diff options
| author | Kim Phillips <kim.phillips@amd.com> | 2023-01-24 10:33:18 -0600 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2023-01-25 17:16:01 +0100 |
| commit | e7862eda309ecfccc36bb5558d937ed3ace07f3f (patch) | |
| tree | f9421d9634c889fc35fcaed4451f0fc759a68644 /Documentation/admin-guide/hw-vuln | |
| parent | faabfcb194a8d0686396e3fff6a5b42911f65191 (diff) | |
x86/cpu: Support AMD Automatic IBRS
The AMD Zen4 core supports a new feature called Automatic IBRS.
It is a "set-and-forget" feature that means that, like Intel's Enhanced IBRS,
h/w manages its IBRS mitigation resources automatically across CPL transitions.
The feature is advertised by CPUID_Fn80000021_EAX bit 8 and is enabled by
setting MSR C000_0080 (EFER) bit 21.
Enable Automatic IBRS by default if the CPU feature is present. It typically
provides greater performance over the incumbent generic retpolines mitigation.
Reuse the SPECTRE_V2_EIBRS spectre_v2_mitigation enum. AMD Automatic IBRS and
Intel Enhanced IBRS have similar enablement. Add NO_EIBRS_PBRSB to
cpu_vuln_whitelist, since AMD Automatic IBRS isn't affected by PBRSB-eIBRS.
The kernel command line option spectre_v2=eibrs is used to select AMD Automatic
IBRS, if available.
Signed-off-by: Kim Phillips <kim.phillips@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Sean Christopherson <seanjc@google.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20230124163319.2277355-8-kim.phillips@amd.com
Diffstat (limited to 'Documentation/admin-guide/hw-vuln')
| -rw-r--r-- | Documentation/admin-guide/hw-vuln/spectre.rst | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/Documentation/admin-guide/hw-vuln/spectre.rst b/Documentation/admin-guide/hw-vuln/spectre.rst index c4dcdb3d0d45..3fe6511c5405 100644 --- a/Documentation/admin-guide/hw-vuln/spectre.rst +++ b/Documentation/admin-guide/hw-vuln/spectre.rst @@ -610,9 +610,9 @@ kernel command line. retpoline,generic Retpolines retpoline,lfence LFENCE; indirect branch retpoline,amd alias for retpoline,lfence - eibrs enhanced IBRS - eibrs,retpoline enhanced IBRS + Retpolines - eibrs,lfence enhanced IBRS + LFENCE + eibrs Enhanced/Auto IBRS + eibrs,retpoline Enhanced/Auto IBRS + Retpolines + eibrs,lfence Enhanced/Auto IBRS + LFENCE ibrs use IBRS to protect kernel Not specifying this option is equivalent to |