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, 137 insertions, 0 deletions

diff --git a/drivers/firmware/imx/misc.c b/drivers/firmware/imx/misc.c
new file mode 100644
index 000000000..d073cb3ce
--- /dev/null
+++ b/drivers/firmware/imx/misc.c
@@ -0,0 +1,137 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2016 Freescale Semiconductor, Inc.
+ * Copyright 2017~2018 NXP
+ *  Author: Dong Aisheng <aisheng.dong@nxp.com>
+ *
+ * File containing client-side RPC functions for the MISC service. These
+ * function are ported to clients that communicate to the SC.
+ *
+ */
+
+#include <linux/firmware/imx/svc/misc.h>
+
+struct imx_sc_msg_req_misc_set_ctrl {
+	struct imx_sc_rpc_msg hdr;
+	u32 ctrl;
+	u32 val;
+	u16 resource;
+} __packed __aligned(4);
+
+struct imx_sc_msg_req_cpu_start {
+	struct imx_sc_rpc_msg hdr;
+	u32 address_hi;
+	u32 address_lo;
+	u16 resource;
+	u8 enable;
+} __packed __aligned(4);
+
+struct imx_sc_msg_req_misc_get_ctrl {
+	struct imx_sc_rpc_msg hdr;
+	u32 ctrl;
+	u16 resource;
+} __packed __aligned(4);
+
+struct imx_sc_msg_resp_misc_get_ctrl {
+	struct imx_sc_rpc_msg hdr;
+	u32 val;
+} __packed __aligned(4);
+
+/*
+ * This function sets a miscellaneous control value.
+ *
+ * @param[in]     ipc         IPC handle
+ * @param[in]     resource    resource the control is associated with
+ * @param[in]     ctrl        control to change
+ * @param[in]     val         value to apply to the control
+ *
+ * @return Returns 0 for success and < 0 for errors.
+ */
+
+int imx_sc_misc_set_control(struct imx_sc_ipc *ipc, u32 resource,
+			    u8 ctrl, u32 val)
+{
+	struct imx_sc_msg_req_misc_set_ctrl msg;
+	struct imx_sc_rpc_msg *hdr = &msg.hdr;
+
+	hdr->ver = IMX_SC_RPC_VERSION;
+	hdr->svc = (uint8_t)IMX_SC_RPC_SVC_MISC;
+	hdr->func = (uint8_t)IMX_SC_MISC_FUNC_SET_CONTROL;
+	hdr->size = 4;
+
+	msg.ctrl = ctrl;
+	msg.val = val;
+	msg.resource = resource;
+
+	return imx_scu_call_rpc(ipc, &msg, true);
+}
+EXPORT_SYMBOL(imx_sc_misc_set_control);
+
+/*
+ * This function gets a miscellaneous control value.
+ *
+ * @param[in]     ipc         IPC handle
+ * @param[in]     resource    resource the control is associated with
+ * @param[in]     ctrl        control to get
+ * @param[out]    val         pointer to return the control value
+ *
+ * @return Returns 0 for success and < 0 for errors.
+ */
+
+int imx_sc_misc_get_control(struct imx_sc_ipc *ipc, u32 resource,
+			    u8 ctrl, u32 *val)
+{
+	struct imx_sc_msg_req_misc_get_ctrl msg;
+	struct imx_sc_msg_resp_misc_get_ctrl *resp;
+	struct imx_sc_rpc_msg *hdr = &msg.hdr;
+	int ret;
+
+	hdr->ver = IMX_SC_RPC_VERSION;
+	hdr->svc = (uint8_t)IMX_SC_RPC_SVC_MISC;
+	hdr->func = (uint8_t)IMX_SC_MISC_FUNC_GET_CONTROL;
+	hdr->size = 3;
+
+	msg.ctrl = ctrl;
+	msg.resource = resource;
+
+	ret = imx_scu_call_rpc(ipc, &msg, true);
+	if (ret)
+		return ret;
+
+	resp = (struct imx_sc_msg_resp_misc_get_ctrl *)&msg;
+	if (val != NULL)
+		*val = resp->val;
+
+	return 0;
+}
+EXPORT_SYMBOL(imx_sc_misc_get_control);
+
+/*
+ * This function starts/stops a CPU identified by @resource
+ *
+ * @param[in]     ipc         IPC handle
+ * @param[in]     resource    resource the control is associated with
+ * @param[in]     enable      true for start, false for stop
+ * @param[in]     phys_addr   initial instruction address to be executed
+ *
+ * @return Returns 0 for success and < 0 for errors.
+ */
+int imx_sc_pm_cpu_start(struct imx_sc_ipc *ipc, u32 resource,
+			bool enable, u64 phys_addr)
+{
+	struct imx_sc_msg_req_cpu_start msg;
+	struct imx_sc_rpc_msg *hdr = &msg.hdr;
+
+	hdr->ver = IMX_SC_RPC_VERSION;
+	hdr->svc = IMX_SC_RPC_SVC_PM;
+	hdr->func = IMX_SC_PM_FUNC_CPU_START;
+	hdr->size = 4;
+
+	msg.address_hi = phys_addr >> 32;
+	msg.address_lo = phys_addr;
+	msg.resource = resource;
+	msg.enable = enable;
+
+	return imx_scu_call_rpc(ipc, &msg, true);
+}
+EXPORT_SYMBOL(imx_sc_pm_cpu_start);