Re: [PATCH v1 1/8] docs: documentation and schema for the new TPM Proxy device

On Tue, May 12, 2020 at 11:21:52AM -0400, Stefan Berger wrote: > On 5/11/20 7:28 AM, Daniel P. Berrangé wrote: >> On Mon, May 11, 2020 at 08:26:53AM -0300, Daniel Henrique Barboza wrote: >>> >>> On 5/11/20 6:57 AM, Daniel P. Berrangé wrote: >>>> On Mon, May 11, 2020 at 11:22:57AM +1000, David Gibson wrote: >>> [...] >>>>> It's a different guest side interface, the H_TPM_COMM hypercall >>>>> instead of the other PAPR TPM interface. To which "why?" is a very >>>>> good question, but it's there now, so there's not much we can do about >>>>> it. >>>> That's ok. Even though its a different guest interface, it is still >>>> conceptually a TPM device at a high level, so we should be reusing >>>> the existing <tpm> device type. At most we should add a new backend >>>> type >>> I think adding a new backend type is sensible. Re-using the passthrough type >>> and making the differentiation with 'model', for a device that doesn't >>> operate exactly as a regular vTPM but can coexist with other vTPM devices, >>> will make for a lot of IFs in the code. >> Currently libvirt only allows a single <tpm>, but we can trivially >> lift that restriction to allow multiple if desired too. > > > QEMU won't accept multiple TIS or CRB devices, though. The commit message says you can do 2 at a time: "Although redundant, there is currently no technical limitation for a guest to assign both a vTPM and a TPM Proxy at the same time." is that text not accurate ?

Regards, Daniel