Re: Recent tpm_tis IRQ handling changes are causing kernel backtraces]

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

Hi,

On 6/30/21 2:47 PM, Hans de Goede wrote:
> Hi,
> 
> On 6/30/21 12:05 AM, Jarkko Sakkinen wrote:
>> On Tue, Jun 29, 2021 at 09:14:39PM +0200, Hans de Goede wrote:
>>> Hi,
>>>
>>> On 6/29/21 8:04 PM, Jarkko Sakkinen wrote:
>>>> On Wed, Jun 23, 2021 at 03:54:59PM +0200, Hans de Goede wrote:
>>>>> Hi,
>>>>>
>>>>> On 6/23/21 3:40 PM, Jarkko Sakkinen wrote:
>>>>>> On Mon, Jun 21, 2021 at 02:04:52PM +0200, Hans de Goede wrote:
>>>>>>> Hi,
>>>>>>>
>>>>>>> On 6/14/21 3:33 PM, 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).
>>>>>>>
>>>>>>> One more status update.
>>>>>>>
>>>>>>> - A new 4th variant of the backtrace has been spotted, where the problem hits
>>>>>>> when called from probe() -> tpm2_auto_startup -> tpm2_do_selftest, see:
>>>>>>> https://bugzilla.redhat.com/show_bug.cgi?id=1958381
>>>>>>>
>>>>>>> - So far all reports with kernel >= 5.12.6 have been on a Dell XPS 13 9310
>>>>>>> models. But the new variant is happening on a Dell XPS 15 9500 and the
>>>>>>> backtrace starting at ima_add_boot_aggregate is also being reported on
>>>>>>> a Dell XPS 15 9500 (as well as on the XPS 13 9310).
>>>>>>>
>>>>>>> Regards,
>>>>>>>
>>>>>>> Hans
>>>>>>
>>>>>> OK, I'll have to query if I could borrow that laptop from someone. It's
>>>>>> fairly common laptop, i.e. might be possible.
>>>>>
>>>>> In the mean time I've also got a report that this variant of the backtrace:
>>>>>
>>>>> 1. Backtrace starting with a call to ima_add_boot_aggregate
>>>>> https://bugzilla.redhat.com/show_bug.cgi?id=1963712
>>>>>
>>>>> Is also still happening with recent 5.12.y kernels on
>>>>> Dell Precision 7750 laptops. Both the Precision 7750 and the XPS 9500 use
>>>>> 10th gen comet lake processors (i7-10750H), where as the XPS 9310 is using
>>>>> an icelake processor. So the common denominator seems to be that they are
>>>>> all 2020 Dell laptop models using the latest Intel CPUs.
>>>>>
>>>>> FYI the complete list of models on which some of the 4 backtrace variants
>>>>> are still seen on recent 5.12.y kernels is now:
>>>>>
>>>>> Dell XPS 13 9310
>>>>> Dell XPS 15 9500
>>>>> Dell Precision 7750
>>>>>
>>>>> Regards,
>>>>>
>>>>> Hans
>>>>
>>>> Does "tpm_tis.interrupts=0" uniformly workaround the issue?
>>>
>>> I unfortunately have not gotten much replies to my request to test with
>>> tpm_tis.interrupts=0, but for those people who have bothered to test
>>> (2 reporters IIRC) using tpm_tis.interrupts=0 does avoid the issue.
>>
>> So we see this in dmesg as first anything from TPM:
>>
>> [    0.904572] tpm_tis STM0125:00: 2.0 TPM (device-id 0x0, rev-id 78)
>>
>> This means that one command is successfully processed by the TPM, i.e.
>> tpm2_probe() in tpm_tis_core_init().
>>
>> My first *guess*  was that IRQ is given by ACPI, would need ACPI dump to
>> confirm (e.g. sudo acpidump > acpi.dump). It cannot be so because otherwise
>> this code path would be executed:
>>
>>         if (!(chip->flags & TPM_CHIP_FLAG_IRQ)) {
>>                 dev_err(&chip->dev, FW_BUG
>>                         "TPM interrupt not working, polling instead\n");
>>
>>                 disable_interrupts(chip);
>>         }
>>
>> TPM_CHIP_FLAG_IRQ is never set, so you should see this message in dmesg if
>> a legit value is given to IRQ by ACPI.  We are probably planning re-enable
>> IRQ code after these type of issues are fully resolved, but right now you
>> should not end up having it enabled (see tpm_tis_send() function).
>>
>> To put this together "if (irq != -1) {" path in tpm_tis_core_init() is
>> never executed. And early in the same function the interrupt hardware is
>> *explicitly* disabled.
>>
>> For me this looks like a hardware bug right now: interrupts stay enabled
>> for some reason.
>>
>> ACPI dump would be useful to verify some of the assumptions in this.
> 
> Ok, I've added a comment to the Fedora bugs for the 4 different backtrace
> variants asking for acpidumps for the Dell XPS 13 9310, Dell XPS 15 9500
> and Dell Precision 7750 laptops.

2 XPS 9310 acpidumps have been attached to:

https://bugzilla.redhat.com/show_bug.cgi?id=1920510
https://bugzilla.redhat.com/show_bug.cgi?id=1964974

Note the reporter of the first bug mentions that he is no longer having
this issue, but we are definitely still getting reports for kernel version
> 5.12.6 (which has the last 2 fixes) from XPS 9310 users...

Maybe there are different BIOS versions in play ? It might be interesting
to compare the 2 acpidumps...

Regards,

Hans