On Fri, Feb 17, 2023 at 08:25:56PM -0600, Limonciello, Mario wrote: > On 2/17/2023 16:05, Jarkko Sakkinen wrote: > > > Perhaps tpm_amd_* ? > > When Jason first proposed this patch I feel the intent was it could cover > multiple deficiencies. > But as this is the only one for now, sure re-naming it is fine. > > > > > Also, just a question: is there any legit use for fTPM's, which are not > > updated? I.e. why would want tpm_crb to initialize with a dysfunctional > > firmware?> > > I.e. the existential question is: is it better to workaround the issue and > > let pass through, or make the user aware that the firmware would really > > need an update. > > > > On 2/17/2023 16:35, Jarkko Sakkinen wrote: > > > > > > Hmm, no reply since Mario posted this. > > > > > > Jarkko, James, what's your stance on this? Does the patch look fine from > > > your point of view? And does the situation justify merging this on the > > > last minute for 6.2? Or should we merge it early for 6.3 and then > > > backport to stable? > > > > > > Ciao, Thorsten > > > > As I stated in earlier response: do we want to forbid tpm_crb in this case > > or do we want to pass-through with a faulty firmware? > > > > Not weighting either choice here I just don't see any motivating points > > in the commit message to pick either, that's all. > > > > BR, Jarkko > > Even if you're not using RNG functionality you can still do plenty of other > things with the TPM. The RNG functionality is what tripped up this issue > though. All of these issues were only raised because the kernel started > using it by default for RNG and userspace wants random numbers all the time. > > If the firmware was easily updatable from all the OEMs I would lean on > trying to encourage people to update. But alas this has been available for > over a year and a sizable number of OEMs haven't distributed a fix. > > The major issue I see with forbidding tpm_crb is that users may have been > using the fTPM for something and taking it away in an update could lead to a > no-boot scenario if they're (for example) tying a policy to PCR values and > can no longer access those. > > If the consensus were to go that direction instead I would want to see a > module parameter that lets users turn on the fTPM even knowing this problem > exists so they could recover. That all seems pretty expensive to me for > this problem. I agree with the last argument. I re-read the commit message and https://www.amd.com/en/support/kb/faq/pa-410. Why this scopes down to only rng? Should TPM2_CC_GET_RANDOM also blocked from /dev/tpm0? BR, Jarkko
