Tools: hv: move to tools buildsystem

There is a nice buildsystem dedicated for userspace tools in Linux kernel tree.
Switch Hyper-V daemons to be built by it.

Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

tools/hv/Build

+hv_kvp_daemon-y += hv_kvp_daemon.o
+hv_vss_daemon-y += hv_vss_daemon.o
+hv_fcopy_daemon-y += hv_fcopy_daemon.o

tools/hv/Makefile

 # SPDX-License-Identifier: GPL-2.0
 # Makefile for Hyper-V tools
-
-WARNINGS = -Wall -Wextra
-CFLAGS = $(WARNINGS) -g $(shell getconf LFS_CFLAGS)
-
-CFLAGS += -D__EXPORTED_HEADERS__ -I../../include/uapi -I../../include
+include ../scripts/Makefile.include
 
 sbindir ?= /usr/sbin
 libexecdir ?= /usr/libexec
 sharedstatedir ?= /var/lib
 
-ALL_PROGRAMS := hv_kvp_daemon hv_vss_daemon hv_fcopy_daemon
+ifeq ($(srctree),)
+srctree := $(patsubst %/,%,$(dir $(CURDIR)))
+srctree := $(patsubst %/,%,$(dir $(srctree)))
+endif
+
+# Do not use make's built-in rules
+# (this improves performance and avoids hard-to-debug behaviour);
+MAKEFLAGS += -r
+
+override CFLAGS += -O2 -Wall -g -D_GNU_SOURCE -I$(OUTPUT)include
+
+ALL_TARGETS := hv_kvp_daemon hv_vss_daemon hv_fcopy_daemon
+ALL_PROGRAMS := $(patsubst %,$(OUTPUT)%,$(ALL_TARGETS))
 
 ALL_SCRIPTS := hv_get_dhcp_info.sh hv_get_dns_info.sh hv_set_ifconfig.sh
 
 all: $(ALL_PROGRAMS)
 
-%: %.c
-	$(CC) $(CFLAGS) -o $@ $^
+export srctree OUTPUT CC LD CFLAGS
+include $(srctree)/tools/build/Makefile.include
+
+HV_KVP_DAEMON_IN := $(OUTPUT)hv_kvp_daemon-in.o
+$(HV_KVP_DAEMON_IN): FORCE
+	$(Q)$(MAKE) $(build)=hv_kvp_daemon
+$(OUTPUT)hv_kvp_daemon: $(HV_KVP_DAEMON_IN)
+	$(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $< -o $@
+
+HV_VSS_DAEMON_IN := $(OUTPUT)hv_vss_daemon-in.o
+$(HV_VSS_DAEMON_IN): FORCE
+	$(Q)$(MAKE) $(build)=hv_vss_daemon
+$(OUTPUT)hv_vss_daemon: $(HV_VSS_DAEMON_IN)
+	$(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $< -o $@
+
+HV_FCOPY_DAEMON_IN := $(OUTPUT)hv_fcopy_daemon-in.o
+$(HV_FCOPY_DAEMON_IN): FORCE
+	$(Q)$(MAKE) $(build)=hv_fcopy_daemon
+$(OUTPUT)hv_fcopy_daemon: $(HV_FCOPY_DAEMON_IN)
+	$(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $< -o $@
 
 clean:
-	$(RM) hv_kvp_daemon hv_vss_daemon hv_fcopy_daemon
+	rm -f $(ALL_PROGRAMS)
+	find $(if $(OUTPUT),$(OUTPUT),.) -name '*.o' -delete -o -name '\.*.d' -delete
 
-install: all
+install: $(ALL_PROGRAMS)
 	install -d -m 755 $(DESTDIR)$(sbindir); \
 	install -d -m 755 $(DESTDIR)$(libexecdir)/hypervkvpd; \
 	install -d -m 755 $(DESTDIR)$(sharedstatedir); \
@@ -33,3 +60,7 @@ install: all
 	for script in $(ALL_SCRIPTS); do \
 		install $$script -m 755 $(DESTDIR)$(libexecdir)/hypervkvpd/$${script%.sh}; \
 	done
+
+FORCE:
+
+.PHONY: all install clean FORCE prepare