linux-kernel - [PATCH v2 3/6] x86/bugs: Remove the X86_FEATURE_USE_IBPB check in ib_prctl

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Message-ID: <20250227012712.3193063-4-yosry.ahmed@linux.dev>
Date: Thu, 27 Feb 2025 01:27:09 +0000
From: Yosry Ahmed <yosry.ahmed@...ux.dev>
To: x86@...nel.org,
	Sean Christopherson <seanjc@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
	Andy Lutomirski <luto@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Jim Mattson <jmattson@...gle.com>,
	kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Yosry Ahmed <yosry.ahmed@...ux.dev>
Subject: [PATCH v2 3/6] x86/bugs: Remove the X86_FEATURE_USE_IBPB check in ib_prctl_set()

If X86_FEATURE_USE_IBPB is not set, then both spectre_v2_user_ibpb and
spectre_v2_user_stibp are set to SPECTRE_V2_USER_NONE in
spectre_v2_user_select_mitigation(). Since ib_prctl_set() already checks
for this before performing the IBPB, the X86_FEATURE_USE_IBPB check is
redundant. Remove it.

Signed-off-by: Yosry Ahmed <yosry.ahmed@...ux.dev>
Acked-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 arch/x86/kernel/cpu/bugs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 754150fc05784..1d7afc40f2272 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -2272,7 +2272,7 @@ static int ib_prctl_set(struct task_struct *task, unsigned long ctrl)
 		if (ctrl == PR_SPEC_FORCE_DISABLE)
 			task_set_spec_ib_force_disable(task);
 		task_update_spec_tif(task);
-		if (task == current && cpu_feature_enabled(X86_FEATURE_USE_IBPB))
+		if (task == current)
 			indirect_branch_prediction_barrier();
 		break;
 	default:
-- 
2.48.1.658.g4767266eb4-goog