linux-kernel - Re: [PATCH] Use global TLB flushes in MTRR code

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 8 Feb 2008 12:44:19 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Andi Kleen <andi@...stfloor.org>, davej@...emonkey.org.uk,
	tglx@...utronix.de, linux-kernel@...r.kernel.org,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH] Use global TLB flushes in MTRR code

> because it's not just an open-coded __tlb_flush_all(), it _disables PGE 
> and keeps it so while the MTRR's are changed on all CPUs_.

Yes and? 

> 
> Your patch adds __flush_tlb_all() which re-enables the PGE bit in cr4, 
> see asm-x86/tlbflush.h:
> 
>         /* clear PGE */
>         write_cr4(cr4 & ~X86_CR4_PGE);
>         /* write old PGE again and flush TLBs */
>         write_cr4(cr4);
> 
> so we'll keep PGE enabled during the MTRR setting - which changes 
> behavior.

It changes behaviour in some minor ways but I don't think it makes any 
difference. PGE only influences TLB flushes (according to its 
specification) and all the TLB flushes still run with PGE disabled.

-Andi

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/