From mboxrd@z Thu Jan 1 00:00:00 1970 From: Manish Jaggi Subject: Re: RFC: [PATCH 1/3] Enhance platform support for PCI Date: Wed, 25 Feb 2015 08:03:00 +0530 Message-ID: <54ED345C.8020902@caviumnetworks.com> References: <54E71BDE.5020106@caviumnetworks.com> <54E7229C.7000301@linaro.org> <54E72452.3090801@caviumnetworks.com> <54E72688.9010005@linaro.org> <54E729F1.6000804@caviumnetworks.com> <54E73010.2050902@caviumnetworks.com> <1424439941.30924.243.camel@citrix.com> <54E74135.4040302@caviumnetworks.com> <1424443185.30924.268.camel@citrix.com> <54EB0813.20909@caviumnetworks.com> <54EB0B7D.6060909@linaro.org> <54EB1401.2050609@caviumnetworks.com> <54EB440C.9010806@linaro.org> <54EB5F86.40607@caviumnetworks.com> <54EB9E13.7060802@linaro.org> <54EBC47E.4040801@caviumnetworks.com> <54EC8007.1090405@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <54EC8007.1090405@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 Cc: prasun.kapoor@cavium.com, Ian Campbell , "Kumar, Vijaya" , xen-devel@lists.xen.org, "Stefano Stabellini (Stefano.Stabellini@citrix.com)" , Jan Beulich List-Id: xen-devel@lists.xenproject.org On 24/02/15 7:13 pm, Julien Grall wrote: > On 24/02/15 00:23, Manish Jaggi wrote: >>> Because you have to parse all the device tree to remove the reference >>> to the second ITS. It's pointless and can be difficult to do it. >>> >> Could you please describe the case where it is difficult > You have to parse every node in the device tree and replace the > msi-parent properties with only one ITS. Thats the idea. > >>> If you are able to emulate on ITS, you can do it for multiple one. >> keeping it simple and similar across dom0/domUs >> Consider a case where a domU is assigned two PCI devices which are >> attached to different nodes. (Node is an entity having its own cores are >> host controllers). > The DOM0 view and guest view of the hardware are different. > > In the case of DOM0, we want to expose the same hardware layout as the > host. So if there is 2 ITS then we should expose the 2 ITS. AFAIK Xen has a microkernel design and timer/mmu/smmu/gic/its are handled by xen and a virtualized interface is provided to the guest. So if none of SMMU in the layout of host is presented to dom0 the same can be valid for multiple ITS. > > In the case of the Guest, we (Xen) controls the memory layout. For Dom0 as well. > Therefore > we can expose only one ITS. If we follow 2 ITS in dom0 and 1 ITS in domU, how do u expect the Xen GIC ITS emulation driver to work. It should check that request came from a dom0 handle it differently. I think this would be *difficult*. > >>>>> IHMO, any ITS trap before this is wrong. >>>> AFAIK guest always sees a virtual ITS, could you please explain what is >>>> wrong in trapping. >>> I never say the trapping is wrong in all case.... The "before" was >>> here for any trap before the PCI has been added to Xen is, IHMO, wrong. >>> >> There is no trap before. > So I still don't understand why you need to parse the device tree node > for PCI device at boot time... > > If it doesn't trap before, you should not need to know the PCI. > > Regards, >