[PATCH MULTISERIES] Optimize Xen barriers

[Tu Dinh <ngoc-tu.dinh@xxxxxxxxxx>]

This series aims to optimize the use of memory barriers in all Windows
PV drivers.

Particularly, the following have been changed:
* x86 is TSO and only needs a compiler barrier as read/write barriers.
  So the xen_* barriers in xen-types.h don't always need to be
  KeMemoryBarrier (which is a full barrier using a locked instruction).
* Barriers right next to Interlocked* operations were deleted, as these
  operations serve as implicit full barriers.
* Ring operations were converted acquire-release semantics instead of
  full barriers.
* As a related change, LockThread tracking was conditioned to debug
  builds.


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Ngoc Tu Dinh | Vates XCP-ng Developer

XCP-ng & Xen Orchestra - Vates solutions

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