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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable 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 D6E67C2D0E8 for ; Wed, 25 Mar 2020 23:11:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B9EC62076A for ; Wed, 25 Mar 2020 23:11:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727590AbgCYXLZ (ORCPT ); Wed, 25 Mar 2020 19:11:25 -0400 Received: from mga03.intel.com ([134.134.136.65]:3368 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727487AbgCYXLZ (ORCPT ); Wed, 25 Mar 2020 19:11:25 -0400 IronPort-SDR: acbVRKwsqd8jjsA9EcdrrR8Z76lv2zO9wLhxDUlzpu7AsHe/wW63YnlJ54DnlVaT4SDqb2zMd1 qspXUvnG0HqA== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Mar 2020 16:11:24 -0700 IronPort-SDR: q1SfkvZ/eKjh21PLtsAMc9gjXTkvpsc68UU2/mRAJlJVCfyeGhTw56vpaYrL2GVtkx0J0w0q4z OlX+tXSt+WwA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,306,1580803200"; d="scan'208";a="236083689" Received: from jacob-builder.jf.intel.com ([10.7.199.155]) by orsmga007.jf.intel.com with ESMTP; 25 Mar 2020 16:11:24 -0700 From: Jacob Pan To: Joerg Roedel , Alex Williamson , "Lu Baolu" , iommu@lists.linux-foundation.org, LKML , David Woodhouse , Jean-Philippe Brucker Cc: "Yi Liu" , "Tian, Kevin" , Raj Ashok , Eric Auger , Jacob Pan Subject: [PATCH v2 1/3] iommu/uapi: Define uapi version and capabilities Date: Wed, 25 Mar 2020 16:17:05 -0700 Message-Id: <1585178227-17061-2-git-send-email-jacob.jun.pan@linux.intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1585178227-17061-1-git-send-email-jacob.jun.pan@linux.intel.com> References: <1585178227-17061-1-git-send-email-jacob.jun.pan@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Having a single UAPI version to govern the user-kernel data structures makes compatibility check straightforward. On the contrary, supporting combinations of multiple versions of the data can be a nightmare to maintain. This patch defines a unified UAPI version to be used for compatibility checks between user and kernel. --- v2: Rewrite extension rules to disallow adding new members. Use padding and union extensions only. --- Signed-off-by: Liu Yi L Signed-off-by: Jacob Pan Link: https://lkml.org/lkml/2020/2/3/1126 --- include/uapi/linux/iommu.h | 53 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h index d7bcbc5f79b0..25dba9198d7f 100644 --- a/include/uapi/linux/iommu.h +++ b/include/uapi/linux/iommu.h @@ -8,6 +8,59 @@ #include +/** + * Current version of the IOMMU user API. This is intended for query + * between user and kernel to determine compatible data structures. + * + * UAPI version can be bumped up with the following rules: + * 1. All data structures passed between user and kernel space share + * the same version number. i.e. any extension to any structure + * results in version number increment. + * + * 2. Data structures are open to extension but closed to modification. + * Extensions are allowed in two places: + * - the padding bytes with a flag bit for each new member + * - new union members at the end of each structure + * + * No new members can be added after padding bytes are exhausted. + * The reason is that the union size can change when new members are + * added, having new member at the end would break backward + * compatibility. Expansion of the union would move the new member + * to different offset between versions. + * + * Flag bits can be added without size change but existing ones + * cannot be altered. + * + * 3. Versions are backward compatible. + * + * 4. Version to size lookup is supported by kernel internal API for each + * API function type. @version is mandatory for new data structures + * and must be at the beginning with type of __u32. + */ +#define IOMMU_UAPI_VERSION 1 +static inline int iommu_get_uapi_version(void) +{ + return IOMMU_UAPI_VERSION; +} + +/* + * Supported UAPI features that can be reported to user space. + * These types represent the capability available in the kernel. + * + * REVISIT: UAPI version also implies the capabilities. Should we + * report them explicitly? + */ +enum IOMMU_UAPI_DATA_TYPES { + IOMMU_UAPI_BIND_GPASID, + IOMMU_UAPI_CACHE_INVAL, + IOMMU_UAPI_PAGE_RESP, + NR_IOMMU_UAPI_TYPE, +}; + +#define IOMMU_UAPI_CAP_MASK ((1 << IOMMU_UAPI_BIND_GPASID) | \ + (1 << IOMMU_UAPI_CACHE_INVAL) | \ + (1 << IOMMU_UAPI_PAGE_RESP)) + #define IOMMU_FAULT_PERM_READ (1 << 0) /* read */ #define IOMMU_FAULT_PERM_WRITE (1 << 1) /* write */ #define IOMMU_FAULT_PERM_EXEC (1 << 2) /* exec */ -- 2.7.4