linux-kernel - Re: 5.3 boot regression caused by 5.3 TPM changes

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Message-ID: <ff73efc3-1951-2982-3ddf-e77005c5fddb@redhat.com>
Date:   Sun, 4 Aug 2019 18:12:32 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc:     Matthew Garrett <mjg59@...gle.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Peter Huewe <peterhuewe@....de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        linux-integrity <linux-integrity@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-efi <linux-efi@...r.kernel.org>
Subject: Re: 5.3 boot regression caused by 5.3 TPM changes

Hi,

On 04-08-19 17:33, Ard Biesheuvel wrote:
> Hi Hans,
> 
> On Sun, 4 Aug 2019 at 13:00, Hans de Goede <hdegoede@...hat.com> wrote:
>>
>> Hi All,
>>
>> While testing 5.3-rc2 on an Irbis TW90 Intel Cherry Trail based
>> tablet I noticed that it does not boot on this device.
>>
>> A git bisect points to commit 166a2809d65b ("tpm: Don't duplicate
>> events from the final event log in the TCG2 log")
>>
>> And I can confirm that reverting just that single commit makes
>> the TW90 boot again.
>>
>> This machine uses AptIO firmware with base component versions
>> of: UEFI 2.4 PI 1.3. I've tried to reproduce the problem on
>> a Teclast X80 Pro which is also CHT based and also uses AptIO
>> firmware with the same base components. But it does not reproduce
>> there. Neither does the problem reproduce on a CHT tablet using
>> InsideH20 based firmware.
>>
>> Note that these devices have a software/firmware TPM-2.0
>> implementation, they do not have an actual TPM chip.
>>
>> Comparing TPM firmware setting between the 2 AptIO based
>> tablets the settings are identical, but the troublesome
>> TW90 does have some more setting then the X80, it has
>> the following settings which are not shown on the X80:
>>
>> Active PCR banks:           SHA-1         (read only)
>> Available PCR banks:        SHA-1,SHA256  (read only)
>> TPM2.0 UEFI SPEC version:   TCG_2         (other possible setting: TCG_1_2
>> Physical Presence SPEC ver: 1.2           (other possible setting: 1.3)
>>
>> I have the feeling that at least the first 2 indicate that
>> the previous win10 installation has actually used the
>> TPM, where as on the X80 the TPM is uninitialized.
>> Note this is just a hunch I could be completely wrong.
>>
>> I would be happy to run any commands to try and debug this
>> or to build a kernel with some patches to gather more info.
>>
>> Note any kernel patches to printk some debug stuff need
>> to be based on 5.3 with 166a2809d65b reverted, without that
>> reverted the device will not boot, and thus I cannot collect
>> logs without it reverted.
>>
> 
> Are you booting a 64-bit kernel on 32-bit firmware?

Yes you are right, I must say that this is somewhat surprising
most Cherry Trail devices do use 64 bit firmware (where as Bay Trail
typically uses 32 bit). But I just checked efibootmgr output and it
says it is booting: \EFI\FEDORA\SHIMIA32.EFI so yeah 32 bit firmware.

Recent Fedora releases take care of this so seamlessly I did not
even realize...

Regards,

Hans