From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753108AbcBVTC1 (ORCPT ); Mon, 22 Feb 2016 14:02:27 -0500 Received: from mga03.intel.com ([134.134.136.65]:23647 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752373AbcBVTCV (ORCPT ); Mon, 22 Feb 2016 14:02:21 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.22,485,1449561600"; d="scan'208";a="921433590" From: Yu-cheng Yu To: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org Cc: Dave Hansen , Andy Lutomirski , Borislav Petkov , Sai Praneeth Prakhya , "Ravi V. Shankar" , Fenghua Yu , Yu-cheng Yu Subject: [PATCH 07/10] x86/xsaves: Fix init_fpstate.header.xcomp_bv Date: Mon, 22 Feb 2016 10:59:56 -0800 Message-Id: <1456167596-3932-1-git-send-email-yu-cheng.yu@intel.com> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In setup_init_fpu_buf(), we use XRSTOR/XRSTORS with xfeatures (xstate_bv) of 0x0 to effectively set all xstate components to init values. We then execute XSAVE/XSAVES on the same buffer to save back init values. This actually does not apply to XSAVES as XSAVES uses optimization. After init, all components are in INIT and not MODIFIED state and will not be saved. There is no need of setting xcomp_bv except for bit 63 to indicate a compacted format. Currently, init_fpstate is used in two ways: (1) With copy_kernel_to_xregs(): because header.xfeatures is zero, the content is not actually read; (2) With memcpy(): to sanitize a standard-format xsave area; the buffer is setup as expected. Signed-off-by: Yu-cheng Yu --- arch/x86/kernel/fpu/xstate.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 13829e1..4087261 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -371,10 +371,10 @@ static void __init setup_init_fpu_buf(void) print_xstate_features(); if (cpu_has_xsaves) - init_fpstate.xsave.header.xcomp_bv = (u64)1 << 63 | xfeatures_mask; + init_fpstate.xsave.header.xcomp_bv = (u64)1 << 63; /* - * Init all the features state with header_bv being 0x0 + * Init all the features state with header.xfeatures being 0x0 */ copy_kernel_to_xregs_booting(&init_fpstate.xsave); -- 1.9.1