Commit e2a9c031 authored by Pawan Gupta's avatar Pawan Gupta Committed by Borislav Petkov (AMD)
Browse files

x86/bugs: Remove its=stuff dependency on retbleed 



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: default avatarPawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250611-eibrs-fix-v4-6-5ff86cac6c61@linux.intel.com
parent 8374a271

arch/x86/kernel/cpu/bugs.c

+6 −8
Original line number Diff line number Diff line
@@ -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;

	}

}