From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.12]) (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 741F54963B for ; Mon, 24 Jun 2024 08:11:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.12 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719216690; cv=none; b=KM7kDwleNQjUOZXeEGlmRg479refEgwg8BPo/hmY+rlSutgMqoOKHsfNUmIPNgQsEda0PbNhAlpcPxjhn+gmhPQ5PaoBeGLcSpKRkaSqEjtceCxjhGoEZ/GTu/CH8VMXD9Fp6T3vihMJAVuuxfPNNATTw3AJCdtC8HH/qJnScJk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719216690; c=relaxed/simple; bh=5/3o+1zuQSrtmWhv6M+q+yIZbsryQ+tIgRK0WSHB310=; h=Message-ID:Date:MIME-Version:Cc:Subject:To:References:From: In-Reply-To:Content-Type; b=Ef8qwKqtzXIoRL0Y/fladdApicmpNnb82c7UPhgPxN8A/3jOglrBMfVAY92BFN0ze2wg4rJY1hYUSIFNSLtGej5Hg6BsN0f3Fnt4bHo2EPFEjNdXGs87+ekRIzSCCy5mb4mcvGx50eg5ALcRWWzB/afbZn4ZvdZtwRMsnnBkYS0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=PggHGIEv; arc=none smtp.client-ip=192.198.163.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none 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="PggHGIEv" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1719216689; x=1750752689; h=message-id:date:mime-version:cc:subject:to:references: from:in-reply-to:content-transfer-encoding; bh=5/3o+1zuQSrtmWhv6M+q+yIZbsryQ+tIgRK0WSHB310=; b=PggHGIEvb3Z53F6uvSIXk8n2OqUD2wdTBlhQS4NdggutEabeolW8jny/ 3nT0IlzpVI0zGAZRS+c8OzD+TatvAPcmaz4iNLgrDUFcj21cfPKmK9cyP xtcLyVHoOyMw1UFG+QWY7JxO7kwCQeILG990gex46Mr2kqDWG17bdcBAL 8Oxb3TXBFdn/wG3dcYaau+eEMTfGybxdsCN95viuSfxkb6ZkM4193ofZ8 XX0+gHoMgVrZ6hDbS+Crw5+dCUnqeJq+0FuZg8idu5MNjgPRIiC/D5Krc Y9AGSsy5yk4Rjmb/19rPZCwg0lVMdbXjcknTd8FOAM2g2hTWlchaio30/ Q==; X-CSE-ConnectionGUID: 3LpFqnIpSLmWqsnb3LhYBg== X-CSE-MsgGUID: c7SPiQ7+QNaSo95sLF3BgQ== X-IronPort-AV: E=McAfee;i="6700,10204,11112"; a="20056091" X-IronPort-AV: E=Sophos;i="6.08,261,1712646000"; d="scan'208";a="20056091" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by fmvoesa106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Jun 2024 01:11:29 -0700 X-CSE-ConnectionGUID: ygUZ6XyEQ2ioYfMvalHL2w== X-CSE-MsgGUID: TRjDnuJtQTKqQzi2uNhiow== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.08,261,1712646000"; d="scan'208";a="47752570" Received: from unknown (HELO [10.124.237.100]) ([10.124.237.100]) by fmviesa004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Jun 2024 01:11:26 -0700 Message-ID: Date: Mon, 24 Jun 2024 16:11:24 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Cc: baolu.lu@linux.intel.com, Will Deacon , Robin Murphy , iommu@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] iommu/vt-d: Remove hardware automatic ATS dependency To: Yi Liu , Joerg Roedel , Kevin Tian , Jacob Pan References: <20240624052501.253405-1-baolu.lu@linux.intel.com> <20240624052501.253405-2-baolu.lu@linux.intel.com> <15590835-ed6a-44a5-94b5-663f159653cc@intel.com> Content-Language: en-US From: Baolu Lu In-Reply-To: <15590835-ed6a-44a5-94b5-663f159653cc@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2024/6/24 16:06, Yi Liu wrote: > On 2024/6/24 13:25, Lu Baolu wrote: >> If a device is listed in the SATC table with ATC_REQUIRED flag set, it >> indicates that the device has a functional requirement to enable its ATC >> (via the ATS capability) for device operation. However, when IOMMU is >> running in the legacy mode, ATS could be automatically supported by the >> hardware so that the OS has no need to support the ATS functionality. > > It seems like if VT-d hw is operating in legacy mode, ATS is enabled > automatically? Yes. > This is really suprising. Maybe I got it wrongly. Could you > elaborate a bit? It's for backward compatible purpose, but I have no hardware details. Best regards, baolu