Re: [Qemu-devel] Is is possible to virtualise or share the TPM?

[Stefan Berger <stefanb@linux.vnet.ibm.com>]

On 08/23/2012 04:05 PM, Corey Bryant wrote:
>
>
> On 08/21/2012 06:31 AM, Jordi Cucurull Juan wrote:
>> Dear all,
>>
>> After applying the TPM patches to QEMU, I was wondering if it is
>> possible to simultaneously use the TPM in more than one virtual machine,
>> i.e. virtualisation of the TPM.
>>
>> According to the paper "Stefan Berger, Ramón Cáceres, Kenneth A.
>> Goldman, Ronald Perez, Reiner Sailer, Leendert van Doorn. vTPM:
>> Virtualizing the Trusted Platform Module" this seems to be possible in
>> Xen. Is not possible in QEMU?
>>
>> Thanks!
>> Jordi.
>>
>>
>
> I don't think the pass-through driver supports use by multiple VMs. 
> Stefan Berger should be able to answer better so I'm adding him to the 
> thread.
>

The pass-through driver cannot provide access for multiple VMs to the 
single hardware TPM on the host. The usage model and the statefulness of 
the TPM (SRK password, owner password, keys) basically 
prevent/complicate this. The implementation for Xen was indep. of the 
Qemu code base today and there we used a software implementation of the 
TPM that provided a private TPm instance to each VM. I have patches for 
this for Qemu but due to an IRC chat in Sept. 2011 they are 'behind' the 
pass-through driver patches.

    Stefan