IGVM: Add support for launching OVMF firmware when using an IGVM file for guest configuration

src/fw_cfg.rs

@@ -217,7 +217,7 @@ impl<'a> FwCfg<'a> {
     // This needs to be &mut self to prevent iterator invalidation, where the caller
     // could do fw_cfg.select() while iterating. Having a mutable reference prevents
     // other references.
-    pub fn iter_flash_regions(&mut self) -> impl Iterator<Item = MemoryRegion<PhysAddr>> + '_ {
+    pub fn iter_flash_regions(&self) -> impl Iterator<Item = MemoryRegion<PhysAddr>> + '_ {
         let num = match self.file_selector("etc/flash") {
             Ok(file) => {
                 self.select(file.selector);

src/svsm.rs

@@ -220,7 +220,7 @@ fn launch_fw() -> Result<(), SvsmError> {
 }
 
 fn validate_flash() -> Result<(), SvsmError> {
-    let mut fw_cfg = FwCfg::new(&CONSOLE_IO);
+    let fw_cfg = FwCfg::new(&CONSOLE_IO);
 
     let flash_regions = fw_cfg.iter_flash_regions().collect::<Vec<_>>();
     let kernel_region = LAUNCH_INFO.kernel_region();