From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) (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 513A515AA for ; Fri, 9 Jun 2023 06:06:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1686290779; x=1717826779; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=pCUTHnlZlVar+pAAYPKyf+GGBotLIiPQRNKzfWEppzc=; b=aeZ3SGhR3WpRihEYYh7FHsTfd7VxtMb7h8QeyiqicqgfuLGtasZqLtWG Ps00el0oOCzeydVUgO66+qDqJxVXyg2ZyIvqwjhPtti8DL1rID3D1tjLN xc3Uo1lcx8Z9fVMEVR2LJLQBpCyY/EoazH/2yPzW0RaIfM+Jcosms37cq jU7SG5C+robRrJLFHb4H1mYYXL1jvTao3fy1A5UA5YwTrhob+mE18+kTA 51h43atIBB5/qUZdRXkg7sp6pF40Cm8LA3SBt1CEaawvAVi7KW1UJcimc 8IxbM5Dl/CRn8QtZMC9A032osxq+SzkkINSt0cttEB7dnhc+H3PjOwK6W w==; X-IronPort-AV: E=McAfee;i="6600,9927,10735"; a="360881590" X-IronPort-AV: E=Sophos;i="6.00,228,1681196400"; d="scan'208";a="360881590" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Jun 2023 23:06:18 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10735"; a="660652218" X-IronPort-AV: E=Sophos;i="6.00,228,1681196400"; d="scan'208";a="660652218" Received: from allen-box.sh.intel.com ([10.239.159.127]) by orsmga003.jf.intel.com with ESMTP; 08 Jun 2023 23:06:17 -0700 From: Lu Baolu To: iommu@lists.linux.dev Cc: linux-kernel@vger.kernel.org, Lu Baolu Subject: [PATCH 1/1] iommu/vt-d: Remove commented-out code Date: Fri, 9 Jun 2023 14:05:14 +0800 Message-Id: <20230609060514.15154-1-baolu.lu@linux.intel.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 --- 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 |= DMA_TLB_READ_DRAIN; -#endif + if (cap_write_drain(iommu->cap)) val |= DMA_TLB_WRITE_DRAIN; -- 2.34.1