Commit a48dc426 authored by Yosry Ahmed's avatar Yosry Ahmed Committed by Ingo Molnar
Browse files

x86/mm: Remove X86_FEATURE_USE_IBPB checks in cond_mitigation() 



The check is performed when either switch_mm_cond_ibpb or
switch_mm_always_ibpb is set. In both cases, X86_FEATURE_USE_IBPB is
always set. Remove the redundant check.

Signed-off-by: default avatarYosry Ahmed <yosry.ahmed@linux.dev>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Acked-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20250227012712.3193063-3-yosry.ahmed@linux.dev
parent 549435aa

arch/x86/mm/tlb.c

+2 −4
Original line number Diff line number Diff line
@@ -437,8 +437,7 @@ static void cond_mitigation(struct task_struct *next) 
		 * both have the IBPB bit set.

		 */

		if (next_mm != prev_mm &&

		    (next_mm | prev_mm) & LAST_USER_MM_IBPB &&

		    cpu_feature_enabled(X86_FEATURE_USE_IBPB))

		    (next_mm | prev_mm) & LAST_USER_MM_IBPB)

			indirect_branch_prediction_barrier();

	}
@@ -448,8 +447,7 @@ static void cond_mitigation(struct task_struct *next) 
		 * different context than the user space task which ran

		 * last on this CPU.

		 */

		if ((prev_mm & ~LAST_USER_MM_SPEC_MASK) != (unsigned long)next->mm &&

		    cpu_feature_enabled(X86_FEATURE_USE_IBPB))

		if ((prev_mm & ~LAST_USER_MM_SPEC_MASK) != (unsigned long)next->mm)

			indirect_branch_prediction_barrier();

	}