KVM: Don't pre-reserve xarray entries when storing empty/NULL attributesgrafted

Skip the xarray reservation loop when clearing all memory attributes, as
storing NULL only erases the entry and never needs to allocate, so no
reservation (and no cleanup of a failed one) is required in that case.

Suggested-by: Sean Christopherson <seanjc@google.com>
Cc: David Ballesteros <davimaba.v@proton.me>
Signed-off-by: Zeng Chi <zengchi@kylinos.cn>
Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com
[sean: split to separate patch]
Signed-off-by: Sean Christopherson <seanjc@google.com>

1 files changed, 236 insertions, 0 deletions

diff --git a/scripts/kconfig/Makefile b/scripts/kconfig/Makefile
new file mode 100644
index 000000000..5baf1c44f
--- /dev/null
+++ b/scripts/kconfig/Makefile
@@ -0,0 +1,236 @@
+# SPDX-License-Identifier: GPL-2.0
+# ===========================================================================
+# Kernel configuration targets
+# These targets are used from top-level makefile
+
+ifdef KBUILD_KCONFIG
+Kconfig := $(KBUILD_KCONFIG)
+else
+Kconfig := Kconfig
+endif
+
+ifndef KBUILD_DEFCONFIG
+KBUILD_DEFCONFIG := defconfig
+endif
+
+ifeq ($(quiet),silent_)
+silent := -s
+endif
+
+export KCONFIG_DEFCONFIG_LIST :=
+ifndef cross_compiling
+kernel-release := $(shell uname -r)
+KCONFIG_DEFCONFIG_LIST += \
+	/lib/modules/$(kernel-release)/.config \
+	/etc/kernel-config \
+	/boot/config-$(kernel-release)
+endif
+KCONFIG_DEFCONFIG_LIST += arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG)
+
+ifneq ($(findstring c, $(KBUILD_EXTRA_WARN)),)
+export KCONFIG_WARN_UNKNOWN_SYMBOLS=1
+endif
+
+ifneq ($(findstring e, $(KBUILD_EXTRA_WARN)),)
+export KCONFIG_WERROR=1
+endif
+
+# We need this, in case the user has it in its environment
+unexport CONFIG_
+
+config-prog	:= conf
+menuconfig-prog	:= mconf
+nconfig-prog	:= nconf
+gconfig-prog	:= gconf
+xconfig-prog	:= qconf
+
+define config_rule
+PHONY += $(1)
+$(1): $(obj)/$($(1)-prog)
+	$(Q)$$< $(silent) $(Kconfig)
+
+PHONY += build_$(1)
+build_$(1): $(obj)/$($(1)-prog)
+endef
+
+$(foreach c, config menuconfig nconfig gconfig xconfig, $(eval $(call config_rule,$(c))))
+
+PHONY += localmodconfig localyesconfig
+localyesconfig localmodconfig: $(obj)/conf
+	$(Q)$(PERL) $(src)/streamline_config.pl --$@ $(srctree) $(Kconfig) > .tmp.config
+	$(Q)if [ -f .config ]; then 				\
+		cmp -s .tmp.config .config ||			\
+		(mv -f .config .config.old.1;			\
+		 mv -f .tmp.config .config;			\
+		 $< $(silent) --oldconfig $(Kconfig);		\
+		 mv -f .config.old.1 .config.old)		\
+	else							\
+		mv -f .tmp.config .config;			\
+		$< $(silent) --oldconfig $(Kconfig);		\
+	fi
+	$(Q)rm -f .tmp.config
+
+# These targets map 1:1 to the commandline options of 'conf'
+#
+# Note:
+#  syncconfig has become an internal implementation detail and is now
+#  deprecated for external use
+simple-targets := oldconfig allnoconfig allyesconfig allmodconfig \
+	alldefconfig randconfig listnewconfig olddefconfig syncconfig \
+	helpnewconfig yes2modconfig mod2yesconfig mod2noconfig
+
+PHONY += $(simple-targets)
+
+$(simple-targets): $(obj)/conf
+	$(Q)$< $(silent) --$@ $(Kconfig)
+
+PHONY += savedefconfig defconfig
+
+savedefconfig: $(obj)/conf
+	$(Q)$< $(silent) --$@=defconfig $(Kconfig)
+
+defconfig: $(obj)/conf
+ifneq ($(wildcard $(srctree)/arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG)),)
+	@$(kecho) "*** Default configuration is based on '$(KBUILD_DEFCONFIG)'"
+	$(Q)$< $(silent) --defconfig=arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG) $(Kconfig)
+else
+	@$(kecho) "*** Default configuration is based on target '$(KBUILD_DEFCONFIG)'"
+	$(Q)$(MAKE) -f $(srctree)/Makefile $(KBUILD_DEFCONFIG)
+endif
+
+%_defconfig: $(obj)/conf
+	$(Q)$< $(silent) --defconfig=arch/$(SRCARCH)/configs/$@ $(Kconfig)
+
+configfiles = $(wildcard $(srctree)/kernel/configs/$(1) $(srctree)/arch/$(SRCARCH)/configs/$(1))
+all-config-fragments = $(call configfiles,*.config)
+config-fragments = $(call configfiles,$@)
+
+cmd_merge_fragments = $(srctree)/scripts/kconfig/merge_config.sh -m $(KCONFIG_CONFIG) $(config-fragments)
+
+%.config: $(obj)/conf
+	$(if $(config-fragments),, $(error $@ fragment does not exists on this architecture))
+	$(call cmd,merge_fragments)
+	$(Q)$(MAKE) -f $(srctree)/Makefile olddefconfig
+
+PHONY += tinyconfig
+tinyconfig:
+	$(Q)KCONFIG_ALLCONFIG=kernel/configs/tiny-base.config $(MAKE) -f $(srctree)/Makefile allnoconfig
+	$(Q)$(MAKE) -f $(srctree)/Makefile tiny.config
+
+# CHECK: -o cache_dir=<path> working?
+PHONY += testconfig
+testconfig: $(obj)/conf
+	$(Q)$(PYTHON3) -B -m pytest $(src)/tests \
+	-o cache_dir=$(abspath $(obj)/tests/.cache) \
+	$(if $(findstring 1,$(KBUILD_VERBOSE)),--capture=no)
+clean-files += tests/.cache
+
+# Help text used by make help
+help:
+	@echo  'Configuration targets:'
+	@echo  '  config	  - Update current config utilising a line-oriented program'
+	@echo  '  nconfig         - Update current config utilising a ncurses menu based program'
+	@echo  '  menuconfig	  - Update current config utilising a menu based program'
+	@echo  '  xconfig	  - Update current config utilising a Qt based front-end'
+	@echo  '  gconfig	  - Update current config utilising a GTK+ based front-end'
+	@echo  '  oldconfig	  - Update current config utilising a provided .config as base'
+	@echo  '  localmodconfig  - Update current config disabling modules not loaded'
+	@echo  '                    except those preserved by LMC_KEEP environment variable'
+	@echo  '  localyesconfig  - Update current config converting local mods to core'
+	@echo  '                    except those preserved by LMC_KEEP environment variable'
+	@echo  '  defconfig	  - New config with default from ARCH supplied defconfig'
+	@echo  '  savedefconfig   - Save current config as ./defconfig (minimal config)'
+	@echo  '  allnoconfig	  - New config where all options are answered with no'
+	@echo  '  allyesconfig	  - New config where all options are accepted with yes'
+	@echo  '  allmodconfig	  - New config selecting modules when possible'
+	@echo  '  alldefconfig    - New config with all symbols set to default'
+	@echo  '  randconfig	  - New config with random answer to all options'
+	@echo  '  yes2modconfig	  - Change answers from yes to mod if possible'
+	@echo  '  mod2yesconfig	  - Change answers from mod to yes if possible'
+	@echo  '  mod2noconfig	  - Change answers from mod to no if possible'
+	@echo  '  listnewconfig   - List new options'
+	@echo  '  helpnewconfig   - List new options and help text'
+	@echo  '  olddefconfig	  - Same as oldconfig but sets new symbols to their'
+	@echo  '                    default value without prompting'
+	@echo  '  tinyconfig	  - Configure the tiniest possible kernel'
+	@echo  '  testconfig	  - Run Kconfig unit tests (requires python3 and pytest)'
+	@echo  ''
+	@echo  'Configuration topic targets:'
+	@$(foreach f, $(all-config-fragments), \
+		if help=$$(grep -m1 '^# Help: ' $(f)); then \
+			printf '  %-25s - %s\n' '$(notdir $(f))' "$${help#*: }"; \
+		fi;)
+
+# ===========================================================================
+# object files used by all kconfig flavours
+common-objs	:= confdata.o expr.o lexer.lex.o menu.o parser.tab.o \
+		   preprocess.o symbol.o util.o
+
+$(obj)/lexer.lex.o: $(obj)/parser.tab.h
+HOSTCFLAGS_lexer.lex.o	:= -I $(src)
+HOSTCFLAGS_parser.tab.o	:= -I $(src)
+
+# conf: Used for defconfig, oldconfig and related targets
+hostprogs	+= conf
+conf-objs	:= conf.o $(common-objs)
+
+# nconf: Used for the nconfig target based on ncurses
+hostprogs	+= nconf
+nconf-objs	:= nconf.o nconf.gui.o mnconf-common.o $(common-objs)
+
+HOSTLDLIBS_nconf       = $(call read-file, $(obj)/nconf-libs)
+HOSTCFLAGS_nconf.o     = $(call read-file, $(obj)/nconf-cflags)
+HOSTCFLAGS_nconf.gui.o = $(call read-file, $(obj)/nconf-cflags)
+
+$(obj)/nconf: | $(obj)/nconf-libs
+$(obj)/nconf.o $(obj)/nconf.gui.o: | $(obj)/nconf-cflags
+
+# mconf: Used for the menuconfig target based on lxdialog
+hostprogs	+= mconf
+lxdialog	:= $(addprefix lxdialog/, \
+		     checklist.o inputbox.o menubox.o textbox.o util.o yesno.o)
+mconf-objs	:= mconf.o $(lxdialog) mnconf-common.o $(common-objs)
+
+HOSTLDLIBS_mconf = $(call read-file, $(obj)/mconf-libs)
+$(foreach f, mconf.o $(lxdialog), \
+  $(eval HOSTCFLAGS_$f = $$(call read-file, $(obj)/mconf-cflags)))
+
+$(obj)/mconf: | $(obj)/mconf-libs
+$(addprefix $(obj)/, mconf.o $(lxdialog)): | $(obj)/mconf-cflags
+
+# qconf: Used for the xconfig target based on Qt
+hostprogs	+= qconf
+qconf-cxxobjs	:= qconf.o qconf-moc.o
+qconf-objs	:= $(common-objs)
+
+HOSTLDLIBS_qconf         = $(call read-file, $(obj)/qconf-libs)
+HOSTCXXFLAGS_qconf.o     = -std=c++11 -fPIC $(call read-file, $(obj)/qconf-cflags)
+HOSTCXXFLAGS_qconf-moc.o = -std=c++11 -fPIC $(call read-file, $(obj)/qconf-cflags)
+$(obj)/qconf: | $(obj)/qconf-libs
+$(obj)/qconf.o $(obj)/qconf-moc.o: | $(obj)/qconf-cflags
+
+quiet_cmd_moc = MOC     $@
+      cmd_moc = $(call read-file, $(obj)/qconf-bin)/moc $< -o $@
+
+$(obj)/qconf-moc.cc: $(src)/qconf.h FORCE | $(obj)/qconf-bin
+	$(call if_changed,moc)
+
+targets += qconf-moc.cc
+
+# gconf: Used for the gconfig target based on GTK+
+hostprogs	+= gconf
+gconf-objs	:= gconf.o $(common-objs)
+
+HOSTLDLIBS_gconf   = $(call read-file, $(obj)/gconf-libs)
+HOSTCFLAGS_gconf.o = $(call read-file, $(obj)/gconf-cflags)
+
+$(obj)/gconf: | $(obj)/gconf-libs
+$(obj)/gconf.o: | $(obj)/gconf-cflags
+
+# check if necessary packages are available, and configure build flags
+cmd_conf_cfg = $< $(addprefix $(obj)/$*conf-, cflags libs bin); touch $(obj)/$*conf-bin
+
+$(obj)/%conf-cflags $(obj)/%conf-libs $(obj)/%conf-bin: $(src)/%conf-cfg.sh
+	$(call cmd,conf_cfg)
+
+clean-files += *conf-cflags *conf-libs *conf-bin