From mboxrd@z Thu Jan 1 00:00:00 1970 From: Manish Subject: Re: [PATCH for 4.6 13/13] xen/iommu: smmu: Add Xen specific code to be able to use the driver Date: Thu, 19 Feb 2015 08:25:46 +0530 Message-ID: <54E550B2.1090605@caviumnetworks.com> References: <1418760534-18163-1-git-send-email-julien.grall@linaro.org> <1418760534-18163-14-git-send-email-julien.grall@linaro.org> <54E3E49D.7000109@caviumnetworks.com> <54E47BE2.5030908@linaro.org>, <54E47D60.7010608@linaro.org> <1424280633785.32004@caviumnetworks.com> <54E4D85C.6090600@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta5.messagelabs.com ([195.245.231.135]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1YOHHe-00049m-5N for xen-devel@lists.xenproject.org; Thu, 19 Feb 2015 02:56:10 +0000 In-Reply-To: <54E4D85C.6090600@linaro.org> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Julien Grall , "Jaggi, Manish" , "xen-devel@lists.xenproject.org" Cc: "stefano.stabellini@citrix.com" , "tim@xen.org" , "ian.campbell@citrix.com" List-Id: xen-devel@lists.xenproject.org On 18/02/15 11:52 pm, Julien Grall wrote: > > > On 18/02/2015 17:30, Jaggi, Manish wrote: >> [manish] There are general comments on the data structures >> (a) I don't see a use case where for same domain (VM) there would be >> different context banks , so linked list may not be required. > > I guess you mean the list in arm_smmu_xen_domain? All the devices > pass-through to a domain may not be protected by the same SMMU. > Therefore the context banks are different. you are right. For each smmu the context bank instance for a xen domain is duplicated with just a change in context bank id. I was thinking can it be minimized. > > Also, for now a context is allocated per-device. It should be rework > to share the context between multiple device protected by the same > SMMU and pass-through to the same domain. Yes, this is exactly I an doing at my end. > >> (b) Also iommu group may not be relevant for the same reason. >> I am curious to find the use cases. > > The iommu_group is used to store the configuration of the device > protected by an SMMU (i.e the stream ids associated to this domain). > > I'm a bit surprised that you think they are not useful... How do we create an iommu_group in xen ? AFAIK an iommu group is a vfio group in linux which is assigned to a a VM. lkvm run -m 512 -k home/Image ... --vfio-groups=48, 51 For Xen There are 2 ways of attaching devices using xl pci-attach or in domU cfg file. Should they create different iommu_groups ? > > Regards, >