Re: [PATCH v2 0/5] tpm_tis: fix interrupts (again)

[Jerry Snitselaar <jsnitsel@redhat.com>]

Jerry Snitselaar @ 2020-10-14 10:01 MST:

> Hans de Goede @ 2020-10-14 09:46 MST:
>
>> Hi,
>>
>> On 10/14/20 6:34 PM, Jerry Snitselaar wrote:
>>> Hans de Goede @ 2020-10-14 09:04 MST:
>>> 
>>>> Hi,
>>>>
>>>> On 10/14/20 5:23 PM, James Bottomley wrote:
>>>>> On Wed, 2020-10-14 at 17:03 +0200, Hans de Goede wrote:
>>>>>> On 10/13/20 6:05 PM, Jerry Snitselaar wrote:
>>>>>>> James Bottomley @ 2020-10-13 08:24 MST:
>>>>>>>> On Tue, 2020-10-13 at 08:15 -0700, Jerry Snitselaar wrote:
>>>>>>>>> Jarkko Sakkinen @ 2020-10-12 18:17 MST:
>>>>> [...]
>>>>>>>>>>     Jerry, once you have some bandwidth (no rush, does not land
>>>>>>>>>> before rc2), it would be great that if you could try this.
>>>>>>>>>> I'm emphasizing this just because of the intersection. I
>>>>>>>>>> think it would also make senset to get tested-by from Nayna.
>>>>>>>>>
>>>>>>>>> I will run some tests on some other systems I have access to.
>>>>>>>>> As noted in the other email I did a quick test with a t490s
>>>>>>>>> with an older bios that exhibits the problem originally
>>>>>>>>> reported when Stefan's patch enabled interrupts.
>>>>>>>>
>>>>>>>> Well, it means there's still some other problem.  I was hoping
>>>>>>>> that because the rainbow pass system originally exhibited the
>>>>>>>> same symptoms (interrupt storm) fixing it would also fix the t490
>>>>>>>> and the ineffective EOI bug looked like a great candidate for
>>>>>>>> being the root cause.
>>>>>>>>
>>>>>>>
>>>>>>> Adding Hans to the list.
>>>>>>>
>>>>>>> IIUC in the t490s case the problem lies with the hardware itself.
>>>>>>> Hans, is that correct?
>>>>>>
>>>>>> More or less. AFAIK / have been told by Lenovo it is an issue with
>>>>>> the configuration of the inerrupt-type of the GPIO pin used for the
>>>>>> IRQ, which is a firmware issue which could be fixed by a BIOS update
>>>>>> (the pin is setup as a direct-irq pin for the APIC, so the OS has no
>>>>>> control of the IRQ type since with APIC irqs this is all supposed to
>>>>>> be setup properly before hand).
>>>>>>
>>>>>> But it is a model specific issue, if we denylist IRQ usage on this
>>>>>> Lenovo model (and probably a few others) then we should be able to
>>>>>> restore the IRQ code to normal functionality for all other device
>>>>>> models which declare an IRQ in their resource tables.
>>>>> I can do that with a quirk, but how do I identify the device?  TPM
>>>>> manufacturer and version? or do I have to use something like the ACPI
>>>>> bios version?
>>>>
>>>> I'm not sure if the TPM ids are unique to one model/series of laptops.
>>>>
>>>> So my idea for this was to match on DMI strings, specifically
>>>> use a DMI match on the DMI_SYS_VENDOR and DMI_PRODUCT_VERSION
>>>> strings (normally one would use DMI_PRODUCT_NAME but for Lenovo
>>>> devices the string which you expect to be in DMI_PRODUCT_NAME
>>>> is actually in DMI_PRODUCT_VERSION).
>>>>
>>>> You can easily get the strings for your device by doing:
>>>>
>>>> cat /sys/class/dmi/id/sys_vendor
>>>> cat /sys/class/dmi/id/product_version
>>>>
>>>> Regards,
>>>>
>>>> Hans
>>> Plus use dmi_get_date(DMI_BIOS_DATE,...) to check
>>> if the bios is older than the fixed bios? Has Lenovo
>>> released the fixed bios?
>>
>> Maybe, the fixed BIOS-es which I have seen (for the X1C8,
>> broken BIOS was a pre-production BIOS) "fixed" this by
>> no longer listing an IRQ in the ACPI resources for the TPM.
>>
>> Which means that the new BIOS still being on the deny list
>> does not matter since the IRQ support won't work anyways as
>> we no longer get an IRQ assigned.
>>
>> So I don't think this is necessary and it will just complicate
>> things unnecessarily. This whole saga has already taken way
>> too long to fix. So IMHO the simplest fix where we just deny
>> list the broken models independent of BIOS versions and move
>> on seems best.
>>
>> Regards,
>>
>> Hans
>
> Yea, probably just best to disable for the model and be done
> with it.
>
> Regards,
> Jerry

# cat /sys/class/dmi/id/sys_vendor
LENOVO
# cat /sys/class/dmi/id/product_version
ThinkPad T490s