Re: [PATCH] tpm: vtpm_proxy: Do not access host's event log

[Stefan Berger <stefanb@linux.vnet.ibm.com>]

On 11/17/2016 03:37 PM, Jarkko Sakkinen wrote:
> On Thu, Nov 17, 2016 at 07:35:05AM -0500, Stefan Berger wrote:
>> On 11/16/2016 03:07 PM, Jason Gunthorpe wrote:
>>> On Wed, Nov 16, 2016 at 12:07:23PM -0500, Stefan Berger wrote:
>>>> The culprit seems to be 'tpm: fix the missing .owner in
>>>> tpm_bios_measurements_ops'
>>> That is unlikely, it is probably the patch before which calls read_log
>>> unconditionally now. That suggests the crashing is a little random..
>> I ran the vtpm driver test suite (with -j32) a few times at that patch and
>> it didn't crash. It crashes severely with later patches applied. Here's the
>> current experimental patch that fixes these problems:
>>
>> iff --git a/drivers/char/tpm/tpm_acpi.c b/drivers/char/tpm/tpm_acpi.c
>> index 0cb43ef..a73295a 100644
>> --- a/drivers/char/tpm/tpm_acpi.c
>> +++ b/drivers/char/tpm/tpm_acpi.c
>> @@ -56,6 +56,9 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
>>
>>       log = &chip->log;
>>
>> +    if (!chip->acpi_dev_handle)
>> +        return 0;
>> +
> If there is a problem in the TPM driver, this does not fix the
> problem. It will mask the problem. Maybe there's an ACPI regression
> in the rc tree?

Following the path from here :

http://lxr.free-electrons.com/source/drivers/acpi/acpica/tbxface.c#L282

acpi_get_table_with_size -> acpi_tb_validate_table -> acpi_tb_acquire_table

I see acpi_os_map_memory being called in acpi_tb_acquire_table but not 
the corresponding acpi_os_unmap_memory...

     Stefan


>
> This is a funky situation because those lines need to be there but
> I do not want them before it is root caused that it is not a TPM
> bug.
>
> /Jarkko
>