From nobody Thu Dec 18 17:44:02 2025 Received: from out-170.mta0.migadu.com (out-170.mta0.migadu.com [91.218.175.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 56BE125A2AB for ; Wed, 19 Feb 2025 22:08:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.170 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740002927; cv=none; b=AW5vnZsJJgRAe0yyudb3GjI8avbt9cZ2m/ho6HM5Oi2gLq4hCZeNBH8M8qTp6OCRV4z/SjTKDTWhbvgOUS/3Kv8m95BeuzGYjuhjME22zJ/fm1DH7uYQVBovYoYQGRxnkCGfCUx9aJxS0yK/b3O5J8JfuMCcVU+C1C6Y+0VtHuY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740002927; c=relaxed/simple; bh=eRr1Dmq8O02AXPN/fkzwMA0sWBd5Pt33yaY5NPBM6tM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=qReA1mOmkcH1XH+8YWo1k/p/kwgNiSzz99UG2ZJi+ahYIwEIu4DrKAdzfsk+XXMC4K4+Gl8hTYP2mm0JfmYxhgZ0CyQAD6jr8Hb6Nq81WuTHQiSS3MBVUQucixSIcrXjZUa1aOWsDGDQFe2d9S57162+1ljoA4iKGqQQG6x0m5g= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=HqeY1Asg; arc=none smtp.client-ip=91.218.175.170 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="HqeY1Asg" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1740002923; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+v/2kXpvCQAou9vsL9jw3ye8Vh42VkQiI85C+TXQhX0=; b=HqeY1AsgDlJKsCzqVfrixzaYMyYcmClcdW8nRk6x1ZhGnG52EbY6YwLWBSrYYQN9ZSjEAW 1gJW0tC37t4A3VPn/RWRiQUsrXY2YI/oxS/CxH2SJLtUg2POGvE3cG/lHIj3KWDuytXSCD h49EQAfKV2DiLlVWBZigVjLYqmkFERE= From: Yosry Ahmed To: x86@kernel.org Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Peter Zijlstra , Josh Poimboeuf , Pawan Gupta , Andy Lutomirski , Sean Christopherson , Paolo Bonzini , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/6] x86/mm: Remove X86_FEATURE_USE_IBPB checks in cond_mitigation() Date: Wed, 19 Feb 2025 22:08:22 +0000 Message-ID: <20250219220826.2453186-3-yosry.ahmed@linux.dev> In-Reply-To: <20250219220826.2453186-1-yosry.ahmed@linux.dev> References: <20250219220826.2453186-1-yosry.ahmed@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" 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: Yosry Ahmed --- arch/x86/mm/tlb.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index be0c1a509869c..e860fc8edfae4 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -437,8 +437,7 @@ static void cond_mitigation(struct task_struct *next) * both have the IBPB bit set. */ if (next_mm !=3D 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(); } =20 @@ -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) !=3D (unsigned long)next->mm && - cpu_feature_enabled(X86_FEATURE_USE_IBPB)) + if ((prev_mm & ~LAST_USER_MM_SPEC_MASK) !=3D (unsigned long)next->mm) indirect_branch_prediction_barrier(); } =20 --=20 2.48.1.601.g30ceb7b040-goog