fixup! Snapshot persistence to disk

Author: ludfjig

src/hyperlight_host/src/hypervisor/hyperlight_vm/x86_64.rs

@@ -365,14 +365,18 @@ impl HyperlightVm {
     ) -> std::result::Result<(), RegisterError> {
         #[cfg(not(feature = "nanvix-unstable"))]
         {
+            // Restore the full special registers from snapshot, but update CR3
+            // to point to the new (relocated) page tables
             let mut sregs = *sregs;
             sregs.cr3 = cr3;
             self.pending_tlb_flush = true;
             self.vm.set_sregs(&sregs)?;
         }
         #[cfg(feature = "nanvix-unstable")]
         {
-            let _ = (cr3, sregs);
+            let _ = (cr3, sregs); // suppress unused warnings
+            // TODO: This is probably not correct.
+            // Let's deal with it when we clean up the nanvix-unstable feature
             self.vm
                 .set_sregs(&CommonSpecialRegisters::standard_real_mode_defaults())?;
         }

src/hyperlight_host/src/hypervisor/surrogate_process.rs

@@ -94,6 +94,7 @@ impl SurrogateProcess {
                 Ok(oe.get().surrogate_base)
             }
             Entry::Vacant(ve) => {
+                // Derive the page protection from the mapping type
                 let page_protection = match mapping {
                     SurrogateMapping::SandboxMemory => PAGE_READWRITE,
                     SurrogateMapping::ReadOnlyFile => PAGE_READONLY,
@@ -122,6 +123,9 @@ impl SurrogateProcess {
                     );
                 }
 
+                // Only set guard pages for SandboxMemory mappings.
+                // File-backed read-only mappings do not need guard pages
+                // because the host does not write to them.
                 if *mapping == SurrogateMapping::SandboxMemory {
                     let mut unused_out_old_prot_flags = PAGE_PROTECTION_FLAGS(0);