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

Signed-off-by: Gayan Perera <[email protected]>

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 +210,24 @@ 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 {
+			// use q35 machine with vmware io port disabled.
+			args = appendArgsIfNoConflict(args, "-machine", "q35,vmport=off")
+			// use tcg accelerator with multi threading with 512MB translation block size
+			// https://qemu-project.gitlab.io/qemu/devel/multi-thread-tcg.html?highlight=tcg
+			// https://qemu-project.gitlab.io/qemu/system/invocation.html?highlight=tcg%20opts
+			// this will make sure each vCPU will be backed by 1 host user thread.
+			args = appendArgsIfNoConflict(args, "-accel", "tcg,thread=multi,tb-size=512")
+			// This will disable CPU S3 state.
+			args = appendArgsIfNoConflict(args, "-global", "ICH9-LPC.disable_s3=1")
+		}
 	case limayaml.AARCH64:
 		cpu := "cortex-a72"
 		if isNativeArch(*y.Arch) {