diff --git a/drivers/virt/gunyah/vm_mgr.c b/drivers/virt/gunyah/vm_mgr.c
index bcc053c86df2..83a2983ac3bc 100644
--- a/drivers/virt/gunyah/vm_mgr.c
+++ b/drivers/virt/gunyah/vm_mgr.c
@@ -27,6 +27,8 @@
 // "From" extent for memory private to guest
 #define GUNYAH_VM_MEM_EXTENT_HOST_PRIVATE_LABEL 2
 
+#define BOOT_CONTEXT_REG_MASK	GUNYAH_VM_BOOT_CONTEXT_REG(0xff, 0xff)
+
 static DEFINE_XARRAY(gunyah_vm_functions);
 
 static void gunyah_vm_put_function(struct gunyah_vm_function *fn)
@@ -551,6 +553,9 @@ static long gunyah_vm_set_boot_context(struct gunyah_vm *ghvm,
 	u8 reg_set, reg_index; /* to check values are reasonable */
 	int ret;
 
+	if (boot_ctx->reg & ~BOOT_CONTEXT_REG_MASK)
+		return -EINVAL;
+
 	reg_set = (boot_ctx->reg >> GUNYAH_VM_BOOT_CONTEXT_REG_SHIFT) & 0xff;
 	reg_index = boot_ctx->reg & 0xff;