From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A2C9BC433DB for ; Tue, 12 Jan 2021 17:30:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 73D502311F for ; Tue, 12 Jan 2021 17:30:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405725AbhALRaI (ORCPT ); Tue, 12 Jan 2021 12:30:08 -0500 Received: from foss.arm.com ([217.140.110.172]:50140 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728956AbhALRaH (ORCPT ); Tue, 12 Jan 2021 12:30:07 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 83E6B1063; Tue, 12 Jan 2021 09:29:21 -0800 (PST) Received: from [10.57.56.43] (unknown [10.57.56.43]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8BC073F719; Tue, 12 Jan 2021 09:29:20 -0800 (PST) Subject: Re: [PATCH] iommu: check for the deferred attach when attaching a device To: lijiang , linux-kernel@vger.kernel.org Cc: "Lendacky, Thomas" , jroedel@suse.de, iommu@lists.linux-foundation.org, will@kernel.org References: <20201226053959.4222-1-lijiang@redhat.com> <33b6f925-71e6-5d9e-74c3-3e1eaf13398e@redhat.com> From: Robin Murphy Message-ID: <8273ce28-5ba6-2a39-5073-ec0f2b12dd2f@arm.com> Date: Tue, 12 Jan 2021 17:29:19 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021-01-05 07:52, lijiang wrote: > 在 2021年01月05日 11:55, lijiang 写道: >> Hi, >> >> Also add Joerg to cc list. >> > > Also add more people to cc list, Jerry Snitselaar and Tom Lendacky. > > Thanks. > >> Thanks. >> Lianbo >> 在 2020年12月26日 13:39, Lianbo Jiang 写道: >>> Currently, because domain attach allows to be deferred from iommu >>> driver to device driver, and when iommu initializes, the devices >>> on the bus will be scanned and the default groups will be allocated. >>> >>> Due to the above changes, some devices could be added to the same >>> group as below: >>> >>> [ 3.859417] pci 0000:01:00.0: Adding to iommu group 16 >>> [ 3.864572] pci 0000:01:00.1: Adding to iommu group 16 >>> [ 3.869738] pci 0000:02:00.0: Adding to iommu group 17 >>> [ 3.874892] pci 0000:02:00.1: Adding to iommu group 17 >>> >>> But when attaching these devices, it doesn't allow that a group has >>> more than one device, otherwise it will return an error. This conflicts >>> with the deferred attaching. Unfortunately, it has two devices in the >>> same group for my side, for example: >>> >>> [ 9.627014] iommu_group_device_count(): device name[0]:0000:01:00.0 >>> [ 9.633545] iommu_group_device_count(): device name[1]:0000:01:00.1 >>> ... >>> [ 10.255609] iommu_group_device_count(): device name[0]:0000:02:00.0 >>> [ 10.262144] iommu_group_device_count(): device name[1]:0000:02:00.1 >>> >>> Finally, which caused the failure of tg3 driver when tg3 driver calls >>> the dma_alloc_coherent() to allocate coherent memory in the tg3_test_dma(). >>> >>> [ 9.660310] tg3 0000:01:00.0: DMA engine test failed, aborting >>> [ 9.754085] tg3: probe of 0000:01:00.0 failed with error -12 >>> [ 9.997512] tg3 0000:01:00.1: DMA engine test failed, aborting >>> [ 10.043053] tg3: probe of 0000:01:00.1 failed with error -12 >>> [ 10.288905] tg3 0000:02:00.0: DMA engine test failed, aborting >>> [ 10.334070] tg3: probe of 0000:02:00.0 failed with error -12 >>> [ 10.578303] tg3 0000:02:00.1: DMA engine test failed, aborting >>> [ 10.622629] tg3: probe of 0000:02:00.1 failed with error -12 >>> >>> In addition, the similar situations also occur in other drivers such >>> as the bnxt_en driver. That can be reproduced easily in kdump kernel >>> when SME is active. >>> >>> Add a check for the deferred attach in the iommu_attach_device() and >>> allow to attach the deferred device regardless of how many devices >>> are in a group. Is this iommu_attach_device() call is coming from iommu-dma? (if not, then whoever's calling it probably shouldn't be) Assuming so, then probably what should happen is to move the handling currently in iommu_dma_deferred_attach() into the core so that it can call __iommu_attach_device() directly - the intent is just to replay that exact call skipped in iommu_group_add_device(), so the legacy external iommu_attach_device() interface isn't really the right tool for the job anyway. That's just slightly awkward since ideally it wants to be done in a way that doesn't result in a redundant out-of-line call for !kdump. Alternatively I suppose it *could* just call ops->attach_dev directly, but then we miss out on the tracepoint, and deferred attach is arguably one of the cases where that's most useful :/ Robin. >>> >>> Signed-off-by: Lianbo Jiang >>> --- >>> drivers/iommu/iommu.c | 5 ++++- >>> 1 file changed, 4 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c >>> index ffeebda8d6de..dccab7b133fb 100644 >>> --- a/drivers/iommu/iommu.c >>> +++ b/drivers/iommu/iommu.c >>> @@ -1967,8 +1967,11 @@ int iommu_attach_device(struct iommu_domain *domain, struct device *dev) >>> */ >>> mutex_lock(&group->mutex); >>> ret = -EINVAL; >>> - if (iommu_group_device_count(group) != 1) >>> + if (!iommu_is_attach_deferred(domain, dev) && >>> + iommu_group_device_count(group) != 1) { >>> + dev_err_ratelimited(dev, "Group has more than one device\n"); >>> goto out_unlock; >>> + } >>> >>> ret = __iommu_attach_group(domain, group); >>> >>> > > _______________________________________________ > iommu mailing list > iommu@lists.linux-foundation.org > https://lists.linuxfoundation.org/mailman/listinfo/iommu >