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From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Tadeusz Struk <tadeusz.struk@intel.com>
Cc: jgg@ziepe.ca, linux-integrity@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org, philip.b.tricca@intel.com,
	James.Bottomley@HansenPartnership.com
Subject: Re: [PATCH v3 0/2] tpm: add support for nonblocking operation
Date: Tue, 19 Jun 2018 16:10:46 +0300	[thread overview]
Message-ID: <20180619131046.GC5609@linux.intel.com> (raw)
In-Reply-To: <152882630662.30206.8805136953394285180.stgit@tstruk-mobl1.jf.intel.com>

On Tue, Jun 12, 2018 at 10:58:26AM -0700, Tadeusz Struk wrote:
> The TCG SAPI specification [1] defines a set of functions, which allows
> applications to use the TPM device in either blocking or non-blocking fashion.
> Each command defined by the specification has a corresponding
> Tss2_Sys_<COMMAND>_Prepare() and Tss2_Sys_<COMMAND>_Complete() call, which
> together with Tss2_Sys_ExecuteAsync() is designed to allow asynchronous
> mode of operation. Currently the TPM driver supports only blocking calls,
> which doesn't allow asynchronous IO operations.
> This patch changes it and adds support for nonblocking write and a new poll
> function to enable applications, which want to take advantage of this feature.
> The new functionality can be tested using standard TPM tools implemented
> in [2], together with modified TCTI from [3].
> 
> [1] https://trustedcomputinggroup.org/wp-content/uploads/TSS_SAPI_Version-1.1_Revision-22_review_030918.pdf
> [2] https://github.com/tpm2-software/tpm2-tools
> [3] https://github.com/tstruk/tpm2-tss/tree/async

For me the value is still a bit questionable. The benchmark looks a bit
flakky to give much figures how this would work with real world workloads.

I read James response and I also have to question why not just a worker
thread in user space? TPM does only one command at a time anyways.

Cannot take this in before I know that user space will (1) adapt to
this and (2) gain value compared to a worker thread.

/Jarkko

WARNING: multiple messages have this Message-ID (diff)
From: jarkko.sakkinen@linux.intel.com (Jarkko Sakkinen)
To: linux-security-module@vger.kernel.org
Subject: [PATCH v3 0/2] tpm: add support for nonblocking operation
Date: Tue, 19 Jun 2018 16:10:46 +0300	[thread overview]
Message-ID: <20180619131046.GC5609@linux.intel.com> (raw)
In-Reply-To: <152882630662.30206.8805136953394285180.stgit@tstruk-mobl1.jf.intel.com>

On Tue, Jun 12, 2018 at 10:58:26AM -0700, Tadeusz Struk wrote:
> The TCG SAPI specification [1] defines a set of functions, which allows
> applications to use the TPM device in either blocking or non-blocking fashion.
> Each command defined by the specification has a corresponding
> Tss2_Sys_<COMMAND>_Prepare() and Tss2_Sys_<COMMAND>_Complete() call, which
> together with Tss2_Sys_ExecuteAsync() is designed to allow asynchronous
> mode of operation. Currently the TPM driver supports only blocking calls,
> which doesn't allow asynchronous IO operations.
> This patch changes it and adds support for nonblocking write and a new poll
> function to enable applications, which want to take advantage of this feature.
> The new functionality can be tested using standard TPM tools implemented
> in [2], together with modified TCTI from [3].
> 
> [1] https://trustedcomputinggroup.org/wp-content/uploads/TSS_SAPI_Version-1.1_Revision-22_review_030918.pdf
> [2] https://github.com/tpm2-software/tpm2-tools
> [3] https://github.com/tstruk/tpm2-tss/tree/async

For me the value is still a bit questionable. The benchmark looks a bit
flakky to give much figures how this would work with real world workloads.

I read James response and I also have to question why not just a worker
thread in user space? TPM does only one command at a time anyways.

Cannot take this in before I know that user space will (1) adapt to
this and (2) gain value compared to a worker thread.

/Jarkko
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  parent reply	other threads:[~2018-06-19 13:10 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-12 17:58 [PATCH v3 0/2] tpm: add support for nonblocking operation Tadeusz Struk
2018-06-12 17:58 ` Tadeusz Struk
2018-06-12 17:58 ` [PATCH v3 1/2] tpm: add ptr to the tpm_space struct to file_priv Tadeusz Struk
2018-06-12 17:58   ` Tadeusz Struk
2018-06-12 17:58 ` [PATCH v3 2/2] tpm: add support for nonblocking operation Tadeusz Struk
2018-06-12 17:58   ` Tadeusz Struk
2018-06-13 17:55   ` J Freyensee
2018-06-13 17:55     ` J Freyensee
2018-06-13 17:55     ` J Freyensee
2018-06-13 18:05     ` Tadeusz Struk
2018-06-13 18:05       ` Tadeusz Struk
2018-06-13 18:05       ` Tadeusz Struk
2018-06-19 13:10 ` Jarkko Sakkinen [this message]
2018-06-19 13:10   ` [PATCH v3 0/2] " Jarkko Sakkinen
2018-06-20  0:45   ` Tadeusz Struk
2018-06-20  0:45     ` Tadeusz Struk
2018-06-20 23:59     ` James Bottomley
2018-06-20 23:59       ` James Bottomley
2018-06-21  1:24       ` Tadeusz Struk
2018-06-21  1:24         ` Tadeusz Struk
2018-06-21  5:26         ` James Bottomley
2018-06-21  5:26           ` James Bottomley
2018-06-21  5:26           ` James Bottomley
2018-06-21 16:20           ` Tadeusz Struk
2018-06-21 16:20             ` Tadeusz Struk
2018-06-21 17:17     ` Jarkko Sakkinen
2018-06-21 17:17       ` Jarkko Sakkinen
2018-06-21 17:36       ` Tadeusz Struk
2018-06-21 17:36         ` Tadeusz Struk

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