linux-kernel - Re: [PATCH 1/2] x86/efi: Map EFI memmap entries in-order at runtime

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Message-Id: <BFDFFBC6-C6CA-4035-8E29-C7220533A787@linaro.org>
Date:	Sat, 26 Sep 2015 13:09:17 -0700
From:	Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:	Matt Fleming <matt@...eblueprint.co.uk>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	Andy Lutomirski <luto@...capital.net>,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Matt Fleming <matt.fleming@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	"Lee, Chun-Yi" <jlee@...e.com>, Borislav Petkov <bp@...e.de>,
	Leif Lindholm <leif.lindholm@...aro.org>,
	Peter Jones <pjones@...hat.com>,
	James Bottomley <JBottomley@...n.com>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Dave Young <dyoung@...hat.com>,
	stable <stable@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Borislav Petkov <bp@...en8.de>,
	Andy Lutomirski <luto@...nel.org>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Brian Gerst <brgerst@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 1/2] x86/efi: Map EFI memmap entries in-order at runtime


> On 26 sep. 2015, at 12:57, Matt Fleming <matt@...eblueprint.co.uk> wrote:
> 
>> On Sat, 26 Sep, at 12:49:26PM, H. Peter Anvin wrote:
>> 
>> It is still a hack unless all relative offsets are preserved.  That
>> is actually simpler, even: no sorting necessary.
> 
> Unless I'm missing something, preserving relative offsets is exactly
> what we do today, modulo PMD_SIZE gaps.
> 

I think what Peter means is preserving the relative offsets inside the entire 1:1 space.

This is not at all what we do currently, and i don't think it is generally feasible on 32-bit (since the physical range may conflict with the virtual kernel mappings)

However, on 64 bit (both arm and x86), this boils down to not calling setVA() in the first place, which i'm all in favor of.
-- 
Ard.

> -- 
> Matt Fleming, Intel Open Source Technology Center
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