Re: [PATCH] tpm: Restore functionality to xen vtpm driver.

From: "Dr. Greg Wettstein" <greg@wind.enjellic.com>
To: Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	greg@enjellic.com, linux-kernel@vger.kernel.org
Cc: dgdegra@tycho.nsa.gov, konrad.wilk@oracle.com,
	jarkko.sakkinen@linux.intel.com
Subject: Re: [PATCH] tpm: Restore functionality to xen vtpm driver.
Date: Fri, 20 Jan 2017 18:29:33 -0600	[thread overview]
Message-ID: <201701210029.v0L0TXdv031435@wind.enjellic.com> (raw)
In-Reply-To: Boris Ostrovsky <boris.ostrovsky@oracle.com> "Re: [PATCH] tpm: Restore functionality to xen vtpm driver." (Jan 20,  5:22pm)

On Jan 20,  5:22pm, Boris Ostrovsky wrote:
} Subject: Re: [PATCH] tpm: Restore functionality to xen vtpm driver.

> On 01/20/2017 10:00 AM, Dr. Greg Wettstein wrote:
> > Functionality of the xen-tpmfront driver was lost secondary to
> > the introduction of xenbus multi-page support in the following
> > commit:
> >
> > ccc9d90a9a8b5c4ad7e9708ec41f75ff9e98d61d
> >
> > xenbus_client: Extend interface to support multi-page ring
> >
> > In this commit a pointer to the shared page address was being
> > passed to the xenbus_grant_ring() function rather then the
> > address of the shared page itself.  This resulted in a situation
> > where the driver would attach to the vtpm-stubdom but any attempt
> > to send a command to the stub domain would timeout.
> >
> > A diagnostic finding for this regression is the following error
> > message being generated when the xen-tpmfront driver probes for a
> > device:
> >
> > <3>vtpm vtpm-0: tpm_transmit: tpm_send: error -62
> >
> > <3>vtpm vtpm-0: A TPM error (-62) occurred attempting to determine the timeouts
> >
> > This fix is relevant to all kernels from 4.1 forward which is the
> > release in which multi-page xenbus support was introduced.
> >
> > Daniel De Graaf formulated the fix by code inspection after the
> > regression point was located.
> >
> > Cc: <stable@vger.kernel.org> # 4.1-

> 4.1+, I believe.

I thought the dash implied 4.1 forward but that may be my
mis-understanding.

In any event the patch should be applied to all stable kernels from
4.1 forward.

We were lucky it wasn't anything more then a 1 character patch.... :-)

Have a good weekend.

Dr. Greg

}-- End of excerpt from Boris Ostrovsky

As always,
Dr. G.W. Wettstein, Ph.D.   Enjellic Systems Development, LLC.
4206 N. 19th Ave.           Specializing in information infra-structure
Fargo, ND  58102            development.
PH: 701-281-1686
FAX: 701-281-3949           EMAIL: greg@enjellic.com
------------------------------------------------------------------------------
"This is a single non-reentrant routine which takes the received packet
 queue and throws it at the networking layers in the hope that something
 useful will emerge."
                                -- dev.c, Linux Networking Sources

-- 