1 files changed, 27 insertions, 0 deletions

diff --git a/arch/x86/kernel/amd_iommu.c b/arch/x86/kernel/amd_iommu.c
index 5eab6a84b9cc..fc97b51f0287 100644
--- a/arch/x86/kernel/amd_iommu.c
+++ b/arch/x86/kernel/amd_iommu.c
@@ -1325,6 +1325,33 @@ static void update_domain(struct protection_domain *domain)
 }
 
 /*
+ * This function is used to add another level to an IO page table. Adding
+ * another level increases the size of the address space by 9 bits to a size up
+ * to 64 bits.
+ */
+static bool increase_address_space(struct protection_domain *domain,
+                                   gfp_t gfp)
+{
+        u64 *pte;
+
+        if (domain->mode == PAGE_MODE_6_LEVEL)
+                /* address space already 64 bit large */
+                return false;
+
+        pte = (void *)get_zeroed_page(gfp);
+        if (!pte)
+                return false;
+
+        *pte             = PM_LEVEL_PDE(domain->mode,
+                                        virt_to_phys(domain->pt_root));
+        domain->pt_root  = pte;
+        domain->mode    += 1;
+        domain->updated  = true;
+
+        return true;
+}
+
+/*
  * If the pte_page is not yet allocated this function is called
  */
 static u64* alloc_pte(struct protection_domain *dom,