runqemu: Add workaround for APIC hang on pre 4.15 kernels on qemux86

On pre 4.15 host kernels, an APIC window emulation bug can cause qemu
to hang. On 64 bit we can use the x2apic, for 32 bit, we just have to
disable the other timer sources and rely on kvm-clock.

[YOCTO #12301]

(From OE-Core rev: 82e67b82ea8e12aa0b7b9db1d84fec0436dec71b)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/runqemu

@@ -510,6 +510,11 @@ class BaseConfig(object):
 
         if os.access(dev_kvm, os.W_OK|os.R_OK):
             self.qemu_opt_script += ' -enable-kvm'
+            if self.get('MACHINE') == "qemux86":
+                # Workaround for broken APIC window on pre 4.15 host kernels which causes boot hangs
+                # See YOCTO #12301
+                # On 64 bit we use x2apic
+                self.kernel_cmdline_script += " clocksource=kvm-clock hpet=disable noapic nolapic"
         else:
             logger.error("You have no read or write permission on /dev/kvm.")
             logger.error("Please change the ownership of this file as described at:")