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From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Leendert van Doorn <leendert@paramecium.org>
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>,
	Nayna Jain <nayna@linux.vnet.ibm.com>,
	"Alexander.Steffen@infineon.com" <Alexander.Steffen@infineon.com>,
	"linux-integrity@vger.kernel.org"
	<linux-integrity@vger.kernel.org>,
	"linux-security-module@vger.kernel.org" 
	<linux-security-module@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"peterhuewe@gmx.de" <peterhuewe@gmx.de>,
	"tpmdd@selhorst.net" <tpmdd@selhorst.net>,
	"patrickc@us.ibm.com" <patrickc@us.ibm.com>,
	"Safford, David (GE Global Research, US)" <david.safford@ge.com>
Subject: Re: [PATCH v4 2/4] tpm: ignore burstcount to improve tpm_tis send() performance
Date: Tue, 28 Nov 2017 22:19:03 +0200	[thread overview]
Message-ID: <20171128201903.ndd4j3xw3ubfaa4y@linux.intel.com> (raw)
In-Reply-To: <694703AB-68E1-4026-937C-61DBBE08DB4B@paramecium.org>

On Mon, Nov 27, 2017 at 07:08:51AM +0000, Leendert van Doorn wrote:
> Hmm, this is almost 20 years old code (
> 
> I think the original code did a burst write and didn't check for error
> conditions until the very last byte write. I seem to remember that
> there was some text in the original standard to that effect (this may
> have gone back as far as IBM's ESS spec).
> 
> The current code does check for error conditions after each write
> byte(s) so I don't think there is any reason for this anymore.
> Changing the while condition to count < len and setting burstcnt =
> min_t(int, burstcnt, len - count) and remove the
> tpm_tis_write8/wait_for_tpm_stat/tpm_tis_status clauses after the
> while loop should be sufficient.

Thank you for sharing this!

> 	Leendert

/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 v4 2/4] tpm: ignore burstcount to improve tpm_tis send() performance
Date: Tue, 28 Nov 2017 22:19:03 +0200	[thread overview]
Message-ID: <20171128201903.ndd4j3xw3ubfaa4y@linux.intel.com> (raw)
In-Reply-To: <694703AB-68E1-4026-937C-61DBBE08DB4B@paramecium.org>

On Mon, Nov 27, 2017 at 07:08:51AM +0000, Leendert van Doorn wrote:
> Hmm, this is almost 20 years old code (
> 
> I think the original code did a burst write and didn't check for error
> conditions until the very last byte write. I seem to remember that
> there was some text in the original standard to that effect (this may
> have gone back as far as IBM's ESS spec).
> 
> The current code does check for error conditions after each write
> byte(s) so I don't think there is any reason for this anymore.
> Changing the while condition to count < len and setting burstcnt =
> min_t(int, burstcnt, len - count) and remove the
> tpm_tis_write8/wait_for_tpm_stat/tpm_tis_status clauses after the
> while loop should be sufficient.

Thank you for sharing this!

> 	Leendert

/Jarkko
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  parent reply	other threads:[~2017-11-28 20:19 UTC|newest]

Thread overview: 63+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-17 20:32 [PATCH v4 0/4] additional TPM performance improvements Nayna Jain
2017-10-17 20:32 ` Nayna Jain
2017-10-17 20:32 ` [PATCH v4 1/4] tpm: move wait_for_tpm_stat() to respective driver files Nayna Jain
2017-10-17 20:32   ` Nayna Jain
2017-10-19 14:21   ` Jarkko Sakkinen
2017-10-19 14:21     ` Jarkko Sakkinen
2017-10-19 17:00     ` Alexander.Steffen
2017-10-19 17:00       ` Alexander.Steffen at infineon.com
2017-10-20  8:56       ` Jarkko Sakkinen
2017-10-20  8:56         ` Jarkko Sakkinen
2017-10-23 13:32         ` Nayna Jain
2017-10-23 13:32           ` Nayna Jain
2017-10-23 13:32           ` Nayna Jain
2017-10-24 13:45           ` Jarkko Sakkinen
2017-10-24 13:45             ` Jarkko Sakkinen
2017-10-17 20:32 ` [PATCH v4 2/4] tpm: ignore burstcount to improve tpm_tis send() performance Nayna Jain
2017-10-17 20:32   ` Nayna Jain
2017-10-18 15:25   ` Jarkko Sakkinen
2017-10-18 15:25     ` Jarkko Sakkinen
2017-10-19 14:23   ` Jarkko Sakkinen
2017-10-19 14:23     ` Jarkko Sakkinen
2017-10-20 14:42   ` Alexander.Steffen
2017-10-20 14:42     ` Alexander.Steffen at infineon.com
2017-10-20 18:02     ` Ken Goldman
2017-10-20 18:02       ` Ken Goldman
2017-10-23  2:57     ` Jarkko Sakkinen
2017-10-23  2:57       ` Jarkko Sakkinen
2017-11-07 18:29     ` Nayna Jain
2017-11-07 18:29       ` Nayna Jain
2017-11-07 18:29       ` Nayna Jain
2017-11-08 11:32       ` Alexander.Steffen
2017-11-08 11:32         ` Alexander.Steffen at infineon.com
2017-11-16 14:34       ` Alexander.Steffen
2017-11-16 14:34         ` Alexander.Steffen at infineon.com
2017-11-22  6:52       ` Alexander.Steffen
2017-11-22  6:52         ` Alexander.Steffen at infineon.com
2017-11-23 14:47         ` Nayna Jain
2017-11-23 14:47           ` Nayna Jain
2017-11-23 16:19           ` Alexander.Steffen
2017-11-23 16:19             ` Alexander.Steffen at infineon.com
2017-11-26 15:22           ` Jarkko Sakkinen
2017-11-26 15:22             ` Jarkko Sakkinen
2017-11-26 16:37             ` Mimi Zohar
2017-11-26 16:37               ` Mimi Zohar
2017-11-27  7:08               ` Leendert van Doorn
2017-11-27  7:08                 ` Leendert van Doorn
2017-11-27  7:08                 ` Leendert van Doorn
2017-11-27 13:22                 ` Mimi Zohar
2017-11-27 13:22                   ` Mimi Zohar
2017-11-27 13:22                   ` Mimi Zohar
2017-11-28 20:19                 ` Jarkko Sakkinen [this message]
2017-11-28 20:19                   ` Jarkko Sakkinen
2017-11-28 20:19                   ` Jarkko Sakkinen
2017-10-17 20:32 ` [PATCH v4 3/4] tpm: reduce tpm polling delay in tpm_tis_core Nayna Jain
2017-10-17 20:32   ` Nayna Jain
2017-10-18 15:24   ` Jarkko Sakkinen
2017-10-18 15:24     ` Jarkko Sakkinen
2017-10-19 14:22     ` Jarkko Sakkinen
2017-10-19 14:22       ` Jarkko Sakkinen
2017-10-17 20:32 ` [PATCH v4 4/4] tpm: use tpm_msleep() value as max delay Nayna Jain
2017-10-17 20:32   ` Nayna Jain
2017-10-19 14:22   ` Jarkko Sakkinen
2017-10-19 14:22     ` Jarkko Sakkinen

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