linux-kernel - Re: [PATCH v2 0/9] introduce mirrored memory support for arm64

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <b2864968-3cc7-dba3-5361-d8ee4cc3482a@huawei.com>
Date:   Wed, 20 Apr 2022 10:13:40 +0800
From:   mawupeng <mawupeng1@...wei.com>
To:     <ardb@...nel.org>
CC:     <akpm@...ux-foundation.org>, <catalin.marinas@....com>,
        <will@...nel.org>, <corbet@....net>, <tglx@...utronix.de>,
        <mingo@...hat.com>, <bp@...en8.de>, <dave.hansen@...ux.intel.com>,
        <x86@...nel.org>, <dvhart@...radead.org>, <andy@...radead.org>,
        <rppt@...nel.org>, <paulmck@...nel.org>, <peterz@...radead.org>,
        <jroedel@...e.de>, <songmuchun@...edance.com>, <macro@...am.me.uk>,
        <frederic@...nel.org>, <W_Armin@....de>, <john.garry@...wei.com>,
        <seanjc@...gle.com>, <tsbogend@...ha.franken.de>,
        <anshuman.khandual@....com>, <chenhuacai@...nel.org>,
        <david@...hat.com>, <gpiccoli@...lia.com>, <mark.rutland@....com>,
        <wangkefeng.wang@...wei.com>, <linux-doc@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-efi@...r.kernel.org>, <linux-ia64@...r.kernel.org>,
        <platform-driver-x86@...r.kernel.org>, <linux-mm@...ck.org>
Subject: Re: [PATCH v2 0/9] introduce mirrored memory support for arm64



在 2022/4/20 2:32, Ard Biesheuvel 写道:
> On Sat, 16 Apr 2022 at 03:32, mawupeng <mawupeng1@...wei.com> wrote:
>>
>>
>>
>> 在 2022/4/14 18:22, Ard Biesheuvel 写道:
>>> On Thu, 14 Apr 2022 at 11:54, Wupeng Ma <mawupeng1@...wei.com> wrote:
>>>>
>>>> From: Ma Wupeng <mawupeng1@...wei.com>
>>>>
>>>> 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?
>>
> 
> Any bootloader, yes.
> 
>> What is the loader signal?
> 
> A protocol installed onto the image handle, as I suggested before. I
> even cc'ed you on a patch that implements this.

Sorry to bother you.
I didn't receive any patches.
Could you share the link?

> 
>> System exists mirrored memory reported by uefi?
>>
> 
> What on earth is the point of any of this if the only use case being
> targeted is efi_fake_mem with arbitrary fake mirrored regions?
> 
> So yes, unless there are systems that need this, I don't see a point
> in merging any of this
We do have mirrored memory reported by uefi and efi_fake_mem is added for easy testing
with qemu/hardware without update UEFI.

> .