CpuCsrAccessSMM, 0174, 18 KB, SMM

SMM driver providing protocol-based access to CPU uncore Control and Status Registers (CSRs), PCIe configuration space, and PCU/VCU mailbox registers across sockets. Dispatches 12 sub-commands: CSR read/write via USRA, PCIe config read/write via MMCFG, PCU/VCU mailbox commands, MMIO direct access, address translation, and BIOS checkpoint.

Key Functions: CpuCsrConfigInit (per-socket config reload from SysHost), PcuMailboxCmd (PCU mailbox command with poll-ready), VcuMailboxCmd (VCU mailbox with retry), MmioGetAddr/MmioRead/MmioWrite (MMIO address translation), UsraRead/UsraWrite (USRA protocol wrappers), GetSocketConfig (box routing dispatch), MailBoxPollReady (TSC-based poll with timeout).

Protocols/Dependencies: USRA Interface Protocol, PCIe RootBridge IO Protocol, SMM Buffer Validation Protocol, Debug Port Protocol.

Platform: Intel Purley (Skylake-SP) / HR650X server, PurleySktPkg/Dxe/CpuCsrAccess/CpuCsrAccess