implement Drop for KvmRunWrapper

In KvmRunWrapper we are mmaping memory for the kvm_run wrapper.
The memory needs to be unmapped before dropping the reference to
KvmRunWrapper.

Signed-off-by: Andreea Florescu <[email protected]>

Author: andreeaflorescu

src/ioctls/mod.rs

@@ -223,6 +223,8 @@ impl CpuId {
 /// threads as raw pointers do not implement `Send` and `Sync`.
 pub struct KvmRunWrapper {
     kvm_run_ptr: *mut u8,
+    // This field is need so we can `munmap` the memory mapped to hold `kvm_run`.
+    mmap_size: usize,
 }
 
 // Send and Sync aren't automatically inherited for the raw address pointer.
@@ -257,6 +259,7 @@ impl KvmRunWrapper {
 
         Ok(KvmRunWrapper {
             kvm_run_ptr: addr as *mut u8,
+            mmap_size: size,
         })
     }
 
@@ -273,6 +276,16 @@ impl KvmRunWrapper {
     }
 }
 
+impl Drop for KvmRunWrapper {
+    fn drop(&mut self) {
+        // This is safe because we mmap the area at kvm_run_ptr ourselves,
+        // and nobody else is holding a reference to it.
+        unsafe {
+            libc::munmap(self.kvm_run_ptr as *mut libc::c_void, self.mmap_size);
+        }
+    }
+}
+
 #[cfg(test)]
 #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 mod tests {

src/ioctls/vcpu.rs

@@ -1042,6 +1042,7 @@ mod tests {
             vcpu: unsafe { File::from_raw_fd(-1) },
             kvm_run_ptr: KvmRunWrapper {
                 kvm_run_ptr: mmap_anonymous(10),
+                mmap_size: 10,
             },
         };
 

tests/coverage

@@ -1 +1 @@
-90.9
+91