tests/docker: restore TESTS/IMAGES filtering

This was broken in the re-factor:

  e86c9a6 ("tests/docker/Makefile.include: add a generic docker-run target")

Rather than unwind the changes just apply the filters to the total set
of available images and tests. That way we don't inadvertently build
images only not to use them later.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reported-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220225172021.3493923-2-alex.bennee@linaro.org>

tests/docker/Makefile.include

@@ -8,13 +8,19 @@ COMMA := ,
 
 HOST_ARCH = $(if $(ARCH),$(ARCH),$(shell uname -m))
 
+# These variables can be set by the user to limit the set of docker
+# images and tests to a more restricted subset
+TESTS ?= %
+IMAGES ?= %
+
 DOCKER_SUFFIX := .docker
 DOCKER_FILES_DIR := $(SRC_PATH)/tests/docker/dockerfiles
 # we don't run tests on intermediate images (used as base by another image)
 DOCKER_PARTIAL_IMAGES := debian10 debian11
 # we don't directly build virtual images (they are used to build other images)
 DOCKER_VIRTUAL_IMAGES := debian-bootstrap debian-toolchain empty
-DOCKER_IMAGES := $(sort $(filter-out $(DOCKER_VIRTUAL_IMAGES), $(notdir $(basename $(wildcard $(DOCKER_FILES_DIR)/*.docker)))))
+__IMAGES := $(sort $(filter-out $(DOCKER_VIRTUAL_IMAGES), $(notdir $(basename $(wildcard $(DOCKER_FILES_DIR)/*.docker)))))
+DOCKER_IMAGES := $(if $(IMAGES), $(filter $(IMAGES), $(__IMAGES)), $(__IMAGES))
 DOCKER_TARGETS := $(patsubst %,docker-image-%,$(DOCKER_IMAGES))
 # Use a global constant ccache directory to speed up repetitive builds
 DOCKER_CCACHE_DIR := $$HOME/.cache/qemu-docker-ccache
@@ -23,16 +29,14 @@ DOCKER_DEFAULT_REGISTRY := registry.gitlab.com/qemu-project/qemu
 endif
 DOCKER_REGISTRY := $(if $(REGISTRY),$(REGISTRY),$(DOCKER_DEFAULT_REGISTRY))
 
-DOCKER_TESTS := $(notdir $(shell \
-	find $(SRC_PATH)/tests/docker/ -name 'test-*' -type f))
+__TESTS := $(notdir $(shell \
+		find $(SRC_PATH)/tests/docker/ -name 'test-*' -type f))
+DOCKER_TESTS := $(if $(TESTS), $(filter $(TESTS), $(__TESTS)), $(__TESTS))
 
 ENGINE := auto
 
 DOCKER_SCRIPT=$(SRC_PATH)/tests/docker/docker.py --engine $(ENGINE)
 
-TESTS ?= %
-IMAGES ?= %
-
 CUR_TIME := $(shell date +%Y-%m-%d-%H.%M.%S.$$$$)
 DOCKER_SRC_COPY := $(BUILD_DIR)/docker-src.$(CUR_TIME)
 
@@ -274,8 +278,8 @@ endif
 	@echo '    TARGET_LIST=a,b,c    Override target list in builds.'
 	@echo '    EXTRA_CONFIGURE_OPTS="..."'
 	@echo '                         Extra configure options.'
-	@echo '    IMAGES="a b c ..":   Filters which images to build or run.'
-	@echo '    TESTS="x y z .."     Filters which tests to run (for docker-test).'
+	@echo '    IMAGES="a b c ..":   Restrict available images to subset.'
+	@echo '    TESTS="x y z .."     Restrict available tests to subset.'
 	@echo '    J=[0..9]*            Overrides the -jN parameter for make commands'
 	@echo '                         (default is 1)'
 	@echo '    DEBUG=1              Stop and drop to shell in the created container'