On 06/29/2017 06:09 PM, Stefan Berger wrote: > On 06/29/2017 08:39 AM, Javier Martinez Canillas wrote:
[snip] >> >>> = TPM backend devices = >>> >>> The TPM implementation is split into two parts. The one part is the hardware >>> interface, such as the TPM TIS interface described earlier, and the TPM >>> backend >>> interface. The backend interfaces implement the interaction with a TPM >>> device, >>> which may be a physical or an emulated device. The split between the front- >>> and backend devices allows a frontend to be connected with any available >>> backend. This enables the TIS interface to be used with the passthrough >>> backend >>> or the (future) swtpm backend. >> So we will need another TPM interface that implements the CRB interface? I > > No. How did you infer that ? > I thought that if the host firmware set the TPM2 Start Method to CRB instead of TIS1.2+cancel, then the guest would have to use the same interface. But now with your patch libvirt doesn't complain anymore about a missing cancel sysfs file and I could access the host TPM2.0 as a pass-through device, even when the host is using the tpm_crb driver while the guest uses the tpm_tis one. Sorry for the confusion, I'm just been learning about the TPM and still trying to make sense of all the different specifications and documents. Best regards, -- Javier Martinez Canillas Software Engineer - Desktop Hardware Enablement Red Hat
