On 8/4/23 17:54, Jarkko Sakkinen wrote:
On Thu Aug 3, 2023 at 9:24 PM EEST, Mario Limonciello wrote:The TPM RNG functionality is not necessary for entropy when the CPU already supports the RDRAND instruction. The TPM RNG functionality was previously disabled on a subset of AMD fTPM series, but reports continue to show problems on some systems causing stutter root caused to TPM RNG functionality. Expand disabling TPM RNG use for all AMD fTPMs whether they have versions that claim to have fixed or not. To accomplish this, move the detection into part of the TPM CRB registration and add a flag indicating that the TPM should opt-out of registration to hwrng. Cc: stable@xxxxxxxxxxxxxxx # 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: daniil.stas@xxxxxxxxxx Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217719 Reported-by: bitlord0xff@xxxxxxxxx Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217212 Reviewed-by: Jason A. Donenfeld <Jason@xxxxxxxxx> Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>I will skip rc5 and send this for rc6 on Monday. Has anyone with suitable AMD system tested this?
Probably obvious; but I tested with a system that can support both dTPM and fTPM and swapped between the two before I sent it.
