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

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Message-ID: <20240604180212.GHZl9WpAfNVERTjMqw@fat_crate.local>
Date: Tue, 4 Jun 2024 20:02:12 +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 Tue, Jun 04, 2024 at 07:09:56PM +0800, Dave Young wrote:
> Anyway there is not such a helper for all cases.

But maybe there should be...

This is not the first case where the need arises to be able to say:

	if (am I a kexeced kernel)

in code.

Perhaps we should have a global var kexeced or so which gets incremented
on each kexec-ed kernel, somewhere in very early boot of the kexec-ed
kernel we do

	kexeced++;

and then other code can query it and know whether this is a kexec-ed
kernel and how many times it got kexec-ed...

-- 
Regards/Gruss,
    Boris.

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