kpatch: clarify that "kpatch unload" isn't supported

Add a user-prompt to the kpatch unload subcommand and make a similiar
mention in the manual page.

Provide an undocumented force option so that QE and dev scripts can
still run unload kpatch modules from scripts.

RHEL-only.

Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
diff -Nupr kpatch-0.6.1.old/kpatch/kpatch kpatch-0.6.1/kpatch/kpatch
--- kpatch-0.6.1.old/kpatch/kpatch	2019-08-28 10:35:01.191259434 -0400
+++ kpatch-0.6.1/kpatch/kpatch	2019-08-28 16:11:13.067926576 -0400
@@ -49,8 +49,8 @@ usage () {
 	echo >&2
 	usage_cmd "load --all" "load all installed patch modules into the running kernel"
 	usage_cmd "load <module>" "load patch module into the running kernel"
-	usage_cmd "unload --all" "unload all patch modules from the running kernel"
-	usage_cmd "unload <module>" "unload patch module from the running kernel"
+	usage_cmd "unload --all (UNSUPPORTED)" "unload all patch modules from the running kernel"
+	usage_cmd "unload <module> (UNSUPPORTED)" "unload patch module from the running kernel"
 	echo >&2
 	usage_cmd "info <module>" "show information about a patch module"
 	echo >&2
@@ -71,6 +71,16 @@ die() {
 	exit 1
 }
 
+confirm_prompt() {
+	local prompt="$1"
+	local answer
+	while true; do
+		read -rp "$prompt [Y/N] " answer
+		[[ $answer == 'Y' || $answer == 'y' ]] && return 0
+		[[ $answer == 'N' || $answer == 'n' ]] && return 1
+	done
+}
+
 __find_module () {
 	MODULE="$1"
 	[[ -f "$MODULE" ]] && return
@@ -406,6 +416,19 @@ unset MODULE
 init_sysfs_var
 
 [[ "$#" -lt 1 ]] && usage
+
+# RHEL-specific support options
+case "$1" in
+"force")
+	# For scripting purposes, support "kpatch force unload".
+	# Shift out the "force" to avoid the user-prompt check below.
+	shift
+	;;
+"unload")
+	confirm_prompt "WARNING: Red Hat doesn't support unloading of kpatches, continue anyway?" || exit 1
+	;;
+esac
+
 case "$1" in
 "load")
 	[[ "$#" -ne 2 ]] && usage
diff -Nupr kpatch-0.6.1.old/man/kpatch.1 kpatch-0.6.1/man/kpatch.1
--- kpatch-0.6.1.old/man/kpatch.1	2019-08-28 10:35:01.191259434 -0400
+++ kpatch-0.6.1/man/kpatch.1	2019-08-28 14:51:23.268198897 -0400
@@ -23,10 +23,10 @@ load --all
 load <module>
        load patch module into the running kernel
 
-unload --all
+unload --all (UNSUPPORTED)
        unload all patch modules from the running kernel
 
-unload <module>
+unload <module> (UNSUPPORTED)
        unload patch module from the running kernel
 
 info <module>