Commit 0fe4aeea authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Borislav Petkov
Browse files

x86/bugs: Do IBPB fallback check only once 



When booting with retbleed=auto, if the kernel wasn't built with
CONFIG_CC_HAS_RETURN_THUNK, the mitigation falls back to IBPB.  Make
sure a warning is printed in that case.  The IBPB fallback check is done
twice, but it really only needs to be done once.

Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
parent 3ebc1700

arch/x86/kernel/cpu/bugs.c

+5 −10
Original line number Original line Diff line number Diff line
@@ -891,18 +891,13 @@ static void __init retbleed_select_mitigation(void) 
	case RETBLEED_CMD_AUTO:

	case RETBLEED_CMD_AUTO:

	default:

	default:

		if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||

		if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||

		    boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {

		    boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)



			if (IS_ENABLED(CONFIG_RETPOLINE) &&

			    IS_ENABLED(CONFIG_CC_HAS_RETURN_THUNK))

			retbleed_mitigation = RETBLEED_MITIGATION_UNRET;

			retbleed_mitigation = RETBLEED_MITIGATION_UNRET;

			else

				retbleed_mitigation = RETBLEED_MITIGATION_IBPB;

		}





		/*

		/*

		 * The Intel mitigation (IBRS) was already selected in

		 * The Intel mitigation (IBRS or eIBRS) was already selected in

		 * spectre_v2_select_mitigation().

		 * spectre_v2_select_mitigation().  'retbleed_mitigation' will

		 * be set accordingly below.

		 */

		 */





		break;

		break;