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* [BUG] Non working HWRNG on AMD Ryzen 5 5500GT
@ 2024-08-15 13:56 Diederik de Haas
  2024-08-15 14:16 ` Tom Lendacky
  2024-08-15 14:22 ` Jason A. Donenfeld
  0 siblings, 2 replies; 7+ messages in thread
From: Diederik de Haas @ 2024-08-15 13:56 UTC (permalink / raw)
  To: Tom Lendacky, John Allen
  Cc: Herbert Xu, David S. Miller, linux-crypto, linux-kernel,
	Diederik de Haas

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Hi,

I recently bought an Asus ROG STRIX B550-F GAMING MB with an
AMD Ryzen 5 5500GT CPU (and installed the latest BIOS: 3607).
I'm running Debian Testing/Sid on it with kernel 6.9 and now 6.10
and it seems to work great.
I've been doing some (unrelated) tests with `rngtest` from the
`rng-tools5` package and wondered how it would fare on my AMD CPU.

And I found out it doesn't work at all!
But on another system I have (Asus ROG CROSSHAIR VII HERO MB +
AMD Ryzen 1800X CPU) it works absolutely fine.

# dmesg | grep ccp
[    5.399853] ccp 0000:07:00.2: ccp: unable to access the device: you might
be running a broken BIOS.
[    5.401031] ccp 0000:07:00.2: tee enabled
[    5.401113] ccp 0000:07:00.2: psp enabled

Found an article [1] which could be relevant and downloaded and ran the
accompanying test program (written by Jason Donenfeld):
# ./amd-rdrand-bug
Your RDRAND() does not have the AMD bug.
# ./test-rdrand
RDRAND() = 0x47c993c0
RDRAND() = 0xec7c697d
... (more seemingly random numbers)
RDRAND() = 0xba858101

I tried it with the latest microcode dd 2024-07-10, but that didn't make
a difference.

So I'd like to know if this may actually be a bug on the kernel side.

Happy to provide additional information or run tests or try patches.

Cheers,
  Diederik

[1] https://arstechnica.com/gadgets/2019/10/how-a-months-old-amd-microcode-bug-destroyed-my-weekend/

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^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2024-08-15 15:22 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2024-08-15 13:56 [BUG] Non working HWRNG on AMD Ryzen 5 5500GT Diederik de Haas
2024-08-15 14:16 ` Tom Lendacky
2024-08-15 14:40   ` Diederik de Haas
2024-08-15 14:53     ` Tom Lendacky
2024-08-15 15:22       ` Diederik de Haas
2024-08-15 14:22 ` Jason A. Donenfeld
2024-08-15 14:56   ` Diederik de Haas

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