linux-kernel - Re: [PATCH v2 3/10] KVM: MMU: fix direct sp's access corruptted

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]

Message-ID: <4C2883D3.2050606@redhat.com>
Date:	Mon, 28 Jun 2010 14:13:23 +0300
From:	Avi Kivity <avi@...hat.com>
To:	Xiao Guangrong <xiaoguangrong@...fujitsu.com>
CC:	Marcelo Tosatti <mtosatti@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	KVM list <kvm@...r.kernel.org>
Subject: Re: [PATCH v2 3/10] KVM: MMU: fix direct sp's access corruptted

On 06/28/2010 01:02 PM, Xiao Guangrong wrote:
>
> Avi Kivity wrote:
>
>    
>> Instead of adding a new bit, can you encode the protection in the direct
>> sp's access bits?  So we'll have one sp for read-only or
>> writeable-but-not-dirty small pages, and another sp for
>> writeable-and-dirty small pages.
>>
>>      
> It looks like it can't solve all problems, it fix the access corrupted,
> but will cause D bit losed:
>
> mapping A and mapping B both are writable-and-dirty, when mapping A write
> #PF occurs, the mapping is writable, then we can't set B's D bit anymore.
>    

If B is writeable-and-dirty, then it's D bit is already set, and we 
don't need to do anything.

If B is writeable-and-clean, then we'll have an spte pointing to a 
read-only sp, so we'll get a write fault on access and an opportunity to 
set the D bit.

> Anyway, i think we should re-intall the mapping when the state is changed. :-(
>    

When the gpte is changed from read-only to writeable or from clean to 
dirty, we need to update the spte, yes.  But that's true for other sptes 
as well, not just large gptes.

-- 
error compiling committee.c: too many arguments to function

--
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/