Re: [Qemu-devel] [PATCH V2] hw/misc: Add simple measurement hardware

[Stefan Berger]

Matthew Garrett <address@hidden> wrote on 08/08/2016 03:43:57 PM:

> 
> On Fri, Aug 5, 2016 at 8:56 PM, Stefan Berger <address@hidden> 
wrote:
> > Matthew Garrett <address@hidden> wrote on 08/05/2016 07:17:12 PM:
> >> This version of the implementation depends on port io, but if there's
> >> interest I'll add mmio as well.
> >
> > Port io is x86 specific, right? I don't think it should stay an x86 
specific
> > device.
> 
> Not strictly, there are other architectures that implement it. But
> yes, most other platforms will want MMIO support. The intent is
> certainly to add that.
> 
> >> -    if (misc.tpm_version != TPM_VERSION_UNSPEC) {
> >> +    if (misc.tpm_version != TPM_VERSION_UNSPEC ||
> >> misc.measurements_io_base) {
> >>          acpi_add_table(table_offsets, tables_blob);
> >>          build_tpm_tcpa(tables_blob, tables->linker, 
tables->tcpalog);
> >>
> >
> > If this device is hitchhiking on the TPM's ACPI tables, then are you 
also
> > making this device mutually exclusive with the TPM ? Of not please do 
so.
> 
> I'll look into the best way to do that.
> 

What's the plan for the driver level in Linux? Are you going to have this 
device's measurement log appear under another path than the TPM path 
/sys/kernel/security/tpm0/{ascii|binary}_bios_measurements? Also, I hope 
that not /dev/tpm0 will be made available. Basically I think it is a mess 
to use another device's ACPI table while not being compatible at all. 
Though a measurement list is necessary for the state of the PCRs to make 
sense.