From 5d0e677397c85bf7897d51841e6a53033d06a607 Mon Sep 17 00:00:00 2001
From: Rolf Neugebauer <rolf.neugebauer@docker.com>
Date: Thu, 1 Feb 2018 16:29:38 +0000
Subject: [PATCH] cmd/qemu: Enable additional accelerators

Upstream qemu supports accelerators other than kvm. Allow the user
to choose. On Linux we still default to 'lvm' if available. On
macOS we try the new 'hvf' accelerator, if available.

Disable acceleration if the host arch does not match requested
qemu arch.

Also change the LINUXKIT_QEMU_KVM env var to LINUXKIT_QEMU_ACCEL
and use the functions in utils.go for env var overrides.

Signed-off-by: Rolf Neugebauer <rolf.neugebauer@docker.com>
---
 src/cmd/linuxkit/run_qemu.go | 58 +++++++++++++++++++++---------------
 1 file changed, 34 insertions(+), 24 deletions(-)

diff --git a/src/cmd/linuxkit/run_qemu.go b/src/cmd/linuxkit/run_qemu.go
index 753eda2bf..7ba1933ab 100644
--- a/src/cmd/linuxkit/run_qemu.go
+++ b/src/cmd/linuxkit/run_qemu.go
@@ -38,7 +38,7 @@ type QemuConfig struct {
 	Arch           string
 	CPUs           string
 	Memory         string
-	KVM            bool
+	Accel          string
 	Containerized  bool
 	QemuBinPath    string
 	QemuImgPath    string
@@ -56,7 +56,8 @@ const (
 )
 
 var (
-	defaultArch string
+	defaultArch  string
+	defaultAccel string
 )
 
 func init() {
@@ -66,6 +67,12 @@ func init() {
 	case "amd64":
 		defaultArch = "x86_64"
 	}
+	switch {
+	case haveKVM():
+		defaultAccel = "kvm:tcg"
+	case runtime.GOOS == "darwin":
+		defaultAccel = "hvf:tcg"
+	}
 }
 
 func haveKVM() bool {
@@ -73,19 +80,6 @@ func haveKVM() bool {
 	return !os.IsNotExist(err)
 }
 
-func envOverrideBool(env string, b *bool) {
-	val := os.Getenv(env)
-	if val == "" {
-		return
-	}
-
-	var err error
-	*b, err = strconv.ParseBool(val)
-	if err != nil {
-		log.Fatal("Unable to parse %q=%q as a boolean", env, val)
-	}
-}
-
 func retrieveMAC(statePath string) net.HardwareAddr {
 	var mac net.HardwareAddr
 	fileName := filepath.Join(statePath, "mac-addr")
@@ -160,7 +154,7 @@ func runQemu(args []string) {
 	fw := flags.String("fw", "", "Path to OVMF firmware for UEFI boot")
 
 	// VM configuration
-	enableKVM := flags.Bool("kvm", haveKVM(), "Enable KVM acceleration")
+	accel := flags.String("accel", defaultAccel, "Choose acceleration mode. Use 'tcg' to disable it.")
 	arch := flags.String("arch", defaultArch, "Type of architecture to use, e.g. x86_64, aarch64")
 	cpus := flags.String("cpus", "1", "Number of CPUs")
 	mem := flags.String("mem", "1024", "Amount of memory in MB")
@@ -185,8 +179,8 @@ func runQemu(args []string) {
 
 	// These envvars override the corresponding command line
 	// options. So this must remain after the `flags.Parse` above.
-	envOverrideBool("LINUXKIT_QEMU_KVM", enableKVM)
-	envOverrideBool("LINUXKIT_QEMU_CONTAINERIZED", qemuContainerized)
+	*accel = getStringValue("LINUXKIT_QEMU_ACCEL", *accel, "")
+	*qemuContainerized = getBoolValue("LINUXKIT_QEMU_CONTAINERIZED", *qemuContainerized)
 
 	if len(remArgs) == 0 {
 		fmt.Println("Please specify the path to the image to boot")
@@ -310,7 +304,7 @@ func runQemu(args []string) {
 		Arch:           *arch,
 		CPUs:           *cpus,
 		Memory:         *mem,
-		KVM:            *enableKVM,
+		Accel:          *accel,
 		Containerized:  *qemuContainerized,
 		QemuBinPath:    *qemuCmd,
 		PublishedPorts: publishFlags,
@@ -429,7 +423,7 @@ func runQemuContainer(config QemuConfig) error {
 		dockerArgs = append(dockerArgs, "--tty")
 	}
 
-	if config.KVM {
+	if strings.Contains(config.Accel, "kvm") {
 		dockerArgs = append(dockerArgs, "--device", "/dev/kvm")
 	}
 
@@ -491,6 +485,7 @@ func buildQemuCmdline(config QemuConfig) (QemuConfig, []string) {
 	qemuArgs = append(qemuArgs, "-m", config.Memory)
 	qemuArgs = append(qemuArgs, "-uuid", config.UUID.String())
 	qemuArgs = append(qemuArgs, "-pidfile", filepath.Join(config.StatePath, "qemu.pid"))
+
 	// Need to specify the vcpu type when running qemu on arm64 platform, for security reason,
 	// the vcpu should be "host" instead of other names such as "cortex-a53"...
 	if config.Arch == "aarch64" {
@@ -501,12 +496,27 @@ func buildQemuCmdline(config QemuConfig) (QemuConfig, []string) {
 		}
 	}
 
-	if config.KVM {
-		qemuArgs = append(qemuArgs, "-enable-kvm")
+	// goArch is the GOARCH equivalent of config.Arch
+	var goArch string
+	switch config.Arch {
+	case "aarch64":
+		goArch = "arm64"
+	case "x86_64":
+		goArch = "amd64"
+	default:
+		log.Fatalf("%s is an unsupported architecture.")
+	}
+
+	if goArch != runtime.GOARCH {
+		log.Infof("Disable acceleration as %s != %s", config.Arch, runtime.GOARCH)
+		config.Accel = ""
+	}
+
+	if config.Accel != "" {
 		if config.Arch == "aarch64" {
-			qemuArgs = append(qemuArgs, "-machine", "virt,gic_version=host")
+			qemuArgs = append(qemuArgs, "-machine", fmt.Sprintf("virt,gic_version=host,accel=%s", config.Accel))
 		} else {
-			qemuArgs = append(qemuArgs, "-machine", "q35,accel=kvm:tcg")
+			qemuArgs = append(qemuArgs, "-machine", fmt.Sprintf("q35,accel=%s", config.Accel))
 		}
 	} else {
 		if config.Arch == "aarch64" {