From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38909) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dJzoQ-0003Tv-1L for qemu-devel@nongnu.org; Sun, 11 Jun 2017 06:09:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dJzoM-00008e-Se for qemu-devel@nongnu.org; Sun, 11 Jun 2017 06:09:37 -0400 Received: from mx1.redhat.com ([209.132.183.28]:4035) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dJzoM-00008R-N1 for qemu-devel@nongnu.org; Sun, 11 Jun 2017 06:09:34 -0400 Date: Sun, 11 Jun 2017 13:09:26 +0300 From: "Michael S. Tsirkin" Message-ID: <20170611130710-mutt-send-email-mst@kernel.org> References: <1496404254-17429-3-git-send-email-peterx@redhat.com> <20170602194523-mutt-send-email-mst@kernel.org> <20170605030725.GF4056@pxdev.xzpeter.org> <20170606234705.GG13397@umbus.fritz.box> <20170607034443.GA7983@pxdev.xzpeter.org> <20170607160445-mutt-send-email-mst@kernel.org> <20170608061150.GA3628@pxdev.xzpeter.org> <20170608215918-mutt-send-email-mst@kernel.org> <20170609015847.GG3628@pxdev.xzpeter.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170609015847.GG3628@pxdev.xzpeter.org> Subject: Re: [Qemu-devel] [PATCH 2/3] exec: simplify address_space_get_iotlb_entry List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Xu Cc: David Gibson , Paolo Bonzini , qemu-devel@nongnu.org, Maxime Coquelin , Jason Wang , Alex Williamson On Fri, Jun 09, 2017 at 09:58:47AM +0800, Peter Xu wrote: > > > The problem is that when I was fixing the problem that vhost had with > > > PT (a764040, "exec: abstract address_space_do_translate()"), I did > > > broke the IOTLB translation a bit (it was using page masks). IMHO we > > > need to fix it first for correctness (patch 1/2). > > > > > > For patch 3, if we can have Jason's patch to allow dynamic > > > iommu_platform switching, that'll be the best, then I can rewrite > > > patch 3 with the switching logic rather than caching anything. But > > > IMHO that can be separated from patch 1/2 if you like. > > > > > > Or do you have better suggestion on how should we fix it? > > > > > > Thanks, > > > > Can we drop masks completely and replace with length? I think we > > should do that instead of trying to fix masks. > > Do you mean to modify IOMMUTLBEntry.addr_mask into length? I think it's better than alternatives. > Again, I am not sure this is good... At least we need to get ack from > David since spapr should be the initial user of it, and possibly also > Alex since vfio should be assuming that (IIUC both in QEMU and kernel) > addr_mask is page masks rather than arbirary length. > > (CC Alex) > > Thanks, Callbacks that need powers of two can easily split up the range. > -- > Peter Xu