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x86/bugs: Remove its=stuff dependency on retbleed

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Allow ITS to enable stuffing independent of retbleed. The dependency is only
on retpoline. It is a valid case for retbleed to be mitigated by eIBRS while
ITS deploys stuffing at the same time.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250611-eibrs-fix-v4-6-5ff86cac6c61@linux.intel.com
This commit is contained in:
Pawan Gupta
2025-06-23 12:29:04 +02:00
committed by Borislav Petkov (AMD)
parent 8374a2719d
commit e2a9c03192
1 changed files with 6 additions and 8 deletions
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arch/x86/kernel/cpu/bugs.c
+6 -8
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@@ -1467,13 +1467,8 @@ static void __init its_update_mitigation(void)
break;
}
/*
* retbleed_update_mitigation() will try to do stuffing if its=stuff.
* If it can't, such as if spectre_v2!=retpoline, then fall back to
* aligned thunks.
*/
if (its_mitigation == ITS_MITIGATION_RETPOLINE_STUFF &&
retbleed_mitigation != RETBLEED_MITIGATION_STUFF)
!cdt_possible(spectre_v2_enabled))
its_mitigation = ITS_MITIGATION_ALIGNED_THUNKS;
pr_info("%s\n", its_strings[its_mitigation]);
@@ -1485,8 +1480,6 @@ static void __init its_apply_mitigation(void)
case ITS_MITIGATION_OFF:
case ITS_MITIGATION_AUTO:
case ITS_MITIGATION_VMEXIT_ONLY:
/* its=stuff forces retbleed stuffing and is enabled there. */
case ITS_MITIGATION_RETPOLINE_STUFF:
break;
case ITS_MITIGATION_ALIGNED_THUNKS:
if (!boot_cpu_has(X86_FEATURE_RETPOLINE))
@@ -1495,6 +1488,11 @@ static void __init its_apply_mitigation(void)
setup_force_cpu_cap(X86_FEATURE_RETHUNK);
set_return_thunk(its_return_thunk);
break;
case ITS_MITIGATION_RETPOLINE_STUFF:
setup_force_cpu_cap(X86_FEATURE_RETHUNK);
setup_force_cpu_cap(X86_FEATURE_CALL_DEPTH);
set_return_thunk(call_depth_return_thunk);
break;
}
}