vgsp-disp: find the instance block by the ctxDMA handle anywhere

The guest BAR1 is a 256 MB window over a 512 MB FB, so the RM writes
vidmem through a shifted BAR1 block and the announced instance PA does
not index the shadow (r1632: hash_nz=0 at 0x1fff0000; scan also empty
where it looked).  Resolve like the hardware does, but empirically:

  parse the announced block; if the handle is not there, search the FB
  shadow (then guest RAM for the coherent-mapping case) for the 64 KB
  block that contains an entry for the ctxDMA handle and _parses_ into
  a valid object entry; use that block's object entry for PA/limit.

Cheap for the 56-per-boot notifier writes: a failed handle is not
rescanned for 5 s.

0 files changed, 0 insertions, 0 deletions