AMD fTPM patches for stable

Hey Greg,

There was recently a bit of a snafoo with a maintainer taking the wrong version of a patch and sending that up to Linus. That patch had incorrect stable@ annotations and had a bug in it. That bug was fixed with a follow up patch. But of course the metadata couldn't be changed easily retroactively.

So I'm emailing to ask you to backport these two patches back to 5.5:

- 554b841d4703 ("tpm: Disable RNG for all AMD fTPMs")
- cacc6e22932f ("tpm: Add a helper for checking hwrng enabled")

I know the stable@ tag says 6.1+, but the actual right tags from the newer versioned patch that didn't get picked are:

Cc [email protected] # 5.5+

Fixes b006c439d58d ("hwrng: core - start hwrng kthread also for untrusted sources")

Fixes f1324bbc4011 ("tpm: disable hwrng for fTPM on some AMD designs")

Fixes 3ef193822b25 ("tpm_crb: fix fTPM on AMD Zen+ CPUs")

Reported-by [email protected]

Closes https://bugzilla.kernel.org/show_bug.cgi?id=217719

Reported-by [email protected]

Closes https://bugzilla.kernel.org/show_bug.cgi?id=217212

Reviewed-by Jason A. Donenfeld <[email protected]>

Signed-off-by Mario Limonciello <[email protected]>

Let me know if you need any more info.

Thanks,
Jason

Quoted 27 lines · Jason A. Donenfeld

Hey Greg,

There was recently a bit of a snafoo with a maintainer taking the wrong version of a patch and sending that up to Linus. That patch had incorrect stable@ annotations and had a bug in it. That bug was fixed with a follow up patch. But of course the metadata couldn't be changed easily retroactively.

So I'm emailing to ask you to backport these two patches back to 5.5:

- 554b841d4703 ("tpm: Disable RNG for all AMD fTPMs")
- cacc6e22932f ("tpm: Add a helper for checking hwrng enabled")

I know the stable@ tag says 6.1+, but the actual right tags from the newer versioned patch that didn't get picked are:

Cc [email protected] # 5.5+

Fixes b006c439d58d ("hwrng: core - start hwrng kthread also for untrusted sources")

Fixes f1324bbc4011 ("tpm: disable hwrng for fTPM on some AMD designs")

Fixes 3ef193822b25 ("tpm_crb: fix fTPM on AMD Zen+ CPUs")

Reported-by [email protected]

Closes https://bugzilla.kernel.org/show_bug.cgi?id=217719

Reported-by [email protected]

Closes https://bugzilla.kernel.org/show_bug.cgi?id=217212

Reviewed-by Jason A. Donenfeld <[email protected]>

Signed-off-by Mario Limonciello <[email protected]>

Quoted 4 lines

Let me know if you need any more info.

Thanks,
Jason

So I had a quick try with the backports to see what happens. 6.1.y and 6.4.y apply cleanly no problem.

However 5.15.y (and presumably 5.5.y) have a variety of issues that I think no longer make it a stable candidate. I started going down the rabbit hole of dependencies and it's massive unless hand modifications are done.

Realistically the problem is most severe in 6.1.y because of b006c439d58d. I don't know it's worth going back any further.