[Xen-devel] [PATCH 0/2] MTRR/PAT virtualization

["Su, Disheng" <disheng.su@xxxxxxxxx>]

Hi,
        The following 2 patches add basic MTRR/PAT support into
hypervisor. When vt-d enabled, direct IO and RAM 
could be mapped to different cache attribute, such as UC or WC, which
will bring some trouble. 
        xen.patch: some data structures of MTRR in xen are exported.
        mtrr_pat.patch: The basic idea is listed below:
          a. MTRR/PAT MSRs are per vcpu. The value of guest MTRR is
initialized in host, after guest E820 table is build. The value of guest
PAT is initialized as default. The host PAT is initialized to cover all
the page attributes.    
          b. The guest page attribute is virtualized through shadow page
attribute. First, get the effective guest page attribute, by calculating
from the combination of guest MTRR/PAT. Then the shadow page attribute
is calculated from effective guest page attribute and host MTRR. If
conflict occurs(e.g effective guest page attribute is WB, host MTRR of
this range is UC, can't set this page attribute as guest required), set
this range as UC. Some lookup tables are added to accelerate above
procedure.

Signed-off-by: Disheng Su <disheng.su@xxxxxxxxx> 

Best Regards,
Disheng, Su

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