linux-kernel - Re: [PATCHv2 1/3] x86, ptdump: Add section for EFI runtime services

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Date:	Tue, 28 Oct 2014 19:57:56 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Mathias Krause <minipli@...glemail.com>
Cc:	Matt Fleming <matt@...sole-pimps.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	x86-ml <x86@...nel.org>, Matt Fleming <matt.fleming@...el.com>
Subject: Re: [PATCHv2 1/3] x86, ptdump: Add section for EFI runtime services

On Sun, Oct 12, 2014 at 02:55:15PM +0200, Mathias Krause wrote:

...

> There's a lengthy comment in arch/x86/platform/efi/efi.c that mentions
> the duplication of pgd entries -- and therefore whole hierarchies --
> between trampoline_pgd and init_level4_pgt. And, ironically, that
> comment is yours from earlier this year. Looks like you forgot about
> that in the meantime ;)

Absolutely - you can see how crazy I am about UEFI :-)

Ok, thanks for refreshing this for me, your patch is good, so

Acked-by: Borislav Petkov <bp@...e.de>

What this whole story shows, however, is that the EFI mappings are in
fact in the kernel page table and this shouldn't be IMO - I'd like to
very much have them split because otherwise there's no need to switch
page tables at all. And besides, having UEFI in its own address space is
a good thing in itself anyway.

So, I've already hacked up something to have a completely separate EFI
page table - need to find out why it doesn't work yet but qemu was
b0rked until recently so we had to deal with that first... bla bla.

Thanks :-)

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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