From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.17]) (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 835974137A2 for ; Tue, 4 Aug 2026 02:48:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.17 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785811715; cv=none; b=Nknm7pITUD3OGb3ibA/YgAVHZYI/4Wa+8vNnl58axmlbf3Bb83c0umFoVefWuc6Jf9/bQB3pLzGuuJ/0lp7+2TzC+Im3NezxQGqeMVxCS+qeAdnW/rRpq0yD0JFOtGfc/lgZPFwWRt329L8cEVynJhjCLHYxXRgOIOp89iU8rdM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785811715; c=relaxed/simple; bh=YDlwD9/B7SoUh5Cw/Q8HBWUAKwRQP4CubhpluDGbVfg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=u8PFAFHE6CmTOpmXZ+pRxki8wShPuHbHwU8N3xNPLWj1QxKF5fJKr/oDH+uVSFL/3n5WfpAbuSgQhxun+O5QAgpPiSSb5GWNB9DtUBPhBWCY8uz5ClVDc/t+6zxBp8risGtlA5WVvsW14hqZEsDpLuHggVdwqfyBAwzDnsoX6qE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=V3tjeRy+; arc=none smtp.client-ip=192.198.163.17 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="V3tjeRy+" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1785811715; x=1817347715; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=YDlwD9/B7SoUh5Cw/Q8HBWUAKwRQP4CubhpluDGbVfg=; b=V3tjeRy+21daXBBtZAVLtuj2mkBJjBXbyWoMEUNtXnZgQxRJsfn/lV37 Ezg+VopjFQ7b/XPOXLC+KmVgeeKqlDrjWAS0UECgXywyAoz9FVQwHnGFj xQZP3m+oFpQvis6tffThLbeGhKLRu3hqXPDQFLH5OeFy37pDbwoVvnw1I 4gQ3tLbINouWj/EjsIy+aKqcAcUWfxkZJ0NeBCBkOIn4mLlnOdFWCgecu zixMYWpNXPxz0FR5IqFc7bSG51dnzXJcMU0nBETi0oslgfYRGPgsZIPEu b9FCkZ9nzTxkNcICE2e5/OWKmrGnFjV4PVROsLiuspWAKj7CGljhjJnjh w==; X-CSE-ConnectionGUID: MS3umrJYTdmlLu/upCFPVA== X-CSE-MsgGUID: SWB0/fxOTZKVdcYECugd2A== X-IronPort-AV: E=McAfee;i="6800,10657,11864"; a="86231251" X-IronPort-AV: E=Sophos;i="6.25,203,1779174000"; d="scan'208";a="86231251" Received: from orviesa006.jf.intel.com ([10.64.159.146]) by fmvoesa111.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Aug 2026 19:48:34 -0700 X-CSE-ConnectionGUID: reCLnf5YTBGBfaYwrWoyGg== X-CSE-MsgGUID: usZu3U3GTWKJsENiGkZKPQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,203,1779174000"; d="scan'208";a="259587470" Received: from allen-box.sh.intel.com ([10.239.159.52]) by orviesa006.jf.intel.com with ESMTP; 03 Aug 2026 19:48:33 -0700 From: Lu Baolu To: Joerg Roedel Cc: ZhaoJinming , Kevin Tian , Dmitry Antipov , Guanghui Feng , Li RongQing , Desnes Nunes , iommu@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [PATCH 05/20] iommu/vt-d: Fix no_iommu to disable platform opt-in Date: Tue, 4 Aug 2026 10:36:59 +0800 Message-ID: <20260804023714.3080506-6-baolu.lu@linux.intel.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260804023714.3080506-1-baolu.lu@linux.intel.com> References: <20260804023714.3080506-1-baolu.lu@linux.intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Kevin Tian If user explicitly requests to disable iommu (via "iommu=off" or "intel_iommu=off"), there is no reason to force enabling it due to platform opt-in (for external-facing devices). User should be aware of any security implication of doing so. "intel_iommu=off" implements this policy by setting no_platform_optin to skip platform opt-in in platform_optin_force_iommu(). However, "iommu=off" (no_iommu=1) doesn't set no_platform_optin hence is broken in this aspect: - detect_intel_iommu() doesn't request ACS if no_iommu=1 - platform_optin_force_iommu() forces iommu on if external-facing devices exist and no_platform_optin is not set This leads to a bad configuration with ACS disabled while DMA remapping is enabled. Instead of setting no_platform_optin (will soon be removed) for no_iommu=1, directly check no_iommu in platform_optin_force_iommu(). Fixes: 89a6079df791 ("iommu/vt-d: Force IOMMU on for platform opt in hint") Cc: stable@vger.kernel.org Signed-off-by: Kevin Tian Signed-off-by: Lu Baolu --- drivers/iommu/intel/iommu.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index cf5f92619943..1a1f27a51063 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -2484,10 +2484,11 @@ static bool has_external_pci(void) static int __init platform_optin_force_iommu(void) { - if (!dmar_platform_optin() || no_platform_optin || !has_external_pci()) + if (no_iommu || !dmar_platform_optin() || no_platform_optin || + !has_external_pci()) return 0; - if (no_iommu || dmar_disabled) + if (dmar_disabled) pr_info("Intel-IOMMU force enabled due to platform opt in\n"); /* @@ -2498,7 +2499,6 @@ static int __init platform_optin_force_iommu(void) iommu_set_default_passthrough(false); dmar_disabled = 0; - no_iommu = 0; return 1; } -- 2.43.0