From f452e514884519f97b229d32acf0735aea96e6d4 Mon Sep 17 00:00:00 2001
From: Akira Moroo <retrage01@gmail.com>
Date: Sun, 30 Jan 2022 19:34:33 +0900
Subject: [PATCH] vmm: Add `BreakPoint` to `VmState`

This commit adds `VmState::BreakPoint` to handle hardware breakpoint.
The VM will enter this state when a breakpoint hits or a debugger
interrupts the execution.

Signed-off-by: Akira Moroo <retrage01@gmail.com>
---
 vmm/src/vm.rs | 25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/vmm/src/vm.rs b/vmm/src/vm.rs
index 380f3edbc..6dc4f7b09 100644
--- a/vmm/src/vm.rs
+++ b/vmm/src/vm.rs
@@ -301,6 +301,7 @@ pub enum VmState {
     Running,
     Shutdown,
     Paused,
+    BreakPoint,
 }
 
 impl VmState {
@@ -310,29 +311,33 @@ impl VmState {
                 VmState::Created | VmState::Shutdown => {
                     Err(Error::InvalidStateTransition(self, new_state))
                 }
-                VmState::Running | VmState::Paused => Ok(()),
+                VmState::Running | VmState::Paused | VmState::BreakPoint => Ok(()),
             },
 
             VmState::Running => match new_state {
                 VmState::Created | VmState::Running => {
                     Err(Error::InvalidStateTransition(self, new_state))
                 }
-                VmState::Paused | VmState::Shutdown => Ok(()),
+                VmState::Paused | VmState::Shutdown | VmState::BreakPoint => Ok(()),
             },
 
             VmState::Shutdown => match new_state {
-                VmState::Paused | VmState::Created | VmState::Shutdown => {
+                VmState::Paused | VmState::Created | VmState::Shutdown | VmState::BreakPoint => {
                     Err(Error::InvalidStateTransition(self, new_state))
                 }
                 VmState::Running => Ok(()),
             },
 
             VmState::Paused => match new_state {
-                VmState::Created | VmState::Paused => {
+                VmState::Created | VmState::Paused | VmState::BreakPoint => {
                     Err(Error::InvalidStateTransition(self, new_state))
                 }
                 VmState::Running | VmState::Shutdown => Ok(()),
             },
+            VmState::BreakPoint => match new_state {
+                VmState::Created | VmState::Running => Ok(()),
+                _ => Err(Error::InvalidStateTransition(self, new_state)),
+            },
         }
     }
 }
@@ -2735,6 +2740,7 @@ mod tests {
                 assert!(state.valid_transition(VmState::Running).is_ok());
                 assert!(state.valid_transition(VmState::Shutdown).is_err());
                 assert!(state.valid_transition(VmState::Paused).is_ok());
+                assert!(state.valid_transition(VmState::BreakPoint).is_ok());
             }
             VmState::Running => {
                 // Check the transitions from Running
@@ -2742,6 +2748,7 @@ mod tests {
                 assert!(state.valid_transition(VmState::Running).is_err());
                 assert!(state.valid_transition(VmState::Shutdown).is_ok());
                 assert!(state.valid_transition(VmState::Paused).is_ok());
+                assert!(state.valid_transition(VmState::BreakPoint).is_ok());
             }
             VmState::Shutdown => {
                 // Check the transitions from Shutdown
@@ -2749,6 +2756,7 @@ mod tests {
                 assert!(state.valid_transition(VmState::Running).is_ok());
                 assert!(state.valid_transition(VmState::Shutdown).is_err());
                 assert!(state.valid_transition(VmState::Paused).is_err());
+                assert!(state.valid_transition(VmState::BreakPoint).is_err());
             }
             VmState::Paused => {
                 // Check the transitions from Paused
@@ -2756,6 +2764,15 @@ mod tests {
                 assert!(state.valid_transition(VmState::Running).is_ok());
                 assert!(state.valid_transition(VmState::Shutdown).is_ok());
                 assert!(state.valid_transition(VmState::Paused).is_err());
+                assert!(state.valid_transition(VmState::BreakPoint).is_err());
+            }
+            VmState::BreakPoint => {
+                // Check the transitions from Breakpoint
+                assert!(state.valid_transition(VmState::Created).is_ok());
+                assert!(state.valid_transition(VmState::Running).is_ok());
+                assert!(state.valid_transition(VmState::Shutdown).is_err());
+                assert!(state.valid_transition(VmState::Paused).is_err());
+                assert!(state.valid_transition(VmState::BreakPoint).is_err());
             }
         }
     }