M4/M5 Macs support SME2, and HVF exposes this functionality in its
public API.

Add support for it in QEMU.

This was tested by running an SME2 benchmark from Arm [0]. savevm and
loadvm during the benchmark's run were used to verify migration works.

[0]:
https://learn.arm.com/learning-paths/cross-platform/multiplying-matrices-with-sme2/1-get-started/

Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
---
Changes in v3:
- Rebased against master now that it supports SME-without-SVE setups for
  gdbstub
- Link to v2: https://lore.kernel.org/qemu-devel/20260115-sme2-hvf-v2-0-2eca481bd7ee@linaro.org

Changes in v2:
- Added stubs if hvf 15.2 headers are not available (suggested by agraf)
- Link to v1: https://lore.kernel.org/qemu-devel/20260114-sme2-hvf-v1-0-ce9599596736@linaro.org

---
Manos Pitsidianakis (2):
      hvf/arm: handle FEAT_SME2 migration
      hvf/arm: expose FEAT_SME2 to guest if available

 target/arm/cpu64.c             |  13 +-
 target/arm/hvf/hvf.c           | 314 +++++++++++++++++++++++++++++++++++++++--
 target/arm/hvf/hvf_sme_stubs.h | 158 +++++++++++++++++++++
 target/arm/hvf/sysreg.c.inc    |   8 ++
 target/arm/hvf_arm.h           |  44 ++++++
 target/arm/machine.c           |   2 +-
 6 files changed, 523 insertions(+), 16 deletions(-)
---
base-commit: 6593154e7d65f61d8f9dbeb98224731b7137c53e
change-id: 20260114-sme2-hvf-105767189521

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