From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f69.google.com (mail-oi0-f69.google.com [209.85.218.69]) by kanga.kvack.org (Postfix) with ESMTP id 2D0B56B0388 for ; Mon, 6 Mar 2017 12:58:50 -0500 (EST) Received: by mail-oi0-f69.google.com with SMTP id 2so144854813oif.7 for ; Mon, 06 Mar 2017 09:58:50 -0800 (PST) Received: from NAM02-CY1-obe.outbound.protection.outlook.com (mail-cys01nam02on0051.outbound.protection.outlook.com. [104.47.37.51]) by mx.google.com with ESMTPS id t44si8345637otc.306.2017.03.06.09.58.49 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 06 Mar 2017 09:58:49 -0800 (PST) Subject: Re: [RFC PATCH v4 26/28] x86: Allow kexec to be used with SME 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> From: Tom Lendacky Message-ID: <998eb58b-eefd-3093-093f-9ae25ddda472@amd.com> Date: Mon, 6 Mar 2017 11:58:40 -0600 MIME-Version: 1.0 In-Reply-To: <20170301092536.GB8353@dhcp-128-65.nay.redhat.com> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Dave Young 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, Rik van Riel , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , 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 On 3/1/2017 3:25 AM, Dave Young wrote: > Hi Tom, Hi Dave, > > 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. Currently there is not. I can look at adding something, maybe just the sme_me_mask value, which if non-zero, would indicate SME is active. > >> 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? I can look into whether something can be done in this area. Any input you can provide as to what would be the best way/place to store the range info so kdump can make use of it, would be greatly appreciated. > >> >>> >>> 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.. I do want kdump to work. I'll investigate further what can be done in this area. Thanks, Tom > > Thanks > Dave > -- 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