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, 40 insertions, 0 deletions

diff --git a/arch/powerpc/boot/treeboot-bamboo.c b/arch/powerpc/boot/treeboot-bamboo.c
new file mode 100644
index 000000000..97b5b161d
--- /dev/null
+++ b/arch/powerpc/boot/treeboot-bamboo.c
@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright IBM Corporation, 2007
+ * Josh Boyer <jwboyer@linux.vnet.ibm.com>
+ *
+ * Based on ebony wrapper:
+ * Copyright 2007 David Gibson, IBM Corporation.
+ */
+#include "ops.h"
+#include "stdio.h"
+#include "44x.h"
+#include "stdlib.h"
+
+BSS_STACK(4096);
+
+#define PIBS_MAC0 0xfffc0400
+#define PIBS_MAC1 0xfffc0500
+char pibs_mac0[6];
+char pibs_mac1[6];
+
+static void read_pibs_mac(void)
+{
+	unsigned long long mac64;
+
+	mac64 = strtoull((char *)PIBS_MAC0, 0, 16);
+	memcpy(&pibs_mac0, (char *)&mac64+2, 6);
+
+	mac64 = strtoull((char *)PIBS_MAC1, 0, 16);
+	memcpy(&pibs_mac1, (char *)&mac64+2, 6);
+}
+
+void platform_init(void)
+{
+	unsigned long end_of_ram = 0x8000000;
+	unsigned long avail_ram = end_of_ram - (unsigned long)_end;
+
+	simple_alloc_init(_end, avail_ram, 32, 64);
+	read_pibs_mac();
+	bamboo_init((u8 *)&pibs_mac0, (u8 *)&pibs_mac1);
+}