virtualbox: support linux host

Fixes #2110

Signed-off-by: Emmanuel Bretelle <chantr4@gmail.com>

drivers/virtualbox/virtualbox.go

@@ -376,7 +376,9 @@ func (d *Driver) Create() error {
 	case "darwin":
 		shareName = "Users"
 		shareDir = "/Users"
-		// TODO "linux"
+	case "linux":
+		shareName = "hosthome"
+		shareDir = "/home"
 	}
 
 	if shareDir != "" && !d.NoShare {

drivers/virtualbox/virtualbox_linux.go

@@ -1,7 +1,21 @@
 package virtualbox
 
+import (
+	"strings"
+
+	"github.com/docker/machine/libmachine/log"
+)
+
 // IsVTXDisabled checks if VT-X is disabled in the BIOS. If it is, the vm will fail to start.
 // If we can't be sure it is disabled, we carry on and will check the vm logs after it's started.
 func (d *Driver) IsVTXDisabled() bool {
+	errmsg := "Couldn't check that VT-X/AMD-v is enabled. Will check that the vm is properly created: %v"
+	output, err := cmdOutput("grep", "vmx", "/proc/cpuinfo")
+	if err != nil {
+		log.Debugf(errmsg, err)
 		return false
 	}
+
+	disabled := !strings.Contains(output, "vmx")
+	return disabled
+}