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

[Greg KH <greg@kroah.com>]

On Thu, Dec 22, 2016 at 02:41:52PM -0600, 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.
> 
> Signed-off-by: Dr. Greg Wettstein <greg@enjellic.com>

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read Documentation/stable_kernel_rules.txt
for how to do this properly.

</formletter>