From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030961AbcGKQOu (ORCPT ); Mon, 11 Jul 2016 12:14:50 -0400 Received: from terminus.zytor.com ([198.137.202.10]:50256 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030843AbcGKQOs (ORCPT ); Mon, 11 Jul 2016 12:14:48 -0400 Date: Mon, 11 Jul 2016 09:14:18 -0700 From: tip-bot for Yu-cheng Yu Message-ID: Cc: yu-cheng.yu@intel.com, linux-kernel@vger.kernel.org, h.peter.anvin@intel.com, tglx@linutronix.de, torvalds@linux-foundation.org, mingo@kernel.org, dave.hansen@intel.com, peterz@infradead.org, fenghua.yu@intel.com, ravi.v.shankar@intel.com, hpa@zytor.com Reply-To: dave.hansen@intel.com, hpa@zytor.com, ravi.v.shankar@intel.com, fenghua.yu@intel.com, peterz@infradead.org, h.peter.anvin@intel.com, linux-kernel@vger.kernel.org, yu-cheng.yu@intel.com, torvalds@linux-foundation.org, mingo@kernel.org, tglx@linutronix.de In-Reply-To: <1468253937-40008-5-git-send-email-fenghua.yu@intel.com> References: <1468253937-40008-5-git-send-email-fenghua.yu@intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/fpu] x86/fpu/xstate: Re-enable XSAVES Git-Commit-ID: b8be15d588060a03569ac85dc4a0247460988f5b X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: b8be15d588060a03569ac85dc4a0247460988f5b Gitweb: http://git.kernel.org/tip/b8be15d588060a03569ac85dc4a0247460988f5b Author: Yu-cheng Yu AuthorDate: Mon, 11 Jul 2016 09:18:57 -0700 Committer: Ingo Molnar CommitDate: Mon, 11 Jul 2016 16:44:01 +0200 x86/fpu/xstate: Re-enable XSAVES We did not handle XSAVES instructions correctly. There were issues in converting between standard and compacted format when interfacing with user-space. These issues have been corrected. Add a WARN_ONCE() to make it clear that XSAVES supervisor states are not yet implemented. Signed-off-by: Yu-cheng Yu Signed-off-by: Fenghua Yu Reviewed-by: Dave Hansen Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Ravi V Shankar Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1468253937-40008-5-git-send-email-fenghua.yu@intel.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/fpu/init.c | 15 --------------- arch/x86/kernel/fpu/xstate.c | 9 +++++++++ 2 files changed, 9 insertions(+), 15 deletions(-) diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c index 60f3839..93982ae 100644 --- a/arch/x86/kernel/fpu/init.c +++ b/arch/x86/kernel/fpu/init.c @@ -230,21 +230,6 @@ static void __init fpu__init_system_xstate_size_legacy(void) } fpu_user_xstate_size = fpu_kernel_xstate_size; - - /* - * Quirk: we don't yet handle the XSAVES* instructions - * correctly, as we don't correctly convert between - * standard and compacted format when interfacing - * with user-space - so disable it for now. - * - * The difference is small: with recent CPUs the - * compacted format is only marginally smaller than - * the standard FPU state format. - * - * ( This is easy to backport while we are fixing - * XSAVES* support. ) - */ - setup_clear_cpu_cap(X86_FEATURE_XSAVES); } /* diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 4fb8dd7..3169bca 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -221,6 +221,15 @@ void fpu__init_cpu_xstate(void) { if (!boot_cpu_has(X86_FEATURE_XSAVE) || !xfeatures_mask) return; + /* + * Make it clear that XSAVES supervisor states are not yet + * implemented should anyone expect it to work by changing + * bits in XFEATURE_MASK_* macros and XCR0. + */ + WARN_ONCE((xfeatures_mask & XFEATURE_MASK_SUPERVISOR), + "x86/fpu: XSAVES supervisor states are not yet implemented.\n"); + + xfeatures_mask &= ~XFEATURE_MASK_SUPERVISOR; cr4_set_bits(X86_CR4_OSXSAVE); xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask);