linux-kernel - Re: [RFC PATCH v3 0/6] Direct Map Removal for guest

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Message-ID: <d467e6bd-c673-415f-8bb0-91603f06498a@intel.com>
Date: Fri, 1 Nov 2024 11:43:52 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: "Manwaring, Derek" <derekmn@...zon.com>
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Subject: Re: [RFC PATCH v3 0/6] Direct Map Removal for guest_memfd

On 11/1/24 11:31, Manwaring, Derek wrote:
>>>From that standpoint I'm still tempted to turn the question around a bit
> for the host kernel's perspective. Like if the host kernel should not
> (and indeed cannot with TDX controls in place) access guest private
> memory, why not remove it from the direct map?

Pretend that the machine check warts aren't there.

It costs performance and complexity, for an only theoretical gain.  This
is especially true for a VMM that's not doing a just doing confidential
guests.  You fracture the direct map to pieces forever (for now).