From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 41l4rQ71bjzDqZm for ; Tue, 7 Aug 2018 16:49:42 +1000 (AEST) Message-ID: <7622efcbb499919616f165266968565b1d329a91.camel@kernel.crashing.org> Subject: Re: [RFC 0/4] Virtio uses DMA API for all devices From: Benjamin Herrenschmidt To: Christoph Hellwig Cc: "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 Date: Tue, 07 Aug 2018 16:44:01 +1000 In-Reply-To: <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> <20180807062731.GA23159@infradead.org> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, 2018-08-06 at 23:27 -0700, Christoph Hellwig wrote: > 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. But you will still call the swiotlb infrastructure, right ? IE, I sitll need to control where/how the swiotlb "pool" is allocated. > > 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 Yes, I saw your series. I'm just back from a week of travel, I plan to start reviewing it this week if Michael doesn't beat me to it. Cheers, Ben.