numa: describe siblings distances within cells

Add support for describing NUMA distances in a domain's <numa> <cell>
XML description.

Below is an example of a 4 node setup:

  <cpu>
    <numa>
      <cell id='0' cpus='0-3' memory='2097152' unit='KiB'>
        <distances>
          <sibling id='0' value='10'/>
          <sibling id='1' value='21'/>
          <sibling id='2' value='31'/>
          <sibling id='3' value='21'/>
        </distances>
      </cell>
      <cell id='1' cpus='4-7' memory='2097152' unit='KiB'>
        <distances>
          <sibling id='0' value='21'/>
          <sibling id='1' value='10'/>
          <sibling id='2' value='21'/>
          <sibling id='3' value='31'/>
        </distances>
      </cell>
      <cell id='2' cpus='8-11' memory='2097152' unit='KiB'>
        <distances>
          <sibling id='0' value='31'/>
          <sibling id='1' value='21'/>
          <sibling id='2' value='10'/>
          <sibling id='3' value='21'/>
        </distances>
      <cell id='3' cpus='12-15' memory='2097152' unit='KiB'>
        <distances>
          <sibling id='0' value='21'/>
          <sibling id='1' value='31'/>
          <sibling id='2' value='21'/>
          <sibling id='3' value='10'/>
        </distances>
      </cell>
    </numa>
  </cpu>

A <cell> defines a NUMA node. <distances> describes the NUMA distance
from the <cell> to the other NUMA nodes (the <sibling>s).  For example,
in above XML description, the distance between NUMA node0 <cell id='0'
...> and NUMA node2 <sibling id='2' ...> is 31.

Valid distance values are '10 <= value <= 255'.  A distance value of 10
represents the distance to the node itself.  A distance value of 20
represents the default value for remote nodes but other values are
possible depending on the physical topology of the system.

When distances are not fully described, any missing sibling distance
values will default to 10 for local nodes and 20 for remote nodes.

If distance is given for A -> B, then we default B -> A to the same
value instead of 20.
Signed-off-by: NWim ten Have <wim.ten.have@oracle.com>
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Signed-off-by: NJim Fehlig <jfehlig@suse.com>

docs/formatdomain.html.in

@@ -1529,7 +1529,69 @@
     </p>
 
     <p>
-      This guest NUMA specification is currently available only for QEMU/KVM.
+      This guest NUMA specification is currently available only for
+      QEMU/KVM and Xen.
+    </p>
+
+    <p>
+      A NUMA hardware architecture supports the notion of distances
+      between NUMA cells. <span class="since">Since 3.10.0</span> it
+      is possible to define the distance between NUMA cells using the
+      <code>distances</code> element within a NUMA <code>cell</code>
+      description. The <code>sibling</code> sub-element is used to
+      specify the distance value between sibling NUMA cells. For more
+      details, see the chapter explaining the system's SLIT (System
+      Locality Information Table) within the ACPI (Advanced
+      Configuration and Power Interface) specification.
+    </p>
+
+<pre>
+...
+&lt;cpu&gt;
+  ...
+  &lt;numa&gt;
+    &lt;cell id='0' cpus='0,4-7' memory='512000' unit='KiB'&gt;
+      &lt;distances&gt;
+        &lt;sibling id='0' value='10'/&gt;
+        &lt;sibling id='1' value='21'/&gt;
+        &lt;sibling id='2' value='31'/&gt;
+        &lt;sibling id='3' value='41'/&gt;
+      &lt;/distances&gt;
+    &lt;/cell&gt;
+    &lt;cell id='1' cpus='1,8-10,12-15' memory='512000' unit='KiB' memAccess='shared'&gt;
+      &lt;distances&gt;
+        &lt;sibling id='0' value='21'/&gt;
+        &lt;sibling id='1' value='10'/&gt;
+        &lt;sibling id='2' value='21'/&gt;
+        &lt;sibling id='3' value='31'/&gt;
+      &lt;/distances&gt;
+    &lt;/cell&gt;
+    &lt;cell id='2' cpus='2,11' memory='512000' unit='KiB' memAccess='shared'&gt;
+      &lt;distances&gt;
+        &lt;sibling id='0' value='31'/&gt;
+        &lt;sibling id='1' value='21'/&gt;
+        &lt;sibling id='2' value='10'/&gt;
+        &lt;sibling id='3' value='21'/&gt;
+      &lt;/distances&gt;
+    &lt;/cell&gt;
+    &lt;cell id='3' cpus='3' memory='512000' unit='KiB'&gt;
+      &lt;distances&gt;
+        &lt;sibling id='0' value='41'/&gt;
+        &lt;sibling id='1' value='31'/&gt;
+        &lt;sibling id='2' value='21'/&gt;
+        &lt;sibling id='3' value='10'/&gt;
+      &lt;/distances&gt;
+    &lt;/cell&gt;
+  &lt;/numa&gt;
+  ...
+&lt;/cpu&gt;
+...</pre>
+
+    <p>
+      Describing distances between NUMA cells is currently only supported
+      by Xen. If no <code>distances</code> are given to describe
+      the SLIT data between different cells, it will default to a scheme
+      using 10 for local and 20 for remote distances.
     </p>
 
     <h3><a id="elementsEvents">Events configuration</a></h3>

docs/schemas/basictypes.rng

@@ -77,6 +77,13 @@
     </choice>
   </define>
 
+  <define name="numaDistanceValue">
+    <data type="unsignedInt">
+      <param name="minInclusive">10</param>
+      <param name="maxInclusive">255</param>
+    </data>
+  </define>
+
   <define name="pciaddress">
     <optional>
       <attribute name="domain">

docs/schemas/cputypes.rng

@@ -129,6 +129,24 @@
           </choice>
         </attribute>
       </optional>
+      <optional>
+        <element name="distances">
+          <oneOrMore>
+            <ref name="numaDistance"/>
+          </oneOrMore>
+        </element>
+      </optional>
+    </element>
+  </define>
+
+  <define name="numaDistance">
+    <element name="sibling">
+      <attribute name="id">
+        <ref name="unsignedInt"/>
+      </attribute>
+      <attribute name="value">
+        <ref name="numaDistanceValue"/>
+      </attribute>
     </element>
   </define>
 

src/conf/numa_conf.c

@@ -29,6 +29,15 @@
 #include "virnuma.h"
 #include "virstring.h"
 
+/*
+ * Distance definitions defined Conform ACPI 2.0 SLIT.
+ * See include/linux/topology.h
+ */
+#define LOCAL_DISTANCE          10
+#define REMOTE_DISTANCE         20
+/* SLIT entry value is a one-byte unsigned integer. */
+#define UNREACHABLE            255
+
 #define VIR_FROM_THIS VIR_FROM_DOMAIN
 
 VIR_ENUM_IMPL(virDomainNumatuneMemMode,
@@ -48,6 +57,8 @@ VIR_ENUM_IMPL(virDomainMemoryAccess, VIR_DOMAIN_MEMORY_ACCESS_LAST,
               "shared",
               "private")
 
+typedef struct _virDomainNumaDistance virDomainNumaDistance;
+typedef virDomainNumaDistance *virDomainNumaDistancePtr;
 
 typedef struct _virDomainNumaNode virDomainNumaNode;
 typedef virDomainNumaNode *virDomainNumaNodePtr;
@@ -66,6 +77,12 @@ struct _virDomainNuma {
         virBitmapPtr nodeset;   /* host memory nodes where this guest node resides */
         virDomainNumatuneMemMode mode;  /* memory mode selection */
         virDomainMemoryAccess memAccess; /* shared memory access configuration */
+
+        struct _virDomainNumaDistance {
+            unsigned int value; /* locality value for node i->j or j->i */
+            unsigned int cellid;
+        } *distances;           /* remote node distances */
+        size_t ndistances;
     } *mem_nodes;           /* guest node configuration */
     size_t nmem_nodes;
 
@@ -686,6 +703,144 @@ virDomainNumatuneNodesetIsAvailable(virDomainNumaPtr numatune,
 }
 
 
+static int
+virDomainNumaDefNodeDistanceParseXML(virDomainNumaPtr def,
+                                     xmlXPathContextPtr ctxt,
+                                     unsigned int cur_cell)
+{
+    int ret = -1;
+    int sibling;
+    char *tmp = NULL;
+    xmlNodePtr *nodes = NULL;
+    size_t i, ndistances = def->nmem_nodes;
+
+    if (!ndistances)
+        return 0;
+
+    /* check if NUMA distances definition is present */
+    if (!virXPathNode("./distances[1]", ctxt))
+        return 0;
+
+    if ((sibling = virXPathNodeSet("./distances[1]/sibling", ctxt, &nodes)) <= 0) {
+        virReportError(VIR_ERR_XML_ERROR, "%s",
+                       _("NUMA distances defined without siblings"));
+        goto cleanup;
+    }
+
+    for (i = 0; i < sibling; i++) {
+        virDomainNumaDistancePtr ldist, rdist;
+        unsigned int sibling_id, sibling_value;
+
+        /* siblings are in order of parsing or explicitly numbered */
+        if (!(tmp = virXMLPropString(nodes[i], "id"))) {
+            virReportError(VIR_ERR_XML_ERROR,
+                           _("Missing 'id' attribute in NUMA "
+                             "distances under 'cell id %d'"),
+                           cur_cell);
+            goto cleanup;
+        }
+
+        /* The "id" needs to be applicable */
+        if (virStrToLong_uip(tmp, NULL, 10, &sibling_id) < 0) {
+            virReportError(VIR_ERR_XML_ERROR,
+                           _("Invalid 'id' attribute in NUMA "
+                             "distances for sibling: '%s'"),
+                           tmp);
+            goto cleanup;
+        }
+        VIR_FREE(tmp);
+
+        /* The "id" needs to be within numa/cell range */
+        if (sibling_id >= ndistances) {
+            virReportError(VIR_ERR_XML_ERROR,
+                           _("'sibling_id %d' does not refer to a "
+                             "valid cell within NUMA 'cell id %d'"),
+                           sibling_id, cur_cell);
+            goto cleanup;
+        }
+
+        /* We need a locality value. Check and correct
+         * distance to local and distance to remote node.
+         */
+        if (!(tmp = virXMLPropString(nodes[i], "value"))) {
+            virReportError(VIR_ERR_XML_ERROR,
+                           _("Missing 'value' attribute in NUMA distances "
+                             "under 'cell id %d' for 'sibling id %d'"),
+                           cur_cell, sibling_id);
+            goto cleanup;
+        }
+
+        /* The "value" needs to be applicable */
+        if (virStrToLong_uip(tmp, NULL, 10, &sibling_value) < 0) {
+            virReportError(VIR_ERR_XML_ERROR,
+                           _("'value %s' is invalid for "
+                             "'sibling id %d' under NUMA 'cell id %d'"),
+                           tmp, sibling_id, cur_cell);
+            goto cleanup;
+        }
+        VIR_FREE(tmp);
+
+        /* Assure LOCAL_DISTANCE <= "value" <= UNREACHABLE
+         * and correct LOCAL_DISTANCE setting if such applies.
+         */
+        if ((sibling_value < LOCAL_DISTANCE ||
+             sibling_value > UNREACHABLE) ||
+            (sibling_id == cur_cell &&
+             sibling_value != LOCAL_DISTANCE) ||
+            (sibling_id != cur_cell &&
+             sibling_value == LOCAL_DISTANCE)) {
+            virReportError(VIR_ERR_XML_ERROR,
+                           _("'value %d' is invalid for "
+                             "'sibling id %d' under NUMA 'cell id %d'"),
+                           sibling_value, sibling_id, cur_cell);
+            goto cleanup;
+        }
+
+        /* Apply the local / remote distance */
+        ldist = def->mem_nodes[cur_cell].distances;
+        if (!ldist) {
+            if (VIR_ALLOC_N(ldist, ndistances) < 0)
+                goto cleanup;
+
+            ldist[cur_cell].value = LOCAL_DISTANCE;
+            ldist[cur_cell].cellid = cur_cell;
+            def->mem_nodes[cur_cell].ndistances = ndistances;
+        }
+
+        ldist[sibling_id].cellid = sibling_id;
+        ldist[sibling_id].value = sibling_value;
+        def->mem_nodes[cur_cell].distances = ldist;
+
+        /* Apply symmetry if none given */
+        rdist = def->mem_nodes[sibling_id].distances;
+        if (!rdist) {
+            if (VIR_ALLOC_N(rdist, ndistances) < 0)
+                goto cleanup;
+
+            rdist[sibling_id].value = LOCAL_DISTANCE;
+            rdist[sibling_id].cellid = sibling_id;
+            def->mem_nodes[sibling_id].ndistances = ndistances;
+        }
+
+        rdist[cur_cell].cellid = cur_cell;
+        if (!rdist[cur_cell].value)
+            rdist[cur_cell].value = sibling_value;
+        def->mem_nodes[sibling_id].distances = rdist;
+    }
+
+    ret = 0;
+
+ cleanup:
+    if (ret) {
+        for (i = 0; i < ndistances; i++)
+            VIR_FREE(def->mem_nodes[i].distances);
+    }
+    VIR_FREE(nodes);
+    VIR_FREE(tmp);
+
+    return ret;
+}
+
 int
 virDomainNumaDefCPUParseXML(virDomainNumaPtr def,
                             xmlXPathContextPtr ctxt)
@@ -694,7 +849,7 @@ virDomainNumaDefCPUParseXML(virDomainNumaPtr def,
     xmlNodePtr oldNode = ctxt->node;
     char *tmp = NULL;
     int n;
-    size_t i;
+    size_t i, j;
     int ret = -1;
 
     /* check if NUMA definition is present */
@@ -712,7 +867,6 @@ virDomainNumaDefCPUParseXML(virDomainNumaPtr def,
     def->nmem_nodes = n;
 
     for (i = 0; i < n; i++) {
-        size_t j;
         int rc;
         unsigned int cur_cell = i;
 
@@ -788,6 +942,10 @@ virDomainNumaDefCPUParseXML(virDomainNumaPtr def,
             def->mem_nodes[cur_cell].memAccess = rc;
             VIR_FREE(tmp);
         }
+
+        /* Parse NUMA distances info */
+        if (virDomainNumaDefNodeDistanceParseXML(def, ctxt, cur_cell) < 0)
+                goto cleanup;
     }
 
     ret = 0;
@@ -815,6 +973,8 @@ virDomainNumaDefCPUFormatXML(virBufferPtr buf,
     virBufferAddLit(buf, "<numa>\n");
     virBufferAdjustIndent(buf, 2);
     for (i = 0; i < ncells; i++) {
+        int ndistances;
+
         memAccess = virDomainNumaGetNodeMemoryAccessMode(def, i);
 
         if (!(cpustr = virBitmapFormat(virDomainNumaGetNodeCpumask(def, i))))
@@ -829,7 +989,32 @@ virDomainNumaDefCPUFormatXML(virBufferPtr buf,
         if (memAccess)
             virBufferAsprintf(buf, " memAccess='%s'",
                               virDomainMemoryAccessTypeToString(memAccess));
-        virBufferAddLit(buf, "/>\n");
+
+        ndistances = def->mem_nodes[i].ndistances;
+        if (!ndistances) {
+            virBufferAddLit(buf, "/>\n");
+        } else {
+            size_t j;
+            virDomainNumaDistancePtr distances = def->mem_nodes[i].distances;
+
+            virBufferAddLit(buf, ">\n");
+            virBufferAdjustIndent(buf, 2);
+            virBufferAddLit(buf, "<distances>\n");
+            virBufferAdjustIndent(buf, 2);
+            for (j = 0; j < ndistances; j++) {
+                if (distances[j].value) {
+                    virBufferAddLit(buf, "<sibling");
+                    virBufferAsprintf(buf, " id='%d'", distances[j].cellid);
+                    virBufferAsprintf(buf, " value='%d'", distances[j].value);
+                    virBufferAddLit(buf, "/>\n");
+                }
+            }
+            virBufferAdjustIndent(buf, -2);
+            virBufferAddLit(buf, "</distances>\n");
+            virBufferAdjustIndent(buf, -2);
+            virBufferAddLit(buf, "</cell>\n");
+        }
+
         VIR_FREE(cpustr);
     }
     virBufferAdjustIndent(buf, -2);