Add support for superpages (hugepages) in PV domain

This patch adds the option "superpages" to the domain configuration
file. If it is set, the domain is populated using 2M pages.

This code does not support fallback to small pages.  If the domain can
not be created with 2M pages, the  create will fail.

The patch also includes support for saving and restoring domains with
the superpage flag set.  However, if a domain has freed small pages
within its physical page array and then extended the array, the
restore will fill in those freed pages.  It will then attempt to
allocate more than its memory limit and will fail.  This is
significant because apparently Linux does this during boot, thus a
freshly booted Linux image can not be saved and restored successfully.

Signed-off-by: Dave McCracken <dcm@mccr.org>

1 files changed, 44 insertions, 11 deletions

diff --git a/tools/libxc/xc_dom_x86.c b/tools/libxc/xc_dom_x86.c
index 6ae9487656..a89eb4fef7 100644
--- a/tools/libxc/xc_dom_x86.c
+++ b/tools/libxc/xc_dom_x86.c
@@ -26,6 +26,9 @@
 
 /* ------------------------------------------------------------------------ */
 
+#define SUPERPAGE_PFN_SHIFT  9
+#define SUPERPAGE_NR_PFNS    (1UL << SUPERPAGE_PFN_SHIFT)
+
 #define bits_to_mask(bits)       (((xen_vaddr_t)1 << (bits))-1)
 #define round_down(addr, mask)   ((addr) & ~(mask))
 #define round_up(addr, mask)     ((addr) | (mask))
@@ -691,7 +694,7 @@ static int x86_shadow(int xc, domid_t domid)
     return rc;
 }
 
-int arch_setup_meminit(struct xc_dom_image *dom)
+int arch_setup_meminit(struct xc_dom_image *dom, int superpages)
 {
     int rc;
     xen_pfn_t pfn, allocsz, i;
@@ -707,19 +710,49 @@ int arch_setup_meminit(struct xc_dom_image *dom)
             return rc;
     }
 
-    /* setup initial p2m */
     dom->p2m_host = xc_dom_malloc(dom, sizeof(xen_pfn_t) * dom->total_pages);
-    for ( pfn = 0; pfn < dom->total_pages; pfn++ )
-        dom->p2m_host[pfn] = pfn;
+    if (superpages)
+    {
+        int count = dom->total_pages >> SUPERPAGE_PFN_SHIFT;
+        xen_pfn_t extents[count];
+
+        xc_dom_printf("Populating memory with %d superpages\n", count);
+        for (pfn = 0; pfn < count; pfn++)
+            extents[pfn] = pfn << SUPERPAGE_PFN_SHIFT;
+        rc = xc_domain_memory_populate_physmap(dom->guest_xc, dom->guest_domid,
+                                               count, SUPERPAGE_PFN_SHIFT, 0,
+                                               extents);
+        if (!rc)
+        {
+            int i, j;
+            xen_pfn_t mfn;
 
-    /* allocate guest memory */
-    for ( i = rc = allocsz = 0; (i < dom->total_pages) && !rc; i += allocsz )
+            /* Expand the returned mfn into the p2m array */
+            pfn = 0;
+            for (i = 0; i < count; i++)
+            {
+                mfn = extents[i];
+                for (j = 0; j < SUPERPAGE_NR_PFNS; j++, pfn++)
+                {
+                    dom->p2m_host[pfn] = mfn + j;
+                }
+            }
+        }
+    } else
     {
-        allocsz = dom->total_pages - i;
-        if ( allocsz > 1024*1024 )
-            allocsz = 1024*1024;
-        rc = xc_domain_memory_populate_physmap(
-            dom->guest_xc, dom->guest_domid, allocsz, 0, 0, &dom->p2m_host[i]);
+        /* setup initial p2m */
+        for ( pfn = 0; pfn < dom->total_pages; pfn++ )
+            dom->p2m_host[pfn] = pfn;
+        
+        /* allocate guest memory */
+        for ( i = rc = allocsz = 0; (i < dom->total_pages) && !rc; i += allocsz )
+        {
+            allocsz = dom->total_pages - i;
+            if ( allocsz > 1024*1024 )
+                allocsz = 1024*1024;
+            rc = xc_domain_memory_populate_physmap(
+                dom->guest_xc, dom->guest_domid, allocsz, 0, 0, &dom->p2m_host[i]);
+        }
     }
 
     return rc;