Re: [PATCH v2 15/15] efi/arm64: Implement ARM64 DRTM in the stub

[Yeoreum Yun <yeoreum.yun@arm.com>]

On Tue, Oct 20, 2026 at 08:34:35PM -0300, Jason Gunthorpe wrote:
> On Wed, Oct 21, 2026 at 12:24:40AM +0100, Yeoreum Yun wrote:
> > One small question...
> > 
> > [..snipped..]
> > 
> > > +void efi_drtm_launch(void)
> > > +{
> > > +	if (efi_drtm_policy == EFI_DRTM_OFF)
> > > +		return;
> > > +
> > > +	/*
> > > +	 * No cache maintenance is required before the launch. v1.4B R42130 in
> > > +	 * Table 22 "DCE preamble requirements" requires the DRTM_PARAMETERS to
> > > +	 * be accessible as Normal Write-Back Cacheable, Inner Shareable memory,
> > > +	 * so the DCE reads them coherently with the writes made above.  R45220
> > > +	 * in Table 30 "DCE requirements for the DLME" then has the DCE clean
> > > +	 * and invalidate the whole DLME region to the Point of Coherency before
> > > +	 * it measures the DLME image, which covers both the Image itself and
> > > +	 * the handoff struct placed in the DLME region. Thus once we jump into
> > > +	 * the kernel with MMU and caches off the CPU will see everything the
> > > +	 * stub wrote.
> > > +	 */
> > > +	arm_drtm_dynamic_launch(drtm_cfg.params_addr);
> > 
> > After launching, How to get eventlogs for measurement of DLEM if
> > tpm_read_log_efi() is used? Doesn't it need to concatenate those
> > event logs from DRTM eventlog in returned DLEM data?
> 
> My plan is a future series will return them as a discrete log bundle
> through attestation subsystem. All of the logs will be available
> consistently that way, CCGL, the EFI and ACPI ones..
> 
> And it will be logically linked to the ROT the DRTM uses in some
> future ROT agile DRTM flow. So we can tell the difference between a
> TPM bare metal launch into PCRs and something like a realm launch into
> REMs.

Make sense. Thanks!

-- 
Sincerely,
Yeoreum Yun