Sean Christopherson 976b74fa60 cpu: Ignore "mitigations" kernel parameter if CPU_MITIGATIONS=n
[ Upstream commit ce0abef6a1d540acef85068e0e82bdf1fbeeb0e9 ]

Explicitly disallow enabling mitigations at runtime for kernels that were
built with CONFIG_CPU_MITIGATIONS=n, as some architectures may omit code
entirely if mitigations are disabled at compile time.

E.g. on x86, a large pile of Kconfigs are buried behind CPU_MITIGATIONS,
and trying to provide sane behavior for retroactively enabling mitigations
is extremely difficult, bordering on impossible.  E.g. page table isolation
and call depth tracking require build-time support, BHI mitigations will
still be off without additional kernel parameters, etc.

  [ bp: Touchups. ]

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240420000556.2645001-3-seanjc@google.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-06-12 11:11:24 +02:00
..
2023-09-05 10:15:22 -07:00
2023-09-05 10:09:31 -07:00
2024-02-16 19:10:52 +01:00
2024-02-23 09:25:03 +01:00