smt: Fix check to detect if a system is running virtually

/sys/hypervisor exists when a host has loaded the kvm modules.

Fixes: #12472
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>

src/initscripts/system/functions

@@ -784,6 +784,11 @@ umount_ramdisk() {
 	rm -rf "${path_tmpfs}"
 }
 
+# Returns true when this system running in a virtual environment
+running_on_hypervisor() {
+	grep -qE "^flags\s+:.*hypervisor" /proc/cpuinfo
+}
+
 # https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/identify_ec2_instances.html
 running_on_ec2() {
 	local uuid

src/initscripts/system/smt

@@ -21,7 +21,7 @@ case "${1}" in
 		fi 2>/dev/null
 
 		# Do not disable SMT inside virtual machines
-		if [ -d "/sys/hypervisor" ]; then
+		if running_on_hypervisor; then
 			exit 0
 		fi