[PATCH 0/4] hw/misc/applesmc: Implement writes, the shutdown watchdog and get-key-type

[Daniel Golle <daniel@makrotopia.org>]

QEMU's AppleSMC device only implements the SMC read command, so every
other command a guest issues fails with kSMCBadCommand. Tracing a macOS
guest shows it relies on two more: the write command (0x11) and
get-key-type (0x13). The missing write command delays boot (macOS retries
failed boot-time key writes) and produces a stream of
SMCWDT::setWatchdogTimer errors at shutdown; the missing get-key-type is
rejected dozens of times during boot.

This series implements what the guest actually uses, one command per
patch for reviewability:

  1/4  add trace events, so the SMC conversation can be observed with
       -trace 'applesmc*' (used to find exactly which commands and keys
       macOS issues).
  2/4  implement the write command (0x11): accept writes and return
       success, removing the boot delay and the shutdown errors.
  3/4  model the "NATi"/"NATJ"/"OSWD" keys as the SMC shutdown watchdog
       they represent, rather than silently accepting the writes: a write
       arms, refreshes or disarms a QEMUTimer whose expiry forces the
       machine down.
  4/4  implement get-key-type (0x13): give each key an SMC type and answer
       the type queries instead of rejecting them.

Traced against a macOS guest before and after: the boot-time key writes
(NTOK, MSDW, QENA, HE0N) now succeed, the shutdown "OSWD" write (a
watchdog disarm) is handled, and the get-key-type rejections become
correct replies (for example REV is reported as {rev, six bytes). The
traced guest only disarms the watchdog; the arm-and-fire path in patch 3
is the documented behaviour for a guest that arms it and was not observed
being triggered. get-key-by-index (0x12) is deliberately not implemented,
as macOS never issues it.

Daniel Golle (4):
  hw/misc/applesmc: Add trace events
  hw/misc/applesmc: Implement the write command
  hw/misc/applesmc: Emulate the SMC shutdown watchdog
  hw/misc/applesmc: Implement the get-key-type command

 hw/misc/applesmc.c   | 174 +++++++++++++++++++++++++++++++++++++++++--
 hw/misc/trace-events |  16 ++++
 2 files changed, 183 insertions(+), 7 deletions(-)


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2.55.0