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:	Sat, 03 Jul 2010 14:48:35 +0300
From:	Avi Kivity <avi@...hat.com>
To:	Marcelo Tosatti <mtosatti@...hat.com>
CC:	Xiao Guangrong <xiaoguangrong@...fujitsu.com>,
	LKML <linux-kernel@...r.kernel.org>,
	KVM list <kvm@...r.kernel.org>
Subject: Re: [PATCH v4 5/6] KVM: MMU: combine guest pte read between walk
 and pte prefetch

On 07/02/2010 08:03 PM, Marcelo Tosatti wrote:
> On Thu, Jul 01, 2010 at 09:55:56PM +0800, Xiao Guangrong wrote:
>    
>> Combine guest pte read between guest pte walk and pte prefetch
>>
>> Signed-off-by: Xiao Guangrong<xiaoguangrong@...fujitsu.com>
>> ---
>>   arch/x86/kvm/paging_tmpl.h |   48 ++++++++++++++++++++++++++++++-------------
>>   1 files changed, 33 insertions(+), 15 deletions(-)
>>      
> Can't do this, it can miss invlpg:
>
> vcpu0			vcpu1
> read guest ptes
> 			modify guest pte
> 			invlpg
> instantiate stale
> guest pte
>
> See how the pte is reread inside fetch with mmu_lock held.
>    

Note, this is fine if the pte is unsync, since vcpu0 will soon invlpg 
it.  It's only broken for sync ptes.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

--
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/

Powered by blists - more mailing lists