linux-kernel - Re: [PATCH v4 3/4] tpm: reduce tpm polling delay in tpm_tis

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20171019142244.7aaqyc3hizzt7n7p@linux.intel.com>
Date:   Thu, 19 Oct 2017 17:22:44 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Nayna Jain <nayna@...ux.vnet.ibm.com>
Cc:     linux-integrity@...r.kernel.org, zohar@...ux.vnet.ibm.com,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, peterhuewe@....de,
        tpmdd@...horst.net, jgunthorpe@...idianresearch.com,
        patrickc@...ibm.com
Subject: Re: [PATCH v4 3/4] tpm: reduce tpm polling delay in tpm_tis_core

On Wed, Oct 18, 2017 at 06:24:47PM +0300, Jarkko Sakkinen wrote:
> On Tue, Oct 17, 2017 at 04:32:31PM -0400, Nayna Jain wrote:
> > The existing wait_for_tpm_stat() polls for the chip status after
> > 5msec sleep. As per TCG ddwg input, it is expected that tpm might
> > return status in few usec. So, reducing the delay in polling to
> > 1msec.
> > Similarly, get_burstcount() function sleeps for 5msec before
> > retrying for next query to burstcount in a loop. If it takes
> > lesser time for TPM to return, this 5msec delay is longer than
> > necessary.
> > 
> > After this change, performance on a TPM 1.2 with an 8 byte
> > burstcount for 1000 extends improved from ~14sec to ~9sec.
> > 
> > Signed-off-by: Nayna Jain <nayna@...ux.vnet.ibm.com>
> 
> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>

Tested-by: Jarkko Sakkinen <jarkkko.sakkinen@...ux.intel.com>

/Jarkko