[PATCH v8 0/3] Add eager FP and Vector context switching support

[Anup Patel]

From: Dave Patel <dave.patel at riscstar.com>

This patch series adds proper support for per-domain floating-point (FP) and
vector (V) contexts in the domain context switch logic. Each domain
now maintains its own FP and vector state, which is saved and restored
during domain switches.

Conditionalize FP and Vector save/restore based on extensions, unconditional
save and restore of floating-point (FP) and Vector registers fails on
generic platform firmware. This firmware must run on multiple platforms
that may lack these extensions.

Address this by conditionally executing FP save/restore only if the underlying
hart supports the F or D extensions. Similarly, perform Vector save/restore
only if the hart supports the Vector extension.

Changes since v7:
- Rebased on latest OpenSBI master
- Addressed all my comments on v7 series

Changes include:

- Add Vector save and restore functionality
- Add Floating Point save and restore functioanlity
- Added `fp_ctx` and `vec_ctx` members to `struct hart_context`.
- Introduced dynamic vector struct allocation for vlenb in 'struct hart_context'
  to allocate and free per-domain FP and vector context.
- Modified `sbi_domain_register()` to initialize FP/Vector context per domain.
- Updated `switch_to_next_domain_context()` to save/restore FP and vector
  contexts safely:
    - Ensures FS/VS fields in `mstatus` are enabled (set to Initial) only if Off.
- Added runtime checks for FP and vector extensions where needed.
- Added SBI_HART_EXT_F, SBI_HART_EXT_D, SBI_HART_EXT_V to enum
  sbi_hart_extensions and the sbi_hart_ext[] array. Use sbi_hart_has_extension()
  to check for these capabilities before performing the context switches

This improves support for multi-domain systems with FP and Vector
extensions, and prevents corruption of FP/Vector state during domain
switches.

Dave Patel (3):
  lib: sbi: Add RISC-V vector context save/restore support
  lib: sbi: Add floating-point context save/restore support.
  lib: sbi: domain FP/Vector context support for context switch

 include/sbi/sbi_fp.h         |  35 +++++++
 include/sbi/sbi_hart.h       |   6 ++
 include/sbi/sbi_vector.h     |  40 ++++++++
 lib/sbi/objects.mk           |   2 +
 lib/sbi/sbi_domain_context.c |  33 ++++++
 lib/sbi/sbi_fp.c             | 192 +++++++++++++++++++++++++++++++++++
 lib/sbi/sbi_hart.c           |   3 +
 lib/sbi/sbi_vector.c         |  94 +++++++++++++++++
 8 files changed, 405 insertions(+)
 create mode 100644 include/sbi/sbi_fp.h
 create mode 100644 include/sbi/sbi_vector.h
 create mode 100644 lib/sbi/sbi_fp.c
 create mode 100644 lib/sbi/sbi_vector.c

-- 
2.43.0