[Xen-devel] Question regarding VM_EXIT and VGA

["Sujata Doshi" <sujatadoshi@xxxxxxxxx>]

Hi
I am working on a project using WINDOWS guest on XEN archticture. I
have a couple of questions.

As I understand when a VM exit occurs due to I/O like say a mouse
interrupt -- the XEN hypervisor gets a notification and it forwards
the I/O request to the qemu-dm in Domain-0 via an event channel. Now
during this VM exit , is the guest OS blocked ?

Specifically, what about VGA writes are they blocked too during a VM
exit ? The following link explains that to speed up performance a
shared memory area was built between qemu and the hvm guest .
http://www.intel.com/technology/itj/2006/v10i3/3-xen/5-performance-tuning-vt-x.htm

But I am unable to understand as to whether is this shared memory area
is still accessible by the guest vga when a VM exit has taken place
due to another I/O event like a mouse click?

Would appreciate if you could answer my queries.
Thanks
Sujata

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