linux-kernel - Re: [PATCH v2] x86/mce: set MCE_IN_KERNEL

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Message-ID: <772e9939-47e4-3c09-d7a0-7952639ad853@huawei.com>
Date:   Mon, 5 Jun 2023 18:34:30 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     Borislav Petkov <bp@...en8.de>, "Luck, Tony" <tony.luck@...el.com>
CC:     "Song, Youquan" <youquan.song@...el.com>,
        "naoya.horiguchi@....com" <naoya.horiguchi@....com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "chu, jane" <jane.chu@...cle.com>
Subject: Re: [PATCH v2] x86/mce: set MCE_IN_KERNEL_COPYIN for all MC-Safe Copy



On 2023/6/3 0:01, Borislav Petkov wrote:
> On Fri, Jun 02, 2023 at 03:12:30PM +0000, Luck, Tony wrote:
>>> As mentioned above, I am focus on copy_mc_XXX calling, it will
>>> abort if the exception fires when accessing the source, and we
>>> want to isolate the corrupted src page, maybe we could a new flag
>>> to indicate this scenario, the *Final Goals* is to let core
>>> do_machine_check to deal with the corrupted src page.
>>
>> A new flag seems like a good direction.
> 
> Before anything happens here, the fate of the now unused EX_TYPE_COPY
> needs to be decided first. Then new stuff.

EX_TYPE_COPY is actually not related EX_TYPE_DEFAULT_MCE_SAFE, but we 
could recheck it again, it seems that mce recover from copy from user
is broken now. Maybe change _ASM_EXTABLE_UA to _ASM_EXTABLE_CPY in
copy_user_64.S again as commit[1] did before.

Thank you for the advice.

[1] 278b917f8cb9 x86/mce: Add _ASM_EXTABLE_CPY for copy user access


> 
> Thx.
>