Merge remote-tracking branch 'remotes/davidhildenbrand/tags/s390x-tcg-2019-09-23...

Fix a bunch of BUGs in the mem-helpers (including the MVC instruction),
especially, to make them behave correctly on faults.

# gpg: Signature made Mon 23 Sep 2019 09:01:21 BST
# gpg:                using RSA key 1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A
# gpg:                issuer "[email protected]"
# gpg: Good signature from "David Hildenbrand <[email protected]>" [unknown]
# gpg:                 aka "David Hildenbrand <[email protected]>" [full]
# Primary key fingerprint: 1BD9 CAAD 735C 4C3A 460D  FCCA 4DDE 10F7 00FF 835A

* remotes/davidhildenbrand/tags/s390x-tcg-2019-09-23: (30 commits)
  tests/tcg: target/s390x: Test MVC
  tests/tcg: target/s390x: Test MVO
  s390x/tcg: MVO: Fault-safe handling
  s390x/tcg: MVST: Fault-safe handling
  s390x/tcg: MVZ: Fault-safe handling
  s390x/tcg: MVN: Fault-safe handling
  s390x/tcg: MVCIN: Fault-safe handling
  s390x/tcg: NC: Fault-safe handling
  s390x/tcg: XC: Fault-safe handling
  s390x/tcg: OC: Fault-safe handling
  s390x/tcg: MVCLU: Fault-safe handling
  s390x/tcg: MVC: Fault-safe handling on destructive overlaps
  s390x/tcg: MVCS/MVCP: Use access_memmove()
  s390x/tcg: Fault-safe memmove
  s390x/tcg: Fault-safe memset
  s390x/tcg: Always use MMU_USER_IDX for CONFIG_USER_ONLY
  s390x/tcg: MVST: Fix storing back the addresses to registers
  s390x/tcg: MVST: Check for specification exceptions
  s390x/tcg: MVCS/MVCP: Properly wrap the length
  s390x/tcg: MVCOS: Lengths are 32 bit in 24/31-bit mode
  ...

Signed-off-by: Peter Maydell <[email protected]>