From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jike Song Subject: Re: [RFC PATCH v4 0/3] Add Mediated device support[was: Add vGPU support] Date: Tue, 31 May 2016 10:29:10 +0800 Message-ID: <7195005e-6461-25fb-9ed9-ec5906b93bec@intel.com> References: <1464119897-10844-1-git-send-email-kwankhede@nvidia.com> <20160525074356.52121ab8@ul30vt.home> <20160527085443.27f937eb@t450s.home> <20160528085630.0fb79cc7@ul30vt.home> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: Kirti Wankhede , "pbonzini@redhat.com" , "kraxel@redhat.com" , "cjia@nvidia.com" , "qemu-devel@nongnu.org" , "kvm@vger.kernel.org" , "Ruan, Shuai" , "Lv, Zhiyuan" , "bjsdjshi@linux.vnet.ibm.com" To: Alex Williamson , "Tian, Kevin" Return-path: Received: from mga11.intel.com ([192.55.52.93]:44132 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1423604AbcEaC3n (ORCPT ); Mon, 30 May 2016 22:29:43 -0400 In-Reply-To: <20160528085630.0fb79cc7@ul30vt.home> Sender: kvm-owner@vger.kernel.org List-ID: On 05/28/2016 10:56 PM, Alex Williamson wrote: > On Fri, 27 May 2016 22:43:54 +0000 > "Tian, Kevin" wrote: > >> >> My impression was that you don't like hypervisor specific thing in VFIO, >> which makes it a bit tricky to accomplish those tasks in kernel. If we >> can add Xen specific logic directly in VFIO (like vfio-iommu-xen you >> mentioned), the whole thing would be easier. > > If vfio is hosted in dom0, then Xen is the platform and we need to > interact with the hypervisor to manage the iommu. That said, there are > aspects of vfio that do not seem to map well to a hypervisor managed > iommu or a Xen-like hypervisor. For instance, how does dom0 manage > iommu groups and what's the distinction of using vfio to manage a > userspace driver in dom0 versus managing a device for another domain. > In the case of kvm, vfio has no dependency on kvm, there is some minor > interaction, but we're not running on kvm and it's not appropriate to > use vfio as a gateway to interact with a hypervisor that may or may not > exist. Thanks, Hi Alex, Beyond iommu, there are other aspects vfio need to interact with Xen? e.g. to pass-through MMIO, one have to call hypercalls to establish EPT mappings. -- Thanks, Jike