Messages in this thread | | | Date | Wed, 15 Mar 2023 16:36:04 +0000 | Subject | Re: [PATCH v5 0/5] iommu: Retire detach_dev callback | From | Steven Price <> |
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On 15/03/2023 15:57, Robin Murphy wrote: > 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): [<c03c42ac>] >> vprintk_emit+0x330/0x354 >> [ 7.228606] hardirqs last disabled at (138390): [<c03c4268>] >> vprintk_emit+0x2ec/0x354 >> [ 7.228617] softirqs last enabled at (137258): [<c03016ac>] >> __do_softirq+0x2f8/0x548 >> [ 7.228628] softirqs last disabled at (137253): [<c0350218>] >> __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.
Ah, that seems to be it. I'll post a patch.
Thanks,
Steve
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