From nobody Sat Feb 7 21:08:16 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6AA37EB64D7 for ; Wed, 14 Jun 2023 02:49:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242484AbjFNCtR (ORCPT ); Tue, 13 Jun 2023 22:49:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38064 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242372AbjFNCsu (ORCPT ); Tue, 13 Jun 2023 22:48:50 -0400 Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6D77D2128 for ; Tue, 13 Jun 2023 19:48:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1686710902; x=1718246902; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=UGWXKlFwoha8aQZA4PcpDVrWAANHfSgY3CsRnwLIe6c=; b=a0+U6IQ5EdhQP35L6gr0wvawf4BRZU/vGOm0zeTiZNIUK6WYApbJhCev R0FDHPlJZIn1jwBbx2UwPwpSmGV5IEP+szU/CotZ44VSW3mlq6NCVANOG PmQ+7q3SCTNCH7JK6/PsMTdqil1Bj4Y4ZIpKF4cJbLn6nPNdwTkWHnV3q 5QnmQLGDHiSqB0TOzIvsbxSE8zuWNECeVu1hMsahLfBWCFCnQR3J1/5xd jbaZXLi0HOnC8KZ8JFl956SNaYA2Kt2pClFzxk6HNm69EnHkopv2dDJ42 eStzxda+Xg2HUnB6Aft/s47DIe6OeQDrtoqWO1BCSgUGTa46FgmE8EydL g==; X-IronPort-AV: E=McAfee;i="6600,9927,10740"; a="348164469" X-IronPort-AV: E=Sophos;i="6.00,241,1681196400"; d="scan'208";a="348164469" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Jun 2023 19:48:21 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10740"; a="711884219" X-IronPort-AV: E=Sophos;i="6.00,241,1681196400"; d="scan'208";a="711884219" Received: from allen-box.sh.intel.com ([10.239.159.127]) by orsmga002.jf.intel.com with ESMTP; 13 Jun 2023 19:48:20 -0700 From: Lu Baolu To: Joerg Roedel Cc: Yanfei Xu , Suhui , iommu@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [PATCH 4/4] iommu/vt-d: Remove commented-out code Date: Wed, 14 Jun 2023 10:47:05 +0800 Message-Id: <20230614024705.88878-5-baolu.lu@linux.intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230614024705.88878-1-baolu.lu@linux.intel.com> References: <20230614024705.88878-1-baolu.lu@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" These lines of code were commented out when they were first added in commit ba39592764ed ("Intel IOMMU: Intel IOMMU driver"). We do not want to restore them because the VT-d spec has deprecated the read/write draining hit. VT-d spec (section 11.4.2): " Hardware implementation with Major Version 2 or higher (VER_REG), always performs required drain without software explicitly requesting a drain in IOTLB invalidation. This field is deprecated and hardware will always report it as 1 to maintain backward compatibility with software. " Remove the code to make the code cleaner. Signed-off-by: Lu Baolu Reviewed-by: Jerry Snitselaar Link: https://lore.kernel.org/r/20230609060514.15154-1-baolu.lu@linux.intel= .com --- drivers/iommu/intel/iommu.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index 4c0b7424c45e..e5c111ff4dd9 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -1312,15 +1312,7 @@ static void __iommu_flush_iotlb(struct intel_iommu *= iommu, u16 did, iommu->name, type); return; } - /* Note: set drain read/write */ -#if 0 - /* - * This is probably to be super secure.. Looks like we can - * ignore it without any impact. - */ - if (cap_read_drain(iommu->cap)) - val |=3D DMA_TLB_READ_DRAIN; -#endif + if (cap_write_drain(iommu->cap)) val |=3D DMA_TLB_WRITE_DRAIN; =20 --=20 2.34.1