Re: [Xen-devel] [PATCH] Fix save/restore of guest PAT table in HAP paging mode.

["Huang2, Wei" <Wei.Huang2@xxxxxxx>]

I tested it with SLES11 SP1 and Windows 7 guest VM. With nested paging enabled, 
I saw XEN saved 0x0007010600070106ULL, instead of default 
0x0007040600070406ULL, to guest disk files. So it behaved as expected.

-Wei

-----Original Message-----
From: Gianluca Guida [mailto:glguida@xxxxxxxxx] 
Sent: Thursday, April 12, 2012 2:32 AM
To: Huang2, Wei
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx; Gianluca Guida
Subject: Re: [Xen-devel] [PATCH] Fix save/restore of guest PAT table in HAP 
paging mode.

On Wed, Apr 11, 2012 at 11:14 PM, Wei Huang <wei.huang2@xxxxxxx> wrote:
> On 04/11/2012 06:04 PM, Gianluca Guida wrote:
>> As a major caveat, I haven't tested this patch on AMD, for lack of
>> hardware.
>
> I can test it on my AMD box tomorrow. BTW from my understanding, this patch
> doesn't have performance implication for nested paging mode, does it?

Thank you! A good but not perfect way is to check that xen-hvmctx
doesn't return on HAP the reset PAT table after a linux/windows guest
has been running. And that its value is actually preserved across
save/restore.

As for the performances in nested mode, as far as I could see, I think
not -- but I haven't looked at eventually hidden details of the nested
vm implementation.

Gianluca



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