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Re: [Xen-devel] [PATCH 2/2] libxc: fix PV vNUMA guest memory allocation

On 07/06/2015 02:30 PM, Wei Liu wrote:
On Mon, Jul 06, 2015 at 02:26:37PM +0100, Andrew Cooper wrote:
On 06/07/15 14:17, Wei Liu wrote:
In 415b58c1 (tools/libxc: Batch memory allocations for PV guests) the
number of super pages is calculated with the number of total pages. That
is wrong. It breaks PV guest vNUMA. The correct number of super pages
should be derived from the number of pages within that virtual NUMA

Also change the name and type of super page variable to match the naming
convention and type of normal page variable. Make the necessary
adjustment to make code compile.

Reported-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
Cc: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
  tools/libxc/xc_dom_x86.c | 10 +++++-----
  1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/libxc/xc_dom_x86.c b/tools/libxc/xc_dom_x86.c
index acd7b3f..faabe96 100644
--- a/tools/libxc/xc_dom_x86.c
+++ b/tools/libxc/xc_dom_x86.c
@@ -879,9 +879,8 @@ int arch_setup_meminit(struct xc_dom_image *dom)
          for ( i = 0; i < nr_vmemranges; i++ )
              unsigned int memflags;
-            uint64_t pages;
+            uint64_t pages, super_pages;
              unsigned int pnode = vnode_to_pnode[vmemranges[i].nid];
-            int nr_spages = dom->total_pages >> SUPERPAGE_PFN_SHIFT;
              xen_pfn_t extents[SUPERPAGE_BATCH_SIZE];
              xen_pfn_t pfn_base_idx;

@@ -891,15 +890,16 @@ int arch_setup_meminit(struct xc_dom_image *dom)

              pages = (vmemranges[i].end - vmemranges[i].start)
                  >> PAGE_SHIFT;
+            super_pages = pages >> SUPERPAGE_PFN_SHIFT;
              pfn_base = vmemranges[i].start >> PAGE_SHIFT;

              for ( pfn = pfn_base; pfn < pfn_base+pages; pfn++ )
                  dom->p2m_host[pfn] = pfn;

              pfn_base_idx = pfn_base;
-            while (nr_spages) {
-                int count = min(nr_spages, SUPERPAGE_BATCH_SIZE);
-                nr_spages -= count;
+            while (super_pages) {
+                int count = min_t(uint64_t, super_pages, SUPERPAGE_BATCH_SIZE);

This line alone indicates that int is not an appropriate type for
count.  unsigned int as as an absolute minimum, as it will be bounded to

Yes, I also need to make count uint64_t.

Is this needed? count should never be larger than 512 (aka SUPERPAGE_BATCH_SIZE).

Ross Lagerwall

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