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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT 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 85A44C282D7 for ; Wed, 30 Jan 2019 11:55:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4756420855 for ; Wed, 30 Jan 2019 11:55:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="JZLvs1o6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730678AbfA3LzQ (ORCPT ); Wed, 30 Jan 2019 06:55:16 -0500 Received: from mail.skyhub.de ([5.9.137.197]:33804 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728480AbfA3LzQ (ORCPT ); Wed, 30 Jan 2019 06:55:16 -0500 Received: from zn.tnic (p200300EC2BCAED00D014CE199A91CB87.dip0.t-ipconnect.de [IPv6:2003:ec:2bca:ed00:d014:ce19:9a91:cb87]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 093481EC04F3; Wed, 30 Jan 2019 12:55:15 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1548849315; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=Y8YW9rjGmwaLyqrBqccCGo+HHNzQcqZ3OGmjrKup0io=; b=JZLvs1o6fykEjPkeZDaykfcQsgAo3WdKAuQ3jPbxSUPI0KVUPQlgQMXkfMxgKt0zHtodY0 GI8b9gE+fM364UhlqkArfnW9xc5tFeEyqLBDzQwn0r9JssCV5Er7cLd9iPlEHA9EZoLHiL 2R+msXlvol2xro2LSwOo/0nUz9FGgJ4= Date: Wed, 30 Jan 2019 12:55:07 +0100 From: Borislav Petkov To: Sebastian Andrzej Siewior Cc: linux-kernel@vger.kernel.org, x86@kernel.org, Andy Lutomirski , Paolo Bonzini , Radim =?utf-8?B?S3LEjW3DocWZ?= , kvm@vger.kernel.org, "Jason A. Donenfeld" , Rik van Riel , Dave Hansen Subject: Re: [PATCH 15/22] x86/entry: Add TIF_NEED_FPU_LOAD Message-ID: <20190130115507.GE18383@zn.tnic> References: <20190109114744.10936-1-bigeasy@linutronix.de> <20190109114744.10936-16-bigeasy@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190109114744.10936-16-bigeasy@linutronix.de> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 09, 2019 at 12:47:37PM +0100, Sebastian Andrzej Siewior wrote: > Add TIF_NEED_FPU_LOAD. This is reserved for loading the FPU registers > before returning to userland. This flag must not be set for systems > without a FPU. > If this flag is cleared, the CPU's FPU register hold the current content > of current()'s FPU register. The in-memory copy (union fpregs_state) is > not valid. > If this flag is set, then all of CPU's FPU register may hold a random > value (except for PKRU) and it is required to load the content of the > FPU register on return to userland. This definitely needs to be written somewhere in arch/x86/include/asm/fpu/internal.h or where we decide to put the FPU handling rules. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.