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| author |  Sean Christopherson <seanjc@google.com>
| 2024-04-19 17:05:55 -0700 |
|---|---|---|
| committer |  Borislav Petkov (AMD) <bp@alien8.de>
| 2024-04-25 15:47:39 +0200 |
| commit | ce0abef6a1d540acef85068e0e82bdf1fbeeb0e9 (patch) | |
| tree | 351692e7d9b06fe49aa7f6d1419cde3a7200d13d /Documentation | |
| parent | cpu: Re-enable CPU mitigations by default for !X86 architectures (diff) | |
| download | linux-ce0abef6a1d540acef85068e0e82bdf1fbeeb0e9.tar.gz linux-ce0abef6a1d540acef85068e0e82bdf1fbeeb0e9.tar.bz2 linux-ce0abef6a1d540acef85068e0e82bdf1fbeeb0e9.zip | |
cpu: Ignore "mitigations" kernel parameter if CPU_MITIGATIONS=n
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
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 902ecd92a29f..213d0719e2b7 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3423,6 +3423,9 @@ 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 |