Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752516AbdFUXl4 (ORCPT ); Wed, 21 Jun 2017 19:41:56 -0400 Received: from mga03.intel.com ([134.134.136.65]:50921 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751835AbdFUXlJ (ORCPT ); Wed, 21 Jun 2017 19:41:09 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.39,370,1493708400"; d="scan'208";a="277139589" From: Andi Kleen To: x86@kernel.org Cc: linux-kernel@vger.kernel.org, Andi Kleen Subject: [PATCH 4/5] x86/xsave: Make XSAVE check the base CPUID features before enabling Date: Wed, 21 Jun 2017 16:41:05 -0700 Message-Id: <20170621234106.16548-5-andi@firstfloor.org> X-Mailer: git-send-email 2.9.4 In-Reply-To: <20170621234106.16548-1-andi@firstfloor.org> References: <20170621234106.16548-1-andi@firstfloor.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1939 Lines: 69 From: Andi Kleen Before enabling XSAVE, not only check the XSAVE specific CPUID bits, but also the base CPUID features of the respective XSAVE feature. This allows to disable individual XSAVE states using the existing clearcpuid= option, which can be useful for performance testing and debugging, and also in general avoids inconsistencies. Signed-off-by: Andi Kleen --- arch/x86/kernel/fpu/xstate.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index c24ac1efb12d..8f0b96320cc9 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -15,6 +15,7 @@ #include #include +#include /* * Although we spell it out in here, the Processor Trace @@ -36,6 +37,19 @@ static const char *xfeature_names[] = "unknown xstate feature" , }; +static short xsave_cpuid_features[] = { + X86_FEATURE_FPU, + X86_FEATURE_XMM, + X86_FEATURE_AVX, + X86_FEATURE_MPX, + X86_FEATURE_MPX, + X86_FEATURE_AVX512F, + X86_FEATURE_AVX512F, + X86_FEATURE_AVX512F, + X86_FEATURE_INTEL_PT, + X86_FEATURE_PKU, +}; + /* * Mask of xstate features supported by the CPU and the kernel: */ @@ -702,6 +716,7 @@ void __init fpu__init_system_xstate(void) unsigned int eax, ebx, ecx, edx; static int on_boot_cpu __initdata = 1; int err; + int i; WARN_ON_FPU(!on_boot_cpu); on_boot_cpu = 0; @@ -735,6 +750,13 @@ void __init fpu__init_system_xstate(void) goto out_disable; } + /* + * Clear XSAVE features that are disabled in the normal CPUID. + */ + for (i = 0; i < ARRAY_SIZE(xsave_cpuid_features); i++) + if (!boot_cpu_has(xsave_cpuid_features[i])) + xfeatures_mask &= ~BIT(i); + xfeatures_mask &= fpu__get_supported_xfeatures_mask(); /* Enable xstate instructions to be able to continue with initialization: */ -- 2.9.4