vgsp-sema: keep the scrubber release alive while the event pump blocks

The guest's PMA scrub wait and the host's status-queue pump can deadlock:
the X server's scrub wait holds the guest RM lock the status consumer
needs, the ring fills, and every critical event post then waits out its
full 200 ms ring-full budget. A service pass can take many seconds, so
the next pass's scrub step - the only thing that can release the scrub
wait - is starved and the guest never makes progress.

Run the scrub step from inside the send path's ring-full wait (service
thread only), and re-resolve the scrubber's finish/host-sema words on
every pass instead of once: the guest re-creates its RM kernel VAS and
re-maps the channel buffer under the same GPU VA (observed: gpfifo VA
0x120064000 moved from PA 0x127e6a000 to 0x1122e9000), so a once-only
resolution authored a page the guest no longer polled. Prefer the RM
kernel VAS (h=0xc) RAM mapping over a client VAS vidmem mapping, and
force re-resolution when a scrubber re-registers.

0 files changed, 0 insertions, 0 deletions