From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1036998AbdEZFDV (ORCPT ); Fri, 26 May 2017 01:03:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35558 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758833AbdEZFDQ (ORCPT ); Fri, 26 May 2017 01:03:16 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 8899B19D229 Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=xpang@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 8899B19D229 Reply-To: xlpang@redhat.com Subject: Re: [PATCH v5 31/32] x86: Add sysfs support for Secure Memory Encryption References: <20170418211612.10190.82788.stgit@tlendack-t1.amdoffice.net> <20170418212212.10190.73484.stgit@tlendack-t1.amdoffice.net> <20170518170153.eqiyat5s6q3yeejl@pd.tnic> <20170526024933.GA3228@dhcp-128-65.nay.redhat.com> To: Dave Young , Borislav Petkov Cc: linux-efi@vger.kernel.org, Brijesh Singh , Toshimitsu Kani , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Matt Fleming , x86@kernel.org, linux-mm@kvack.org, Alexander Potapenko , "H. Peter Anvin" , Larry Woodman , linux-arch@vger.kernel.org, kvm@vger.kernel.org, Jonathan Corbet , Joerg Roedel , linux-doc@vger.kernel.org, kasan-dev@googlegroups.com, Ingo Molnar , Andrey Ryabinin , Tom Lendacky , Rik van Riel , Arnd Bergmann , Konrad Rzeszutek Wilk , xlpang@redhat.com, Andy Lutomirski , Thomas Gleixner , Dmitry Vyukov , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, "Michael S. Tsirkin" , Paolo Bonzini From: Xunlei Pang Message-ID: <5927B767.3010701@redhat.com> Date: Fri, 26 May 2017 13:04:39 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <20170526024933.GA3228@dhcp-128-65.nay.redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Fri, 26 May 2017 05:03:16 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/26/2017 at 10:49 AM, Dave Young wrote: > Ccing Xunlei he is reading the patches see what need to be done for > kdump. There should still be several places to handle to make kdump work. > > On 05/18/17 at 07:01pm, Borislav Petkov wrote: >> On Tue, Apr 18, 2017 at 04:22:12PM -0500, Tom Lendacky wrote: >>> Add sysfs support for SME so that user-space utilities (kdump, etc.) can >>> determine if SME is active. >> But why do user-space tools need to know that? >> >> I mean, when we load the kdump kernel, we do it with the first kernel, >> with the kexec_load() syscall, AFAICT. And that code does a lot of >> things during that init, like machine_kexec_prepare()->init_pgtable() to >> prepare the ident mapping of the second kernel, for example. >> >> What I'm aiming at is that the first kernel knows *exactly* whether SME >> is enabled or not and doesn't need to tell the second one through some >> sysfs entries - it can do that during loading. >> >> So I don't think we need any userspace things at all... > If kdump kernel can get the SME status from hardware register then this > should be not necessary and this patch can be dropped. Yes, I also agree with dropping this one. Regards, Xunlei