Re: [PATCH v3 05/19] xen/arm: mm: Add support for the contiguous bit

[Julien Grall]

Hi,

On 21/02/2022 10:22, Julien Grall wrote:

@@ -1333,21 +1386,34 @@ static int xen_pt_update(unsigned long virt,
      while ( left )
      {
          unsigned int order, level;
+        unsigned int nr_contig;
+        unsigned int new_flags;

level = xen_pt_mapping_level(vfn, mfn, left, flags);

          order = XEN_PT_LEVEL_ORDER(level);

ASSERT(left >= BIT(order, UL)); - rc = xen_pt_update_entry(root, pfn_to_paddr(vfn), mfn, level, flags);

-        if ( rc )
-            break;
+        /*
+         * Check if we can set the contiguous mapping and update the
+         * flags accordingly.
+         */
+        nr_contig = xen_pt_check_contig(vfn, mfn, level, left, flags);
+        new_flags = flags | ((nr_contig > 1) ? _PAGE_CONTIG : 0);

- vfn += 1U << order;

-        if ( !mfn_eq(mfn, INVALID_MFN) )
-            mfn = mfn_add(mfn, 1U << order);
+        for ( ; nr_contig > 0; nr_contig-- )
+        {
+            rc = xen_pt_update_entry(root, pfn_to_paddr(vfn), mfn, level,
+                                     new_flags);
+            if ( rc )
+                break;

- left -= (1U << order);

+            vfn += 1U << order;
+            if ( !mfn_eq(mfn, INVALID_MFN) )
+                mfn = mfn_add(mfn, 1U << order);
+
+            left -= (1U << order);
+        }

I forgot to add:

if ( rc )
  break;

Without it, the outer loop will never exit in case of an error.

Cheers,

--
Julien Grall