platform: add virt_to_phys checks for debugging

Some platforms will require translation from virtual to physical address
in order to perform page validation by virtual address.  Therefore, on
other platforms, force a call to `virt_to_phys()` in debug builds to
increas the number of test environments that can detect possible
translation failures to add in debugging.

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

kernel/src/platform/native.rs

@@ -18,6 +18,9 @@ use crate::types::PageSize;
 use crate::utils::immut_after_init::ImmutAfterInitCell;
 use crate::utils::MemoryRegion;
 
+#[cfg(debug_assertions)]
+use crate::mm::virt_to_phys;
+
 static CONSOLE_IO: NativeIOPort = NativeIOPort::new();
 static CONSOLE_SERIAL: ImmutAfterInitCell<SerialPort<'_>> = ImmutAfterInitCell::uninit();
 
@@ -108,6 +111,18 @@ impl SvsmPlatform for NativePlatform {
         _region: MemoryRegion<VirtAddr>,
         _op: PageValidateOp,
     ) -> Result<(), SvsmError> {
+        #[cfg(debug_assertions)]
+        {
+            // Ensure that it is possible to translate this virtual address to
+            // a physical address.  This is not necessary for correctness
+            // here, but since other platformss may rely on virtual-to-physical
+            // translation, it is helpful to force a translation here for
+            // debugging purposes just to help catch potential errors when
+            // testing on native.
+            for va in _region.iter_pages(PageSize::Regular) {
+                let _ = virt_to_phys(va);
+            }
+        }
         Ok(())
     }
 

kernel/src/platform/snp.rs

@@ -25,6 +25,9 @@ use crate::types::PageSize;
 use crate::utils::immut_after_init::ImmutAfterInitCell;
 use crate::utils::MemoryRegion;
 
+#[cfg(debug_assertions)]
+use crate::mm::virt_to_phys;
+
 use core::sync::atomic::{AtomicU32, Ordering};
 
 static CONSOLE_IO: SVSMIOPort = SVSMIOPort::new();
@@ -182,6 +185,18 @@ impl SvsmPlatform for SnpPlatform {
         region: MemoryRegion<VirtAddr>,
         op: PageValidateOp,
     ) -> Result<(), SvsmError> {
+        #[cfg(debug_assertions)]
+        {
+            // Ensure that it is possible to translate this virtual address to
+            // a physical address.  This is not necessary for correctness
+            // here, but since other platformss may rely on virtual-to-physical
+            // translation, it is helpful to force a translation here for
+            // debugging purposes just to help catch potential errors when
+            // testing on SNP.
+            for va in region.iter_pages(PageSize::Regular) {
+                let _ = virt_to_phys(va);
+            }
+        }
         pvalidate_range(region, PvalidateOp::from(op))
     }