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 41l4Lz5cqdzDqBx for ; Tue, 7 Aug 2018 16:27:39 +1000 (AEST) Date: Mon, 6 Aug 2018 23:27:31 -0700 From: Christoph Hellwig To: Benjamin Herrenschmidt Cc: "Michael S. Tsirkin" , Christoph Hellwig , 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: <20180807062731.GA23159@infradead.org> References: <20180803220443-mutt-send-email-mst@kernel.org> <051fd78e15595b414839fa8f9d445b9f4d7576c6.camel@kernel.crashing.org> <20180805031046-mutt-send-email-mst@kernel.org> <20180806164106-mutt-send-email-mst@kernel.org> <20180806233024-mutt-send-email-mst@kernel.org> <0967fc30001323e6e38ed12c8dba8ee3d1aa13f5.camel@kernel.crashing.org> <20180807002857-mutt-send-email-mst@kernel.org> <93518075238a07e9f011774d89bdc652c083f1ba.camel@kernel.crashing.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <93518075238a07e9f011774d89bdc652c083f1ba.camel@kernel.crashing.org> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, Aug 07, 2018 at 08:13:56AM +1000, Benjamin Herrenschmidt wrote: > It would be indeed ideal if all we had to do was setup some kind of > bus_dma_mask on all PCI devices and have virtio automagically insert > swiotlb when necessary. For 4.20 I plan to remove the swiotlb ops and instead do the bounce buffering in the common code, including a direct call to the direct ops to avoid retpoline overhead. For that you still need a flag in virtio that instead of blindly working physical addresses it needs to be treated like a real device in terms of DMA. And for powerpc to make use of that I need to get the dma series I posted last week reviewed and included, otherwise powerpc will have to be excepted (like arm, where rmk didn't like the way the code was factored, everything else has already been taken care of). https://lists.linuxfoundation.org/pipermail/iommu/2018-July/028989.html