Xen devel - Aug 2007 - [PATCH][SVM] Greatly reduce total number of CR8 intercepts

[SVM] Greatly reduce total number of CR8 intercepts

This patch reduces the number of CR8 intercept to a fraction of the
number of CR8 intercepts without.  First, CR8 read intercepts are
completely disabled since the SVM vTPR is kept kept in sync with the HVM
vLAPIC TPR.  Second, CR8 write intercepts are enabled and disabled based
upon certain conditions.  Most of the time, CR8 write intercepts are
disabled.  They are enabled only when there is a pending interrupt that
can''t be delivered because of either the current ISR or TPR (aka PPR)
because this is the only time the TPR matters.

With this patch, the number of CR8 intercepts dropped from around
10,000,000 to around 6,000 during boot of Windows 2003 Server 64-bit
(this is a rough estimate).

Signed-off-by: Travis Betak <travis.betak@amd.com>

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