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, 162 insertions, 0 deletions

diff --git a/include/trace/events/iommu.h b/include/trace/events/iommu.h
new file mode 100644
index 000000000..373007e56
--- /dev/null
+++ b/include/trace/events/iommu.h
@@ -0,0 +1,162 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * iommu trace points
+ *
+ * Copyright (C) 2013 Shuah Khan <shuah.kh@samsung.com>
+ *
+ */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM iommu
+
+#if !defined(_TRACE_IOMMU_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_IOMMU_H
+
+#include <linux/tracepoint.h>
+
+struct device;
+
+DECLARE_EVENT_CLASS(iommu_group_event,
+
+	TP_PROTO(int group_id, struct device *dev),
+
+	TP_ARGS(group_id, dev),
+
+	TP_STRUCT__entry(
+		__field(int, gid)
+		__string(device, dev_name(dev))
+	),
+
+	TP_fast_assign(
+		__entry->gid = group_id;
+		__assign_str(device);
+	),
+
+	TP_printk("IOMMU: groupID=%d device=%s",
+			__entry->gid, __get_str(device)
+	)
+);
+
+DEFINE_EVENT(iommu_group_event, add_device_to_group,
+
+	TP_PROTO(int group_id, struct device *dev),
+
+	TP_ARGS(group_id, dev)
+
+);
+
+DEFINE_EVENT(iommu_group_event, remove_device_from_group,
+
+	TP_PROTO(int group_id, struct device *dev),
+
+	TP_ARGS(group_id, dev)
+);
+
+DECLARE_EVENT_CLASS(iommu_device_event,
+
+	TP_PROTO(struct device *dev),
+
+	TP_ARGS(dev),
+
+	TP_STRUCT__entry(
+		__string(device, dev_name(dev))
+	),
+
+	TP_fast_assign(
+		__assign_str(device);
+	),
+
+	TP_printk("IOMMU: device=%s", __get_str(device)
+	)
+);
+
+DEFINE_EVENT(iommu_device_event, attach_device_to_domain,
+
+	TP_PROTO(struct device *dev),
+
+	TP_ARGS(dev)
+);
+
+TRACE_EVENT(map,
+
+	TP_PROTO(unsigned long iova, phys_addr_t paddr, size_t size),
+
+	TP_ARGS(iova, paddr, size),
+
+	TP_STRUCT__entry(
+		__field(u64, iova)
+		__field(u64, paddr)
+		__field(size_t, size)
+	),
+
+	TP_fast_assign(
+		__entry->iova = iova;
+		__entry->paddr = paddr;
+		__entry->size = size;
+	),
+
+	TP_printk("IOMMU: iova=0x%016llx - 0x%016llx paddr=0x%016llx size=%zu",
+		  __entry->iova, __entry->iova + __entry->size, __entry->paddr,
+		  __entry->size
+	)
+);
+
+TRACE_EVENT(unmap,
+
+	TP_PROTO(unsigned long iova, size_t size, size_t unmapped_size),
+
+	TP_ARGS(iova, size, unmapped_size),
+
+	TP_STRUCT__entry(
+		__field(u64, iova)
+		__field(size_t, size)
+		__field(size_t, unmapped_size)
+	),
+
+	TP_fast_assign(
+		__entry->iova = iova;
+		__entry->size = size;
+		__entry->unmapped_size = unmapped_size;
+	),
+
+	TP_printk("IOMMU: iova=0x%016llx - 0x%016llx size=%zu unmapped_size=%zu",
+		  __entry->iova, __entry->iova + __entry->size,
+		  __entry->size, __entry->unmapped_size
+	)
+);
+
+DECLARE_EVENT_CLASS(iommu_error,
+
+	TP_PROTO(struct device *dev, unsigned long iova, int flags),
+
+	TP_ARGS(dev, iova, flags),
+
+	TP_STRUCT__entry(
+		__string(device, dev_name(dev))
+		__string(driver, dev_driver_string(dev))
+		__field(u64, iova)
+		__field(int, flags)
+	),
+
+	TP_fast_assign(
+		__assign_str(device);
+		__assign_str(driver);
+		__entry->iova = iova;
+		__entry->flags = flags;
+	),
+
+	TP_printk("IOMMU:%s %s iova=0x%016llx flags=0x%04x",
+			__get_str(driver), __get_str(device),
+			__entry->iova, __entry->flags
+	)
+);
+
+DEFINE_EVENT(iommu_error, io_page_fault,
+
+	TP_PROTO(struct device *dev, unsigned long iova, int flags),
+
+	TP_ARGS(dev, iova, flags)
+);
+#endif /* _TRACE_IOMMU_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>