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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=no 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 7F6A1C433DF for ; Thu, 14 May 2020 15:25:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5B2C020756 for ; Thu, 14 May 2020 15:25:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726659AbgENPZf (ORCPT ); Thu, 14 May 2020 11:25:35 -0400 Received: from mga06.intel.com ([134.134.136.31]:42920 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726056AbgENPZf (ORCPT ); Thu, 14 May 2020 11:25:35 -0400 IronPort-SDR: /rKbp9lSq4uFDVylUEPvhTK9wfLK1N2G0sik70JIZ7FqtZxi54OuXiU2MQTeENBOZ9x7bBxcm5 SIFeUsYN5ULA== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 May 2020 08:25:34 -0700 IronPort-SDR: Ng2hBVYJXHRSIZgay8eUBPE0EZoRJvviZ2qMfzj8FYvf8AGmaHPL90x4D+uUNQg0wv84fsgGmS hylSshRCqn8g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,391,1583222400"; d="scan'208";a="298071283" Received: from jacob-builder.jf.intel.com (HELO jacob-builder) ([10.7.199.155]) by fmsmga002.fm.intel.com with ESMTP; 14 May 2020 08:25:33 -0700 Date: Thu, 14 May 2020 08:31:43 -0700 From: Jacob Pan To: Christoph Hellwig Cc: Lu Baolu , iommu@lists.linux-foundation.org, LKML , Joerg Roedel , David Woodhouse , Jean-Philippe Brucker , Eric Auger , Yi Liu , "Tian, Kevin" , Raj Ashok , Alex Williamson , Jonathan Cameron , jacob.jun.pan@linux.intel.com Subject: Re: [PATCH v13 3/8] iommu/vt-d: Add nested translation helper function Message-ID: <20200514083143.6400d813@jacob-builder> In-Reply-To: <20200514055424.GC22388@infradead.org> References: <1589410909-38925-1-git-send-email-jacob.jun.pan@linux.intel.com> <1589410909-38925-4-git-send-email-jacob.jun.pan@linux.intel.com> <20200514055424.GC22388@infradead.org> Organization: OTC X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 13 May 2020 22:54:24 -0700 Christoph Hellwig wrote: > > + * 1. CPU vs. IOMMU > > + * 2. Guest vs. Host. > > + */ > > + switch (addr_width) { > > +#ifdef CONFIG_X86 > > + case ADDR_WIDTH_5LEVEL: > > + if (cpu_feature_enabled(X86_FEATURE_LA57) && > > + cap_5lp_support(iommu->cap)) { > > + pasid_set_flpm(pte, 1); > > + } else { > > + dev_err_ratelimited(dev, "5-level paging > > not supported\n"); > > + return -EINVAL; > > + } > > + break; > > The normal style would be to handle the early error return first: > > if (!cpu_feature_enabled(X86_FEATURE_LA57) || > !cap_5lp_support(iommu->cap)) { > dev_err_ratelimited(dev, > "5-level paging not supported\n"); > return -EINVAL; > } > > pasid_set_flpm(pte, 1); > break; > Sounds good. I was thinking in positive logic. thanks