linux-kernel - Re: [PATCH -next v4 2/3] x86/mce: rename MCE_IN_KERNEL_COPYIN to MCE_IN_KERNEL_COPY

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Date: Fri, 2 Feb 2024 20:42:57 +0100
From: Borislav Petkov <bp@...en8.de>
To: "Luck, Tony" <tony.luck@...el.com>
Cc: Tong Tiangen <tongtiangen@...wei.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"wangkefeng.wang@...wei.com" <wangkefeng.wang@...wei.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"x86@...nel.org" <x86@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
	Andy Lutomirski <luto@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Naoya Horiguchi <naoya.horiguchi@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Guohanjun <guohanjun@...wei.com>
Subject: Re: [PATCH -next v4 2/3] x86/mce: rename MCE_IN_KERNEL_COPYIN to
 MCE_IN_KERNEL_COPY_MC

On Fri, Feb 02, 2024 at 06:44:32PM +0000, Luck, Tony wrote:
> At least on Intel you can only get a machine check for operation on poison data LOAD.
> Not for a STORE. I believe that is generally true - other arches to confirm.

So what happens if you store to a poisoned cacheline on Intel? It'll
raise a poison consumption error when that cacheline is loaded in the
cache? Because you need to load that line into the cache for writing,
I'd presume...

What happens if you have bits flipped in the cacheline you want to write
to?

That's fine because you're overwriting them anyway?

I'd presume ECC check gets performed on cacheline load and then you'll
have to raise an #MC...

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette