xc: use XENMEM_claim_pages hypercall during guest creation.

We add an extra parameter to the structures passed to the
PV routine (arch_setup_meminit) and HVM routine (setup_guest)
that determines whether the claim hypercall is to be done.

The contents of the 'claim_enabled' is defined as an 'int'
in case the hypercall expands in the future with extra
flags (for example for per-NUMA allocation). For right now
the proper values are: 0 to disable it or 1 to enable
it.

If the hypervisor does not support this function, the
xc_domain_claim_pages and xc_domain_get_outstanding_pages
will silently return 0 (and set errno to zero).

Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
[v2: Updated per Ian's recommendations]
[v3: Added support for out-of-sync hypervisor]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/tools/libxc/xc_dom_x86.c b/tools/libxc/xc_dom_x86.c
index eb9ac07434..d89526d789 100644
--- a/tools/libxc/xc_dom_x86.c
+++ b/tools/libxc/xc_dom_x86.c
@@ -706,6 +706,13 @@ int arch_setup_meminit(struct xc_dom_image *dom)
     }
     else
     {
+        /* try to claim pages for early warning of insufficient memory avail */
+        if ( dom->claim_enabled ) {
+            rc = xc_domain_claim_pages(dom->xch, dom->guest_domid,
+                                       dom->total_pages);
+            if ( rc )
+                return rc;
+        }
         /* setup initial p2m */
         for ( pfn = 0; pfn < dom->total_pages; pfn++ )
             dom->p2m_host[pfn] = pfn;
@@ -722,6 +729,11 @@ int arch_setup_meminit(struct xc_dom_image *dom)
                 dom->xch, dom->guest_domid, allocsz,
                 0, 0, &dom->p2m_host[i]);
         }
+
+        /* Ensure no unclaimed pages are left unused.
+         * OK to call if hadn't done the earlier claim call. */
+        (void)xc_domain_claim_pages(dom->xch, dom->guest_domid,
+                                    0 /* cancels the claim */);
     }
 
     return rc;