From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58626) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1f6BZS-00086V-5U for qemu-devel@nongnu.org; Wed, 11 Apr 2018 04:57:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1f6BZN-0005pa-BO for qemu-devel@nongnu.org; Wed, 11 Apr 2018 04:57:38 -0400 Received: from mga03.intel.com ([134.134.136.65]:28504) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1f6BZN-0005om-0U for qemu-devel@nongnu.org; Wed, 11 Apr 2018 04:57:33 -0400 Date: Wed, 11 Apr 2018 16:55:25 +0800 From: Tiwei Bie Message-ID: <20180411085525.ius2cj2z2e2j6vs7@debian> References: <20180411072027.5656-1-tiwei.bie@intel.com> <20180411080036.GD13887@xz-mi> <20180411082556.3hjaubnnw3hbpnp3@debian> <20180411083716.GE13887@xz-mi> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20180411083716.GE13887@xz-mi> Subject: Re: [Qemu-devel] [RFC] vhost-user: introduce F_NEED_ALL_IOTLB protocol feature List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Xu Cc: mst@redhat.com, jasowang@redhat.com, qemu-devel@nongnu.org, dan.daly@intel.com, cunming.liang@intel.com, zhihong.wang@intel.com On Wed, Apr 11, 2018 at 04:37:16PM +0800, Peter Xu wrote: > On Wed, Apr 11, 2018 at 04:25:56PM +0800, Tiwei Bie wrote: > > On Wed, Apr 11, 2018 at 04:00:36PM +0800, Peter Xu wrote: > > > On Wed, Apr 11, 2018 at 03:20:27PM +0800, Tiwei Bie wrote: > > > > > > [...] > > > > > > > This is just a RFC for now. It seems that, it doesn't work > > > > as expected when guest is using kernel driver (To handle > > > > this case, it seems that some RAM regions' events also need > > > > to be listened). Any comments would be appreciated! Thanks! > > > > > > Hi, Tiwei, > > > > > > What's your kernel command line in the guest? Is iommu=pt there? > > > > Yeah, you are right! The related things in kernel command line are: > > > > iommu=pt intel_iommu=on > > > > Hmm, how will this param affect vIOMMU's behaviour?.. > > If iommu=pt is there, guest kernel will try to bypass IOMMU, the IOMMU > regions will be disabled completely in that case, hence it's very > possible that your IOMMU memory listeners won't get anything useful. > > Maybe you can consider removing iommu=pt in the guest parameter to see > whether the guest kernel driver could work. Cool. I'll give it a try! Considering we may also need to handle the iommu=pt case, is there any event in QEMU can be used to know whether the IOMMU regions are disabled or enabled by the guest? Best regards, Tiwei Bie > > -- > Peter Xu