From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH V2 RFC] fixup! virtio: convert to use DMA api Date: Wed, 27 Apr 2016 16:58:51 +0200 Message-ID: <20160427145851.GJ17926@8bytes.org> References: <1461245745-6710-1-git-send-email-mst@redhat.com> <20160421135416.GE11775@citrix.com> <1461759501.118304.149.camel@infradead.org> <20160427153345-mutt-send-email-mst@redhat.com> <20160427142331.GH17926@8bytes.org> <20160427173603-mutt-send-email-mst@redhat.com> <20160427175031-mutt-send-email-mst@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20160427175031-mutt-send-email-mst@redhat.com> Sender: linux-kernel-owner@vger.kernel.org To: "Michael S. Tsirkin" Cc: Andy Lutomirski , David Woodhouse , Kevin Wolf , Wei Liu , Andy Lutomirski , qemu-block@nongnu.org, Christian Borntraeger , Jason Wang , Stefano Stabellini , "qemu-devel@nongnu.org Developers" , peterx@redhat.com, "linux-kernel@vger.kernel.org" , Amit Shah , iommu@lists.linux-foundation.org, Stefan Hajnoczi , kvm list , Cornelia Huck , Paolo Bonzini , Linux Virtualization , Anthony PERARD List-Id: iommu@lists.linux-foundation.org On Wed, Apr 27, 2016 at 05:54:57PM +0300, Michael S. Tsirkin wrote: > Point is, QEMU is not the only virtio implementation out there. > So we can't know no virtio implementations have an IOMMU as long as > linux supports this IOMMU. > virtio always used physical addresses since it was born and if it > changes that it must do this in a way that does not break existing > users. FWIW, virtio in qemu can continue to just use physical addresses. But qemu needs to advertise that fact correctly to the OS in the DMAR table. This way old kernels (where virtio does not use DMA-API) will also continue to work on the fixed qemu. Joerg From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44490) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1avQvZ-0001VQ-9z for qemu-devel@nongnu.org; Wed, 27 Apr 2016 10:58:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1avQvY-0005no-JW for qemu-devel@nongnu.org; Wed, 27 Apr 2016 10:58:57 -0400 Date: Wed, 27 Apr 2016 16:58:51 +0200 From: Joerg Roedel Message-ID: <20160427145851.GJ17926@8bytes.org> References: <1461245745-6710-1-git-send-email-mst@redhat.com> <20160421135416.GE11775@citrix.com> <1461759501.118304.149.camel@infradead.org> <20160427153345-mutt-send-email-mst@redhat.com> <20160427142331.GH17926@8bytes.org> <20160427173603-mutt-send-email-mst@redhat.com> <20160427175031-mutt-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160427175031-mutt-send-email-mst@redhat.com> Subject: Re: [Qemu-devel] [PATCH V2 RFC] fixup! virtio: convert to use DMA api List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: Andy Lutomirski , David Woodhouse , Kevin Wolf , Wei Liu , Andy Lutomirski , qemu-block@nongnu.org, Christian Borntraeger , Jason Wang , Stefano Stabellini , "qemu-devel@nongnu.org Developers" , peterx@redhat.com, "linux-kernel@vger.kernel.org" , Amit Shah , iommu@lists.linux-foundation.org, Stefan Hajnoczi , kvm list , Cornelia Huck , Paolo Bonzini , Linux Virtualization , Anthony PERARD On Wed, Apr 27, 2016 at 05:54:57PM +0300, Michael S. Tsirkin wrote: > Point is, QEMU is not the only virtio implementation out there. > So we can't know no virtio implementations have an IOMMU as long as > linux supports this IOMMU. > virtio always used physical addresses since it was born and if it > changes that it must do this in a way that does not break existing > users. FWIW, virtio in qemu can continue to just use physical addresses. But qemu needs to advertise that fact correctly to the OS in the DMAR table. This way old kernels (where virtio does not use DMA-API) will also continue to work on the fixed qemu. Joerg