel.org, joe@perches.com, elfring@users.sourceforge.net, david@gibson.dropbear.id.au, jasowang@redhat.com, mpe@ellerman.id.au, linuxram@us.ibm.com, haren@linux.vnet.ibm.com, paulus@samba.org, srikar@linux.vnet.ibm.com, robin.murphy@arm.com, jean-philippe.brucker@arm.com, marc.zyngier@arm.com Subject: Re: [RFC 0/4] Virtio uses DMA API for all devices Message-ID: <20180803160246.GA13794@infradead.org> References: <20180801083639.GF26378@infradead.org> <26c1d3d50d8e081eed44fe9940fbefed34598cbd.camel@kernel.crashing.org> <20180802182959-mutt-send-email-mst@kernel.org> <82ccef6ec3d95ee43f3990a4a2d0aea87eb45e89.camel@kernel.crashing.org> <20180802200646-mutt-send-email-mst@kernel.org> <20180802225738-mutt-send-email-mst@kernel.org> <20180803070507.GA1344@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, Aug 03, 2018 at 10:58:36AM -0500, Benjamin Herrenschmidt wrote: > On Fri, 2018-08-03 at 00:05 -0700, Christoph Hellwig wrote: > > > 2- Make virtio use the DMA API with our custom platform-provided > > > swiotlb callbacks when needed, that is when not using IOMMU *and* > > > running on a secure VM in our case. > > > > And total NAK the customer platform-provided part of this. We need > > a flag passed in from the hypervisor that the device needs all bus > > specific dma api treatment, and then just use the normal plaform > > dma mapping setup. > > Christoph, as I have explained already, we do NOT have a way to provide > such a flag as neither the hypervisor nor qemu knows anything about > this when the VM is created. Well, if your setup is so fucked up I see no way to support it in Linux. Let's end the discussion right now then.