From: Peter Huewe <peterhuewe-Mmb7MZpHnFY@public.gmane.org> To: tpmdd-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, Ken Goldman <kgold-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org> Cc: linux-ima-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, linux-security-module-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Subject: Re: [PATCH v2 1/4] tpm: ignore burstcount to improve tpm_tis send() performance. Date: Wed, 13 Sep 2017 12:01:20 -0700 [thread overview] Message-ID: <5C86BF5C-76AA-47DB-B15B-DE524823CF9F@gmx.de> (raw) In-Reply-To: <3c418974-a4c7-518e-b218-f6373c10209e-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org> Am 13. September 2017 11:52:12 GMT-07:00 schrieb Ken Goldman <kgold-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>: >On 9/6/2017 12:12 PM, Jason Gunthorpe wrote: >> >> The problem with this approach is that the TPM could totally block >> the CPU for very long periods of time. >> >> It seems very risky to enable.. >> > >How would you characterize "very long"? > >The TPM vendors confirm that they empty the FIFO at internal speeds >that >are comparable to the bus speed. Thus, any stall will be sub-usec. Is >that an issue? If the tpm does behave correctly, this is fine. If the tpm hangs for whatever reason, your machine is frozen and you will never figure out why. That's my concern there. However ddwg seems fine. > >In addition, new TPMs have ever larger FIFO's, making stalls less >likely >going forward. But also reduced the polling loops that introduce the performance penalty ;) > > >------------------------------------------------------------------------------ >Check out the vibrant tech community on one of the world's most >engaging tech sites, Slashdot.org! http://sdm.link/slashdot >_______________________________________________ >tpmdd-devel mailing list >tpmdd-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org >https://lists.sourceforge.net/lists/listinfo/tpmdd-devel -- Sent from my mobile ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot
next prev parent reply other threads:[~2017-09-13 19:01 UTC|newest] Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-09-06 12:56 [PATCH v2 0/4] additional TPM performance improvements Nayna Jain 2017-09-06 12:56 ` [PATCH v2 3/4] tpm: reduce tpm_msleep() time in get_burstcount() Nayna Jain 2017-09-13 1:00 ` Jarkko Sakkinen 2017-09-15 12:40 ` Nayna Jain [not found] ` <20170906125643.5070-1-nayna-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org> 2017-09-06 12:56 ` [PATCH v2 1/4] tpm: ignore burstcount to improve tpm_tis send() performance Nayna Jain 2017-09-06 16:12 ` Jason Gunthorpe 2017-09-13 18:52 ` [tpmdd-devel] " Ken Goldman [not found] ` <3c418974-a4c7-518e-b218-f6373c10209e-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org> 2017-09-13 19:01 ` Peter Huewe [this message] 2017-09-13 0:45 ` Jarkko Sakkinen [not found] ` <20170912222010.ltm76m5vy2kupydi-VuQAYsv1563Yd54FQh9/CA@public.gmane.org> 2017-09-13 18:39 ` Peter Huewe 2017-09-13 23:10 ` Jarkko Sakkinen 2017-09-15 12:29 ` Nayna Jain 2017-09-15 15:19 ` Jarkko Sakkinen 2017-09-06 12:56 ` [PATCH v2 2/4] tpm: define __wait_for_tpm_stat to specify variable polling sleep time Nayna Jain 2017-09-13 0:58 ` Jarkko Sakkinen 2017-09-15 12:37 ` Nayna Jain 2017-09-15 15:20 ` Jarkko Sakkinen 2017-09-06 12:56 ` [PATCH v2 4/4] tpm: use tpm_msleep() value as max delay Nayna Jain 2017-09-13 0:47 ` Jarkko Sakkinen 2017-09-14 9:25 ` Nayna Jain 2017-09-14 12:28 ` Jarkko Sakkinen 2017-09-06 12:56 ` [PATCH 2/4] tpm: define __wait_for_tpm_stat to specify variable polling sleep time Nayna Jain 2017-09-06 12:58 ` Nayna 2017-09-06 12:56 ` [PATCH 1/4] tpm: ignore burstcount to improve tpm_tis send() performance Nayna Jain [not found] ` <20170906125643.5070-6-nayna-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org> 2017-09-06 12:58 ` Nayna 2017-09-07 16:18 ` [PATCH v2 0/4] additional TPM performance improvements Jarkko Sakkinen 2017-09-11 15:20 ` [tpmdd-devel] " Alexander.Steffen
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