The patch attached utilise the snoop control
capability in shadow with VT-d code.
We compute the shadow PAT index in leaf page entries now
as:
1)      
No VT-d assigned: let shadow
PAT index as WB, handled already in shadow code before.
2)      
direct assigned MMIO area:
let shadow code compute the shadow PAT with gMTRR=UC and gPAT value.
3)      
Snoop control enable: let
shadow PAT index as WB.
4)      
Snoop control disable:
 let shadow code compute the shadow PAT with gMTRR and gPAT, handled
already in shadow code before
 
Signed-off-by: Xin,
Xiaohui <xiaohui.xin@xxxxxxxxx>