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 41mHk86BgYzDqBy for ; Thu, 9 Aug 2018 16:03:28 +1000 (AEST) Date: Wed, 8 Aug 2018 22:40:13 -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: <20180809054013.GA20507@infradead.org> References: <20180807062117.GD32709@infradead.org> <20180807135505.GA29034@infradead.org> <2103ecfe52d23cec03f185d08a87bfad9c9d82b5.camel@kernel.crashing.org> <20180808063158.GA2474@infradead.org> <4b596883892b5cb5560bef26fcd249e7107173ac.camel@kernel.crashing.org> <20180808123036.GA2525@infradead.org> <20180808232210-mutt-send-email-mst@kernel.org> <98eb367ce322ad84baa31e3c7beffc4a42be8458.camel@kernel.crashing.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <98eb367ce322ad84baa31e3c7beffc4a42be8458.camel@kernel.crashing.org> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, Aug 09, 2018 at 08:13:32AM +1000, Benjamin Herrenschmidt wrote: > > > - if (xen_domain()) > > > + if (xen_domain() || pseries_secure_vm()) > > > return true; > > > > I don't think it's pseries specific actually. E.g. I suspect AMD SEV > > might benefit from the same kind of hack. > > As long as they can provide the same guarantee that the DMA ops are > completely equivalent between virtio and other PCI devices, at least on > the same bus, ie, we don't have to go hack special DMA ops. > > I think the latter is really what Christoph wants to avoid for good > reasons. Yes. I also generally want to avoid too much arch specific magic. FYI, I'm off to a week-long vacation today, don't expect quick replies.