Re: Recent tpm_tis IRQ handling changes are causing kernel backtraces

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 6/15/21 3:01 PM, Jarkko Sakkinen wrote:
> On Mon, Jun 14, 2021 at 03:33:33PM +0200, Hans de Goede wrote:
>> Hi,
>>
>> On 6/1/21 6:04 PM, Hans de Goede wrote:
>>> Hi,
>>>
>>> On 5/31/21 6:36 AM, Jarkko Sakkinen wrote:
>>>>> Interestingly enough the first backtrace is also happening on a:
>>>>> "Dell Inc. XPS 13 9310/0MRT12, BIOS 2.2.0 04/06/2021"
>>>>>
>>>>> So it seems that at least with 5.12.6 (which has the last 2 fixes)
>>>>> all reports are about the XPS 13 9310. I wonder if there is an
>>>>> issue with the TPM interrupt line on the XPS 13 9310; I've asked the
>>>>> reporters to try adding tpm_tis.interrupts=0 to their kernel commandline.
>>>>
>>>> This is helpful for sure that these all are happening on matching hardware.
>>>
>>> So our kernel-backtrace tracking info (ABRT) just recorded a third backtrace
>>> with a kernel >= 5.12.6, again on the XPS 13 9310, so now we have 3 variants:
>>>
>>> 1. Backtrace starting with a call to ima_add_boot_aggregate
>>> https://bugzilla.redhat.com/show_bug.cgi?id=1963712
>>>
>>> 2. Backtrace starting with a call to tpm_dev_async_work:
>>> https://bugzilla.redhat.com/show_bug.cgi?id=1964974
>>> (note this one is not easily reproducible)
>>>
>>> 3. Backtrace starting with a call to rng_dev_read:
>>> https://bugzilla.redhat.com/show_bug.cgi?id=1920510
>>>
>>> 3. is the new one. All bugs linked above are public, all 3 backtraces
>>> so far have only been reported on the XPS 13 9310 (with kernel >= 5.12.6)
>>> and I've asked all the reporters to check if tpm_tis.interrupts=0 helps.
>>
>> Quick status update, I've got a response from a XPS 13 9310 user in:
>>
>> https://bugzilla.redhat.com/show_bug.cgi?id=1920510
>>
>> Indicating that a. he can reproduce this with the latest >= 5.12.6 kernels;
>> and b. it goes away when specifying tpm_tis.interrupts=0 as I expected
>> (I expected this because all the bug-reports started when the interrupt
>> code got fixed/re-enabled a while ago).
>>
>> Si I think that there just is something broken wrt the interrupt setup
>> on the XPS 13 9310 and that we should probably add an antry for the
>> XPS 13 9310 to the already existing tpm_tis_dmi_table pointing to the
>> also already existing tpm_tis_disable_irq callback.
>>
>> If other people agree that that is probably the best way forward ?
>> then I can prepare a patch and ask the user to test this.
>>
>> Regards,
>>
>> Hans
> 
> I think it all roots down to the use of TPM before tpm2_probe(), i.e.
> TPM is not in expected state when tpm_chip_start() is called. I
> suggested to try out adding tpm_chip_stop() right before
> tpm_chip_start() in another response.
> 
> That's only thing that makes logically sense to me at least.

Shouldn't there the be some completion somewhere with get completed
at the end of probe(), with the read-path which is involved in this
case blocking on this?

If you can prepare a kernel-patch to test, then I can build a Fedora
kernel rpm with the patch added for the user to test.

Regards,

Hans