x86/amd_node: Fix PCI device reference counting in amd_smn_init()grafted

The local "root" pointer is a temporary variable used during the device
search. Therefore, refcount related to the search iterators should be cleaned
up after the search is complete.

Use the __free() cleanup macro to ensure the refcount is decremented when the
temporary pointer goes out of scope.

Additionally, increment the refcount when caching a root pointer. This ensures
the in-use refcount is separate from the temporary search refcounting.

Finally, drop the redundant "root = NULL" before the second search loop. The
pci_get_class() iterator always decrements the refcount of its "from"
argument, so the first loop can only fall through with "root" already NULL.

Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching")
Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com
Reported-by: Sashiko <sashiko-bot@kernel.org>
Assisted-by: LLM
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com

1 files changed, 51 insertions, 0 deletions

diff --git a/arch/x86/tools/Makefile b/arch/x86/tools/Makefile
new file mode 100644
index 000000000..39a183fff
--- /dev/null
+++ b/arch/x86/tools/Makefile
@@ -0,0 +1,51 @@
+# SPDX-License-Identifier: GPL-2.0
+PHONY += posttest
+
+ifneq ($(findstring 1, $(KBUILD_VERBOSE)),)
+  posttest_verbose = -v
+else
+  posttest_verbose =
+endif
+
+ifeq ($(CONFIG_64BIT),y)
+  posttest_64bit = -y
+else
+  posttest_64bit = -n
+endif
+
+reformatter = $(srctree)/arch/x86/tools/objdump_reformat.awk
+chkobjdump = $(srctree)/arch/x86/tools/chkobjdump.awk
+
+quiet_cmd_posttest = TEST    $@
+      cmd_posttest = $(OBJDUMP) -d -j .text $(objtree)/vmlinux | $(AWK) -f $(reformatter) | $(obj)/insn_decoder_test $(posttest_64bit) $(posttest_verbose)
+
+quiet_cmd_sanitytest = TEST    $@
+      cmd_sanitytest = $(obj)/insn_sanity $(posttest_64bit) -m 1000000
+
+posttest: $(obj)/insn_decoder_test vmlinux $(obj)/insn_sanity
+	$(call cmd,posttest)
+	$(call cmd,sanitytest)
+
+hostprogs += insn_decoder_test insn_sanity
+
+# -I needed for generated C source and C source which in the kernel tree.
+HOSTCFLAGS_insn_decoder_test.o := -Wall -I$(srctree)/tools/arch/x86/lib/ -I$(srctree)/tools/arch/x86/include/ -I$(objtree)/arch/x86/lib/
+
+HOSTCFLAGS_insn_sanity.o := -Wall -I$(srctree)/tools/arch/x86/lib/ -I$(srctree)/tools/arch/x86/include/ -I$(objtree)/arch/x86/lib/
+
+# Dependencies are also needed.
+$(obj)/insn_decoder_test.o: $(srctree)/tools/arch/x86/lib/insn.c $(srctree)/tools/arch/x86/lib/inat.c $(srctree)/tools/arch/x86/include/asm/inat_types.h $(srctree)/tools/arch/x86/include/asm/inat.h $(srctree)/tools/arch/x86/include/asm/insn.h $(objtree)/arch/x86/lib/inat-tables.c
+
+$(obj)/insn_sanity.o: $(srctree)/tools/arch/x86/lib/insn.c $(srctree)/tools/arch/x86/lib/inat.c $(srctree)/tools/arch/x86/include/asm/inat_types.h $(srctree)/tools/arch/x86/include/asm/inat.h $(srctree)/tools/arch/x86/include/asm/insn.h $(objtree)/arch/x86/lib/inat-tables.c
+
+HOST_EXTRACFLAGS += -I$(srctree)/tools/include -I$(srctree)/include/uapi \
+		    -I$(srctree)/arch/$(SUBARCH)/include/uapi
+
+hostprogs	+= relocs vdso2c
+relocs-objs	:= relocs_32.o relocs_64.o relocs_common.o
+
+always-y	:= $(hostprogs)
+
+PHONY += $(hostprogs)
+$(hostprogs): %: $(obj)/%
+	@: