From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: "Safford, David (GE Global Research, US)" <david.safford@ge.com>
Cc: "linux-integrity@vger.kernel.org"
<linux-integrity@vger.kernel.org>,
"Wiseman, Monty (GE Global Research, US)" <monty.wiseman@ge.com>
Subject: Re: [PATCH] tpm_crb - workaround broken ACPI tables
Date: Thu, 11 Jul 2019 17:10:58 +0300 [thread overview]
Message-ID: <20190711141058.xfqpsfh4rzcjksth@linux.intel.com> (raw)
In-Reply-To: <BCA04D5D9A3B764C9B7405BBA4D4A3C035EF7BC7@ALPMBAPA12.e2k.ad.ge.com>
On Thu, Jul 11, 2019 at 12:29:30PM +0000, Safford, David (GE Global Research, US) wrote:
> Most x86 desktops and laptops have firmware TPMs which support the
> CRB interface. Unfortunately, the linux tpm_crb driver depends on
> perfectly correct ACPI tables, and there are a *lot* of systems out
> there with broken tpm_crb entries. (Not one of my five tpm_crb
> systems works with the existing driver.) While it is good to
> encourage vendors to fix their firmware, many refuse ("It works on
> Windows"), leaving users in the lurch.
>
> This patch adds a kernel parameter "tpm_crb.force=1" that works
> around the problem in every case I have tested so far. Basically
> it does two things:
> - it trusts the cmd and resp addresses in the CRB registers
> - it ignores all alleged IO resource conflicts
>
> Both workarounds make sense. If there really were an address conflict,
> or if the register values really were wrong, the device would not be
> working at all. And testing with this patch has shown that in every
> case (so far), the problem has been bogus ACPI entries.
>
> This patch is against the upstream 5.2 kernel.
>
> Signed-off-by: David Safford <david.safford@ge.com>
Will give a detailed review but generally we workaround firmware
issues when possible so in that way there is no argument here.
/Jarkko
next prev parent reply other threads:[~2019-07-11 14:11 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-11 12:29 [PATCH] tpm_crb - workaround broken ACPI tables Safford, David (GE Global Research, US)
2019-07-11 14:10 ` Jarkko Sakkinen [this message]
2019-07-11 14:58 ` Jason Gunthorpe
2019-07-11 16:44 ` Safford, David (GE Global Research, US)
2019-07-11 18:50 ` Jason Gunthorpe
2019-07-11 19:31 ` Safford, David (GE Global Research, US)
2019-07-11 20:33 ` Matthew Garrett
2019-07-12 12:41 ` Safford, David (GE Global Research, US)
2019-07-12 15:06 ` Jason Gunthorpe
2019-07-12 15:48 ` Jarkko Sakkinen
2019-07-12 18:24 ` Matthew Garrett
2019-07-12 19:05 ` Safford, David (GE Global Research, US)
2019-07-12 20:36 ` Matthew Garrett
2019-07-14 19:28 ` Safford, David (GE Global Research, US)
2019-07-14 23:48 ` Matthew Garrett
2019-07-15 19:44 ` Matthew Garrett
2019-07-11 19:16 ` Jarkko Sakkinen
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