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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 86016C433EF for ; Tue, 9 Nov 2021 01:36:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5CAA8610A3 for ; Tue, 9 Nov 2021 01:36:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239706AbhKIBiz (ORCPT ); Mon, 8 Nov 2021 20:38:55 -0500 Received: from mga05.intel.com ([192.55.52.43]:9878 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243195AbhKIBiU (ORCPT ); Mon, 8 Nov 2021 20:38:20 -0500 X-IronPort-AV: E=McAfee;i="6200,9189,10162"; a="318555844" X-IronPort-AV: E=Sophos;i="5.87,218,1631602800"; d="scan'208";a="318555844" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Nov 2021 17:28:21 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.87,218,1631602800"; d="scan'208";a="641693040" Received: from chang-linux-3.sc.intel.com ([172.25.66.175]) by fmsmga001.fm.intel.com with ESMTP; 08 Nov 2021 17:28:21 -0800 From: "Chang S. Bae" To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, tglx@linutronix.de, dave.hansen@linux.intel.com, bp@alien8.de, mingo@redhat.com, yang.zhong@intel.com, jing2.liu@intel.com, chang.seok.bae@intel.com Subject: [PATCH v2 0/2] x86: Fix ARCH_REQ_XCOMP_PERM and update the test Date: Mon, 8 Nov 2021 17:21:20 -0800 Message-Id: <20211109012122.1142-1-chang.seok.bae@intel.com> X-Mailer: git-send-email 2.17.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The recent x86 dynamic state support incorporates the arch_prctl option to request permission before using a dynamic state. It was designed to add the requested feature in the group leader's permission bitmask so that every thread can reference this master bitmask. The group leader is assumed to be unchanged here. The mainline is the case as a group leader is identified at fork() or exec() time only. This master bitmask should include non-dynamic features always, as they are permitted by default. Users may check them via ARCH_GET_XCOMP_PERM. But, in hindsight, the implementation does overwrite the bitmask with the requested bit only, instead of adding the bit to the existing one. This overwrite effectively revokes the permission that is granted already. Fix the code and also update the selftest to disclose the issue if there is. Reported-by: Yang Zhong Cc: Thomas Gleixner Cc: Dave Hansen Changes from v1: * Change the mask value only. Chang S. Bae (2): x86/arch_prctl: Fix ARCH_REQ_XCOMP_PERM selftests/x86/amx: Update the ARCH_REQ_XCOMP_PERM test arch/x86/kernel/fpu/xstate.c | 2 +- tools/testing/selftests/x86/amx.c | 16 ++++++++++++++-- 2 files changed, 15 insertions(+), 3 deletions(-) base-commit: 9a6cf455a952725422f4fb10848839989f833579 -- 2.17.1