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 v5:
- Fix NEON registers getting zeroed when loading vmstate by setting SVCR first
- Link to v4: https://lore.kernel.org/qemu-devel/20260227-sme2-hvf-v4-0-3dae31a1876d@linaro.org

Changes in v4:
- Set cpu->sme_vq.supported in hvf_arm_set_cpu_features_from_host (thanks Richard)
- Removed two rogue lines that were smuggled in by git-rebase (thanks Mohamed)
- Link to v3: https://lore.kernel.org/qemu-devel/20260226-sme2-hvf-v3-0-ea5763dbeba2@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/hvf/hvf.c           | 323 +++++++++++++++++++++++++++++++++++++++--
 target/arm/hvf/hvf_sme_stubs.h | 158 ++++++++++++++++++++
 target/arm/hvf/sysreg.c.inc    |   8 +
 target/arm/hvf_arm.h           |  41 ++++++
 target/arm/machine.c           |   2 +-
 5 files changed, 517 insertions(+), 15 deletions(-)
---
base-commit: d8a9d97317d03190b34498741f98f22e2a9afe3e
change-id: 20260114-sme2-hvf-105767189521

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