From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754466AbcGKNR6 (ORCPT ); Mon, 11 Jul 2016 09:17:58 -0400 Received: from mga04.intel.com ([192.55.52.120]:2997 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754165AbcGKNR4 (ORCPT ); Mon, 11 Jul 2016 09:17:56 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.28,346,1464678000"; d="scan'208";a="1019448937" From: "Fenghua Yu" To: "Ingo Molnar" , "Thomas Gleixner" , "H. Peter Anvin" , "Dave Hansen" , "Ravi V Shankar" Cc: Yu-cheng Yu , "Fenghua Yu" , "x86" , "linux-kernel" Subject: [PATCH 4/4] x86/fpu/xstate: Re-enable XSAVES Date: Mon, 11 Jul 2016 09:18:57 -0700 Message-Id: <1468253937-40008-5-git-send-email-fenghua.yu@intel.com> X-Mailer: git-send-email 1.8.0.1 In-Reply-To: <1468253937-40008-1-git-send-email-fenghua.yu@intel.com> References: <1468253937-40008-1-git-send-email-fenghua.yu@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Yu-cheng Yu 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 --- 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); -- 2.5.0