From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933024AbdBVPOJ (ORCPT ); Wed, 22 Feb 2017 10:14:09 -0500 Received: from aserp1040.oracle.com ([141.146.126.69]:16802 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932928AbdBVPNx (ORCPT ); Wed, 22 Feb 2017 10:13:53 -0500 Subject: Re: [PATCH] xen: do not re-use pirq number cached in pci device msi msg data To: Bjorn Helgaas References: <04f2a09f-59be-a720-bc98-4afb53171790@oracle.com> <20170113200751.20125-1-ddstreet@ieee.org> <20170113223035.GE23066@char.us.oracle.com> <0c2b4d6a-93e7-90a2-ffaf-fa423fb022d5@suse.com> <72f8b025-e858-5e54-d900-50fbec46fea6@oracle.com> <20170222142810.GA28359@bhelgaas-glaptop.roam.corp.google.com> Cc: Juergen Gross , Dan Streetman , Konrad Rzeszutek Wilk , Stefano Stabellini , Dan Streetman , Bjorn Helgaas , xen-devel@lists.xenproject.org, linux-kernel , linux-pci@vger.kernel.org From: Boris Ostrovsky Message-ID: <3379a82f-04b7-152a-1577-bf99b1c638cc@oracle.com> Date: Wed, 22 Feb 2017 10:14:53 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.6.0 MIME-Version: 1.0 In-Reply-To: <20170222142810.GA28359@bhelgaas-glaptop.roam.corp.google.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Source-IP: aserv0021.oracle.com [141.146.126.233] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/22/2017 09:28 AM, Bjorn Helgaas wrote: > On Tue, Feb 21, 2017 at 10:58:39AM -0500, Boris Ostrovsky wrote: >> On 02/21/2017 10:45 AM, Juergen Gross wrote: >>> On 21/02/17 16:31, Dan Streetman wrote: >>>> On Fri, Jan 13, 2017 at 5:30 PM, Konrad Rzeszutek Wilk >>>> wrote: >>>>> On Fri, Jan 13, 2017 at 03:07:51PM -0500, Dan Streetman wrote: >>>>>> Revert the main part of commit: >>>>>> af42b8d12f8a ("xen: fix MSI setup and teardown for PV on HVM guests") >>>>>> >>>>>> That commit introduced reading the pci device's msi message data to see >>>>>> if a pirq was previously configured for the device's msi/msix, and re-use >>>>>> that pirq. At the time, that was the correct behavior. However, a >>>>>> later change to Qemu caused it to call into the Xen hypervisor to unmap >>>>>> all pirqs for a pci device, when the pci device disables its MSI/MSIX >>>>>> vectors; specifically the Qemu commit: >>>>>> c976437c7dba9c7444fb41df45468968aaa326ad >>>>>> ("qemu-xen: free all the pirqs for msi/msix when driver unload") >>>>>> >>>>>> Once Qemu added this pirq unmapping, it was no longer correct for the >>>>>> kernel to re-use the pirq number cached in the pci device msi message >>>>>> data. All Qemu releases since 2.1.0 contain the patch that unmaps the >>>>>> pirqs when the pci device disables its MSI/MSIX vectors. >>>>>> >>>>>> This bug is causing failures to initialize multiple NVMe controllers >>>>>> under Xen, because the NVMe driver sets up a single MSIX vector for >>>>>> each controller (concurrently), and then after using that to talk to >>>>>> the controller for some configuration data, it disables the single MSIX >>>>>> vector and re-configures all the MSIX vectors it needs. So the MSIX >>>>>> setup code tries to re-use the cached pirq from the first vector >>>>>> for each controller, but the hypervisor has already given away that >>>>>> pirq to another controller, and its initialization fails. >>>>>> >>>>>> This is discussed in more detail at: >>>>>> https://lists.xen.org/archives/html/xen-devel/2017-01/msg00447.html >>>>>> >>>>>> Fixes: af42b8d12f8a ("xen: fix MSI setup and teardown for PV on HVM guests") >>>>>> Signed-off-by: Dan Streetman >>>>> Acked-by: Konrad Rzeszutek Wilk >>>> This doesn't seem to be applied yet, is it still waiting on another >>>> ack? Or maybe I'm looking at the wrong git tree... >>> Am I wrong or shouldn't this go through the PCI tree? Konrad? >> Konrad is away this week but since pull request for Xen tree just went >> out we should probably wait until rc1 anyway (unless something big comes >> up before that). > I assume this should go via the Xen or x86 tree, since that's how most > arch/x86/pci/xen.c patches have been handled, including af42b8d12f8a. > If you think otherwise, let me know. OK, I applied it to Xen tree's for-linus-4.11. -boris