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  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:	Mon, 11 Aug 2014 10:40:44 -0700
From:	Matthew Rushton <>
To:	Boris Ostrovsky <>,
	Matt Wilson <>,
	David Vrabel <>
	Matt Rushton <>
Subject: Re: [PATCH v2 2/2] xen/setup: Remap Xen Identity Mapped RAM

On 08/01/14 08:56, Boris Ostrovsky wrote:
> On 08/01/2014 11:52 AM, Matt Wilson wrote:
>> On Fri, Aug 01, 2014 at 03:52:28PM +0100, David Vrabel wrote:
>>> On 31/07/14 18:43, David Vrabel wrote:
>>>> On 20/07/14 01:01, Matt Rushton wrote:
>>>>> Instead of ballooning up and down dom0 memory this remaps the 
>>>>> existing mfns
>>>>> that were replaced by the identity map. The reason for this is 
>>>>> that the
>>>>> existing implementation ballooned memory up and and down which 
>>>>> caused dom0
>>>>> to have discontiguous pages. In some cases this resulted in the 
>>>>> use of bounce
>>>>> buffers which reduced network I/O performance significantly. This 
>>>>> change will
>>>>> honor the existing order of the pages with the exception of some 
>>>>> boundary
>>>>> conditions.
>>>>> To do this we need to update both the Linux p2m table and the Xen 
>>>>> m2p table.
>>>>> Particular care must be taken when updating the p2m table since 
>>>>> it's important
>>>>> to limit table memory consumption and reuse the existing leaf 
>>>>> pages which get
>>>>> freed when an entire leaf page is set to the identity map. To 
>>>>> implement this,
>>>>> mapping updates are grouped into blocks with table entries getting 
>>>>> cached
>>>>> temporarily and then released.
>>>>> On my test system before:
>>>>> Total pages: 2105014
>>>>> Total contiguous: 1640635
>>>>> After:
>>>>> Total pages: 2105014
>>>>> Total contiguous: 2098904
>>>> Applied to devel/for-linus-3.17
>>> Unfortunately, this produces too many WARNINGs on some boxes or
>>> with certain configurations.
>> Hi David,
>> Do you have more information about the systems or configurations that
>> showed a problem?
> This appears to be happening on 32-bit dom0.
> -boris

I just pushed a v3 version of the patch set which should fix the issue. 
There was casting issue that would affect 32-bit builds.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

Powered by blists - more mailing lists