From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f197.google.com (mail-qt0-f197.google.com [209.85.216.197]) by kanga.kvack.org (Postfix) with ESMTP id 29E196B0292 for ; Fri, 26 May 2017 01:03:18 -0400 (EDT) Received: by mail-qt0-f197.google.com with SMTP id y31so93018qty.7 for ; Thu, 25 May 2017 22:03:18 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id h42si5357303qtc.247.2017.05.25.22.03.16 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 25 May 2017 22:03:17 -0700 (PDT) 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> From: Xunlei Pang Message-ID: <5927B767.3010701@redhat.com> Date: Fri, 26 May 2017 13:04:39 +0800 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 Sender: owner-linux-mm@kvack.org List-ID: 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 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org