From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [RFC V2] virtio: Add platform specific DMA API translation for virito devices Date: Mon, 4 Jun 2018 19:34:19 +0300 Message-ID: <20180604193310-mutt-send-email-mst__29235.345303505$1528129959$gmane$org@kernel.org> References: <20180522063317.20956-1-khandual@linux.vnet.ibm.com> <20180523213703-mutt-send-email-mst@kernel.org> <20180604153558-mutt-send-email-mst@kernel.org> <20180604125530.GA16378@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Benjamin Herrenschmidt Cc: robh@kernel.org, mpe@ellerman.id.au, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Christoph Hellwig , joe@perches.com, david@gibson.dropbear.id.au, linuxppc-dev@lists.ozlabs.org, elfring@users.sourceforge.net, Anshuman Khandual List-Id: virtualization@lists.linuxfoundation.org On Mon, Jun 04, 2018 at 11:14:36PM +1000, Benjamin Herrenschmidt wrote: > On Mon, 2018-06-04 at 05:55 -0700, Christoph Hellwig wrote: > > On Mon, Jun 04, 2018 at 03:43:09PM +0300, Michael S. Tsirkin wrote: > > > Another is that given the basic functionality is in there, optimizations > > > can possibly wait until per-device quirks in DMA API are supported. > > > > We have had per-device dma_ops for quite a while. > > I've asked Ansuman to start with a patch that converts virtio to use > DMA ops always, along with an init quirk to hookup "direct" ops when > the IOMMU flag isn't set. > > This will at least remove that horrid duplication of code path we have > in there. > > Then we can just involve the arch in that init quirk so we can chose an > alternate set of ops when running a secure VM. > > This is completely orthogonal to whether an iommu exist qemu side or > not, and should be entirely solved on the Linux side. > > Cheers, > Ben. Sounds good to me. -- MST