Re: [PATCH v9 01/11] KEYS: trusted: Use get_random-fallback for TPM

Jarkko Sakkinen
2026-03-23T05:34:43Z

On Mon, Mar 23, 2026 at 07:26:38AM +0200, Jarkko Sakkinen wrote:
> On Thu, Mar 19, 2026 at 10:28:03AM -0400, Mimi Zohar wrote:
> > On Wed, 2026-03-18 at 10:36 -0700, Chris Fenner wrote:
> > > Apologies if my long message derailed this discussion. I meant to
> > > support Mimi's concern here and project a future vision where
> > > TCG_TPM2_HMAC doesn't conflict with other features.
> > >
> > > More concisely, I think that:
> > >
> > > > tpm2_get_random() is costly when TCG_TPM2_HMAC is enabled
> > >
> > > is not a compelling argument for removing TPM as an RNG source,
> > > because TCG_TPM2_HMAC is known to have poor performance already
> > > anyway.
> >
> > Agreed. Thanks, Chris! FYI, we raised concerns about IMA performance with the
> > TPM HMAC and encrypted feature while it was being developed. James had some
> > ideas, at the time, as to how to resolve the performance issue for IMA. Yet it
> > was upstreamed without those changes and with CONFIG_TCG_TPM2_HMAC enabled by
> > default on x86 systems.
> >
> > Jarkko has queued this patch in the "queue" branch, without indicating whether
> > it will eventually be upstreamed or not.
>
> Yes and there's been multiple months of time to comment this and I
> backed up the patch set there, which is not same as applying it.

There's quite many other patches in that patch set also in the queue
branch. This was largeriy past life for me when these comments came.
Really don't understand what is suddenly going on tnh and for one
not that interesting patch.

BR, Jarkko