feat(quickemu): warn on unstable TSC for macOS Ventura+ on AMD

- Add check_macos_tsc_stability() to detect unstable TSC on Linux hosts
with
  AuthenticAMD CPUs when launching macOS Ventura+ guests
- Log a clear warning to the VM log and prompt interactively to continue
or
  abort to avoid guest freezes
- Abort by default in non-interactive mode to prevent unattended VM
hangs
- Add --ignore-tsc-warning to bypass the check and invoke the check
during
  vm_boot so it runs early in startup
Closes #1273

Signed-off-by: Martin Wimpress <martin@wimpress.org>

quickemu

@@ -38,6 +38,94 @@ function ignore_msrs_alert() {
     fi
 }
 
+# Check for TSC instability that can cause macOS Ventura+ to freeze on AMD Ryzen mobile CPUs.
+# Returns 0 if check passes or user acknowledges warning, exits with 1 if user aborts.
+# Reference: https://github.com/quickemu-project/quickemu/issues/1273
+function check_macos_tsc_stability() {
+  # Gate 1: Only on Linux hosts
+  if [ "${OS_KERNEL}" != "Linux" ]; then
+    return 0
+  fi
+
+  # Gate 2: Only for AMD CPUs
+  if [ "${HOST_CPU_VENDOR}" != "AuthenticAMD" ]; then
+    return 0
+  fi
+
+  # Gate 3: Only for macOS guests
+  if [ "${guest_os}" != "macos" ]; then
+    return 0
+  fi
+
+  # Gate 4: Only for macOS Ventura (13) and newer
+  case ${macos_release} in
+    ventura|sonoma|sequoia|tahoe) ;;
+    *) return 0 ;;
+  esac
+
+  # Gate 5: Skip if user has already set tsc=reliable in kernel cmdline
+  local cmdline=""
+  if [ -r /proc/cmdline ]; then
+    cmdline=$(cat /proc/cmdline)
+    if [[ "${cmdline}" == *"tsc=reliable"* ]]; then
+      return 0
+    fi
+  fi
+
+  # Gate 6: Check if TSC is the current clocksource (indicates stable TSC)
+  local clocksource_path="/sys/devices/system/clocksource/clocksource0/current_clocksource"
+  local current_clocksource=""
+  if [ -r "${clocksource_path}" ]; then
+    current_clocksource=$(cat "${clocksource_path}")
+    if [ "${current_clocksource}" == "tsc" ]; then
+      return 0
+    fi
+  else
+    # Cannot determine clocksource - assume OK and let user discover issues
+    return 0
+  fi
+
+  # All gates failed - this system is at risk
+  # Check if warning should be skipped
+  if [ "${IGNORE_TSC_WARNING}" == "1" ]; then
+    echo " - TSC:      WARNING! Unstable TSC detected (clocksource: ${current_clocksource})"
+    echo "             Proceeding anyway due to --ignore-tsc-warning flag."
+    return 0
+  fi
+
+  # Display warning and prompt user
+  echo " - TSC:      WARNING! Unstable TSC detected (clocksource: ${current_clocksource})"
+  echo "             macOS ${macos_release^} may freeze on AMD Ryzen mobile CPUs."
+  echo
+  echo "             Fix: Add 'tsc=reliable' to kernel boot parameters and reboot."
+  echo "             Or:  Use macOS Big Sur (11) or Monterey (12) instead."
+  echo "             See: https://github.com/quickemu-project/quickemu/wiki/03-Create-macOS-virtual-machines#tsc-instability-on-amd-ryzen-mobile-cpus"
+  echo
+
+  # Log the warning
+  echo "TSC_WARNING: clocksource=${current_clocksource} macos_release=${macos_release} cpu_vendor=${HOST_CPU_VENDOR}" >> "${VMDIR}/${VMNAME}.log"
+
+  # Interactive prompt - check if stdin is a terminal
+  if [ -t 0 ]; then
+    echo -n "Do you want to continue anyway? [y/N] "
+    read -r response
+    case "${response}" in
+      [yY]|[yY][eE][sS])
+        echo " - TSC:      Proceeding despite unstable TSC warning."
+        return 0
+        ;;
+      *)
+        echo " - TSC:      Aborting. Please apply one of the solutions above."
+        exit 1
+        ;;
+    esac
+  else
+    # Non-interactive mode - abort by default for safety
+    echo "ERROR! Non-interactive mode detected. Use --ignore-tsc-warning to bypass this check."
+    exit 1
+  fi
+}
+
 function delete_shortcut() {
     local SHORTCUT_DIR="${HOME}/.local/share/applications"
     if [ -e "${SHORTCUT_DIR}/${VMNAME}.desktop" ]; then
@@ -1364,6 +1452,7 @@ function vm_boot() {
 
     configure_cpu
     configure_ram
+    check_macos_tsc_stability
     configure_bios
     configure_os_quirks
     configure_storage
@@ -1848,6 +1937,7 @@ function usage() {
     echo "  --display                         : Select display backend. 'sdl' (default), 'cocoa', 'gtk', 'none', 'spice' or 'spice-app'"
     echo "  --fullscreen                      : Starts VM in full screen mode (Ctl+Alt+f to exit)"
     echo "  --ignore-msrs-always              : Configure KVM to always ignore unhandled machine-specific registers"
+    echo "  --ignore-tsc-warning              : Skip TSC stability warning for macOS VMs on AMD"
     echo "  --kill                            : Kill the VM process if it is running"
     echo "  --offline                         : Override all network settings and start the VM offline"
     echo "  --shortcut                        : Create a desktop shortcut"
@@ -2110,6 +2200,7 @@ sound_duplex="${sound_duplex:-hda-micro}"
 ACCESS=""
 ACTIONS=()
 BRAILLE=""
+IGNORE_TSC_WARNING=""
 CPU_PINNING=""
 FULLSCREEN=""
 MONITOR_CMD=""
@@ -2202,6 +2293,9 @@ else
             -ignore-msrs-always|--ignore-msrs-always)
                 ignore_msrs_always
                 exit;;
+            -ignore-tsc-warning|--ignore-tsc-warning)
+                IGNORE_TSC_WARNING="1"
+                shift;;
             -kill|--kill)
                 ACTIONS+=(kill_vm)
                 shift;;