Re: ndctl cxl test suite fails in arm64 QEMU

[Itaru Kitayama <itaru.kitayama@linux.dev>]

Hi Jonathan, Alison,

> On Feb 28, 2025, at 23:34, Itaru Kitayama <itaru.kitayama@linux.dev> wrote:
> 
> On Tue, Feb 25, 2025 at 02:40:25PM -0800, Alison Schofield wrote:
>> On Tue, Feb 25, 2025 at 01:09:57PM +0900, Itaru Kitayama wrote:
>>> Hi,
>>> 
>>> Has anyone noticed the ndctl cxl test suite failures I reported below on arm64, QEMU emulation?
>>> 
>>> https://github.com/pmem/ndctl/issues/278
>>> 
>>> I’m using Jonathan’s latest CXL capable QEMU [1], and the latest CXL kernel [2].
>> 
>> Hi Itaru,
>> 
>> Looking at region.c:size_store() it seems that alloc_hpa() is failing.
>> (kstrtou64 is arch independent and it works for me with same script &
>> value)
>> 
>> Check the dmesg log at the time of the failure. alloc_hpa() may be
>> emitting a message.  (In the run_qemu.sh cmdline add '--cxl-debug')
> 
> dynamic debug reported this (kernel is without kaslr, today's cxl/next):
> 
> [  193.267649] device: 'region4': device_add
> [  193.267931] bus: 'cxl': add device region4
> [  193.268284] cxl region4: bus: 'cxl': __driver_probe_device: matched device with driver cxl_region
> [  193.268333] cxl region4: bus: 'cxl': really_probe: probing driver cxl_region with device
> [  193.268401] cxl_region region4: no default pinctrl state
> [  193.268482] cxl_region region4: probe with driver cxl_region rejects match -6
> 
> does the above show the region4 was not added properly? The sysfs
> entries are there after the out of range failure.

The driver/cxl/core/region.c’s size_store() triggers a sequence of: 

alloc_hpa()
alloc_free_mem_region()
get_free_mem_region() // with flags set to 0, retruns -ERANGE

While I am looking at the resource core code, do you think this is caused by the old firmware I am using
when booting QEMU built off of your CXL topic branch? Suggestions are welcome.

Itaru. 

> 
> Itaru.
> 
>> 
>> Sounds like Marc is on to something and maybe the KASLR is known
>> to cause this problem.
>> 
>> Thanks for posting to this list and send any further questions or
>> comments. Happy to have you using run_qemu.sh and the cxl tests!
>> 
>> Alison
>> 
>> 
>>> 
>>> [1] https://gitlab.com/jic23/qemu/ cxl-2025-02-20
>>> [2] https://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl.git/
>>> 
>>> Thanks,
>>> Itaru.