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 4F97FC433FE for ; Mon, 8 Nov 2021 23:42:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3B3A5611C1 for ; Mon, 8 Nov 2021 23:42:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240953AbhKHXos (ORCPT ); Mon, 8 Nov 2021 18:44:48 -0500 Received: from mga03.intel.com ([134.134.136.65]:5566 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231401AbhKHXor (ORCPT ); Mon, 8 Nov 2021 18:44:47 -0500 X-IronPort-AV: E=McAfee;i="6200,9189,10162"; a="232292395" X-IronPort-AV: E=Sophos;i="5.87,218,1631602800"; d="scan'208";a="232292395" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Nov 2021 15:42:01 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.87,218,1631602800"; d="scan'208";a="641642466" Received: from chang-linux-3.sc.intel.com ([172.25.66.175]) by fmsmga001.fm.intel.com with ESMTP; 08 Nov 2021 15:42:01 -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 0/2] x86: Fix ARCH_REQ_XCOMP_PERM and update the test Date: Mon, 8 Nov 2021 15:34:59 -0800 Message-Id: <20211108233501.11516-1-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: (1) update each task's permission bitmask, instead of the group leader's. (2) 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 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