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, 27 insertions, 0 deletions

diff --git a/drivers/hv/Makefile b/drivers/hv/Makefile
new file mode 100644
index 000000000..888a748cc
--- /dev/null
+++ b/drivers/hv/Makefile
@@ -0,0 +1,27 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_HYPERV_VMBUS)	+= hv_vmbus.o
+obj-$(CONFIG_HYPERV_UTILS)	+= hv_utils.o
+obj-$(CONFIG_HYPERV_BALLOON)	+= hv_balloon.o
+obj-$(CONFIG_MSHV_ROOT)		+= mshv_root.o
+obj-$(CONFIG_MSHV_VTL)          += mshv_vtl.o
+
+CFLAGS_hv_trace.o = -I$(src)
+CFLAGS_hv_balloon.o = -I$(src)
+
+hv_vmbus-y := vmbus_drv.o \
+		 hv.o connection.o channel.o \
+		 channel_mgmt.o ring_buffer.o hv_trace.o
+hv_vmbus-$(CONFIG_HYPERV_TESTING)	+= hv_debugfs.o
+hv_utils-y := hv_util.o hv_kvp.o hv_snapshot.o hv_utils_transport.o
+mshv_root-y := mshv_root_main.o mshv_synic.o mshv_eventfd.o mshv_irq.o \
+	       mshv_root_hv_call.o mshv_portid_table.o mshv_regions.o
+mshv_root-$(CONFIG_DEBUG_FS) += mshv_debugfs.o
+mshv_root-$(CONFIG_TRACEPOINTS) += mshv_trace.o
+mshv_vtl-y := mshv_vtl_main.o
+
+# Code that must be built-in
+obj-$(CONFIG_HYPERV) += hv_common.o
+obj-$(subst m,y,$(CONFIG_MSHV_ROOT)) += hv_proc.o
+ifneq ($(CONFIG_MSHV_ROOT)$(CONFIG_MSHV_VTL),)
+	obj-y += mshv_common.o
+endif