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| author | Sean Christopherson <seanjc@google.com> | 2024-04-20 03:05:55 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-05-30 10:48:48 +0300 |
| commit | 386248134388f4c3f26f821a516dff8aded5c499 (patch) | |
| tree | 4fdcb1145e1dd1a1074b8dd548d40e5b0ebc7ff1 /Documentation | |
| parent | f41b17fe8549fffdf09f6c1501977665bb8b7b67 (diff) | |
| download | linux-386248134388f4c3f26f821a516dff8aded5c499.tar.xz | |
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>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 31fdaf4fe9dd..9bfc972af240 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3399,6 +3399,9 @@ arch-independent options, each of which is an aggregation of existing arch-specific options. + Note, "mitigations" is supported if and only if the + kernel was built with CPU_MITIGATIONS=y. + off Disable all optional CPU mitigations. This improves system performance, but it may also |