feat: add option to print MircomState

Add subcommand in InfoVmStateSubCommand to print the VmState.
The output of this command can be used to diff between 2 different
snapshot files.

Signed-off-by: Sudan Landge <sudanl@amazon.com>

src/snapshot-editor/src/info.rs

@@ -32,6 +32,12 @@ pub enum InfoVmStateSubCommand {
         #[arg(short, long)]
         vmstate_path: PathBuf,
     },
+    /// Print readable MicroVM state.
+    VmState {
+        /// Path to the vmstate file.
+        #[arg(short, long)]
+        vmstate_path: PathBuf,
+    },
 }
 
 pub fn info_vmstate_command(command: InfoVmStateSubCommand) -> Result<(), InfoVmStateError> {
@@ -41,6 +47,7 @@ pub fn info_vmstate_command(command: InfoVmStateSubCommand) -> Result<(), InfoVm
         InfoVmStateSubCommand::VcpuStates { vmstate_path } => {
             info(&vmstate_path, info_vcpu_states)?
         }
+        InfoVmStateSubCommand::VmState { vmstate_path } => info(&vmstate_path, info_vmstate)?,
     }
     Ok(())
 }
@@ -87,3 +94,17 @@ fn info_vcpu_states(state: &MicrovmState, _: u16) -> Result<(), InfoVmStateError
     }
     Ok(())
 }
+
+fn info_vmstate(vmstate: &MicrovmState, version: u16) -> Result<(), InfoVmStateError> {
+    println!("{vmstate:#?}");
+    match FC_VERSION_TO_SNAP_VERSION
+        .iter()
+        .find(|(_, &v)| v == version)
+    {
+        Some((key, _)) => {
+            println!("v{key}");
+            Ok(())
+        }
+        None => Err(InfoVmStateError::InvalidVersion(version)),
+    }
+}

src/vmm/src/vstate/vcpu/x86_64.rs

@@ -5,8 +5,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the THIRD-PARTY file.
 
-use std::fmt::Debug;
 use std::collections::{HashMap, HashSet};
+use std::fmt::Debug;
 
 use kvm_bindings::{
     kvm_debugregs, kvm_lapic_state, kvm_mp_state, kvm_regs, kvm_sregs, kvm_vcpu_events, kvm_xcrs,
@@ -574,28 +574,27 @@ pub struct VcpuState {
     pub tsc_khz: Option<u32>,
 }
 
-impl Debug for VcpuState{
+impl Debug for VcpuState {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         let mut debug_kvm_regs: Vec<kvm_bindings::kvm_msrs> = Vec::new();
-        for kvm_msrs in self.saved_msrs.iter()
-        {
+        for kvm_msrs in self.saved_msrs.iter() {
             debug_kvm_regs = kvm_msrs.clone().into_raw();
             debug_kvm_regs.sort_by_key(|msr| (msr.nmsrs, msr.pad));
         }
         f.debug_struct("VcpuState")
-        .field("cpuid", &self.cpuid)
-        .field("msrs", &self.msrs)
-        .field("saved_msrs", &debug_kvm_regs)
-        .field("debug_regs", &self.debug_regs)
-        .field("lapic", &self.lapic)
-        .field("mp_state", &self.mp_state)
-        .field("regs", &self.regs)
-        .field("sregs", &self.sregs)
-        .field("vcpu_events", &self.vcpu_events)
-        .field("xcrs", &self.xcrs)
-        .field("xsave", &self.xsave)
-        .field("tsc_khz", &self.tsc_khz)
-        .finish()
+            .field("cpuid", &self.cpuid)
+            .field("msrs", &self.msrs)
+            .field("saved_msrs", &debug_kvm_regs)
+            .field("debug_regs", &self.debug_regs)
+            .field("lapic", &self.lapic)
+            .field("mp_state", &self.mp_state)
+            .field("regs", &self.regs)
+            .field("sregs", &self.sregs)
+            .field("vcpu_events", &self.vcpu_events)
+            .field("xcrs", &self.xcrs)
+            .field("xsave", &self.xsave)
+            .field("tsc_khz", &self.tsc_khz)
+            .finish()
     }
 }