x86/CPU/AMD: Add RDSEED fix for Zen5

Browse source

commit 607b9fb2ce upstream.

There's an issue with RDSEED's 16-bit and 32-bit register output
variants on Zen5 which return a random value of 0 "at a rate inconsistent
with randomness while incorrectly signaling success (CF=1)". Search the
web for AMD-SB-7055 for more detail.

Add a fix glue which checks microcode revisions.

  [ bp: Add microcode revisions checking, rewrite. ]

Cc: stable@vger.kernel.org
Signed-off-by: Gregory Price <gourry@gourry.net>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20251018024010.4112396-1-gourry@gourry.net
[ bp: 6.12 backport: use the alternative microcode version checking. ]
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

Gregory Price 2025-10-20 11:13:55 +02:00 • committed by Greg Kroah-Hartman

parent 958999dbd1

commit e980de2ff1

1 changed files with 35 additions and 0 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

35

arch/x86/kernel/cpu/amd.c

View file