[PATCH v2 4/4] iommu: Get DT/ACPI parsing into the proper probe path

[Anders Roxell]

From: Robin Murphy <robin.murphy at arm.com>

> On 2025-03-13 9:56 am, Marek Szyprowski wrote:
> [...]
> > This patch landed in yesterday's linux-next as commit bcb81ac6ae3c
> > ("iommu: Get DT/ACPI parsing into the proper probe path"). In my tests I
> > found it breaks booting of ARM64 RK3568-based Odroid-M1 board
> > (arch/arm64/boot/dts/rockchip/rk3568-odroid-m1.dts). Here is the
> > relevant kernel log:
> 
> ...and the bug-flushing-out begins!
> 
> > Unable to handle kernel NULL pointer dereference at virtual address
> > 00000000000003e8
> > Mem abort info:
> >     ESR = 0x0000000096000004
> >     EC = 0x25: DABT (current EL), IL = 32 bits
> >     SET = 0, FnV = 0
> >     EA = 0, S1PTW = 0
> >     FSC = 0x04: level 0 translation fault
> > Data abort info:
> >     ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
> >     CM = 0, WnR = 0, TnD = 0, TagAccess = 0
> >     GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
> > [00000000000003e8] user address but active_mm is swapper
> > Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
> > Modules linked in:
> > CPU: 3 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.14.0-rc3+ #15533
> > Hardware name: Hardkernel ODROID-M1 (DT)
> > pstate: 00400009 (nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> > pc : devm_kmalloc+0x2c/0x114
> > lr : rk_iommu_of_xlate+0x30/0x90
> > ...
> > Call trace:
> >    devm_kmalloc+0x2c/0x114 (P)
> >    rk_iommu_of_xlate+0x30/0x90
> 
> Yeah, looks like this is doing something a bit questionable which can't
> work properly. TBH the whole dma_dev thing could probably be cleaned up
> now that we have proper instances, but for now does this work?
> 
> (annoyingly none of my Rockchip boards are set up for testing right now, 
> but I might have time to dig one out later)
> 
> Thanks,
> Robin.
> 
> ----->8-----
> 
> Subject: [PATCH] iommu/rockchip: Allocate per-device data sensibly
> 
> Now that DT-based probing is finally happening in the right order again,
> it reveals an issue in Rockchip's of_xlate, which can now be called
> during registration, but is using the global dma_dev which is only
> assigned later. However, this makes little sense when we're already
> looking up the correct IOMMU device, who should logically be the owner
> of the devm allocation anyway.
> 
> Fixes: bcb81ac6ae3c ("iommu: Get DT/ACPI parsing into the proper probe 
> path")
> Signed-off-by: Robin Murphy <robin.murphy at arm.com>

This patch fixed the boot on rockpi4.
Applied it ontop of next-20250313

Tested-by: Anders Roxell <anders.roxell at linaro.org>

Cheers,
Anders