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: 9545935 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 B759960415 for ; Mon, 30 Jan 2017 18:43:04 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A9E822811E for ; Mon, 30 Jan 2017 18:43:04 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9DB6E2818B; Mon, 30 Jan 2017 18:43:04 +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=-1.9 required=2.0 tests=BAYES_00 autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [65.50.211.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 1256C2811E for ; Mon, 30 Jan 2017 18:43:04 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1cYGut-0007EA-1a; Mon, 30 Jan 2017 18:43:03 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1cYGul-0007A1-Sv for linux-arm-kernel@lists.infradead.org; Mon, 30 Jan 2017 18:43:01 +0000 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> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20170130_104255_956880_E8763AAA X-CRM114-Status: GOOD ( 17.96 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.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); 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)