linux-kernel - Re: [PATCH v3 2/6] arm64/mirror: arm64 enabling

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Message-ID: <174f988c-ea14-9f10-40e1-7bdddcef5d35@huawei.com>
Date:   Fri, 10 Jun 2022 18:24:35 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     Ard Biesheuvel <ardb@...nel.org>
CC:     Wupeng Ma <mawupeng1@...wei.com>, Jonathan Corbet <corbet@....net>,
        "Will Deacon" <will@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "Borislav Petkov" <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        X86 ML <x86@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        Mike Rapoport <rppt@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Kees Cook <keescook@...omium.org>, <songmuchun@...edance.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        <damien.lemoal@...nsource.wdc.com>,
        Stephen Boyd <swboyd@...omium.org>,
        Wei Liu <wei.liu@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        David Hildenbrand <david@...hat.com>,
        "Anshuman Khandual" <anshuman.khandual@....com>,
        Zhen Lei <thunder.leizhen@...wei.com>, <gpiccoli@...lia.com>,
        Huacai Chen <chenhuacai@...nel.org>,
        "Geert Uytterhoeven" <geert@...ux-m68k.org>,
        <vijayb@...ux.microsoft.com>,
        "Linux Doc Mailing List" <linux-doc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        linux-efi <linux-efi@...r.kernel.org>,
        <platform-driver-x86@...r.kernel.org>,
        "Linux Memory Management List" <linux-mm@...ck.org>,
        linux-riscv <linux-riscv@...ts.infradead.org>
Subject: Re: [PATCH v3 2/6] arm64/mirror: arm64 enabling - find mirrored
 memory ranges


On 2022/6/10 17:34, Ard Biesheuvel wrote:
> On Fri, 10 Jun 2022 at 11:27, Kefeng Wang <wangkefeng.wang@...wei.com> wrote:
>>
>> On 2022/6/7 17:38, Wupeng Ma wrote:
>>> From: Ma Wupeng <mawupeng1@...wei.com>
>>>
>>> Commit b05b9f5f9dcf ("x86, mirror: x86 enabling - find mirrored memory ranges")
>>> introduced mirrored memory support for x86 and this could be used on arm64.
>>>
>>> Since we only support this feature on arm64, efi_find_mirror() won't be placed
>>> into efi_init(), which is used by riscv/arm/arm64, it is added in setup_arch()
>>> to scan the memory map and mark mirrored memory in memblock.
>> Move into efi_init() looks better, it won't bring negative effects on
>> arm/riscv.
>>
>> but let's maintainer to make a decision.
>>
>> Reviewed-by: Kefeng Wang <wangkefeng.wang@...wei.com>
>>
> I don't disagree with that in principle, but x86 calls the efi fake
> memmap stuff between efi_init() and efi_find_mirror(), and I already
> indicated that I don't want to enable fake memmap on !X86.

I mean move into efi_init() in drivers/firmware/efi/efi-init.c which 
only used

in arm32/arm64/riscv.

>
> But I do think there is some room for improvement here: we could move
> things like efi_mokvar_table_init() and efi_esrt_init() into
> efi_init() as well, and make efi_fake_memmap() do nothing on !X86 so
> we can move it into efi_init() too.

x86 has own efi_init() in arch/x86/platform/efi/efi.c, it seams that all 
the above

function could move into x86's own efi_init(), not sure, but we could do 
it later

if it possible.

>
>>> Signed-off-by: Ma Wupeng <mawupeng1@...wei.com>
>>> ---
>>>    Documentation/admin-guide/kernel-parameters.txt | 2 +-
>>>    arch/arm64/kernel/setup.c                       | 1 +
>>>    2 files changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
>>> index 8090130b544b..e3537646b6f7 100644
>>> --- a/Documentation/admin-guide/kernel-parameters.txt
>>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>>> @@ -2301,7 +2301,7 @@
>>>
>>>        keepinitrd      [HW,ARM]
>>>
>>> -     kernelcore=     [KNL,X86,IA-64,PPC]
>>> +     kernelcore=     [KNL,X86,IA-64,PPC,ARM64]
>>>                        Format: nn[KMGTPE] | nn% | "mirror"
>>>                        This parameter specifies the amount of memory usable by
>>>                        the kernel for non-movable allocations.  The requested
>>> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
>>> index cf3a759f10d4..6e9acd7ecf0f 100644
>>> --- a/arch/arm64/kernel/setup.c
>>> +++ b/arch/arm64/kernel/setup.c
>>> @@ -328,6 +328,7 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
>>>
>>>        xen_early_init();
>>>        efi_init();
>>> +     efi_find_mirror();
>>>
>>>        if (!efi_enabled(EFI_BOOT) && ((u64)_text % MIN_KIMG_ALIGN) != 0)
>>>             pr_warn(FW_BUG "Kernel image misaligned at boot, please fix your bootloader!");
> .