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Date: Thu, 30 Sep 2021 21:30:06 +0200
From: Borislav Petkov <bp@alien8.de>
To: "Luck, Tony" <tony.luck@intel.com>
Cc: "Williams, Dan J" <dan.j.williams@intel.com>,
	Linux NVDIMM <nvdimm@lists.linux.dev>,
	Jane Chu <jane.chu@oracle.com>, Luis Chamberlain <mcgrof@suse.com>
Subject: Re: [RFT PATCH] x86/pat: Fix set_mce_nospec() for pmem
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On Thu, Sep 30, 2021 at 05:28:12PM +0000, Luck, Tony wrote:
> > Question is, can we even access a hwpoisoned page to retrieve that data
> > or are we completely in the wrong weeds here? Tony?
> 
> Hardware scope for poison is a cache line (64 bytes for DDR, may be larger
> for the internals of 3D-Xpoint memory).

I don't mean from the hw aspect but from the OS one: my simple thinking
is, *if* a page is marked as HW poison, any further mapping or accessing
of the page frame is prevented by the mm code.

So you can't access *any* bits there so why do we even bother with whole
or not whole page? Page is gone...

-- 
Regards/Gruss,
    Boris.

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