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x86/speculation: Add basic IBPB (Indirect Branch Prediction Barrier) support

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Expose indirect_branch_prediction_barrier() for use in subsequent patches.

[ tglx: Add IBPB status to spectre_v2 sysfs file ]

Co-developed-by: KarimAllah Ahmed <karahmed@amazon.de>
Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Cc: gnomes@lxorguk.ukuu.org.uk
Cc: ak@linux.intel.com
Cc: ashok.raj@intel.com
Cc: dave.hansen@intel.com
Cc: arjan@linux.intel.com
Cc: torvalds@linux-foundation.org
Cc: peterz@infradead.org
Cc: bp@alien8.de
Cc: pbonzini@redhat.com
Cc: tim.c.chen@linux.intel.com
Cc: gregkh@linux-foundation.org
Link: https://lkml.kernel.org/r/1516896855-7642-8-git-send-email-dwmw@amazon.co.uk
This commit is contained in:
David Woodhouse
2018-01-25 16:14:15 +00:00
committed by Thomas Gleixner
parent a5b2966364
commit 20ffa1caec
3 changed files with 24 additions and 1 deletions
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10
arch/x86/kernel/cpu/bugs.c
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@@ -263,6 +263,13 @@ retpoline_auto:
setup_force_cpu_cap(X86_FEATURE_RSB_CTXSW);
pr_info("Filling RSB on context switch\n");
}
/* Initialize Indirect Branch Prediction Barrier if supported */
if (boot_cpu_has(X86_FEATURE_SPEC_CTRL) ||
boot_cpu_has(X86_FEATURE_AMD_PRED_CMD)) {
setup_force_cpu_cap(X86_FEATURE_IBPB);
pr_info("Enabling Indirect Branch Prediction Barrier\n");
}
}
#undef pr_fmt
@@ -292,7 +299,8 @@ ssize_t cpu_show_spectre_v2(struct device *dev,
if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2))
return sprintf(buf, "Not affected\n");
return sprintf(buf, "%s%s\n", spectre_v2_strings[spectre_v2_enabled],
return sprintf(buf, "%s%s%s\n", spectre_v2_strings[spectre_v2_enabled],
boot_cpu_has(X86_FEATURE_IBPB) ? ", IPBP" : "",
spectre_v2_bad_module ? " - vulnerable module loaded" : "");
}
#endif