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Hi List, <BR>
<BR>
I prepared some notes for CR3 involvement in different IO<BR>
operations, so here are the notes<BR>
<BR>
- memory-mapped IO & DMA IO: <BR>
- Each such operation involves MOV to/from CR3 :<BR>
- MOV from CR3 causes "Unconditional VM exit"<BR>
- MOV to CR3 causes "Conditional VM exit" :<BR>
- The MOV to CR3 instruction causes a VM exit unless the value of its<BR>
source operand is equal to one of the CR3-target values specified in <BR>
the VMCS (controlled by Hypervisor). This feature allows a guest kernel to <BR>
change the CR3 value without causing a world switch to the hypervisor,<BR>
provided that the value written into the CR3 register was previously <BR>
specified by the hypervisor in the CR3-Target registers. An execution <BR>
of MOV to CR3 in VMX non-root operation does not cause a VM exit if <BR>
its source operand matches one of these previsously stored values. <BR>
If the CR3-target count is n, only the first n (0 .. (n-1)) CR3-target <BR>
values do not cause VM-Exit. nth value causes VM-Exit. if n=0 , <BR>
MOV to CR3 always causes VM-Exit.<BR>
<BR>
Please comment if I understood something incorrectly here.<BR>
<BR>
Regards,<BR>
K Arun Kumar
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