From patchwork Thu Feb 27 01:27:08 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yosry Ahmed X-Patchwork-Id: 13993486 Received: from out-174.mta0.migadu.com (out-174.mta0.migadu.com [91.218.175.174]) (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 D5F8E199223 for ; Thu, 27 Feb 2025 01:27:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.174 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740619657; cv=none; b=DPK8BnWKKoeFgxlmDUe/brRtwXfEgg8o3xrCv5rdl5LhpN+ydjie53rOCyeIZyI6z6HB8kCn2H8RGOSJUDSXcs6oZbbIU7iYO2Aidqtq6/oiZOvs6bYU5n6aq76i9GJplVUVA7poKba9CD6pxSgE+H7SoNDR6UZLi05m00Me7gA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740619657; c=relaxed/simple; bh=nRTvcm/STflAUNTshhDiW2xSDILXeIC73ZVPtltoxMs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=uxYiQiSOVhKJUNWoqV1Ukprpp5aSJQLKFTOSuHWVXNd7MHOLa/H1d5Lgrka706NHJIkarQUMZY9QVuxyh6vRxd0GWkKg+p4gwI7UUpi6CE95494twxIr0WJ6A4C87C3UMmU1heJmk5YON2szXWo8tXAIAILmTVE2TID0LFMC1bU= 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=bkqPAXfp; arc=none smtp.client-ip=91.218.175.174 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="bkqPAXfp" 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=1740619653; 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=quLOmbx6xPKhUW5STb4KYNYxrnHTcaUOYh+FWYsnrjE=; b=bkqPAXfpaMrYDMS9JlsW5hexwxCPpXA86swIkN4cxvMKz8PJ+UsXYo8vepb2IsnLH1m6wY 1a39wC7lW+Q4KwCWvGYiweV+oBMOjHyPASe5o9CJIAnPMeDFML4MZiXvcMR/HnBUqkB2Ms XQJISAEAK+wSi6YVzE3QjoEdmbTVOlM= From: Yosry Ahmed To: x86@kernel.org, Sean Christopherson Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Pawan Gupta , Andy Lutomirski , Peter Zijlstra , Josh Poimboeuf , Paolo Bonzini , Jim Mattson , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Yosry Ahmed Subject: [PATCH v2 2/6] x86/mm: Remove X86_FEATURE_USE_IBPB checks in cond_mitigation() Date: Thu, 27 Feb 2025 01:27:08 +0000 Message-ID: <20250227012712.3193063-3-yosry.ahmed@linux.dev> In-Reply-To: <20250227012712.3193063-1-yosry.ahmed@linux.dev> References: <20250227012712.3193063-1-yosry.ahmed@linux.dev> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT 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 Acked-by: Josh Poimboeuf --- 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 != 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(); }