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=-2.3 required=3.0 tests=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 3F3FAC43382 for ; Fri, 28 Sep 2018 07:57:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 07BBA21754 for ; Fri, 28 Sep 2018 07:57:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 07BBA21754 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=alien8.de 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 S1729142AbeI1OTl (ORCPT ); Fri, 28 Sep 2018 10:19:41 -0400 Received: from mail.skyhub.de ([5.9.137.197]:59958 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728804AbeI1OTl (ORCPT ); Fri, 28 Sep 2018 10:19:41 -0400 X-Virus-Scanned: Nedap ESD1 at mail.skyhub.de Received: from mail.skyhub.de ([127.0.0.1]) by localhost (blast.alien8.de [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id YGZO4WlCcvF9; Fri, 28 Sep 2018 09:57:10 +0200 (CEST) Received: from zn.tnic (p200300EC2BCA5700329C23FFFEA6A903.dip0.t-ipconnect.de [IPv6:2003:ec:2bca:5700:329c:23ff:fea6:a903]) (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 079CC1EC032B; Fri, 28 Sep 2018 09:57:09 +0200 (CEST) Date: Fri, 28 Sep 2018 09:57:11 +0200 From: Borislav Petkov To: lijiang Cc: linux-kernel@vger.kernel.org, kexec@lists.infradead.org, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, akpm@linux-foundation.org, dan.j.williams@intel.com, thomas.lendacky@amd.com, bhelgaas@google.com, baiyaowei@cmss.chinamobile.com, tiwai@suse.de, brijesh.singh@amd.com, dyoung@redhat.com, bhe@redhat.com, jroedel@suse.de Subject: Re: [PATCH v7 RESEND 2/4] kexec: allocate unencrypted control pages for kdump in case SME is enabled Message-ID: <20180928075654.GA20768@zn.tnic> References: <20180927071954.29615-1-lijiang@redhat.com> <20180927071954.29615-3-lijiang@redhat.com> <20180927165323.GC19779@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: 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 Fri, Sep 28, 2018 at 11:52:21AM +0800, lijiang wrote: > There are two functions that are usually called in pairs, they are: > arch_kexec_post_alloc_pages() and arch_kexec_pre_free_pages(). > > One marks the pages as decrypted, another one marks the pages as encrypted. > > But for the crash control pages, no need to call arch_kexec_pre_free_pages(), > there are three reasons: > 1. Crash pages are reserved in memblock, these pages are only used by kdump, > no other people uses these pages; > > 2. Whenever crash pages are allocated, these pages are always marked as > decrypted(when SME is active); > > 3. If we plan to call the arch_kexe_pre_free_pages(), we have to store these > pages to somewhere, which will have more code changes. I don't think any of that answers the question *why* control pages do not need to be marked encrypted again. And I think the reason is simple: because you don't really need to, because once the crash kernel is done, you reboot the box. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.