Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752620AbdCAJwh (ORCPT ); Wed, 1 Mar 2017 04:52:37 -0500 Received: from mx1.redhat.com ([209.132.183.28]:48822 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752430AbdCAJwc (ORCPT ); Wed, 1 Mar 2017 04:52:32 -0500 Date: Wed, 1 Mar 2017 17:27:44 +0800 From: Dave Young To: Tom Lendacky Cc: Konrad Rzeszutek Wilk , linux-arch@vger.kernel.org, linux-efi@vger.kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, iommu@lists.linux-foundation.org, kexec@lists.infradead.org, Rik van Riel , Radim =?utf-8?B?S3LEjW3DocWZ?= , Toshimitsu Kani , Arnd Bergmann , Jonathan Corbet , Matt Fleming , "Michael S. Tsirkin" , Joerg Roedel , Paolo Bonzini , Brijesh Singh , Ingo Molnar , Alexander Potapenko , Andy Lutomirski , "H. Peter Anvin" , Borislav Petkov , Andrey Ryabinin , Thomas Gleixner , Larry Woodman , Dmitry Vyukov Subject: Re: [RFC PATCH v4 26/28] x86: Allow kexec to be used with SME Message-ID: <20170301092736.GA8491@dhcp-128-65.nay.redhat.com> References: <20170216154158.19244.66630.stgit@tlendack-t1.amdoffice.net> <20170216154755.19244.51276.stgit@tlendack-t1.amdoffice.net> <20170217155756.GJ30272@char.us.ORACLE.com> <20170301092536.GB8353@dhcp-128-65.nay.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170301092536.GB8353@dhcp-128-65.nay.redhat.com> User-Agent: Mutt/1.7.1 (2016-10-04) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Wed, 01 Mar 2017 09:27:55 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1713 Lines: 45 Add kexec list.. On 03/01/17 at 05:25pm, Dave Young wrote: > Hi Tom, > > On 02/17/17 at 10:43am, Tom Lendacky wrote: > > On 2/17/2017 9:57 AM, Konrad Rzeszutek Wilk wrote: > > > On Thu, Feb 16, 2017 at 09:47:55AM -0600, Tom Lendacky wrote: > > > > Provide support so that kexec can be used to boot a kernel when SME is > > > > enabled. > > > > > > Is the point of kexec and kdump to ehh, dump memory ? But if the > > > rest of the memory is encrypted you won't get much, will you? > > > > Kexec can be used to reboot a system without going back through BIOS. > > So you can use kexec without using kdump. > > > > For kdump, just taking a quick look, the option to enable memory > > encryption can be provided on the crash kernel command line and then > > Is there a simple way to get the SME status? Probably add some sysfs > file for this purpose. > > > crash kernel can would be able to copy the memory decrypted if the > > pagetable is set up properly. It looks like currently ioremap_cache() > > is used to map the old memory page. That might be able to be changed > > to a memremap() so that the encryption bit is set in the mapping. That > > will mean that memory that is not marked encrypted (EFI tables, swiotlb > > memory, etc) would not be read correctly. > > Manage to store info about those ranges which are not encrypted so that > memremap can handle them? > > > > > > > > > Would it make sense to include some printk to the user if they > > > are setting up kdump that they won't get anything out of it? > > > > Probably a good idea to add something like that. > > It will break kdump functionality, it should be fixed instead of > just adding printk to warn user.. > > Thanks > Dave