From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37358) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cT2eN-0004Dm-Uh for qemu-devel@nongnu.org; Mon, 16 Jan 2017 03:28:24 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cT2eJ-0004xI-34 for qemu-devel@nongnu.org; Mon, 16 Jan 2017 03:28:23 -0500 Received: from mx1.redhat.com ([209.132.183.28]:44726) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cT2eI-0004wf-Tv for qemu-devel@nongnu.org; Mon, 16 Jan 2017 03:28:19 -0500 References: <1484276800-26814-1-git-send-email-peterx@redhat.com> <1484276800-26814-13-git-send-email-peterx@redhat.com> <397afe71-b4cd-ba48-6d76-a7b27e1128f9@redhat.com> <20170116074359.GD30108@pxdev.xzpeter.org> <8efe289b-e26a-60bc-51ae-582beff069fb@redhat.com> <20170116081833.GJ30108@pxdev.xzpeter.org> From: Jason Wang Message-ID: Date: Mon, 16 Jan 2017 16:28:10 +0800 MIME-Version: 1.0 In-Reply-To: <20170116081833.GJ30108@pxdev.xzpeter.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH RFC v3 12/14] intel_iommu: do replay when context invalidate List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Xu Cc: tianyu.lan@intel.com, kevin.tian@intel.com, mst@redhat.com, jan.kiszka@siemens.com, bd.aviv@gmail.com, qemu-devel@nongnu.org, alex.williamson@redhat.com On 2017=E5=B9=B401=E6=9C=8816=E6=97=A5 16:18, Peter Xu wrote: > On Mon, Jan 16, 2017 at 03:52:10PM +0800, Jason Wang wrote: >> >> On 2017=E5=B9=B401=E6=9C=8816=E6=97=A5 15:43, Peter Xu wrote: >>> On Mon, Jan 16, 2017 at 01:53:54PM +0800, Jason Wang wrote: >>>> On 2017=E5=B9=B401=E6=9C=8813=E6=97=A5 11:06, Peter Xu wrote: >>>>> Before this one we only invalidate context cache when we receive co= ntext >>>>> entry invalidations. However it's possible that the invalidation al= so >>>>> contains a domain switch (only if cache-mode is enabled for vIOMMU)= . >>>> So let's check for CM before replaying? >>> When CM is not set, there should have no device needs >>> IOMMU_NOTIFIER_MAP notifies. So IMHO it won't hurt if we replay here >>> (so the notifier_list will only contain UNMAP notifiers at most, and >>> sending UNMAP to those devices should not affect them at all). >>> >>> If we check CM before replay, it'll be faster when guest change iommu >>> domain for a specific device. But after all this kind of operation is >>> extremely rare, while if we check CM bit, we have a "assumption" in >>> the code that MAP is depending on CM. In that case, to make the codes >>> cleaner, I'd slightly prefer not check it here. How do you think? >> Ok, I think maybe it's better to add a comment here. > How about this? > > + /* > + * So a device is moving out of (or moving into) a > + * domain, a replay() suites here to notify all the > + * IOMMU_NOTIFIER_MAP registers about this change. > + * This won't bring bad even if we have no such > + * notifier registered - the IOMMU notification > + * framework will skip MAP notifications if that > + * happened. > + */ > memory_region_iommu_replay_all(&vtd_as->iommu); > > Thanks, > > -- peterx I'm fine with this. Thanks