Windows guest PV driver issues

["John S" <johnsutherland@xxxxxxxxxxxxx>]

To anyone running windows HVM guests with the PV drivers. I am experiencing 
issues on windows guests when copying large files between two guest virtual 
block devices. The copy halts after only a few GB and drops to 0 bytes/s, the 
storage is fine and seeing no IO.

I've tried on windows server 2016 and 2019, both seem to do it. My dom0 is 
Debian Buster running their most recent release of xen4.11. The same test on 
linux guests works without issue.

AMD EPYC 7302 16-Core Processor
release                : 4.19.0-8-amd64
machine                : x86_64
xen_major              : 4
xen_minor              : 11
xen_extra              : .4-pre
xen_version            : 4.11.4-pre
xen_caps               : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 
hvm-3.0-x86_32p hvm-3.0-x86_64 


Cheers,
John S