On Fri, Feb 17, 2023 at 04:18:39PM +0100, Thorsten Leemhuis wrote:
On 14.02.23 21:19, Mario Limonciello wrote:
AMD has issued an advisory indicating that having fTPM enabled in BIOS can cause "stuttering" in the OS. This issue has been fixed in newer versions of the fTPM firmware, but it's up to system designers to decide whether to distribute it.
This issue has existed for a while, but is more prevalent starting with kernel 6.1 because commit b006c439d58db ("hwrng: core - start hwrng kthread also for untrusted sources") started to use the fTPM for hwrng by default. However, all uses of /dev/hwrng result in unacceptable stuttering.
So, simply disable registration of the defective hwrng when detecting these faulty fTPM versions.
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