From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:52835) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TMIup-0005bv-Ki for qemu-devel@nongnu.org; Thu, 11 Oct 2012 09:35:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TMIui-0002Vi-N7 for qemu-devel@nongnu.org; Thu, 11 Oct 2012 09:35:07 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59817) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TMIui-0002VZ-F3 for qemu-devel@nongnu.org; Thu, 11 Oct 2012 09:35:00 -0400 Message-ID: <5076CAFE.8060205@redhat.com> Date: Thu, 11 Oct 2012 15:34:54 +0200 From: Avi Kivity MIME-Version: 1.0 References: <1349962023-560-1-git-send-email-avi@redhat.com> <1349962023-560-8-git-send-email-avi@redhat.com> <20121011133155.GA8983@redhat.com> In-Reply-To: <20121011133155.GA8983@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC v1 7/7] vhost: abort if an emulated iommu is used List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: qemu-devel@nongnu.org, liu ping fan , Blue Swirl , Alex Williamson , Anthony Liguori , Paolo Bonzini On 10/11/2012 03:31 PM, Michael S. Tsirkin wrote: > On Thu, Oct 11, 2012 at 03:27:03PM +0200, Avi Kivity wrote: >> vhost doesn't support guest iommus yet, indicate it to the user >> by gently depositing a core on their disk. >> >> Signed-off-by: Avi Kivity > > Actually there is no problem. virtio bypasses an IOMMU, > so vhost works fine by writing into guest memory directly. > > So I don't think we need this patch. The pci subsystem should set up the iommu so that it ignores virtio devices. If it does, an emulated iommu will not reach vhost. If it doesn't, then it will, and the assert() will alert us that we have a bug. -- error compiling committee.c: too many arguments to function