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, 71 insertions, 0 deletions

diff --git a/include/soc/tegra/flowctrl.h b/include/soc/tegra/flowctrl.h
new file mode 100644
index 000000000..2a60bd493
--- /dev/null
+++ b/include/soc/tegra/flowctrl.h
@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Functions and macros to control the flowcontroller
+ *
+ * Copyright (c) 2010-2012, NVIDIA Corporation. All rights reserved.
+ */
+
+#ifndef __SOC_TEGRA_FLOWCTRL_H__
+#define __SOC_TEGRA_FLOWCTRL_H__
+
+#define FLOW_CTRL_HALT_CPU0_EVENTS	0x0
+#define FLOW_CTRL_WAITEVENT		(2 << 29)
+#define FLOW_CTRL_WAIT_FOR_INTERRUPT	(4 << 29)
+#define FLOW_CTRL_JTAG_RESUME		(1 << 28)
+#define FLOW_CTRL_SCLK_RESUME		(1 << 27)
+#define FLOW_CTRL_HALT_CPU_IRQ		(1 << 10)
+#define	FLOW_CTRL_HALT_CPU_FIQ		(1 << 8)
+#define FLOW_CTRL_HALT_LIC_IRQ		(1 << 11)
+#define FLOW_CTRL_HALT_LIC_FIQ		(1 << 10)
+#define FLOW_CTRL_HALT_GIC_IRQ		(1 << 9)
+#define FLOW_CTRL_HALT_GIC_FIQ		(1 << 8)
+#define FLOW_CTRL_CPU0_CSR		0x8
+#define	FLOW_CTRL_CSR_INTR_FLAG		(1 << 15)
+#define FLOW_CTRL_CSR_EVENT_FLAG	(1 << 14)
+#define FLOW_CTRL_CSR_ENABLE_EXT_CRAIL	(1 << 13)
+#define FLOW_CTRL_CSR_ENABLE_EXT_NCPU	(1 << 12)
+#define FLOW_CTRL_CSR_ENABLE_EXT_MASK ( \
+		FLOW_CTRL_CSR_ENABLE_EXT_NCPU | \
+		FLOW_CTRL_CSR_ENABLE_EXT_CRAIL)
+#define FLOW_CTRL_CSR_ENABLE		(1 << 0)
+#define FLOW_CTRL_HALT_CPU1_EVENTS	0x14
+#define FLOW_CTRL_CPU1_CSR		0x18
+
+#define TEGRA20_FLOW_CTRL_CSR_WFE_CPU0		(1 << 4)
+#define TEGRA20_FLOW_CTRL_CSR_WFE_BITMAP	(3 << 4)
+#define TEGRA20_FLOW_CTRL_CSR_WFI_BITMAP	0
+
+#define TEGRA30_FLOW_CTRL_CSR_WFI_CPU0		(1 << 8)
+#define TEGRA30_FLOW_CTRL_CSR_WFE_BITMAP	(0xF << 4)
+#define TEGRA30_FLOW_CTRL_CSR_WFI_BITMAP	(0xF << 8)
+
+#ifndef __ASSEMBLER__
+#ifdef CONFIG_SOC_TEGRA_FLOWCTRL
+u32 flowctrl_read_cpu_csr(unsigned int cpuid);
+void flowctrl_write_cpu_csr(unsigned int cpuid, u32 value);
+void flowctrl_write_cpu_halt(unsigned int cpuid, u32 value);
+
+void flowctrl_cpu_suspend_enter(unsigned int cpuid);
+void flowctrl_cpu_suspend_exit(unsigned int cpuid);
+#else
+static inline u32 flowctrl_read_cpu_csr(unsigned int cpuid)
+{
+	return 0;
+}
+
+static inline void flowctrl_write_cpu_csr(unsigned int cpuid, u32 value)
+{
+}
+
+static inline void flowctrl_write_cpu_halt(unsigned int cpuid, u32 value) {}
+
+static inline void flowctrl_cpu_suspend_enter(unsigned int cpuid)
+{
+}
+
+static inline void flowctrl_cpu_suspend_exit(unsigned int cpuid)
+{
+}
+#endif /* CONFIG_SOC_TEGRA_FLOWCTRL */
+#endif /* __ASSEMBLER__ */
+#endif /* __SOC_TEGRA_FLOWCTRL_H__ */