[Xen-devel] [PATCH 1 of 2] x86/numa: Correct assumption that each NUMA node has memory

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

It is now quite easy to buy servers with incorrectly populated DIMMs, especially
with AMD Magny-Cours and Interlagos systems which have two NUMA nodes per 
socket.

Currently, Xen will assign all CPUs on nodes without memory to node 0, which
leads to interestingly wrong NUMA information, causing numa aware functionality
such as alloc_domheap_pages() to get things very wrong.

This patch splits the current logic to accept NUMA nodes without memory, which
corrects the accounting of CPUs to online NUMA nodes.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

diff -r 7b0dc7f3ddfe -r a2dbed3582e5 xen/arch/x86/setup.c
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -195,8 +195,10 @@ void __devinit srat_detect_node(int cpu)
     u32 apicid = x86_cpu_to_apicid[cpu];
 
     node = apicid_to_node[apicid];
-    if ( node == NUMA_NO_NODE || !node_online(node) )
+    if ( node == NUMA_NO_NODE )
         node = 0;
+
+    node_set_online(node);
     numa_set_node(cpu, node);
 
     if ( opt_cpu_info && acpi_numa > 0 )
diff -r 7b0dc7f3ddfe -r a2dbed3582e5 xen/arch/x86/srat.c
--- a/xen/arch/x86/srat.c
+++ b/xen/arch/x86/srat.c
@@ -23,7 +23,8 @@
 
 static struct acpi_table_slit *__read_mostly acpi_slit;
 
-static nodemask_t nodes_parsed __initdata;
+static nodemask_t memory_nodes_parsed __initdata;
+static nodemask_t processor_nodes_parsed __initdata;
 static nodemask_t nodes_found __initdata;
 static struct node nodes[MAX_NUMNODES] __initdata;
 static u8 __read_mostly pxm2node[256] = { [0 ... 255] = NUMA_NO_NODE };
@@ -221,6 +222,7 @@ acpi_numa_processor_affinity_init(struct
                return;
        }
        apicid_to_node[pa->apic_id] = node;
+       node_set(node, processor_nodes_parsed);
        acpi_numa = 1;
        printk(KERN_INFO "SRAT: PXM %u -> APIC %u -> Node %u\n",
               pxm, pa->apic_id, node);
@@ -287,7 +289,7 @@ acpi_numa_memory_affinity_init(struct ac
                return;
        }
        nd = &nodes[node];
-       if (!node_test_and_set(node, nodes_parsed)) {
+       if (!node_test_and_set(node, memory_nodes_parsed)) {
                nd->start = start;
                nd->end = end;
        } else {
@@ -324,7 +326,7 @@ static int nodes_cover_memory(void)
 
                do {
                        found = 0;
-                       for_each_node_mask(j, nodes_parsed)
+                       for_each_node_mask(j, memory_nodes_parsed)
                                if (start < nodes[j].end
                                    && end > nodes[j].start) {
                                        if (start >= nodes[j].start) {
@@ -418,6 +420,7 @@ void __init srat_parse_regions(u64 addr)
 int __init acpi_scan_nodes(u64 start, u64 end)
 {
        int i;
+       nodemask_t all_nodes_parsed;
 
        /* First clean up the node list */
        for (i = 0; i < MAX_NUMNODES; i++)
@@ -441,17 +444,26 @@ int __init acpi_scan_nodes(u64 start, u6
                return -1;
        }
 
+       nodes_or(all_nodes_parsed, memory_nodes_parsed, processor_nodes_parsed);
+
        /* Finally register nodes */
-       for_each_node_mask(i, nodes_parsed)
+       for_each_node_mask(i, all_nodes_parsed)
        {
-               if ((nodes[i].end - nodes[i].start) < NODE_MIN_SIZE)
-                       continue;
+               u64 size = nodes[i].end - nodes[i].start;
+               if ( size == 0 )
+                       printk(KERN_WARNING "SRAT: Node %u has no memory. "
+                              "BIOS Bug or mis-configured hardware?\n", i);
+
+               else if (size < NODE_MIN_SIZE)
+                       printk(KERN_WARNING "SRAT: Node %u has only %"PRIu64
+                              " bytes of memory. BIOS Bug?\n", i, size);
+
                setup_node_bootmem(i, nodes[i].start, nodes[i].end);
        }
        for (i = 0; i < nr_cpu_ids; i++) {
                if (cpu_to_node[i] == NUMA_NO_NODE)
                        continue;
-               if (!node_isset(cpu_to_node[i], nodes_parsed))
+               if (!node_isset(cpu_to_node[i], processor_nodes_parsed))
                        numa_set_node(i, NUMA_NO_NODE);
        }
        numa_init_array();

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