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, 43 insertions, 0 deletions

diff --git a/scripts/Makefile.dtbinst b/scripts/Makefile.dtbinst
new file mode 100644
index 000000000..9d920419a
--- /dev/null
+++ b/scripts/Makefile.dtbinst
@@ -0,0 +1,43 @@
+# SPDX-License-Identifier: GPL-2.0
+# ==========================================================================
+# Installing dtb files
+#
+# Installs all dtb files listed in $(dtb-y) either in the
+# INSTALL_DTBS_PATH directory or the default location:
+#
+#   $INSTALL_PATH/dtbs/$KERNELRELEASE
+# ==========================================================================
+
+PHONY := __dtbs_install
+__dtbs_install:
+
+include include/config/auto.conf
+include $(srctree)/scripts/Kbuild.include
+
+dst := $(INSTALL_DTBS_PATH)
+
+quiet_cmd_dtb_install = INSTALL $@
+      cmd_dtb_install = install -D -m 0644 $< $@
+
+$(dst)/%: $(obj)/%
+	$(call cmd,dtb_install)
+
+dtbs := $(patsubst $(obj)/%,%,$(call read-file, $(obj)/dtbs-list))
+
+ifdef CONFIG_ARCH_WANT_FLAT_DTB_INSTALL
+
+define gen_install_rules
+$(dst)/%: $(obj)/$(1)%
+	$$(call cmd,dtb_install)
+endef
+
+$(foreach d, $(sort $(dir $(dtbs))), $(eval $(call gen_install_rules,$(d))))
+
+dtbs := $(notdir $(dtbs))
+
+endif # CONFIG_ARCH_WANT_FLAT_DTB_INSTALL
+
+__dtbs_install: $(addprefix $(dst)/, $(dtbs))
+	@:
+
+.PHONY: $(PHONY)