linux-kernel - Re: [tip:efi/core] x86/mm/pat: Use _PAGE_GLOBAL bit for EFI page table mappings

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Message-ID: <20160224164139.GF3888@pd.tnic>
Date:	Wed, 24 Feb 2016 17:41:39 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Matt Fleming <matt@...eblueprint.co.uk>,
	Andy Lutomirski <luto@...capital.net>
Cc:	Sai Praneeth Prakhya <sai.praneeth.prakhya@...el.com>,
	"Ravi V. Shankar" <ravi.v.shankar@...el.com>,
	Toshi Kani <toshi.kani@...com>,
	Brian Gerst <brgerst@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Luis Rodriguez <mcgrof@...e.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>, ricardo.neri@...el.com,
	Hugh Dickins <hughd@...gle.com>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>
Subject: Re: [tip:efi/core] x86/mm/pat: Use _PAGE_GLOBAL bit for EFI page
 table mappings

On Wed, Feb 24, 2016 at 05:20:02PM +0100, Borislav Petkov wrote:
> That's mixed mode. I think you mean the FLUSH_TLB_ALL in efi_call.
> That's EFI on 64-bit but that is mandated by the spec, AFAIR.

Ok, so mfleming set me straight on IRC - that's tip/master I should be
staring at.

In any case, I think we should do __flush_tlb_all() in efi_call_cirt()
just in case, for the simple reason that EFI could be installing some
funky TLB entries which we don't want. I'm not saying it does and it
probably won't but what's stopping it?

Or am I being overly paranoid?

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.