loader: fix page table relocation identity mapping

openvmm/openvmm_core/src/worker/vm_loaders/igvm.rs

@@ -1217,6 +1217,14 @@ fn load_igvm_x86(
             relocation_region.base_gpa..=relocation_region.base_gpa + relocation_region.size - 1,
             offset as i64,
         );
+        // The page table region is itself relocatable and must stay identity
+        // mapped, so its own range needs fixing up too. Otherwise the leaf
+        // entry mapping it keeps the pre-relocation VA and the root is
+        // unmapped.
+        reloc_regions.insert(
+            page_table_fixup.gpa..=page_table_fixup.gpa + page_table_fixup.size - 1,
+            offset as i64,
+        );
         let page_table = page_table_fixup
             .build(offset as i64, reloc_regions, page_table_cpu_state)
             .map_err(Error::PageTableBuilder)?;

vm/loader/src/paravisor.rs

@@ -409,6 +409,12 @@ where
     )?;
     offset += heap_size;
 
+    // Some loaders only fix up identity map entries that overlap the relocation
+    // region, so keep the page table region in the same large page as it.
+    if offset.is_multiple_of(X64_LARGE_PAGE_SIZE) {
+        offset += HV_PAGE_SIZE;
+    }
+
     // The end of memory used by the loader, excluding pagetables.
     let end_of_underhill_mem = offset;
 
@@ -1155,6 +1161,12 @@ where
     )?;
     next_addr += heap_size;
 
+    // Some loaders only fix up identity map entries that overlap the relocation
+    // region, so keep the page table region in the same large page as it.
+    if next_addr.is_multiple_of(u64::from(Arm64PageSize::Large)) {
+        next_addr += HV_PAGE_SIZE;
+    }
+
     // The end of memory used by the loader, excluding pagetables.
     let end_of_underhill_mem = next_addr;