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, 65 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-driver-ivpu b/Documentation/ABI/testing/sysfs-driver-ivpu
new file mode 100644
index 000000000..91685774e
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-ivpu
@@ -0,0 +1,65 @@
+What:		/sys/bus/pci/drivers/intel_vpu/.../npu_busy_time_us
+Date:		May 2024
+KernelVersion:	6.11
+Contact:	dri-devel@lists.freedesktop.org
+Description:	Time in microseconds that the device spent executing jobs. The time is
+		counted when and only when there are jobs submitted to firmware. This time
+		can be used to measure the utilization of NPU, either by calculating the
+		difference between two timepoints or monitoring utilization percentage by
+		reading periodically. Recommended read period is 1 second to avoid impact
+		on job submission performance. Read-only.
+
+What:		/sys/bus/pci/drivers/intel_vpu/.../npu_memory_utilization
+Date:		Jan 2025
+KernelVersion:	6.15
+Contact:	dri-devel@lists.freedesktop.org
+Description:	Current NPU memory utilization in bytes. Reports the total size of all
+		resident buffer objects allocated for NPU use. Read-only.
+
+What:		/sys/bus/pci/drivers/intel_vpu/.../freq/hw_min_freq
+Date:		April 2026
+KernelVersion:	7.2
+Contact:	dri-devel@lists.freedesktop.org
+Description:	Minimum frequency in MHz supported by the NPU hardware. This is a
+		hardware capability and cannot be changed. Read-only.
+
+What:		/sys/bus/pci/drivers/intel_vpu/.../freq/hw_efficient_freq
+Date:		April 2026
+KernelVersion:	7.2
+Contact:	dri-devel@lists.freedesktop.org
+Description:	Most efficient operating frequency in MHz for the NPU. This represents
+		the frequency at which the NPU operates most efficiently in terms of power
+		and performance. Read-only.
+
+What:		/sys/bus/pci/drivers/intel_vpu/.../freq/hw_max_freq
+Date:		April 2026
+KernelVersion:	7.2
+Contact:	dri-devel@lists.freedesktop.org
+Description:	Maximum frequency in MHz supported by the NPU hardware. This is a
+		hardware capability and cannot be changed. Read-only.
+
+What:		/sys/bus/pci/drivers/intel_vpu/.../freq/current_freq
+Date:		April 2026
+KernelVersion:	7.2
+Contact:	dri-devel@lists.freedesktop.org
+Description:	Current operating frequency in MHz of the NPU. The value is valid only
+		when the device is active; returns 0 when idle. The actual frequency may
+		be lower than the requested range due to power or thermal constraints.
+		Read-only.
+
+What:		/sys/bus/pci/drivers/intel_vpu/.../freq/set_min_freq
+Date:		April 2026
+KernelVersion:	7.2
+Contact:	dri-devel@lists.freedesktop.org
+Description:	Configured minimum operating frequency in MHz (50XX devices and newer).
+		Values written are clamped to hardware limits (hw_min_freq to hw_max_freq).
+		If set_min_freq exceeds set_max_freq, the driver clamps set_min_freq to
+		set_max_freq when selecting the operating frequency. Read-write.
+
+What:		/sys/bus/pci/drivers/intel_vpu/.../freq/set_max_freq
+Date:		April 2026
+KernelVersion:	7.2
+Contact:	dri-devel@lists.freedesktop.org
+Description:	Configured maximum operating frequency in MHz (50XX devices and newer).
+		Values written are clamped to hardware limits (hw_min_freq to hw_max_freq).
+		Read-write.