refactor(aarch64): remove Result type from apply_template

On aarch64 `apply_template` cannot fail, so no reason for `Result`
return type.

Signed-off-by: Egor Lazarchuk <[email protected]>

Author: ShadowCurse

src/vmm/src/arch/aarch64/mod.rs

@@ -50,9 +50,7 @@ pub enum ConfigurationError {
     /// Cannot load kernel due to invalid memory configuration or invalid kernel image: {0}
     KernelLoader(#[from] linux_loader::loader::Error),
     /// Error creating vcpu configuration: {0}
-    VcpuConfig(CpuConfigurationError),
-    /// Error applying vcpu template: {0}
-    VcpuApplyTemplate(CpuConfigurationError),
+    VcpuConfig(#[from] CpuConfigurationError),
     /// Error configuring the vcpu: {0}
     VcpuConfigure(KvmVcpuError),
 }
@@ -80,12 +78,10 @@ pub fn configure_system_for_boot(
     boot_cmdline: Cmdline,
 ) -> Result<(), ConfigurationError> {
     // Construct the base CpuConfiguration to apply CPU template onto.
-    let cpu_config =
-        CpuConfiguration::new(cpu_template, vcpus).map_err(ConfigurationError::VcpuConfig)?;
+    let cpu_config = CpuConfiguration::new(cpu_template, vcpus)?;
 
     // Apply CPU template to the base CpuConfiguration.
-    let cpu_config = CpuConfiguration::apply_template(cpu_config, cpu_template)
-        .map_err(ConfigurationError::VcpuApplyTemplate)?;
+    let cpu_config = CpuConfiguration::apply_template(cpu_config, cpu_template);
 
     let vcpu_config = VcpuConfig {
         vcpu_count: machine_config.vcpu_count,

src/vmm/src/cpu_config/aarch64/mod.rs

@@ -49,10 +49,7 @@ impl CpuConfiguration {
     }
 
     /// Creates new guest CPU config based on the provided template
-    pub fn apply_template(
-        mut self,
-        template: &CustomCpuTemplate,
-    ) -> Result<Self, CpuConfigurationError> {
+    pub fn apply_template(mut self, template: &CustomCpuTemplate) -> Self {
         for (modifier, mut reg) in template.reg_modifiers.iter().zip(self.regs.iter_mut()) {
             match reg.size() {
                 RegSize::U32 => {
@@ -73,7 +70,7 @@ impl CpuConfiguration {
                 _ => unreachable!("Only 32, 64 and 128 bit wide registers are supported"),
             }
         }
-        Ok(self)
+        self
     }
 
     /// Returns ids of registers that are changed