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, 82 insertions, 0 deletions

diff --git a/drivers/edac/mce_amd.h b/drivers/edac/mce_amd.h
new file mode 100644
index 000000000..4811b18d9
--- /dev/null
+++ b/drivers/edac/mce_amd.h
@@ -0,0 +1,82 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _EDAC_MCE_AMD_H
+#define _EDAC_MCE_AMD_H
+
+#include <linux/notifier.h>
+
+#include <asm/mce.h>
+
+#define EC(x)				((x) & 0xffff)
+
+#define LOW_SYNDROME(x)			(((x) >> 15) & 0xff)
+#define HIGH_SYNDROME(x)		(((x) >> 24) & 0xff)
+
+#define TLB_ERROR(x)			(((x) & 0xFFF0) == 0x0010)
+#define MEM_ERROR(x)			(((x) & 0xFF00) == 0x0100)
+#define BUS_ERROR(x)			(((x) & 0xF800) == 0x0800)
+#define INT_ERROR(x)			(((x) & 0xF4FF) == 0x0400)
+
+#define TT(x)				(((x) >> 2) & 0x3)
+#define TT_MSG(x)			tt_msgs[TT(x)]
+#define II(x)				(((x) >> 2) & 0x3)
+#define II_MSG(x)			ii_msgs[II(x)]
+#define LL(x)				((x) & 0x3)
+#define LL_MSG(x)			ll_msgs[LL(x)]
+#define TO(x)				(((x) >> 8) & 0x1)
+#define TO_MSG(x)			to_msgs[TO(x)]
+#define PP(x)				(((x) >> 9) & 0x3)
+#define PP_MSG(x)			pp_msgs[PP(x)]
+#define UU(x)				(((x) >> 8) & 0x3)
+#define UU_MSG(x)			uu_msgs[UU(x)]
+
+#define R4(x)				(((x) >> 4) & 0xf)
+#define R4_MSG(x)			((R4(x) < 9) ?  rrrr_msgs[R4(x)] : "Wrong R4!")
+
+extern const char * const pp_msgs[];
+
+enum tt_ids {
+	TT_INSTR = 0,
+	TT_DATA,
+	TT_GEN,
+	TT_RESV,
+};
+
+enum ll_ids {
+	LL_RESV = 0,
+	LL_L1,
+	LL_L2,
+	LL_LG,
+};
+
+enum ii_ids {
+	II_MEM = 0,
+	II_RESV,
+	II_IO,
+	II_GEN,
+};
+
+enum rrrr_ids {
+	R4_GEN	= 0,
+	R4_RD,
+	R4_WR,
+	R4_DRD,
+	R4_DWR,
+	R4_IRD,
+	R4_PREF,
+	R4_EVICT,
+	R4_SNOOP,
+};
+
+/*
+ * per-family decoder ops
+ */
+struct amd_decoder_ops {
+	bool (*mc0_mce)(u16, u8);
+	bool (*mc1_mce)(u16, u8);
+	bool (*mc2_mce)(u16, u8);
+};
+
+void amd_register_ecc_decoder(void (*f)(int, struct mce *));
+void amd_unregister_ecc_decoder(void (*f)(int, struct mce *));
+
+#endif /* _EDAC_MCE_AMD_H */