whp: implement safe wrappers for VM, vCPU, and instruction emulation

This commit introduces the foundational Rust abstractions for the Windows
Hypervisor Platform (WHP) backend. It encapsulates the raw C FFI bindings
into safe, idiomatic Rust structs (`WhpVm`, `WhpVcpu`, and `WhpEmulator`).

Key features include:
- Partition & vCPU Management: Safe wrappers for partition configuration,
  CPUID masking, memory mapping, and `WHvRunVirtualProcessor` exit routing.
- High-Performance Register I/O: Introduces const-generic helpers
  (`get_registers<N>` and `set_registers<N>`) to guarantee stack-allocated,
  zero-overhead register reads/writes on the VM-exit hot path.
- Robust TSC Calibration: Implements accurate host TSC frequency detection
  via CPUID 0x15/0x16, with a reliable `QueryPerformanceCounter` (QPC)
  calibration fallback for AMD/older hardware.
- Emulation: Integrates WHP's built-in x86 emulator for MMIO and PIO handling.
- Undocumented WHP Workarounds: Implements the `clear_halt_suspend` workaround
  using `WHvRegisterInternalActivityState`. This ports a known QEMU/crosvm fix
  that manually clears the `HaltSuspend` bit, preventing vCPUs from freezing
  when interrupts are injected via `WHvRequestInterrupt` while in a HLT state.

Signed-off-by: lstocchi <lstocchi@redhat.com>

Author: lstocchi

Cargo.lock

@@ -15,6 +15,7 @@ members = [
     "src/vmm",
     "src/aws_nitro",
     "src/rutabaga_gfx",
+    "src/whp",
 ]
 exclude = ["examples/gtk_display"]
 resolver = "2"

Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "krun-whp"
+version = "0.1.0-1.18.0"
+authors = ["The libkrun Authors"]
+edition = "2021"
+description = "Windows Hypervisor Platform backend for libkrun"
+license = "Apache-2.0"
+repository = "https://github.com/containers/libkrun"
+
+[dependencies]
+log = "0.4.0"
+
+[target.'cfg(target_os = "windows")'.dependencies]
+windows-sys = { version = "0.61.2", features = [
+    "Win32_Foundation",
+    "Win32_System_Hypervisor",
+    "Win32_System_Performance",
+] }