Add Sspmp, Sspmpen, and Smpmpdeleg extension definitions

[ybc-alkaid]

This PR adds Unified Database extension definitions for RISC-V S-level Physical Memory Protection (SPMP), consisting of three extensions:

Sspmp: Core SPMP mechanism for S-mode memory protection.
Sspmpen: Per-entry enable bits via the spmpen CSR.
Smpmpdeleg: PMP-to-SPMP resource sharing via the mpmpdeleg CSR.

References:
SPMP specification: riscv/riscv-isa-manual#2573
SPMP arch test suites: riscv/riscv-arch-test#1166

[Copilot]

Pull request overview

This PR adds Unified Database (UDB) extension definitions for the RISC-V Supervisor Physical Memory Protection (SPMP) feature set, capturing the base mechanism and two related CSRs for enable control and delegation from PMP.

Changes:

• Add a new privileged extension definition for Sspmp (Supervisor Physical Memory Protection).
• Add a new privileged extension definition for Sspmpen (per-entry enable control via spmpen).
• Add a new privileged extension definition for Smpmpdeleg (delegation control via mpmpdeleg).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 5 comments.

File	Description
spec/std/isa/ext/Sspmp.yaml	Defines the core SPMP supervisor protection mechanism and its dependencies.
spec/std/isa/ext/Sspmpen.yaml	Defines Sspmpen and requires Sspmp as a prerequisite.
spec/std/isa/ext/Smpmpdeleg.yaml	Defines Smpmpdeleg (PMP-to-SPMP resource sharing) and its base privilege requirements.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 72.21%. Comparing base (a1225d7) to head (996a685).
⚠️ Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1817      +/-   ##
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- Coverage   72.24%   72.21%   -0.04%     
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  Files          52       52              
  Lines       27671    27740      +69     
  Branches     6009     6012       +3     
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+ Hits        19992    20033      +41     
- Misses       7679     7707      +28     

Flag	Coverage Δ
idlc	76.16% <ø> (-0.03%)	⬇️

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 4 changed files in this pull request and generated 5 comments.

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 4 changed files in this pull request and generated 3 comments.

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