From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 98977C282C2 for ; Thu, 7 Feb 2019 21:31:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6100B2146E for ; Thu, 7 Feb 2019 21:31:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726914AbfBGVbp (ORCPT ); Thu, 7 Feb 2019 16:31:45 -0500 Received: from mga01.intel.com ([192.55.52.88]:55823 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726512AbfBGVbo (ORCPT ); Thu, 7 Feb 2019 16:31:44 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 07 Feb 2019 13:31:43 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.58,345,1544515200"; d="scan'208";a="113234116" Received: from linux.intel.com ([10.54.29.200]) by orsmga007.jf.intel.com with ESMTP; 07 Feb 2019 13:31:43 -0800 Received: from [10.54.74.33] (skuppusw-desk.jf.intel.com [10.54.74.33]) by linux.intel.com (Postfix) with ESMTP id 125605802E1; Thu, 7 Feb 2019 13:31:43 -0800 (PST) Reply-To: sathyanarayanan.kuppuswamy@linux.intel.com Subject: Re: [PATCH v1 1/1] iommu/vt-d: Enable PRI only if the device enables PASID. To: David Woodhouse , "Raj, Ashok" Cc: joro@8bytes.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Jacob Pan References: <142748f6a00153f9926fe2a9dc30cf3cd89164cd.1549408090.git.sathyanarayanan.kuppuswamy@linux.intel.com> <0faf4f6a5bbd8cbee84aa78c40ab15216c2b8f0e.camel@infradead.org> <20190207210936.GH103220@otc-nc-03> <9393b9b2c15564ee84b627a73fb34bd17ebe4a7f.camel@infradead.org> From: sathyanarayanan kuppuswamy Organization: Intel Message-ID: Date: Thu, 7 Feb 2019 13:30:24 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <9393b9b2c15564ee84b627a73fb34bd17ebe4a7f.camel@infradead.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/7/19 1:15 PM, David Woodhouse wrote: > On Thu, 2019-02-07 at 13:09 -0800, Raj, Ashok wrote: >> You are right.. they are completely orthogonal. We just don't have >> a way to handle the page-requests for request without PASID's. >> >> There are some of the vIOMMU work to pass the PRI to who owns >> the device, and we can certainly relax it then. This is just to reflect >> what support exists today. FWIW, even the native driver maybe be able >> to resolve this if supported. > As things stand, if a device makes a PRI request without a PASID, it'll > get told that we didn't manage to bring the page in for it. Which is > true. > > What's the actual problem being fixed by this patch? Since the request is going to fail any way why go through the process of enabling it ? Once the functionality (PRI without PASID) is supported, then they can revert this patch. Just we are trying to expose whats currently supported clearly. > Yes, we're going > to want to hook up a way to pass the PRI to the right place... but why > add *another* thing that's just going to have to be fixed, by reverting > this patch? > -- Sathyanarayanan Kuppuswamy Linux kernel developer