Map the IGVM parameters into the page tables constructed by the kernel

Signed-off-by: Jon Lange <jlange@microsoft.com>

src/kernel_launch.rs

@@ -23,7 +23,9 @@ pub struct KernelLaunchInfo {
     pub kernel_fs_end: u64,
     pub cpuid_page: u64,
     pub secrets_page: u64,
-    pub igvm_params: u64,
+    pub igvm_params_phys_addr: u64,
+    pub igvm_params_virt_addr: u64,
+    pub igvm_params_size: u64,
 }
 
 impl KernelLaunchInfo {

src/stage2.rs

@@ -331,7 +331,9 @@ pub extern "C" fn stage2_main(launch_info: &Stage1LaunchInfo) {
         kernel_fs_end: u64::from(launch_info.kernel_fs_end),
         cpuid_page: config.get_cpuid_page_address(),
         secrets_page: config.get_secrets_page_address(),
-        igvm_params: u64::from(igvm_params_virt_address),
+        igvm_params_phys_addr: launch_info.igvm_params as u64,
+        igvm_params_virt_addr: u64::from(igvm_params_virt_address),
+        igvm_params_size: igvm_params_size as u64,
     };
 
     let mem_info = memory_info();

src/svsm.rs

@@ -425,8 +425,8 @@ pub extern "C" fn svsm_main() {
     //debug_break();
 
     let launch_info = &*LAUNCH_INFO;
-    let config = if launch_info.igvm_params != 0 {
-        let igvm_params = IgvmParams::new(VirtAddr::from(launch_info.igvm_params));
+    let config = if launch_info.igvm_params_virt_addr != 0 {
+        let igvm_params = IgvmParams::new(VirtAddr::from(launch_info.igvm_params_virt_addr));
         SvsmConfig::IgvmConfig(igvm_params)
     } else {
         SvsmConfig::FirmwareConfig(FwCfg::new(&CONSOLE_IO))

src/svsm_paging.rs

@@ -23,8 +23,10 @@ pub fn init_page_table(launch_info: &KernelLaunchInfo, kernel_elf: &elf::Elf64Fi
 
     // Install mappings for the kernel's ELF segments each.
     // The memory backing the kernel ELF segments gets allocated back to back
-    // from the physical memory region by the Stage2 loader.
-    let mut phys = PhysAddr::from(launch_info.kernel_region_phys_start);
+    // from the physical memory region by the Stage2 loader, following
+    // the IGVM parameters (if any).
+    let igvm_params_size: usize = launch_info.igvm_params_size.try_into().unwrap();
+    let mut phys = PhysAddr::from(launch_info.kernel_region_phys_start) + igvm_params_size;
     for segment in kernel_elf.image_load_segment_iter(launch_info.kernel_region_virt_start) {
         let vaddr_start = VirtAddr::from(segment.vaddr_range.vaddr_begin);
         let vaddr_end = VirtAddr::from(segment.vaddr_range.vaddr_end);
@@ -45,6 +47,20 @@ pub fn init_page_table(launch_info: &KernelLaunchInfo, kernel_elf: &elf::Elf64Fi
         phys = phys + segment_len;
     }
 
+    // Map the IGVM parameters if present.
+    if launch_info.igvm_params_virt_addr != 0 {
+        let igvm_params_virt_addr = VirtAddr::from(launch_info.igvm_params_virt_addr);
+
+        pgtable
+            .map_region(
+                igvm_params_virt_addr,
+                igvm_params_virt_addr + igvm_params_size,
+                PhysAddr::from(launch_info.igvm_params_phys_addr),
+                PTEntryFlags::data(),
+            )
+            .expect("Failed to map IGVM parameters");
+    }
+
     // Map subsequent heap area.
     pgtable
         .map_region(