dragonball: add kernel config.

It is used for holding guest kernel configuration information.

Fixes: #4257

Signed-off-by: Liu Jiang <gerry@linux.alibaba.com>
Signed-off-by: wllenyj <wllenyj@linux.alibaba.com>
Signed-off-by: Chao Wu <chaowu@linux.alibaba.com>

src/dragonball/Cargo.toml

@@ -21,6 +21,7 @@ dbs-utils = "0.1.0"
 kvm-bindings = "0.5.0"
 kvm-ioctls = "0.11.0"
 libc = "0.2.39"
+linux-loader = "0.4.0"
 log = "0.4.14"
 nix = "0.23.1"
 serde = "1.0.27"

src/dragonball/src/vm/kernel_config.rs

@@ -0,0 +1,67 @@
+// Copyright (C) 2022 Alibaba Cloud. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+use std::fs::File;
+
+/// Structure to hold guest kernel configuration information.
+pub struct KernelConfigInfo {
+    /// The descriptor to the kernel file.
+    kernel_file: File,
+    /// The descriptor to the initrd file, if there is one
+    initrd_file: Option<File>,
+    /// The commandline for guest kernel.
+    cmdline: linux_loader::cmdline::Cmdline,
+}
+
+impl KernelConfigInfo {
+    /// Create a KernelConfigInfo instance.
+    pub fn new(
+        kernel_file: File,
+        initrd_file: Option<File>,
+        cmdline: linux_loader::cmdline::Cmdline,
+    ) -> Self {
+        KernelConfigInfo {
+            kernel_file,
+            initrd_file,
+            cmdline,
+        }
+    }
+
+    /// Get a mutable reference to the kernel file.
+    pub fn kernel_file_mut(&mut self) -> &mut File {
+        &mut self.kernel_file
+    }
+
+    /// Get a mutable reference to the initrd file.
+    pub fn initrd_file_mut(&mut self) -> Option<&mut File> {
+        self.initrd_file.as_mut()
+    }
+
+    /// Get a shared reference to the guest kernel boot parameter object.
+    pub fn kernel_cmdline(&self) -> &linux_loader::cmdline::Cmdline {
+        &self.cmdline
+    }
+
+    /// Get a mutable reference to the guest kernel boot parameter object.
+    pub fn kernel_cmdline_mut(&mut self) -> &mut linux_loader::cmdline::Cmdline {
+        &mut self.cmdline
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use vmm_sys_util::tempfile::TempFile;
+
+    #[test]
+    fn test_kernel_config_info() {
+        let kernel = TempFile::new().unwrap();
+        let initrd = TempFile::new().unwrap();
+        let mut cmdline = linux_loader::cmdline::Cmdline::new(1024);
+        cmdline.insert_str("ro").unwrap();
+        let mut info = KernelConfigInfo::new(kernel.into_file(), Some(initrd.into_file()), cmdline);
+
+        assert_eq!(info.cmdline.as_str(), "ro");
+        assert!(info.initrd_file_mut().is_some());
+    }
+}

src/dragonball/src/vm/mod.rs

@@ -3,6 +3,9 @@
 
 use serde_derive::{Deserialize, Serialize};
 
+mod kernel_config;
+pub use self::kernel_config::KernelConfigInfo;
+
 /// Configuration information for user defined NUMA nodes.
 #[derive(Clone, Debug, Default, Serialize, Deserialize, PartialEq)]
 pub struct NumaRegionInfo {