diff --git a/arch/x86/kernel/amd_node.c b/arch/x86/kernel/amd_node.c
index 408b9fd48349..762585775b5a 100644
--- a/arch/x86/kernel/amd_node.c
+++ b/arch/x86/kernel/amd_node.c
@@ -38,7 +38,6 @@ static struct pci_dev **amd_roots;
 
 /* Protect the PCI config register pairs used for SMN. */
 static DEFINE_MUTEX(smn_mutex);
-static bool smn_exclusive;
 
 #define SMN_INDEX_OFFSET	0x60
 #define SMN_DATA_OFFSET		0x64
@@ -91,11 +90,16 @@ static int __amd_smn_rw(u8 i_off, u8 d_off, u16 node, u32 address, u32 *value, b
 	if (node >= amd_num_nodes())
 		return err;
 
-	root = amd_roots[node];
-	if (!root)
+	/*
+	 * Uninitialized amd_roots indicates pci_request_config_region_exclusive()
+	 * didn't run or failed and thus the kernel cannot rely on having
+	 * exclusive access to SMN registers so prevent that.
+	 */
+	if (!amd_roots)
 		return err;
 
-	if (!smn_exclusive)
+	root = amd_roots[node];
+	if (!root)
 		return err;
 
 	guard(mutex)(&smn_mutex);
@@ -313,8 +317,6 @@ static int __init amd_smn_init(void)
 		debugfs_create_file("value",	0600, debugfs_dir, NULL, &smn_value_fops);
 	}
 
-	smn_exclusive = true;
-
 	return 0;
 }