On 12/26/21 21:24, Stefan Berger wrote:
On 12/25/21 07:38, Yuri Konotopov wrote:
Trying to boot VM with TPM 2.0 CRB in passthrough mode without this
change
I got "Requested buffer size of 3968 is smaller than host TPM's fixed
buffer size of 4096".
I suppose the host has a TIS interface.
The reason it gives this message is that the response this TPM may
send back could be 4096 bytes in size but the CRB of the VM can only
catch 3968 bytes, so there's a mismatch. You may not be able to use
the CRB in passthrough mode. I would try to have the VM use the TIS.
For TPM passthrough the host TPM's buffer size basically has to match
the VM's buffer size so that
- apps inside the VM cannot create longer commands than what the host
device can accept
- apps inside the VM cannot create commands that cause the TPM to return
responses that are bigger than what the VM's TPM buffer can accept
Stefan
