From patchwork Mon Jan 30 18:42:31 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Robin Murphy X-Patchwork-Id: 9545939 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 3C6DD604CC for ; Mon, 30 Jan 2017 18:43:20 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2FE852816B for ; Mon, 30 Jan 2017 18:43:20 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 249FF281A7; Mon, 30 Jan 2017 18:43:20 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3DF5A2816B for ; Mon, 30 Jan 2017 18:43:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753872AbdA3SnR (ORCPT ); Mon, 30 Jan 2017 13:43:17 -0500 Received: from foss.arm.com ([217.140.101.70]:50062 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753819AbdA3SnQ (ORCPT ); Mon, 30 Jan 2017 13:43:16 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 55E4414F6; Mon, 30 Jan 2017 10:42:35 -0800 (PST) Received: from [10.1.211.60] (e110467-lin.cambridge.arm.com [10.1.211.60]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 38E893F24D; Mon, 30 Jan 2017 10:42:33 -0800 (PST) Subject: Re: [PATCH V7 01/11] iommu/of: Refactor of_iommu_configure() for error handling To: Sricharan , 'Tomasz Nowicki' , will.deacon@arm.com, joro@8bytes.org, lorenzo.pieralisi@arm.com, iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, m.szyprowski@samsung.com, bhelgaas@google.com, linux-pci@vger.kernel.org, linux-acpi@vger.kernel.org References: <1485188293-20263-1-git-send-email-sricharan@codeaurora.org> <1485188293-20263-2-git-send-email-sricharan@codeaurora.org> <4388779a-0e83-fadc-83f4-98c46c88d42e@semihalf.com> <009901d278c7$34fee230$9efca690$@codeaurora.org> <003601d27ac6$84866840$8d9338c0$@codeaurora.org> From: Robin Murphy Message-ID: <8387d057-15bd-500c-134e-0e731ff837d6@arm.com> Date: Mon, 30 Jan 2017 18:42:31 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: <003601d27ac6$84866840$8d9338c0$@codeaurora.org> Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On 30/01/17 07:00, Sricharan wrote: > Hi Robin, > >>> [..] >>> >>>>>> +const struct iommu_ops *of_iommu_configure(struct device *dev, >>>>>> + struct device_node *master_np) >>>>>> +{ >>>>>> + const struct iommu_ops *ops; >>>>>> + >>>>>> + if (!master_np) >>>>>> + return NULL; >>>>>> + >>>>>> + if (dev_is_pci(dev)) >>>>>> + ops = of_pci_iommu_init(to_pci_dev(dev), master_np); >>>>> >>>>> I gave the whole patch set a try on ThunderX. really_probe() is failing >>>>> on dma_configure()->of_pci_iommu_init() for each PCI device. >>>> >>>> When you say "failing", do you mean cleanly, or with a crash? I've >>>> managed to hit __of_match_node() dereferencing NULL from >>>> of_iommu_xlate() in a horribly complicated chain of events, which I'm >>>> trying to figure out now, and I wonder if the two might be related. >>> >>> Sorry that there is crash still. __of_match_node seems to checking >>> for NULL arguments , feels like some invalid pointer was passed in. >>> Is there any particular sequence to try for this ? >> >> Ah, I did figure it out - it wasn't actually a NULL dereference, but an >> unmapped address. Turns out __iommu_of_table is in initdata, so any >> driver probing after init, connected to an unprobed IOMMU (in this case >> disabled in DT), trips over trying to match the now-freed table. I'm >> working on the fix - technically the bug's in my patch (#2) anyway ;) >> > > Ok, thanks for bringing this out. There is also an issue that > Sinan has mentioned while testing the ACPI hotplug path, probably > its related to the above, not sure. I will try to check more on that > in the meanwhile. Then, taking your fix and fixing the hotplug case > i will do one more repost. OK, I've finally settled on the below fixup for patch #2 - I have some follow-on ideas for eventually getting of the magic table altogether, but they can wait until we've got the baseline functionality sorted. Updated full patch here: http://www.linux-arm.org/git?p=linux-rm.git;a=commitdiff;h=5616af885f7c5c24f7239d5c689583b2b583c407 Robin. -----8<----- { @@ -105,7 +118,7 @@ static const struct iommu_ops ops = iommu_get_instance(fwnode); if ((ops && !ops->of_xlate) || - (!ops && !of_match_node(&__iommu_of_table, iommu_spec->np))) + (!ops && !of_iommu_driver_present(iommu_spec->np))) return NULL; err = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops); --- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c index 349bd1d01612..1f92d98237d5 100644 --- a/drivers/iommu/of_iommu.c +++ b/drivers/iommu/of_iommu.c @@ -96,6 +96,19 @@ int of_get_dma_window(struct device_node *dn, const char *prefix, int index, } EXPORT_SYMBOL_GPL(of_get_dma_window); +static bool of_iommu_driver_present(struct device_node *np) +{ + /* + * If the IOMMU still isn't ready by the time we reach init, assume + * it never will be. We don't want to defer indefinitely, nor attempt + * to dereference __iommu_of_table after it's been freed. + */ + if (system_state > SYSTEM_BOOTING) + return false; + + return of_match_node(&__iommu_of_table, np); +} + static const struct iommu_ops *of_iommu_xlate(struct device *dev, struct of_phandle_args *iommu_spec)