On Sep 18, 2017, at 11:49 PM, Laurent Pinchart <[email protected]<mailto:[email protected]>> wrote:
Hi Ananth, On Tuesday, 19 September 2017 03:43:05 EEST Jasty, Ananth wrote: Hi, with your IPMMU driver enabled under 4.13 we’re seeing a crash on boot: [ 13.785164] Unable to handle kernel NULL pointer dereference at virtual address 00000018 [ 13.793254] [0000000000000018] user address but active_mm is swapper [ 13.799600] Internal error: Oops: 96000004 [#1] SMP [ 13.804466] Modules linked in: aes_neon_bs aes_neon_blk crypto_simd cryptd [ 13.811334] CPU: 152 PID: 1529 Comm: kworker/152:1 Not tainted 4.13.0-9-generic #10-Ubuntu [ 13.819584] Hardware name: Default string Cavium ThunderX2/Default string, BIOS 5.13 07/20/2017 [ 13.828285] Workqueue: events deferred_probe_work_func [ 13.833410] task: ffff80bee93d0000 task.stack: ffff80bee93dc000 [ 13.839330] PC is at iommu_ops_from_fwnode+0x4c/0x90 [ 13.844282] LR is at iommu_ops_from_fwnode+0x28/0x90 The ARM SMMUv3 driver (which our platform implements) seems to be losing iommu_ops to the IPMMU driver. You seem not to be the first one to notice: https://patchwork.kernel.org/patch/9956449/ Wow, he did not beat me by much. Note: our platform uses ACPI for device enumeration. I have no way to test this, but is there a reason the set_iommu isn’t in _probe? I can't recall what the reason was I'm afraid. arm-smmu-v3.c does do the set_iommu in probe, and thus far there have been no confirmed fatalities, but I can't speak authoritatively. I'll leave you all to it then. Thanks, Ananth diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c index 2a38aa1..d4c72da 100644 --- a/drivers/iommu/ipmmu-vmsa.c +++ b/drivers/iommu/ipmmu-vmsa.c @@ -1066,6 +1066,9 @@ static int ipmmu_probe(struct platform_device *pdev) platform_set_drvdata(pdev, mmu); + if (!iommu_present(&platform_bus_type)) + bus_set_iommu(&platform_bus_type, &ipmmu_ops); + return 0; } @@ -1108,9 +1111,6 @@ static int __init ipmmu_init(void) if (ret < 0) return ret; - if (!iommu_present(&platform_bus_type)) - bus_set_iommu(&platform_bus_type, &ipmmu_ops); - return 0; } If I’m wrong, my apologies. -- Regards, Laurent Pinchart
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