vmm, devices: Move logging of 0x80 timestamp to its own device

This is a cleaner approach to handling the I/O port write to 0x80.
Whilst doing this also use generate the timestamp at the start of the VM
creation. For consistency use the same timestamp for the ARM equivalent.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

devices/src/legacy/debug_port.rs

@@ -0,0 +1,86 @@
+// Copyright © 2022 Intel Corporation
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+use std::fmt;
+use std::time::Instant;
+use vm_device::BusDevice;
+
+/// Debug I/O port, see:
+/// https://www.intel.com/content/www/us/en/support/articles/000005500/boards-and-kits.html
+///
+/// Since we're not a physical platform, we can freely assign code ranges for
+/// debugging specific parts of our virtual platform.
+pub enum DebugIoPortRange {
+    Firmware,
+    Bootloader,
+    Kernel,
+    Userspace,
+    Custom,
+}
+
+#[cfg(target_arch = "x86_64")]
+const DEBUG_IOPORT_PREFIX: &str = "Debug I/O port";
+
+#[cfg(target_arch = "x86_64")]
+impl DebugIoPortRange {
+    fn from_u8(value: u8) -> DebugIoPortRange {
+        match value {
+            0x00..=0x1f => DebugIoPortRange::Firmware,
+            0x20..=0x3f => DebugIoPortRange::Bootloader,
+            0x40..=0x5f => DebugIoPortRange::Kernel,
+            0x60..=0x7f => DebugIoPortRange::Userspace,
+            _ => DebugIoPortRange::Custom,
+        }
+    }
+}
+
+#[cfg(target_arch = "x86_64")]
+impl fmt::Display for DebugIoPortRange {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            DebugIoPortRange::Firmware => write!(f, "{}: Firmware", DEBUG_IOPORT_PREFIX),
+            DebugIoPortRange::Bootloader => write!(f, "{}: Bootloader", DEBUG_IOPORT_PREFIX),
+            DebugIoPortRange::Kernel => write!(f, "{}: Kernel", DEBUG_IOPORT_PREFIX),
+            DebugIoPortRange::Userspace => write!(f, "{}: Userspace", DEBUG_IOPORT_PREFIX),
+            DebugIoPortRange::Custom => write!(f, "{}: Custom", DEBUG_IOPORT_PREFIX),
+        }
+    }
+}
+
+pub struct DebugPort {
+    timestamp: Instant,
+}
+
+impl DebugPort {
+    pub fn new(timestamp: Instant) -> Self {
+        Self { timestamp }
+    }
+}
+
+impl BusDevice for DebugPort {
+    fn read(&mut self, _base: u64, _offset: u64, _data: &mut [u8]) {
+        error!("Invalid read to debug port")
+    }
+
+    fn write(
+        &mut self,
+        _base: u64,
+        _offset: u64,
+        data: &[u8],
+    ) -> Option<std::sync::Arc<std::sync::Barrier>> {
+        let elapsed = self.timestamp.elapsed();
+
+        let code = data[0];
+        info!(
+            "[{} code 0x{:x}] {}.{:>06} seconds",
+            DebugIoPortRange::from_u8(code),
+            code,
+            elapsed.as_secs(),
+            elapsed.as_micros()
+        );
+
+        None
+    }
+}