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, 276 insertions, 0 deletions

diff --git a/drivers/bcma/host_soc.c b/drivers/bcma/host_soc.c
new file mode 100644
index 000000000..20b1816c5
--- /dev/null
+++ b/drivers/bcma/host_soc.c
@@ -0,0 +1,276 @@
+/*
+ * Broadcom specific AMBA
+ * System on Chip (SoC) Host
+ *
+ * Licensed under the GNU/GPL. See COPYING for details.
+ */
+
+#include "bcma_private.h"
+#include "scan.h"
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/bcma/bcma.h>
+#include <linux/bcma/bcma_soc.h>
+
+static u8 bcma_host_soc_read8(struct bcma_device *core, u16 offset)
+{
+	return readb(core->io_addr + offset);
+}
+
+static u16 bcma_host_soc_read16(struct bcma_device *core, u16 offset)
+{
+	return readw(core->io_addr + offset);
+}
+
+static u32 bcma_host_soc_read32(struct bcma_device *core, u16 offset)
+{
+	return readl(core->io_addr + offset);
+}
+
+static void bcma_host_soc_write8(struct bcma_device *core, u16 offset,
+				 u8 value)
+{
+	writeb(value, core->io_addr + offset);
+}
+
+static void bcma_host_soc_write16(struct bcma_device *core, u16 offset,
+				 u16 value)
+{
+	writew(value, core->io_addr + offset);
+}
+
+static void bcma_host_soc_write32(struct bcma_device *core, u16 offset,
+				 u32 value)
+{
+	writel(value, core->io_addr + offset);
+}
+
+#ifdef CONFIG_BCMA_BLOCKIO
+static void bcma_host_soc_block_read(struct bcma_device *core, void *buffer,
+				     size_t count, u16 offset, u8 reg_width)
+{
+	void __iomem *addr = core->io_addr + offset;
+
+	switch (reg_width) {
+	case sizeof(u8): {
+		u8 *buf = buffer;
+
+		while (count) {
+			*buf = __raw_readb(addr);
+			buf++;
+			count--;
+		}
+		break;
+	}
+	case sizeof(u16): {
+		__le16 *buf = buffer;
+
+		WARN_ON(count & 1);
+		while (count) {
+			*buf = (__force __le16)__raw_readw(addr);
+			buf++;
+			count -= 2;
+		}
+		break;
+	}
+	case sizeof(u32): {
+		__le32 *buf = buffer;
+
+		WARN_ON(count & 3);
+		while (count) {
+			*buf = (__force __le32)__raw_readl(addr);
+			buf++;
+			count -= 4;
+		}
+		break;
+	}
+	default:
+		WARN_ON(1);
+	}
+}
+
+static void bcma_host_soc_block_write(struct bcma_device *core,
+				      const void *buffer,
+				      size_t count, u16 offset, u8 reg_width)
+{
+	void __iomem *addr = core->io_addr + offset;
+
+	switch (reg_width) {
+	case sizeof(u8): {
+		const u8 *buf = buffer;
+
+		while (count) {
+			__raw_writeb(*buf, addr);
+			buf++;
+			count--;
+		}
+		break;
+	}
+	case sizeof(u16): {
+		const __le16 *buf = buffer;
+
+		WARN_ON(count & 1);
+		while (count) {
+			__raw_writew((__force u16)(*buf), addr);
+			buf++;
+			count -= 2;
+		}
+		break;
+	}
+	case sizeof(u32): {
+		const __le32 *buf = buffer;
+
+		WARN_ON(count & 3);
+		while (count) {
+			__raw_writel((__force u32)(*buf), addr);
+			buf++;
+			count -= 4;
+		}
+		break;
+	}
+	default:
+		WARN_ON(1);
+	}
+}
+#endif /* CONFIG_BCMA_BLOCKIO */
+
+static u32 bcma_host_soc_aread32(struct bcma_device *core, u16 offset)
+{
+	if (WARN_ONCE(!core->io_wrap, "Accessed core has no wrapper/agent\n"))
+		return ~0;
+	return readl(core->io_wrap + offset);
+}
+
+static void bcma_host_soc_awrite32(struct bcma_device *core, u16 offset,
+				  u32 value)
+{
+	if (WARN_ONCE(!core->io_wrap, "Accessed core has no wrapper/agent\n"))
+		return;
+	writel(value, core->io_wrap + offset);
+}
+
+static const struct bcma_host_ops bcma_host_soc_ops = {
+	.read8		= bcma_host_soc_read8,
+	.read16		= bcma_host_soc_read16,
+	.read32		= bcma_host_soc_read32,
+	.write8		= bcma_host_soc_write8,
+	.write16	= bcma_host_soc_write16,
+	.write32	= bcma_host_soc_write32,
+#ifdef CONFIG_BCMA_BLOCKIO
+	.block_read	= bcma_host_soc_block_read,
+	.block_write	= bcma_host_soc_block_write,
+#endif
+	.aread32	= bcma_host_soc_aread32,
+	.awrite32	= bcma_host_soc_awrite32,
+};
+
+int __init bcma_host_soc_register(struct bcma_soc *soc)
+{
+	struct bcma_bus *bus = &soc->bus;
+
+	/* iomap only first core. We have to read some register on this core
+	 * to scan the bus.
+	 */
+	bus->mmio = ioremap(BCMA_ADDR_BASE, BCMA_CORE_SIZE * 1);
+	if (!bus->mmio)
+		return -ENOMEM;
+
+	/* Host specific */
+	bus->hosttype = BCMA_HOSTTYPE_SOC;
+	bus->ops = &bcma_host_soc_ops;
+
+	/* Initialize struct, detect chip */
+	bcma_init_bus(bus);
+
+	return 0;
+}
+
+int __init bcma_host_soc_init(struct bcma_soc *soc)
+{
+	struct bcma_bus *bus = &soc->bus;
+	int err;
+
+	/* Scan bus and initialize it */
+	err = bcma_bus_early_register(bus);
+	if (err)
+		iounmap(bus->mmio);
+
+	return err;
+}
+
+#ifdef CONFIG_OF
+static int bcma_host_soc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct bcma_bus *bus;
+	int err;
+
+	/* Alloc */
+	bus = devm_kzalloc(dev, sizeof(*bus), GFP_KERNEL);
+	if (!bus)
+		return -ENOMEM;
+
+	bus->dev = dev;
+
+	/* Map MMIO */
+	bus->mmio = of_iomap(np, 0);
+	if (!bus->mmio)
+		return -ENOMEM;
+
+	/* Host specific */
+	bus->hosttype = BCMA_HOSTTYPE_SOC;
+	bus->ops = &bcma_host_soc_ops;
+
+	/* Initialize struct, detect chip */
+	bcma_init_bus(bus);
+
+	/* Register */
+	err = bcma_bus_register(bus);
+	if (err)
+		goto err_unmap_mmio;
+
+	platform_set_drvdata(pdev, bus);
+
+	return err;
+
+err_unmap_mmio:
+	iounmap(bus->mmio);
+	return err;
+}
+
+static void bcma_host_soc_remove(struct platform_device *pdev)
+{
+	struct bcma_bus *bus = platform_get_drvdata(pdev);
+
+	bcma_bus_unregister(bus);
+	iounmap(bus->mmio);
+	platform_set_drvdata(pdev, NULL);
+}
+
+static const struct of_device_id bcma_host_soc_of_match[] = {
+	{ .compatible = "brcm,bus-axi", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, bcma_host_soc_of_match);
+
+static struct platform_driver bcma_host_soc_driver = {
+	.driver = {
+		.name = "bcma-host-soc",
+		.of_match_table = bcma_host_soc_of_match,
+	},
+	.probe		= bcma_host_soc_probe,
+	.remove		= bcma_host_soc_remove,
+};
+
+int __init bcma_host_soc_register_driver(void)
+{
+	return platform_driver_register(&bcma_host_soc_driver);
+}
+
+void __exit bcma_host_soc_unregister_driver(void)
+{
+	platform_driver_unregister(&bcma_host_soc_driver);
+}
+#endif /* CONFIG_OF */