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 E488FC4332F for ; Wed, 10 Nov 2021 00:39:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C987761221 for ; Wed, 10 Nov 2021 00:39:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231246AbhKJAl6 (ORCPT ); Tue, 9 Nov 2021 19:41:58 -0500 Received: from mga09.intel.com ([134.134.136.24]:28355 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230457AbhKJAl4 (ORCPT ); Tue, 9 Nov 2021 19:41:56 -0500 X-IronPort-AV: E=McAfee;i="6200,9189,10163"; a="232416063" X-IronPort-AV: E=Sophos;i="5.87,221,1631602800"; d="scan'208";a="232416063" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Nov 2021 16:39:09 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.87,221,1631602800"; d="scan'208";a="642354122" Received: from chang-linux-3.sc.intel.com ([172.25.66.175]) by fmsmga001.fm.intel.com with ESMTP; 09 Nov 2021 16:39:08 -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 v3 0/2] x86: Fix ARCH_REQ_XCOMP_PERM and update the test Date: Tue, 9 Nov 2021 16:32:07 -0800 Message-Id: <20211110003209.21666-1-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 Fixed the authorship from V2: https://lore.kernel.org/lkml/20211109012122.1142-1-chang.seok.bae@intel.com/ --- 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. Cc: Yang Zhong Cc: Thomas Gleixner Cc: Dave Hansen Chang S. Bae (1): selftests/x86/amx: Update the ARCH_REQ_XCOMP_PERM test Yang Zhong (1): x86/arch_prctl: Fix the ARCH_REQ_XCOMP_PERM implementation 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