Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7FB39C61DA4 for ; Wed, 15 Mar 2023 15:59:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232844AbjCOP7D (ORCPT ); Wed, 15 Mar 2023 11:59:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56458 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232831AbjCOP6z (ORCPT ); Wed, 15 Mar 2023 11:58:55 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 7347E907A9 for ; Wed, 15 Mar 2023 08:58:17 -0700 (PDT) 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 7C0774B3; Wed, 15 Mar 2023 08:58:31 -0700 (PDT) Received: from [10.57.53.4] (unknown [10.57.53.4]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C51263F67D; Wed, 15 Mar 2023 08:57:43 -0700 (PDT) Message-ID: <1f697bcf-31f9-7e04-a8e7-1609cf330af3@arm.com> Date: Wed, 15 Mar 2023 15:57:38 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH v5 0/5] iommu: Retire detach_dev callback Content-Language: en-GB To: Steven Price , Lu Baolu , Joerg Roedel , Jason Gunthorpe , Christoph Hellwig , Kevin Tian , Will Deacon , Jean-Philippe Brucker Cc: Suravee Suthikulpanit , Vasant Hegde , Hector Martin , Sven Peter , Rob Clark , Marek Szyprowski , Krzysztof Kozlowski , Andy Gross , Bjorn Andersson , Yong Wu , Matthias Brugger , Heiko Stuebner , Matthew Rosato , Orson Zhai , Baolin Wang , Chunyan Zhang , Chen-Yu Tsai , Thierry Reding , iommu@lists.linux.dev, linux-kernel@vger.kernel.org References: <20230110025408.667767-1-baolu.lu@linux.intel.com> <26a5d1b8-40b3-b1e4-bc85-740409c26838@arm.com> From: Robin Murphy In-Reply-To: <26a5d1b8-40b3-b1e4-bc85-740409c26838@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2023-03-15 15:49, Steven Price wrote: > On 10/01/2023 02:54, Lu Baolu wrote: >> Hi folks, >> >> The iommu core calls the driver's detach_dev domain op callback only when >> a device is finished assigning to user space and >> iommu_group_release_dma_owner() is called to return the device to the >> kernel, where iommu core wants to set the default domain to the device but >> the driver didn't provide one. The code looks like: >> >> /* >> * New drivers should support default domains and so the detach_dev() op >> * will never be called. Otherwise the NULL domain represents some >> * platform specific behavior. >> */ >> if (!new_domain) { >> if (WARN_ON(!group->domain->ops->detach_dev)) >> return -EINVAL; >> __iommu_group_for_each_dev(group, group->domain, >> iommu_group_do_detach_device); >> group->domain = NULL; >> return 0; >> } >> >> In other words, if the iommu driver provides default domains, the >> .detach_dev callback will never be called; Otherwise, the .detach_dev >> callback is actually called to return control back to the platform DMA >> ops, other than detaching the domain from device. >> >> This series cleanups this by: >> >> - If the IOMMU driver provides default domains, remove .detach_dev >> callback. >> - Adds a new set_platform_dma iommu op. Any IOMMU driver that doesn't >> provide default domain should implement set_platform_dma callback >> instead. >> - Retire .detach_dev callback. >> >> This series originates from various discussion in the community. Thanks >> to Jason, Robin and all others for their ideas. >> >> The whole series is available on github: >> https://github.com/LuBaolu/intel-iommu/commits/iommu-retire-detach_dev-v5 >> >> Change log: >> v5: >> - Merge some patches to make the series cute. No functionality changes. >> - Check the op directly and WARN_ON the lack of any necessary >> callbacks. Get rid of the ret and EINVAL. >> >> v4: >> - https://lore.kernel.org/linux-iommu/20230104125725.271850-1-baolu.lu@linux.intel.com/ >> - Drop the patch which renamed .attach_dev to .set_dev. As Robin said, >> "... I also wouldn't say that "attach" loses its meaning in a context >> where an equivalent "detach" operation is only ever implicit in >> reattaching to something else...". If we have a better name in the >> future, we can do it in other series. >> - Adjust the patch of "iommu: Add set_platform_dma_ops iommu ops" >> according to Jason's following suggestion " ... This is a bit ugly, >> it would be better to make the previous patch call set_platform_dma >> if it is set instead of detach_dev and then these patches should just >> rename the driver's fsl_pamu_detach_device to >> fsl_pamu_set_platform_dma ..." >> - Add a new patch to remove deferred attach check from >> __iommu_detach_domain() path. Make it a separate patch as the >> prerequisite to remove __iommu_detach_device() helper. >> - Rename set_platform_dma to set_platform_dma_ops to make it more >> meaningful. >> >> v3: >> - https://lore.kernel.org/linux-iommu/20221128064648.1934720-1-baolu.lu@linux.intel.com/ >> - Setting blocking domain is not conceptually equal to detach_dev. >> Dropped all blocking domain related staffs in the previous version. >> >> v2: >> - https://lore.kernel.org/linux-iommu/20220826123014.52709-1-baolu.lu@linux.intel.com/ >> - Replace .detach_dev callback with static block domain ops; >> - Rename .attach_dev to .set_dev. >> >> v1: >> - https://lore.kernel.org/linux-iommu/20220516015759.2952771-1-baolu.lu@linux.intel.com/ >> >> Jason Gunthorpe (1): >> iommu: Remove deferred attach check from __iommu_detach_device() >> >> Lu Baolu (4): >> iommu: Remove detach_dev callbacks >> iommu: Add set_platform_dma_ops iommu ops >> iommu: Add set_platform_dma_ops callbacks >> iommu: Remove detach_dev callback >> >> include/linux/iommu.h | 8 ++- >> include/trace/events/iommu.h | 7 -- >> drivers/iommu/amd/iommu.c | 26 ------- >> drivers/iommu/apple-dart.c | 24 ------- >> drivers/iommu/arm/arm-smmu/qcom_iommu.c | 23 ------ >> drivers/iommu/exynos-iommu.c | 1 - >> drivers/iommu/fsl_pamu_domain.c | 6 +- >> drivers/iommu/iommu-traces.c | 1 - >> drivers/iommu/iommu.c | 94 ++++++++++++------------- >> drivers/iommu/ipmmu-vmsa.c | 16 ----- >> drivers/iommu/msm_iommu.c | 6 +- >> drivers/iommu/mtk_iommu.c | 9 --- >> drivers/iommu/mtk_iommu_v1.c | 4 +- >> drivers/iommu/omap-iommu.c | 6 +- >> drivers/iommu/rockchip-iommu.c | 1 - >> drivers/iommu/s390-iommu.c | 7 +- >> drivers/iommu/sprd-iommu.c | 16 ----- >> drivers/iommu/sun50i-iommu.c | 1 - >> drivers/iommu/tegra-gart.c | 6 +- >> drivers/iommu/tegra-smmu.c | 5 +- >> 20 files changed, 69 insertions(+), 198 deletions(-) >> > > I hit a problem with this series on a Firefly-RK3288, I bisected down to > 1b932ceddd19 ("iommu: Remove detach_dev callbacks"). The first splat is: > > [ 7.227853] ------------[ cut here ]------------ > [ 7.227900] WARNING: CPU: 0 PID: 9 at drivers/iommu/iommu.c:2198 __iommu_group_set_domain+0xb4/0xc8 > [ 7.227920] Modules linked in: > [ 7.227935] CPU: 0 PID: 9 Comm: kworker/u8:0 Not tainted 6.3.0-rc1 #1 > [ 7.227942] Hardware name: Rockchip (Device Tree) > [ 7.227948] Workqueue: events_unbound deferred_probe_work_func > [ 7.227964] unwind_backtrace from show_stack+0x10/0x14 > [ 7.227978] show_stack from dump_stack_lvl+0x58/0x70 > [ 7.227992] dump_stack_lvl from __warn+0x7c/0x1dc > [ 7.228008] __warn from warn_slowpath_fmt+0xbc/0x1a0 > [ 7.228022] warn_slowpath_fmt from __iommu_group_set_domain+0xb4/0xc8 > [ 7.228035] __iommu_group_set_domain from iommu_detach_device+0x84/0xf8 > [ 7.228046] iommu_detach_device from arm_iommu_detach_device+0x24/0xc4 > [ 7.228057] arm_iommu_detach_device from rockchip_drm_dma_attach_device+0x30/0x74 > [ 7.228073] rockchip_drm_dma_attach_device from vop_crtc_atomic_enable+0xf8/0xab0 > [ 7.228085] vop_crtc_atomic_enable from drm_atomic_helper_commit_modeset_enables+0xb0/0x2a0 > [ 7.228097] drm_atomic_helper_commit_modeset_enables from drm_atomic_helper_commit_tail_rpm+0x44/0x8c > [ 7.228111] drm_atomic_helper_commit_tail_rpm from commit_tail+0x9c/0x184 > [ 7.228124] commit_tail from drm_atomic_helper_commit+0x164/0x18c > [ 7.228137] drm_atomic_helper_commit from drm_atomic_commit+0xb0/0xe8 > [ 7.228153] drm_atomic_commit from drm_client_modeset_commit_atomic+0x240/0x288 > [ 7.228166] drm_client_modeset_commit_atomic from drm_client_modeset_commit_locked+0x60/0x1cc > [ 7.228174] drm_client_modeset_commit_locked from drm_client_modeset_commit+0x24/0x40 > [ 7.228183] drm_client_modeset_commit from drm_fb_helper_set_par+0xb8/0xf8 > [ 7.228197] drm_fb_helper_set_par from fbcon_init+0x2a0/0x534 > [ 7.228211] fbcon_init from visual_init+0xc0/0x108 > [ 7.228224] visual_init from do_bind_con_driver+0x1bc/0x3a8 > [ 7.228237] do_bind_con_driver from do_take_over_console+0x134/0x1d4 > [ 7.228251] do_take_over_console from do_fbcon_takeover+0x6c/0xcc > [ 7.228264] do_fbcon_takeover from fbcon_fb_registered+0x198/0x1a8 > [ 7.228277] fbcon_fb_registered from register_framebuffer+0x1d0/0x268 > [ 7.228292] register_framebuffer from __drm_fb_helper_initial_config_and_unlock+0x358/0x578 > [ 7.228308] __drm_fb_helper_initial_config_and_unlock from drm_fbdev_client_hotplug+0x6c/0xa8 > [ 7.228322] drm_fbdev_client_hotplug from drm_fbdev_generic_setup+0x84/0x174 > [ 7.228335] drm_fbdev_generic_setup from rockchip_drm_bind+0x1dc/0x200 > [ 7.228349] rockchip_drm_bind from try_to_bring_up_aggregate_device+0x200/0x2d8 > [ 7.228368] try_to_bring_up_aggregate_device from component_master_add_with_match+0xc4/0xf8 > [ 7.228380] component_master_add_with_match from rockchip_drm_platform_probe+0x150/0x254 > [ 7.228392] rockchip_drm_platform_probe from platform_probe+0x5c/0xb8 > [ 7.228405] platform_probe from really_probe+0xe0/0x400 > [ 7.228417] really_probe from __driver_probe_device+0x9c/0x1fc > [ 7.228431] __driver_probe_device from driver_probe_device+0x30/0xc0 > [ 7.228445] driver_probe_device from __device_attach_driver+0xa8/0x120 > [ 7.228460] __device_attach_driver from bus_for_each_drv+0x84/0xdc > [ 7.228474] bus_for_each_drv from __device_attach+0xb0/0x20c > [ 7.228488] __device_attach from bus_probe_device+0x8c/0x90 > [ 7.228502] bus_probe_device from deferred_probe_work_func+0x98/0xe0 > [ 7.228515] deferred_probe_work_func from process_one_work+0x290/0x740 > [ 7.228528] process_one_work from worker_thread+0x54/0x518 > [ 7.228536] worker_thread from kthread+0xf0/0x110 > [ 7.228548] kthread from ret_from_fork+0x14/0x2c > [ 7.228561] Exception stack(0xf084dfb0 to 0xf084dff8) > [ 7.228567] dfa0: 00000000 00000000 00000000 00000000 > [ 7.228573] dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 > [ 7.228579] dfe0: 00000000 00000000 00000000 00000000 00000013 00000000 > [ 7.228585] irq event stamp: 138379 > [ 7.228592] hardirqs last enabled at (138385): [] vprintk_emit+0x330/0x354 > [ 7.228606] hardirqs last disabled at (138390): [] vprintk_emit+0x2ec/0x354 > [ 7.228617] softirqs last enabled at (137258): [] __do_softirq+0x2f8/0x548 > [ 7.228628] softirqs last disabled at (137253): [] __irq_exit_rcu+0x14c/0x170 > [ 7.228639] ---[ end trace 0000000000000000 ]--- > > (complete log attached) > > I'm not sure how to debug this. From the callstack I can see that > __iommu_group_set_domain is getting a NULL new_domain which triggers > a call to __iommu_group_do_set_platform_dma which is WARNing because > there is no set_platform_dma_ops callback. The NULL new_domain is > because group->default_domain is NULL in __iommu_group_set_core_domain. > > So is the logic in the first patch that there is a default domain > incorrect for this rockchip driver? Or is this callpath just hitting > the function before the default domain can be created? > > Help debugging this would be appreciated - I'm not very familiar > with this area of code. It's the same thing Marek hit on Exynos: drivers which run on 32-bit Arm need a .set_platform_dma op, regardless of whether they support default domains on other platforms which use those. Cheers, Robin.