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Borislav Petkov 7879fc4bdc x86/rdrand: Sanity-check RDRAND output
It turned out recently that on certain AMD F15h and F16h machines, due
to the BIOS dropping the ball after resume, yet again, RDRAND would not
function anymore:

  c49a0a8013 ("x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h")

Add a silly test to the CPU bringup path, to sanity-check the random
data RDRAND returns and scream as loudly as possible if that returned
random data doesn't change.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Pu Wen <puwen@hygon.cn>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/CAHk-=wjWPDauemCmLTKbdMYFB0UveMszZpcrwoUkJRRWKrqaTw@mail.gmail.com
History 2019-10-01 19:55:32 +02:00
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Linux kernel
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There are several guides for kernel developers and users. These guides can
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In order to build the documentation, use ``make htmldocs`` or
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