From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753126AbcEIUvv (ORCPT ); Mon, 9 May 2016 16:51:51 -0400 Received: from mga11.intel.com ([192.55.52.93]:32004 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752938AbcEIUvO (ORCPT ); Mon, 9 May 2016 16:51:14 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,601,1455004800"; d="scan'208";a="100071053" From: Yu-cheng Yu To: linux-kernel@vger.kernel.org, x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar Cc: Dave Hansen , Andy Lutomirski , Borislav Petkov , Sai Praneeth Prakhya , "Ravi V. Shankar" , Fenghua Yu , Yu-cheng Yu Subject: [PATCH v5 13/13] x86/xsaves: Re-enable XSAVES Date: Mon, 9 May 2016 13:46:10 -0700 Message-Id: <0b0e65bcd82d181432532adfc349cc85b50bd644.1462816638.git.yu-cheng.yu@intel.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- arch/x86/kernel/fpu/init.c | 15 --------------- arch/x86/kernel/fpu/xstate.c | 10 ++++++++++ 2 files changed, 10 insertions(+), 15 deletions(-) diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c index 549ff59..cdd45ac 100644 --- a/arch/x86/kernel/fpu/init.c +++ b/arch/x86/kernel/fpu/init.c @@ -228,21 +228,6 @@ static void __init fpu__init_system_xstate_size_legacy(void) } user_xstate_size = 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 2e6dbfe..80c6d87 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -217,6 +217,16 @@ void fpu__init_cpu_xstate(void) if (!cpu_has_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); } -- 1.9.1