Hi,
On 6/4/20 11:17 AM, Jerry Snitselaar wrote:
On Thu May 07 20, Hans de Goede wrote:
Hi All,
On 4/10/20 11:06 PM, Jarkko Sakkinen wrote:
On Thu, Apr 09, 2020 at 11:10:44PM +0200, Hans de Goede wrote:
Since commit dda8b2af395b ("tpm: Revert "tpm_tis_core: Set
TPM_CHIP_FLAG_IRQ before probing for interrupts"") we no longer set
the TPM_CHIP_FLAG_IRQ ever.
So the whole IRQ probing code is not useful, worse we rely on the
IRQ-test path of tpm_tis_send() to call disable_interrupts() if
interrupts do not work, but that path never gets entered because we
never set the TPM_CHIP_FLAG_IRQ.
So the remaining IRQ probe code calls request_irq() and never calls
free_irq() even when the interrupt is not working.
On some systems, e.g. the Lenovo X1 8th gen, the interrupt we try
to use and never free creates an interrupt storm followed by
an "irq XX: nobody cared" oops.
Since it is non-functional at the moment anyways, lets just completely
disable the IRQ code in tpm_tis_core for now.
Fixes: dda8b2af395b ("tpm: Revert "tpm_tis_core: Set TPM_CHIP_FLAG_IRQ before probing for interrupts"")
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
Note I'm working with Lenovo to try and get to the bottom of this.
---
OK if I recall correctly the reason for reverting was that the fixes
Stefan was sending were broken and no access to hardware were the
issues would be visible. The reason for not doing anything til this
day is that we don't have T490 available.
So as promised I have been in contact with Lenovo about this.
Specifically I have been in contact with Lenovo about seeing an
IRQ storm when the tpm_tis code tries to use the IRQ on a X1 carbon
8th gen (X1C8), because of the now public plan that Lenovo will
offer ordering this model with Fedora pre-installed:
https://lwn.net/Articles/818595/
On the X1C8 the problem has been diagnosed to be a misconfigured
GPIO pin on the CPU (the SoC). The X1C8 uses an SPI connected
TPM chip with its IRQ connected to a GPIO on the SoC which is
configured in Direct IRQ mode, so that it directly asserts
IRQs on one of the APIC IRQs. The problem is that due to the
misconfiguration as soon as the IRQ is enabled it fires
continuously.
For the X1C8 this should be fixed in the BIOS of the first
batch which gets shipped out to customers so there we should
not have to worry about this.
It is likely (but not yet confirmed) that the issue on the T490
is the same, although on my test X1C8 device I got an IRQ storm,
followed by the kernel disabling the IRQ, not a non booting system.
I guess this might be due to kernel configuration differences.
Assuming that the issue on the T490 is the same, we might see a
BIOS update fixing this, but given that non-booting is
'not good ("tm")' even if there will be a BIOS fix we should
still do something at the kernel level to also work with the
older unfixed BIOS which is already out there.
I've been thinking about this and I'm afraid that the only thing
what we can do is add a DMI product-name (product-version for Lenovo)
string based blacklist for IRQ usage to drivers/char/tpm/tpm_tis.c
and set tpm_info.irq = -1 for devices on that list.
My plan is to prepare a RFC patch of such a blacklist, while we
wait for confirmation that the root cause on the T490 is the same
as on the X1C8, but before I work on that I'm wondering if
people agree that that is the best approach, or if there are
other suggestions for dealing with this ?
Regards,
Hans
Jarrko,
Any thoughts about how we should move forward on dealing with this?
I've got a report about the original problem Stefan was dealing with,
where the tpm isn't powered on when it tries to send a command to
generate an interrupt. The tpm is functioning so it isn't urgent,
but it would be good to get this cleaned up so users aren't getting
transmit errors and firmware bug messages. Hans did you make any
progress on the blacklist patch?
Not really. I wanted to confirm on the X1C8 which I have on loan
from Lenovo that it indeed was the GPIO pin misconfiguration which
was the issue. But even though the Lenovo BIOS team claimed that they
have fixed the root cause now, the workaround of not listing any
IRQ for the TPM is also still in place in the latest BIOS I have.
So I cannot test that the IRQ storm is gone with the newer BIOS :|
Still the GPIO pin misconfiguration likely was the issue of the
storm I was seeing on the X1C8 and also the T490s likely has the
same issue. I should actually receive a T490s loaner soon-ish,
because of some unrelated (Builtin privacy screen) work I'm doing.
Once I have received the T490s then I can test things on the T490s:
1. Revert the reverts so that in theory we get working TPM IRQ
support in the kernel again
2. Check that the T490s does not like this
3. Write and test a blacklist patch
I'll ping my colleague who has arranged the loaner to ask what
the status is on it.
Regards,
Hans
