Fix #471: Improve x86_64 emulation on arm64 platform

This change will use qemu64 cpu for better emulation
and add some extra parameters like tcg accel and
force multi threading where multiple host threads will
be used for vcpus according to qemu documentation.
Added few more extra parameters which are used by
UTM for better emulation of x86_64

Author: gayanper

pkg/qemu/qemu.go

@@ -134,9 +134,11 @@ func appendArgsIfNoConflict(args []string, k, v string) []string {
 		return append(args, k)
 	}
 
-	if origV, ok := argValue(args, k); ok {
-		logrus.Warnf("Not adding QEMU argument %q %q, as it conflicts with %q %q", k, v, k, origV)
-		return args
+	if k != "-global" {
+		if origV, ok := argValue(args, k); ok {
+			logrus.Warnf("Not adding QEMU argument %q %q, as it conflicts with %q %q", k, v, k, origV)
+			return args
+		}
 	}
 	return append(args, k, v)
 }
@@ -208,12 +210,19 @@ func Cmdline(cfg Config) (string, []string, error) {
 	}
 	switch *y.Arch {
 	case limayaml.X8664:
-		cpu := "Haswell-v4"
+		cpu := "qemu64"
 		if isNativeArch(*y.Arch) {
 			cpu = "host"
 		}
 		args = appendArgsIfNoConflict(args, "-cpu", cpu)
-		args = appendArgsIfNoConflict(args, "-machine", "q35,accel="+accel)
+		if isNativeArch(*y.Arch) {
+			args = appendArgsIfNoConflict(args, "-machine", "q35,accel="+accel)
+		} else {
+			args = appendArgsIfNoConflict(args, "-machine", "q35,vmport=off")
+			args = appendArgsIfNoConflict(args, "-accel", "tcg,thread=multi,tb-size=512")
+			args = appendArgsIfNoConflict(args, "-global", "PIIX4_PM.disable_s3=1")
+			args = appendArgsIfNoConflict(args, "-global", "ICH9-LPC.disable_s3=1")
+		}
 	case limayaml.AARCH64:
 		cpu := "cortex-a72"
 		if isNativeArch(*y.Arch) {