Re: [tpmdd-devel] tpm device not showing up in /dev anymore

[Jerry Snitselaar <jsnitsel@redhat.com>]

On Wed Jan 03 18, Laurent Bigonville wrote:
>Le 17/11/17 a 14:16, Jarkko Sakkinen a ecrit :
>>On Tue, Nov 14, 2017 at 07:17:11AM -0800, James Bottomley wrote:
>>>On Tue, 2017-11-14 at 16:59 +0200, Jarkko Sakkinen wrote:
>>>>On Sat, Nov 11, 2017 at 01:31:32PM -0700, Jerry Snitselaar wrote:
>>>>>On Sat Nov 11 17, Jason Gunthorpe wrote:
>>>>>>On Sat, Nov 11, 2017 at 12:12:57PM -0700, Jerry Snitselaar wrote:
>>>>>>
>>>>>>>Before the release_locality code would only actually release
>>>>>>>the locality if the request use bit was set. So after it
>>>>>>>grabbed the locality during probe it probably never released
>>>>>>>it. The idea with the new code was to release it when it was no
>>>>>>>longer needed so another requester would be able to take the
>>>>>>>tpm without having to wait for it to be released.
>>>>>>If I recall, this was so that system level things outside linux
>>>>>>could access the TPM properly??
>>>>>>
>>>>>Yes, that is what drove this initially. I believe Jarkko was also
>>>>>thinking of the possibility in the future where something like a vm
>>>>>could request a locality as well, but that is just a hazy
>>>>>recollection of emails from back then.
>>>>This was something I recall discussing in LPC 2016 in the hallway at
>>>>least :-) A tidbit but it could make sense to tie it to VMM, not VM.
>>>I think we should be extremely wary of different localities before we
>>>have a cast iron definition of what they mean.  All the TPM PC spec
>>>says is that locality 4 is reserved for firmware (meaning the kernel
>>>should have no access) and it implies there's a privilege hierarchy,
>>>making 4 the most privileged and 0 the least but leaves all the
>>>definition to the OS.  Since we only have four other localities to play
>>>with, we need a global definition of what they mean in Linux (and who
>>>protects them) otherwise we'll get conflicting uses.  What does Windows
>>>use them for?
>>>
>>>James
>>No idea. If I had to guess, they use only one locality for OS as this
>>what PTT/fTPM had when it didn't have localities. At least their
>>implementation works with only one locality.
>>
>
>No more idea then? :(

Hi Laurent,

Can you try the following debug patch (earlier idea of adding a sleep to allow
tpm to complete state transition):

--8<--

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index fdde971bc810..6a9325b02059 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -80,6 +80,7 @@ static void release_locality(struct tpm_chip *chip, int l)
 	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
 
 	tpm_tis_write8(priv, TPM_ACCESS(l), TPM_ACCESS_ACTIVE_LOCALITY);
+	tpm_msleep(200);
 }
 
 static int request_locality(struct tpm_chip *chip, int l)
-- 
2.15.0