From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56657) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bfhoV-0003VQ-MD for qemu-devel@nongnu.org; Fri, 02 Sep 2016 02:18:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bfhoS-00008t-Ap for qemu-devel@nongnu.org; Fri, 02 Sep 2016 02:18:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58608) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bfhoS-00008k-52 for qemu-devel@nongnu.org; Fri, 02 Sep 2016 02:18:52 -0400 Date: Fri, 2 Sep 2016 14:18:47 +0800 From: Peter Xu Message-ID: <20160902061847.GC18496@pxdev.xzpeter.org> References: <1472526419-5900-11-git-send-email-jasowang@redhat.com> <20160829213702.536df0df@t450s.home> <76fb2f05-4f9c-3e91-d301-3e0a6d4cabaf@redhat.com> <20160901022929.GA3558@pxdev.xzpeter.org> <20160831204342.77fbe728@t450s.home> <20160901035848.GC3558@pxdev.xzpeter.org> <20160902141504.05950823@voom.fritz.box> <20160902053733.GB10595@pxdev.xzpeter.org> <20160902161014.7e53530b@voom.fritz.box> <20160902061557.GB18496@pxdev.xzpeter.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20160902061557.GB18496@pxdev.xzpeter.org> Subject: Re: [Qemu-devel] [PATCH for 2.8 10/11] Revert "intel_iommu: Throw hw_error on notify_started" List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Gibson Cc: Alex Williamson , Jason Wang , mst@redhat.com, qemu-devel@nongnu.org, pbonzini@redhat.com, cornelia.huck@de.ibm.com, wexu@redhat.com, vkaplans@redhat.com On Fri, Sep 02, 2016 at 02:15:57PM +0800, Peter Xu wrote: > > No, implement the full notifier, and a listener which only wants the > > invalidates can just ignore callbacks which add new mappings. > > > > As I said, you'll need this to get VFIO working with vIOMMU which > > someone is bound to want soon enough anyway. > > But for vhost cases, we do not need CM bit enabled. That might be the > difference? > > I think we need to have vhost working even without CM bit. Device > IOTLB should be able to achieve that. The problem is that, IMHO we should be very careful on enabling CM bit. After enabling it, system might get slower (though I haven't tried it yet), or even very slow? So maybe we will only enable it when really needed (e.g., to do device passthrough and build the shadow table). -- peterx