Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932161AbaLIONf (ORCPT ); Tue, 9 Dec 2014 09:13:35 -0500 Received: from mga03.intel.com ([134.134.136.65]:16309 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753147AbaLIONb (ORCPT ); Tue, 9 Dec 2014 09:13:31 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.07,545,1413270000"; d="scan'208";a="620991591" Message-ID: <54870302.5050703@linux.intel.com> Date: Tue, 09 Dec 2014 22:11:14 +0800 From: Jiang Liu Organization: Intel User-Agent: Mozilla/5.0 (Windows NT 6.2; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Marc Zyngier , Yijing Wang , Bjorn Helgaas , Thomas Gleixner CC: "linux-arm-kernel@lists.infradead.org" , "linux-pci@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Will Deacon , "suravee.suthikulpanit@amd.com" Subject: Re: [PATCH 2/6] PCI/MSI: add hooks to populate the msi_domain field References: <1418069543-21969-1-git-send-email-marc.zyngier@arm.com> <1418069543-21969-3-git-send-email-marc.zyngier@arm.com> <5486585B.40000@huawei.com> <5486C8BA.8030608@arm.com> <5486E3BF.70703@huawei.com> <5486E747.4010804@arm.com> <5486EF4E.5020704@linux.intel.com> <5487012B.4040505@arm.com> In-Reply-To: <5487012B.4040505@arm.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2014/12/9 22:03, Marc Zyngier wrote: > Hi Gerry, > > On 09/12/14 12:47, Jiang Liu wrote: >> On 2014/12/9 20:12, Marc Zyngier wrote: >>> Yijing, >>> >>> On 09/12/14 11:57, Yijing Wang wrote: >>>>>>> +void __weak pcibios_set_phb_msi_domain(struct pci_bus *bus) >>>>>>> +{ >>>>>>> +} >>>>>>> + >>>>>>> +static void pci_set_bus_msi_domain(struct pci_bus *bus) >>>>>>> +{ >>>>>>> + struct pci_dev *bridge = bus->self; >>>>>>> + >>>>>>> + if (!bridge) >>>>>>> + pcibios_set_phb_msi_domain(bus); >>>>>>> + else >>>>>>> + dev_set_msi_domain(&bus->dev, dev_get_msi_domain(&bridge->dev)); >>>>>>> +} >>>>>> >>>>>> >>>>>> Hi Marc, we can not assume pci devices under same phb share the same msi irq domain, >>>>>> now in x86, pci devices under the same phb may associate different msi irq domain. >>>> >>>> Hi Marc, >>>> >>>>> >>>>> Well, this is not supposed to be a perfect solution yet, but instead a >>>>> basis for discussion. What I'd like to find out is: >>>>> >>>>> - What is the minimum granularity for associating a device with its MSI >>>>> domain in existing platforms? >>>> >>>> PCI device, after Gerry's msi irq domain patchset which now in linux-next, >>>> in x86, we will find msi irq domain by pci_dev. >>> >>> Are you *really* associating the MSI domain on a per pci-device basis? >>> That is, you have devices on the same PCI bus talking to different MSI hw? >> Hi Marc, >> This is a little wild:( >> On x86 platform with Intel VT-d(not the case for AMD-v), >> interrupt remapping is tight to DMA remapping (IOMMU) unit. >> For most common cases, IOMMU unit manages PCI bus and its sub-hierarchy. >> But it may also manage a specific PCI device. This is typically used to >> provide QoS for audio device by using dedicated IOMMU unit to avoid >> resource contention on DMA remapping tables. BIOS uses ACPI table to >> report PCI bus/device to IOMMU unit mapping relationship. (To be honest, >> I have no really experience with such a hardware platform yet, just for >> theoretical analysis) >> On the other hand, we now support hierarchy irqdomain. So to >> support per-PCI IOMMU unit case, we need maintain irqdomain at PCI >> device level. >> This piece of code from your [4/6] is flexible enough, which >> retrieves msi_domain from PCI device, then fallback to PCI bus, >> then fallback to platform specific method. >> domain = dev_get_msi_domain(&dev->dev); >> if (!domain && dev->bus->msi) >> domain = dev->bus->msi->domain; >> if (!domain) >> domain = arch_get_pci_msi_domain(dev); > > OK. But what I'd really like to see is a way to setup the > device<->domain binding as early as possible, without having to use more > conditional code in pci_msi_get_domain. > > IOW, can we do something similar to what pci_set_bus_msi_domain and > pci_set_msi_domain do in this patch? Hi Marc, I have checked x86 code, we could set pci_dev->msi_domain when creating PCI devices, just need to find some hook points into PCI core next step. If arch code doesn't set pci_dev->msi_domain, PCI MSI core may provide a default way to set pci_dev->msi_domain. This may make the implementation simpler, I guess:) Thanks! Gerry > > Thanks, > > M. > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/