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=-8.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,T_DKIMWL_WL_HIGH,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=unavailable 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 0F2C5C2BCA1 for ; Fri, 7 Jun 2019 17:10:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D8FD82146E for ; Fri, 7 Jun 2019 17:10:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559927400; bh=zTE9Vnc80prCH8PSEwnKTNhjRC5uBLiJcuWCP0FnZBQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=DmyoysFmo8loZPPRwSVX4pK+iV/itBIh9LXMLOwWYcbGUYzk8FF6FCYPWl0CsM6L5 EkuT6hwhLjYRirar3Am8KzZ90pWfGdG/OHPlXvG43HxjK9tsoivLl+l8ZBg7LxuuF8 4xCoUkVTxBwJsagPD+4j7FnTlNqeZQi7B+RWIuJo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731212AbfFGRJw (ORCPT ); Fri, 7 Jun 2019 13:09:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:43582 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730196AbfFGRJw (ORCPT ); Fri, 7 Jun 2019 13:09:52 -0400 Received: from sol.localdomain (c-24-5-143-220.hsd1.ca.comcast.net [24.5.143.220]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1712B208E3; Fri, 7 Jun 2019 17:09:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559927391; bh=zTE9Vnc80prCH8PSEwnKTNhjRC5uBLiJcuWCP0FnZBQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ZgApmZjjjZArxNzMJS92zb1duXOLfAHnxFWRojQpdAga3W+RgadVqRoCPs2s886O9 WexWxrHwX2eTwI87ZGkFjAOzQdHA71NFyKrqbDFaLMhyP+sGDlo9ITk+SkKm/mEv1Y zCNDruhQwMAkzM7sov7CcGUS7Weuon4IZXp/aAi4= Date: Fri, 7 Jun 2019 10:09:49 -0700 From: Eric Biggers To: Sebastian Andrzej Siewior Cc: x86-ml , Borislav Petkov , Dave Hansen , Thomas Gleixner , Andy Lutomirski , "H. Peter Anvin" , Ingo Molnar , Jann Horn , "Jason A. Donenfeld" , kvm ML , Paolo Bonzini , Radim =?utf-8?B?S3LEjW3DocWZ?= , Rik van Riel , linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86/fpu: Update kernel's FPU state before using for the fsave header Message-ID: <20190607170949.GA648@sol.localdomain> References: <20190604185358.GA820@sol.localdomain> <20190605140405.2nnpqslnjpfe2ig2@linutronix.de> <20190605173256.GA86462@gmail.com> <20190606173026.ty7c4cvftrvfrwy3@linutronix.de> <20190607142915.y52mfmgk5lvhll7n@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190607142915.y52mfmgk5lvhll7n@linutronix.de> User-Agent: Mutt/1.12.0 (2019-05-25) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Jun 07, 2019 at 04:29:16PM +0200, Sebastian Andrzej Siewior wrote: > In commit > > 39388e80f9b0c ("x86/fpu: Don't save fxregs for ia32 frames in copy_fpstate_to_sigframe()") > > I removed the statement > | if (ia32_fxstate) > | copy_fxregs_to_kernel(fpu); > > and argued that is was wrongly merged because the content was already > saved in kernel's state and the content. > This was wrong: It is required to write it back because it is only saved > on the user-stack and save_fsave_header() reads it from task's > FPU-state. I missed that part… > > Save x87 FPU state unless thread's FPU registers are already up to date. > > Fixes: 39388e80f9b0c ("x86/fpu: Don't save fxregs for ia32 frames in copy_fpstate_to_sigframe()") > Reported-by: Eric Biggers > Signed-off-by: Sebastian Andrzej Siewior > --- > arch/x86/kernel/fpu/signal.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c > index 060d6188b4533..0071b794ed193 100644 > --- a/arch/x86/kernel/fpu/signal.c > +++ b/arch/x86/kernel/fpu/signal.c > @@ -62,6 +62,11 @@ static inline int save_fsave_header(struct task_struct *tsk, void __user *buf) > struct user_i387_ia32_struct env; > struct _fpstate_32 __user *fp = buf; > > + fpregs_lock(); > + if (!test_thread_flag(TIF_NEED_FPU_LOAD)) > + copy_fxregs_to_kernel(&tsk->thread.fpu); > + fpregs_unlock(); > + > convert_from_fxsr(&env, tsk); > > if (__copy_to_user(buf, &env, sizeof(env)) || > -- > 2.20.1 > Tested-by: Eric Biggers - Eric