This series implements FF-A 1.2 PARTITION_INFO_GET_REGS support,
providing register-based partition info retrieval as an efficient
alternative to the RX buffer-based PARTITION_INFO_GET.

The serie is also introducing a caching system for the list of secure
partitions to prevent retrieving it on each VM call as we expect it to
be static and not changing over time.

The patches are organized as follows:
- patch 1 is modifying existing code to prepare for GET_REGS support by
  adding a start_index in the existing internal function
- patch 2 is introducing the secure partition list caching
- patch 3 is removing the existing suscribers list to directly use the
  cached secure partition list
- patch 4 is adding GET_REGS support

Changes since v1 (Jens comments):
- rework SP cache handling to enforce 1.1+ structure size
- ensure unaligned-safe reads
- remove checks for SBZ fields
- tighten tag handling

Bertrand Marquis (4):
  xen/arm: ffa: Add start_index to VM partinfo helper
  xen/arm: ffa: Cache SP partition info at init
  xen/arm: ffa: Drop SP subscriber lists
  xen/arm: ffa: Add cached GET_REGS support

 xen/arch/arm/tee/ffa.c          |  23 +-
 xen/arch/arm/tee/ffa_partinfo.c | 565 ++++++++++++++++++++++----------
 xen/arch/arm/tee/ffa_private.h  |   4 +-
 3 files changed, 410 insertions(+), 182 deletions(-)

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2.52.0