From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 74696C4707A for ; Sun, 23 May 2021 19:39:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 59E9A6117A for ; Sun, 23 May 2021 19:39:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232195AbhEWTk5 (ORCPT ); Sun, 23 May 2021 15:40:57 -0400 Received: from mga07.intel.com ([134.134.136.100]:12061 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232009AbhEWTj6 (ORCPT ); Sun, 23 May 2021 15:39:58 -0400 IronPort-SDR: ncBjkgSqMH1QrG2HMSKfUjMFQORK9XfyII4cKgLINdHMQ94P0DQ4VkaYOr/x0qdHgszlc4XE+k W1H8YaHIMX5g== X-IronPort-AV: E=McAfee;i="6200,9189,9993"; a="265703543" X-IronPort-AV: E=Sophos;i="5.82,319,1613462400"; d="scan'208";a="265703543" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 May 2021 12:38:29 -0700 IronPort-SDR: pW0i4o6A+8STy2bRHvm9yaPzFGeq+4YaoEIKgckMIxuHFFlImlHxxtt+KvleMDf6iFWo8nwjXR W6RV4tTzRrVQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.82,319,1613462400"; d="scan'208";a="407467141" Received: from chang-linux-3.sc.intel.com ([172.25.66.175]) by fmsmga007.fm.intel.com with ESMTP; 23 May 2021 12:38:29 -0700 From: "Chang S. Bae" To: bp@suse.de, luto@kernel.org, tglx@linutronix.de, mingo@kernel.org, x86@kernel.org Cc: len.brown@intel.com, dave.hansen@intel.com, jing2.liu@intel.com, ravi.v.shankar@intel.com, linux-kernel@vger.kernel.org, chang.seok.bae@intel.com Subject: [PATCH v5 25/28] x86/fpu/xstate: Skip writing zeros to signal frame for dynamic user states if in INIT-state Date: Sun, 23 May 2021 12:32:56 -0700 Message-Id: <20210523193259.26200-26-chang.seok.bae@intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210523193259.26200-1-chang.seok.bae@intel.com> References: <20210523193259.26200-1-chang.seok.bae@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org By default, for xstate features in the INIT-state, XSAVE writes zeros to the uncompressed destination buffer. E.g., if you are not using AVX-512, you will still get a bunch of zeros on the signal stack where live AVX-512 data would go. For 'dynamic user state' (currently only XTILEDATA), explicitly skip this data transfer. The result is that the user buffer for the AMX region will not be touched by XSAVE. Signed-off-by: Chang S. Bae Reviewed-by: Len Brown Cc: x86@kernel.org Cc: linux-kernel@vger.kernel.org --- Changes from v4: * Added as a new patch. --- arch/x86/include/asm/fpu/internal.h | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h index 4a3436684805..131f2557fc85 100644 --- a/arch/x86/include/asm/fpu/internal.h +++ b/arch/x86/include/asm/fpu/internal.h @@ -354,11 +354,27 @@ static inline void copy_kernel_to_xregs(struct xregs_state *xstate, u64 mask) */ static inline int copy_xregs_to_user(struct xregs_state __user *buf) { - u64 mask = current->thread.fpu.state_mask; - u32 lmask = mask; - u32 hmask = mask >> 32; + u64 state_mask = current->thread.fpu.state_mask; + u64 dynamic_state_mask; + u32 lmask, hmask; int err; + dynamic_state_mask = state_mask & xfeatures_mask_user_dynamic; + if (dynamic_state_mask && boot_cpu_has(X86_FEATURE_XGETBV1)) { + u64 dynamic_xinuse, dynamic_init; + u64 xinuse = xgetbv(1); + + dynamic_xinuse = xinuse & dynamic_state_mask; + dynamic_init = ~(xinuse) & dynamic_state_mask; + if (dynamic_init) { + state_mask &= ~xfeatures_mask_user_dynamic; + state_mask |= dynamic_xinuse; + } + } + + lmask = state_mask; + hmask = state_mask >> 32; + /* * Clear the xsave header first, so that reserved fields are * initialized to zero. -- 2.17.1