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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2CA98C4332F for ; Sat, 16 Apr 2022 02:17:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229577AbiDPCT0 (ORCPT ); Fri, 15 Apr 2022 22:19:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51876 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229454AbiDPCTA (ORCPT ); Fri, 15 Apr 2022 22:19:00 -0400 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A45A93C72F; Fri, 15 Apr 2022 19:16:24 -0700 (PDT) Received: from dggpemm500021.china.huawei.com (unknown [172.30.72.55]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4KgFtl21SZzCr3Z; Sat, 16 Apr 2022 09:27:43 +0800 (CST) Received: from dggpemm500014.china.huawei.com (7.185.36.153) by dggpemm500021.china.huawei.com (7.185.36.109) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Sat, 16 Apr 2022 09:32:04 +0800 Received: from [10.174.178.120] (10.174.178.120) by dggpemm500014.china.huawei.com (7.185.36.153) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Sat, 16 Apr 2022 09:32:02 +0800 Message-ID: <6de859df-e1c3-e9aa-4530-3b61b9c69a28@huawei.com> Date: Sat, 16 Apr 2022 09:32:01 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH v2 0/9] introduce mirrored memory support for arm64 To: CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , References: <20220414101314.1250667-1-mawupeng1@huawei.com> From: mawupeng In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.178.120] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpemm500014.china.huawei.com (7.185.36.153) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org 在 2022/4/14 18:22, Ard Biesheuvel 写道: > On Thu, 14 Apr 2022 at 11:54, Wupeng Ma wrote: >> >> From: Ma Wupeng >> >> Commit b05b9f5f9dcf ("x86, mirror: x86 enabling - find mirrored memory ranges") >> introduced mirrored memory support for x86. This support rely on UEFI to >> report mirrored memory address ranges. See UEFI 2.5 spec pages 157-158: >> >> http://www.uefi.org/sites/default/files/resources/UEFI%202_5.pdf >> >> Memory mirroring is a technique used to separate memory into two separate >> channels, usually on a memory device, like a server. In memory mirroring, >> one channel is copied to another to create redundancy. This method makes >> input/output (I/O) registers and memory appear with more than one address >> range because the same physical byte is accessible at more than one >> address. Using memory mirroring, higher memory reliability and a higher >> level of memory consolidation are possible. >> >> Arm64 can support this too. So mirrored memory support is added to support >> arm64. >> >> Efi_fake_mem is used for testing mirrored features and will not be used in >> production environment. This test features can fake memory's attribute >> values. >> >> The reason why efi_fake_mem support is put first is that memory's attribute >> is reported by BIOS which is hard to simulate. With this support, any arm64 >> machines with efi support can easily test mirrored features. >> >> The main purpose of this patchset is to introduce mirrored support for >> arm64 and we have already fixed the problems we had which is shown in >> patch #5 to patch #7 and try to bring total isolation in patch #8 which >> will disable mirror feature if kernelcore is not specified. >> >> In order to test this support in arm64: >> - patch this patchset >> - add efi_fake_mem=8G@0:0x10000 in kernel parameter to simulate mirrored >> memroy between phy addr 0-8G. >> - add kernelcore=mirror in kernel parameter >> - start you kernel >> > > As I explained before: > > - NAK to EFI fake_mem support on arm64 fake_mem support on arm64 will be removed in subsequent version. > - NAK to the whole series until you come up with a proposal on how to > locate the static kernel image itself into more reliable memory, as > there is really no point to any of this otherwise. Sorry I am not familiar with this, as you metioned before, > you have to iterate over the memory map and look for regions with > the desired attribute, and allocate those pages explicitly. Do you mean this is x86, commit c05cd79750fb ("x86/boot/KASLR: Prefer mirrored memory regions for the kernel physical address"). I will do some research. > I'd prefer to implement this in the bootloader, and only add minimal > logic to the stub to respect the placement of the kernel by the loader > if the loader signals it to do so. Does this bootloader refer to grub and then add minimal logic to arm64-stub.c? What is the loader signal? System exists mirrored memory reported by uefi? Thanks for reviewing, sorry for my ignorance on this. > .