[Xen-devel] [PATCH 3/4] Enable VirtualPC 2007 run on top of XEN: REPS prefix emulation

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

REPS prefix emulation for INS and OUTS is already in xen. Can we enable
REPS for "stos" and "movs" in paging mode? Although it doesn't benefit a
lot for normal hvm guest, in virtualpc case, I have to do that.
VirtualPC will call "reps stos"(ecx=0x400, eax=0) a lot, about 1000
times per second. It seems to clear a L1 page table page, it can't be
fast unshadowed in check_for_early_unshadow and it's even ReadOnly in
guest page table(CR0.wp = 0). So we get 0x400 * 1000 times page faults
per second, so CPU cycle is almost wasted on it.


Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Signed-off-by: Disheng Su <disheng.su.com>

Attachment: 3_emualte_reps_prefix.patch
Description: 3_emualte_reps_prefix.patch

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