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| author | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-09-25 11:13:51 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-09-25 11:13:51 +0200 |
| commit | 56fb05093756ed55ba1cdf5d432a68004da67860 (patch) | |
| tree | 87dc333d4f606f375d6253eb5b8ef6f04674ffa6 /Documentation/admin-guide/hw-vuln/srso.rst | |
| parent | b6a153b0829afbc63032e8271d3ca9a19e704e03 (diff) | |
| parent | da274362a7bd9ab3a6e46d15945029145ebce672 (diff) | |
Merge v6.12.49linux-rolling-lts
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/admin-guide/hw-vuln/srso.rst')
| -rw-r--r-- | Documentation/admin-guide/hw-vuln/srso.rst | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/Documentation/admin-guide/hw-vuln/srso.rst b/Documentation/admin-guide/hw-vuln/srso.rst index 2ad1c05b8c88..66af95251a3d 100644 --- a/Documentation/admin-guide/hw-vuln/srso.rst +++ b/Documentation/admin-guide/hw-vuln/srso.rst @@ -104,7 +104,20 @@ The possible values in this file are: (spec_rstack_overflow=ibpb-vmexit) + * 'Mitigation: Reduced Speculation': + This mitigation gets automatically enabled when the above one "IBPB on + VMEXIT" has been selected and the CPU supports the BpSpecReduce bit. + + It gets automatically enabled on machines which have the + SRSO_USER_KERNEL_NO=1 CPUID bit. In that case, the code logic is to switch + to the above =ibpb-vmexit mitigation because the user/kernel boundary is + not affected anymore and thus "safe RET" is not needed. + + After enabling the IBPB on VMEXIT mitigation option, the BpSpecReduce bit + is detected (functionality present on all such machines) and that + practically overrides IBPB on VMEXIT as it has a lot less performance + impact and takes care of the guest->host attack vector too. In order to exploit vulnerability, an attacker needs to: |