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, 81 insertions, 0 deletions

diff --git a/arch/mips/rb532/setup.c b/arch/mips/rb532/setup.c
new file mode 100644
index 000000000..51af9d374
--- /dev/null
+++ b/arch/mips/rb532/setup.c
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * setup.c - boot time setup code
+ */
+
+#include <linux/init.h>
+#include <linux/export.h>
+
+#include <asm/bootinfo.h>
+#include <asm/reboot.h>
+#include <asm/time.h>
+#include <linux/ioport.h>
+
+#include <asm/mach-rc32434/rb.h>
+#include <asm/mach-rc32434/pci.h>
+
+struct pci_reg __iomem *pci_reg;
+EXPORT_SYMBOL(pci_reg);
+
+static struct resource pci0_res[] = {
+	{
+		.name = "pci_reg0",
+		.start = PCI0_BASE_ADDR,
+		.end = PCI0_BASE_ADDR + sizeof(struct pci_reg),
+		.flags = IORESOURCE_MEM,
+	}
+};
+
+static void rb_machine_restart(char *command)
+{
+	/* just jump to the reset vector */
+	writel(0x80000001, IDT434_REG_BASE + RST);
+	((void (*)(void)) KSEG1ADDR(0x1FC00000u))();
+}
+
+static void rb_machine_halt(void)
+{
+	for (;;)
+		continue;
+}
+
+void __init plat_mem_setup(void)
+{
+	u32 val;
+
+	_machine_restart = rb_machine_restart;
+	_machine_halt = rb_machine_halt;
+	pm_power_off = rb_machine_halt;
+
+	set_io_port_base(KSEG1);
+
+	pci_reg = ioremap(pci0_res[0].start,
+				pci0_res[0].end - pci0_res[0].start);
+	if (!pci_reg) {
+		printk(KERN_ERR "Could not remap PCI registers\n");
+		return;
+	}
+
+	val = __raw_readl(&pci_reg->pcic);
+	val &= 0xFFFFFF7;
+	__raw_writel(val, (void *)&pci_reg->pcic);
+
+#ifdef CONFIG_PCI
+	/* Enable PCI interrupts in EPLD Mask register */
+	*epld_mask = 0x0;
+	*(epld_mask + 1) = 0x0;
+#endif
+	write_c0_wired(0);
+}
+
+const char *get_system_type(void)
+{
+	switch (mips_machtype) {
+	case MACH_MIKROTIK_RB532A:
+		return "Mikrotik RB532A";
+		break;
+	default:
+		return "Mikrotik RB532";
+		break;
+	}
+}