linux-kernel - Re: [PATCH v7 1/3] efi/x86: Fix EFI memory map corruption with kexec

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Message-ID: <20240605074257.GAZmAXAbkc5TGVds5u@fat_crate.local>
Date: Wed, 5 Jun 2024 09:42:57 +0200
From: Borislav Petkov <bp@...en8.de>
To: Dave Young <dyoung@...hat.com>
Cc: Mike Rapoport <rppt@...nel.org>, "Kalra, Ashish" <ashish.kalra@....com>,
	tglx@...utronix.de, mingo@...hat.com, dave.hansen@...ux.intel.com,
	x86@...nel.org, rafael@...nel.org, hpa@...or.com,
	peterz@...radead.org, adrian.hunter@...el.com,
	sathyanarayanan.kuppuswamy@...ux.intel.com, jun.nakajima@...el.com,
	rick.p.edgecombe@...el.com, thomas.lendacky@....com,
	michael.roth@....com, seanjc@...gle.com, kai.huang@...el.com,
	bhe@...hat.com, kirill.shutemov@...ux.intel.com, bdas@...hat.com,
	vkuznets@...hat.com, dionnaglaze@...gle.com, anisinha@...hat.com,
	jroedel@...e.de, ardb@...nel.org, kexec@...ts.infradead.org,
	linux-coco@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 1/3] efi/x86: Fix EFI memory map corruption with kexec

On Wed, Jun 05, 2024 at 10:53:44AM +0800, Dave Young wrote:
> It's something good to have but not must for the time being,  also no
> idea how to save the status across boot, for EFI boot case probably a
> EFI var can be used;

Yes.

> but how can it be cleared in case of physical boot.  Otherwise
> probably injecting some kernel parameters, anyway this needs more
> thinking.

Yeah, this'll need proper analysis whether we can even do that reliably.

We need to increment it only on the kexec reboot paths and clear it on
the normal reboot paths.

Thx.

-- 
Regards/Gruss,
    Boris.

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