diff --git a/vmm/src/vm.rs b/vmm/src/vm.rs
index 3d88f3587..1a2d3e1e8 100644
--- a/vmm/src/vm.rs
+++ b/vmm/src/vm.rs
@@ -491,7 +491,8 @@ impl VmOps for VmOpsHandler {
     #[cfg(target_arch = "x86_64")]
     fn pio_read(&self, port: u64, data: &mut [u8]) -> result::Result<(), HypervisorVmError> {
         if let Err(vm_device::BusError::MissingAddressRange) = self.io_bus.read(port, data) {
-            info!("Guest PIO read to unregistered address 0x{port:x}");
+            info!("Guest PIO read from unregistered address 0x{port:x}");
+            data.fill(0xff); // 0xff is sentinel value for invalid reads
         }
         Ok(())
     }