Re: [Xen-devel][PATCH] patch to support super page (2M) with EPT

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

Overall your changes to common code seem a bit more invasive than in the Intel patch. In particular I don’t understand why you made such changes to common/memory.c. The other patch makes far fewer changes (and even some of those would go away since they have erroneously changed the populate_physmap interface). So my feeling is that the Intel patch is a slightly more elegant base to start with: extra changes that your patch makes really need to be accounted for.

 -- Keir

On 12/5/08 18:28, "Huang2, Wei" <Wei.Huang2@xxxxxxx> wrote:

Here is a revised version. I get rid of 4MB support, as suggested. I did not see the issue mentioned by Xiaohui related to splitting last 2M into 4KB pages. But anyway, I attached two versions for your reference. Keir, please let me know if you have comments.

 
-Wei

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From: Keir Fraser [mailto:keir.fraser@xxxxxxxxxxxxx]
Sent: Monday, May 12, 2008 2:03 AM
To: Xin, Xiaohui; Huang2, Wei; xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel][PATCH] patch to support super page (2M) with EPT

Yes, absolutely no need for 4M page support. We do not support the 32-bit non-PAE build target any more.

 -- Keir

On 12/5/08 06:04, "Xin, Xiaohui" <xiaohui.xin@xxxxxxxxx> wrote:

Some comments here:
1) Basically 4M pages  allocations is not hardware naturally for EPT, we only use 2M super pages now.  
I remembered that Keir said that 2M pages allocation is sufficient, and he  removed all the pure 32bit support already.
2)  If we don’t allocate  the last 2M area with 4kb pages, the EPT will meet some problem. Xen will set  one of the 4k page
     there to be invalid,  logically that means we should invalid the all the 2M page if we allocate it  with 2M, and then the
     special pages Xen used  in the high end of the guest memory can not be used then. May we know how you  cope with  that?
 
Thanks
Xiaohui
 

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From:  xen-devel-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx]  On Behalf Of Huang2, Wei
Sent: Monday, May 12, 2008 12:36  PM
To: Xin, Xiaohui;  xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: RE: [Xen-devel][PATCH] patch  to support super page (2M) with EPT

This is the latest one I created. Please review it and  I will re-submit.
 
1.       It includes the  patch for p2m-ept.c, directly from your previous patch.  

2.       Xc_hvm_create.c  is based on my original approach. It includes support for both 2MB and 4MB  pages. Also it considers the case of odd page size (such as 255MB). But I did  not allocate the last 2MB area using 4KB  pages. Let me know if it is a  big issue.

3.       The rest are  pretty similar.


Thanks,
 
-Wei
 

From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx]  On Behalf Of Huang2, Wei
Sent: Sunday, May 11, 2008 3:34  PM
To: Xin, Xiaohui;  xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: RE: [Xen-devel][PATCH] patch  to support super page (2M) with EPT

Could we work together for a common solution? As far  as I can see, it largely overlaps with my super page patch. The major  difference is between p2m.c and  p2m-ept.c.
 
-Wei
 

From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx]  On Behalf Of Xin, Xiaohui
Sent: Friday, May 09, 2008 4:11  AM
To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject:  [Xen-devel][PATCH] patch to support super page (2M) with  EPT

Attached are the patches to support  super page with EPT. We only support 2M size. And shadow may still work fine  with 4K pages.
The patches can be split into 3 parts. Apply order is as  attached.
 
tool.diff
To allocate 2M physical contiguous memory  in guest except the first 2M and the last 2M.
The first 2M covers special  memory, and Xen use the last few pages in guest memory to do special  things.
We let them to be 4K pages as normal.
super_page_common.patch  
To modify the p2m interfaces by adding an order parameter, such as  guest_physmap_add_page(), p2m_set_entry(),  etc.
p2m-ept-file.patch
           To  handle the EPT tables to support super page.             
 
 
Signed-off-by:  Xin Xiaohui <xiaohui.xin@xxxxxxxxx>
Signed-off-by: Li Xin, B  <xin.b.li@xxxxxxxxx>
 

 

 

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