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/ > 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. > 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
