kernel_samsung_a53x/Documentation
Kim Phillips 9392cffe0d x86/cpu: Support AMD Automatic IBRS
commit e7862eda309ecfccc36bb5558d937ed3ace07f3f upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-11-19 09:22:13 +01:00
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ABI net: sysfs: Fix /sys/class/net/<iface> path for statistics 2024-11-18 12:13:28 +01:00
accounting Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
admin-guide x86/cpu: Support AMD Automatic IBRS 2024-11-19 09:22:13 +01:00
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