drm/vmwgfx: Introduce VMware mks-guest-stats

drm/vmwgfx: Introduce VMware mks-guest-stats

VMware mks-guest-stats mechanism allows the collection of performance stats from
guest userland GL contexts, as well as from vmwgfx kernelspace, via a set of sw-
defined performance counters. The userspace performance counters are (de)registerd
with vmware-vmx-stats hypervisor via new iocts. The vmwgfx kernelspace counters
are controlled at build-time via a new config DRM_VMWGFX_MKSSTATS.

* Add vmw_mksstat_{add|remove|reset}_ioctl controlling the tracking of
  mks-guest-stats in guest winsys contexts
* Add DRM_VMWGFX_MKSSTATS config to drivers/gpu/drm/vmwgfx/Kconfig controlling
  the instrumentation of vmwgfx for kernelspace mks-guest-stats counters
* Instrument vmwgfx vmw_execbuf_ioctl to collect mks-guest-stats according to
  DRM_VMWGFX_MKSSTATS

Signed-off-by: Martin Krastev <krastevm@vmware.com>
Reviewed-by: Zack Rusin <zackr@vmware.com>
Signed-off-by: Zack Rusin <zackr@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210609172307.131929-3-zackr@vmware.com