linux-kernel - Re: [PATCH] tpm: increase timeout for kselftests

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Message-ID: <51a14f28-ce94-ade9-6512-a265f7b32dfb@infineon.com>
Date:   Fri, 20 May 2022 15:28:42 +0200
From:   Stefan Mahnke-Hartmann <stefan.mahnke-hartmann@...ineon.com>
To:     Jarkko Sakkinen <jarkko@...nel.org>,
        Johannes Holland <johannes.holland@...ineon.com>
CC:     <linux-integrity@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <peterhuewe@....de>, <jgg@...pe.ca>,
        <stefan.mahnke-hartmann@...ineon.com>
Subject: Re: [PATCH] tpm: increase timeout for kselftests



On 11.05.22 17:14, Jarkko Sakkinen wrote:
> On Tue, May 10, 2022 at 01:16:08PM +0200, Johannes Holland wrote:
>> Due to CreatePrimary commands which need to create RSA keys of
>> increasing size, the timeout value need to be raised, as well.
>> Default is 300s.
>>
>> Signed-off-by: Johannes Holland <johannes.holland@...ineon.com>
>> ---
>> A timeout of anything below 600s still lead to occasional timeouts for
>> me. Therefore, I propose 600s as a new value. 
>>
>>  tools/testing/selftests/tpm2/settings | 2 ++
>>  1 file changed, 2 insertions(+)
>>  create mode 100644 tools/testing/selftests/tpm2/settings
>>
>> diff --git a/tools/testing/selftests/tpm2/settings b/tools/testing/selftests/tpm2/settings
>> new file mode 100644
>> index 000000000000..919bc3803f03
>> --- /dev/null
>> +++ b/tools/testing/selftests/tpm2/settings
>> @@ -0,0 +1,2 @@
>> +timeout=600
>> +
>> -- 
>> 2.34.1
>>
> Could cope but I did not get why it needs to be raised.

The TPM2 SpaceTest testsuite currently creates 8 primary RSA 2k keys + 1 for
setup. Generating a RSA2k key can take up to ~1-2 minutes on some of our TPMs.
=> 2x9 = 18 minutes. In the kernel we even define a duration timeout for rsa2k
keygen of 5 min per key! (TPM2_DURATION_LONG_LONG = 300000) => up to 45 minutes
would be "acceptable".

However since the average key generation time is much faster, a value of ~10
minutes should be fine enough.

The reason why you did not experience this yet on your test system is either
because PTT TPMs are faster in that respect and/or some TPMs implement pre-gen
mechanisms for key generation, (or just plain luck)

BR, Stefan

> BR, Jarkko