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=-2.1 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, URIBL_BLOCKED,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 2EFA7C433F5 for ; Fri, 7 Sep 2018 11:22:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DE5D320844 for ; Fri, 7 Sep 2018 11:22:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="hQ6qmHJi" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DE5D320844 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728119AbeIGQCp (ORCPT ); Fri, 7 Sep 2018 12:02:45 -0400 Received: from merlin.infradead.org ([205.233.59.134]:55404 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727597AbeIGQCp (ORCPT ); Fri, 7 Sep 2018 12:02:45 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=Z3Nd7ZIp4WmOWGI94vPTqYGjqDJTj78oMv5r92i9wXc=; b=hQ6qmHJiNE1pRwqPOK1o51ZQh zrUfSl3U9qCdz/WtV5jMbPoneitrQyT2m3WrmP0OnufkHrZneG7FfcKPSCfghWt1VGW+WqPZkp6ty 0DEjtIqzQ17VB+AdpHOUSzpIXn61ioNQbOEgwBYWpdJFd6YPGOyqmZxz0Fn3dUYDPYYpTE/2y8lDd T+m8VMN+GBwMYmeQhooQpXOwITvBl6DG3gzNGLWCJiOWN9XTBH/cY9pGV3phVZqkdfrmM6MEJZ8pI yMxMGsfOYotRjaAZixXwBMkTR1TTfSkKQRuakvHF6KHQNOq38NyhbODUPOs4hH+KwCvTp6LA3ff4e D25v6Yzmw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fyEq0-0001R7-Ne; Fri, 07 Sep 2018 11:22:08 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 80C3820191BFB; Fri, 7 Sep 2018 13:22:07 +0200 (CEST) Date: Fri, 7 Sep 2018 13:22:07 +0200 From: Peter Zijlstra To: Sai Praneeth Prakhya Cc: linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, ricardo.neri@intel.com, matt@codeblueprint.co.uk, Al Stone , Borislav Petkov , Ingo Molnar , Andy Lutomirski , Bhupesh Sharma , Thomas Gleixner , Ard Biesheuvel Subject: Re: [PATCH V4 3/3] x86/efi: Introduce EFI_PAGE_FAULT_HANDLER Message-ID: <20180907112207.GS24106@hirez.programming.kicks-ass.net> References: <1536276468-28499-1-git-send-email-sai.praneeth.prakhya@intel.com> <1536276468-28499-4-git-send-email-sai.praneeth.prakhya@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1536276468-28499-4-git-send-email-sai.praneeth.prakhya@intel.com> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 06, 2018 at 04:27:48PM -0700, Sai Praneeth Prakhya wrote: > From: Sai Praneeth > > There may exist some buggy UEFI firmware implementations that might > access efi regions other than EFI_RUNTIME_SERVICES_ even > after the kernel has assumed control of the platform. This violates UEFI > specification. > > If selected, this debug option will print a warning message if the UEFI > firmware tries to access any memory region which it shouldn't. Along > with the warning, the efi page fault handler will also try to recover > from the page fault triggered by the firmware so that the machine > doesn't hang. Why make this optional?