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, 75 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-driver-ppi b/Documentation/ABI/testing/sysfs-driver-ppi
new file mode 100644
index 000000000..1a56fc507
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-ppi
@@ -0,0 +1,75 @@
+What:		/sys/class/tpm/tpmX/ppi/
+Date:		August 2012
+KernelVersion:	3.6
+Contact:	xiaoyan.zhang@intel.com
+Description:
+		This folder includes the attributes related with PPI (Physical
+		Presence Interface). Only if TPM is supported by BIOS, this
+		folder makes sense. The folder path can be got by command
+		'find /sys/ -name 'pcrs''. For the detail information of PPI,
+		please refer to the PPI specification from
+
+		http://www.trustedcomputinggroup.org/
+
+		In Linux 4.2 ppi was moved to the character device directory.
+		A symlink from tpmX/device/ppi to tpmX/ppi to provide backwards
+		compatibility.
+
+What:		/sys/class/tpm/tpmX/ppi/version
+Date:		August 2012
+Contact:	xiaoyan.zhang@intel.com
+Description:
+		This attribute shows the version of the PPI supported by the
+		platform.
+		This file is readonly.
+
+What:		/sys/class/tpm/tpmX/ppi/request
+Date:		August 2012
+Contact:	xiaoyan.zhang@intel.com
+Description:
+		This attribute shows the request for an operation to be
+		executed in the pre-OS environment. It is the only input from
+		the OS to the pre-OS environment. The request should be an
+		integer value range from 1 to 160, and 0 means no request.
+		This file can be read and written.
+
+What:		/sys/class/tpm/tpmX/ppi/response
+Date:		August 2012
+Contact:	xiaoyan.zhang@intel.com
+Description:
+		This attribute shows the response to the most recent operation
+		request it acted upon. The format is "<request> <response num>
+		: <response description>".
+		This file is readonly.
+
+What:		/sys/class/tpm/tpmX/ppi/transition_action
+Date:		August 2012
+Contact:	xiaoyan.zhang@intel.com
+Description:
+		This attribute shows the platform-specific action that should
+		take place in order to transition to the BIOS for execution of
+		a requested operation. The format is "<action num>: <action
+		description>".
+		This file is readonly.
+
+What:		/sys/class/tpm/tpmX/ppi/tcg_operations
+Date:		August 2012
+Contact:	xiaoyan.zhang@intel.com
+Description:
+		This attribute shows whether it is allowed to request an
+		operation to be executed in the pre-OS environment by the BIOS
+		for the requests defined by TCG, i.e. requests from 1 to 22.
+		The format is "<request> <status num>: <status description>".
+		This attribute is only supported by PPI version 1.2+.
+		This file is readonly.
+
+What:		/sys/class/tpm/tpmX/ppi/vs_operations
+Date:		August 2012
+Contact:	xiaoyan.zhang@intel.com
+Description:
+		This attribute shows whether it is allowed to request an
+		operation to be executed in the pre-OS environment by the BIOS
+		for the verdor specific requests, i.e. requests from 128 to
+		255. The format is same with tcg_operations. This attribute
+		is also only supported by PPI version 1.2+.
+		This file is readonly.