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, 107 insertions, 0 deletions

diff --git a/include/xen/acpi.h b/include/xen/acpi.h
new file mode 100644
index 000000000..c66a84616
--- /dev/null
+++ b/include/xen/acpi.h
@@ -0,0 +1,107 @@
+/******************************************************************************
+ * acpi.h
+ * acpi file for domain 0 kernel
+ *
+ * Copyright (c) 2011 Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
+ * Copyright (c) 2011 Yu Ke <ke.yu@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#ifndef _XEN_ACPI_H
+#define _XEN_ACPI_H
+
+#include <linux/types.h>
+
+typedef int (*get_gsi_from_sbdf_t)(u32 sbdf);
+
+#ifdef CONFIG_XEN_DOM0
+#include <asm/xen/hypervisor.h>
+#include <xen/xen.h>
+#include <linux/acpi.h>
+
+int xen_acpi_notify_hypervisor_sleep(u8 sleep_state,
+				     u32 pm1a_cnt, u32 pm1b_cnd);
+int xen_acpi_notify_hypervisor_extended_sleep(u8 sleep_state,
+				     u32 val_a, u32 val_b);
+
+static inline int xen_acpi_suspend_lowlevel(void)
+{
+	/*
+	* Xen will save and restore CPU context, so
+	* we can skip that and just go straight to
+	* the suspend.
+	*/
+	acpi_enter_sleep_state(ACPI_STATE_S3);
+	return 0;
+}
+
+static inline void xen_acpi_sleep_register(void)
+{
+	if (xen_initial_domain()) {
+		acpi_os_set_prepare_sleep(
+			&xen_acpi_notify_hypervisor_sleep);
+		acpi_os_set_prepare_extended_sleep(
+			&xen_acpi_notify_hypervisor_extended_sleep);
+
+		acpi_suspend_lowlevel = xen_acpi_suspend_lowlevel;
+	}
+}
+int xen_pvh_setup_gsi(int gsi, int trigger, int polarity);
+int xen_acpi_get_gsi_info(struct pci_dev *dev,
+						  int *gsi_out,
+						  int *trigger_out,
+						  int *polarity_out);
+void xen_acpi_register_get_gsi_func(get_gsi_from_sbdf_t func);
+int xen_acpi_get_gsi_from_sbdf(u32 sbdf);
+#else
+static inline void xen_acpi_sleep_register(void)
+{
+}
+
+static inline int xen_pvh_setup_gsi(int gsi, int trigger, int polarity)
+{
+	return -1;
+}
+
+static inline int xen_acpi_get_gsi_info(struct pci_dev *dev,
+						  int *gsi_out,
+						  int *trigger_out,
+						  int *polarity_out)
+{
+	return -1;
+}
+
+static inline void xen_acpi_register_get_gsi_func(get_gsi_from_sbdf_t func)
+{
+}
+
+static inline int xen_acpi_get_gsi_from_sbdf(u32 sbdf)
+{
+	return -1;
+}
+#endif
+
+#endif	/* _XEN_ACPI_H */