From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thiago Jung Bauermann Subject: Re: [RFC PATCH] virtio_ring: Use DMA API if guest memory is encrypted Date: Mon, 04 Feb 2019 16:15:41 -0200 Message-ID: <875ztzxvw2.fsf@morokweng.localdomain> References: <87zhrj8kcp.fsf@morokweng.localdomain> <87womn8inf.fsf@morokweng.localdomain> <20190129134750-mutt-send-email-mst@kernel.org> <6c68f7f7-1b28-6eba-9b8b-2c32efac9701@redhat.com> <20190129213137-mutt-send-email-mst@kernel.org> <20190130074427.GA29516@lst.de> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-reply-to: <20190130074427.GA29516@lst.de> Sender: linux-kernel-owner@vger.kernel.org To: Christoph Hellwig Cc: "Michael S. Tsirkin" , Jason Wang , virtualization@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, David Gibson , Alexey Kardashevskiy , Paul Mackerras , Benjamin Herrenschmidt , Ram Pai , Jean-Philippe Brucker List-Id: iommu@lists.linux-foundation.org Christoph Hellwig writes: > On Tue, Jan 29, 2019 at 09:36:08PM -0500, Michael S. Tsirkin wrote: >> This has been discussed ad nauseum. virtio is all about compatibility. >> Losing a couple of lines of code isn't worth breaking working setups. >> People that want "just use DMA API no tricks" now have the option. >> Setting a flag in a feature bit map is literally a single line >> of code in the hypervisor. So stop pushing for breaking working >> legacy setups and just fix it in the right place. > > I agree with the legacy aspect. What I am missing is an extremely > strong wording that says you SHOULD always set this flag for new > hosts, including an explanation why. My understanding of ACCESS_PLATFORM is that it means "this device will behave in all aspects like a regular device attached to this bus". Is that it? Therefore it should be set because it's the sane thing to do? -- Thiago Jung Bauermann IBM Linux Technology Center