linux-kernel - Re: [PATCH v8 01/13] x86: export set_direct_map_valid

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Message-ID: <9409531b-589b-4a54-b122-06a3cf0846f3@intel.com>
Date: Fri, 5 Dec 2025 09:26:56 -0800
From: Dave Hansen <dave.hansen@...el.com>
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Subject: Re: [PATCH v8 01/13] x86: export set_direct_map_valid_noflush to KVM
 module

On 12/5/25 08:57, Kalyazin, Nikita wrote:
...
> +EXPORT_SYMBOL_FOR_MODULES(set_direct_map_valid_noflush, "kvm");

I think this export is a bad idea. The interface is abhorrent enough,
but exporting it just invites abuse and bugs.

I think what this really needs is a pair of helpers that are just:

	folio_zap_direct_map()
and
	folio_restore_direct_map()

that take a folio. *Those* can get exported to modules and those should
internally flush the TLB and not expect callers to do it.