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, 134 insertions, 0 deletions

diff --git a/drivers/ptp/ptp_vmw.c b/drivers/ptp/ptp_vmw.c
new file mode 100644
index 000000000..14fc587d0
--- /dev/null
+++ b/drivers/ptp/ptp_vmw.c
@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * Copyright (C) 2020 VMware, Inc., Palo Alto, CA., USA
+ *
+ * PTP clock driver for VMware precision clock virtual device.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/acpi.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/ptp_clock_kernel.h>
+#include <asm/hypervisor.h>
+#include <asm/vmware.h>
+
+#define VMWARE_CMD_PCLK(nr) ((nr << 16) | 97)
+#define VMWARE_CMD_PCLK_GETTIME VMWARE_CMD_PCLK(0)
+
+static struct ptp_clock *ptp_vmw_clock;
+
+
+static int ptp_vmw_pclk_read(u64 *ns)
+{
+	u32 ret, nsec_hi, nsec_lo;
+
+	ret = vmware_hypercall3(VMWARE_CMD_PCLK_GETTIME, 0,
+				&nsec_hi, &nsec_lo);
+	if (ret == 0)
+		*ns = ((u64)nsec_hi << 32) | nsec_lo;
+	return ret;
+}
+
+/*
+ * PTP clock ops.
+ */
+
+static int ptp_vmw_adjtime(struct ptp_clock_info *info, s64 delta)
+{
+	return -EOPNOTSUPP;
+}
+
+static int ptp_vmw_adjfine(struct ptp_clock_info *info, long delta)
+{
+	return -EOPNOTSUPP;
+}
+
+static int ptp_vmw_gettime(struct ptp_clock_info *info, struct timespec64 *ts)
+{
+	u64 ns;
+
+	if (ptp_vmw_pclk_read(&ns) != 0)
+		return -EIO;
+	*ts = ns_to_timespec64(ns);
+	return 0;
+}
+
+static int ptp_vmw_settime(struct ptp_clock_info *info,
+			  const struct timespec64 *ts)
+{
+	return -EOPNOTSUPP;
+}
+
+static int ptp_vmw_enable(struct ptp_clock_info *info,
+			 struct ptp_clock_request *request, int on)
+{
+	return -EOPNOTSUPP;
+}
+
+static struct ptp_clock_info ptp_vmw_clock_info = {
+	.owner		= THIS_MODULE,
+	.name		= "ptp_vmw",
+	.max_adj	= 0,
+	.adjtime	= ptp_vmw_adjtime,
+	.adjfine	= ptp_vmw_adjfine,
+	.gettime64	= ptp_vmw_gettime,
+	.settime64	= ptp_vmw_settime,
+	.enable		= ptp_vmw_enable,
+};
+
+/*
+ * ACPI driver ops for VMware "precision clock" virtual device.
+ */
+
+static int ptp_vmw_acpi_probe(struct platform_device *pdev)
+{
+	ptp_vmw_clock = ptp_clock_register(&ptp_vmw_clock_info, NULL);
+	if (IS_ERR(ptp_vmw_clock)) {
+		pr_err("failed to register ptp clock\n");
+		return PTR_ERR(ptp_vmw_clock);
+	}
+	return 0;
+}
+
+static void ptp_vmw_acpi_remove(struct platform_device *pdev)
+{
+	ptp_clock_unregister(ptp_vmw_clock);
+}
+
+static const struct acpi_device_id ptp_vmw_acpi_device_ids[] = {
+	{ "VMW0005", 0 },
+	{ "", 0 },
+};
+
+MODULE_DEVICE_TABLE(acpi, ptp_vmw_acpi_device_ids);
+
+static struct platform_driver ptp_vmw_acpi_driver = {
+	.probe = ptp_vmw_acpi_probe,
+	.remove = ptp_vmw_acpi_remove,
+	.driver = {
+		.name = "ptp_vmw_acpi",
+		.acpi_match_table = ptp_vmw_acpi_device_ids,
+	},
+};
+
+static int __init ptp_vmw_init(void)
+{
+	if (x86_hyper_type != X86_HYPER_VMWARE)
+		return -1;
+	return platform_driver_register(&ptp_vmw_acpi_driver);
+}
+
+static void __exit ptp_vmw_exit(void)
+{
+	platform_driver_unregister(&ptp_vmw_acpi_driver);
+}
+
+module_init(ptp_vmw_init);
+module_exit(ptp_vmw_exit);
+
+MODULE_DESCRIPTION("VMware virtual PTP clock driver");
+MODULE_AUTHOR("VMware, Inc.");
+MODULE_LICENSE("Dual BSD/GPL");