Re: [PATCH v2 10/10] xen/x86: add detection of memory interleaves for different nodes

[Wei Chen]

Hi Jan,

On 2022/4/26 17:20, Jan Beulich wrote:
On 18.04.2022 11:07, Wei Chen wrote:
--- a/xen/arch/x86/srat.c
+++ b/xen/arch/x86/srat.c
@@ -271,6 +271,35 @@ acpi_numa_processor_affinity_init(const struct 
acpi_srat_cpu_affinity *pa)
                       pxm, pa->apic_id, node);
  }
  
+/*
+ * Check to see if there are other nodes within this node's range.
+ * We just need to check full contains situation. Because overlaps
+ * have been checked before by conflicting_memblks.
+ */
+static bool __init check_node_memory_interleave(nodeid_t nid,
+                                                paddr_t start, paddr_t end)
+{
+       nodeid_t i;
+       const struct node *nd = &nodes[nid];
+
+       for_each_node_mask(i, memory_nodes_parsed)
+       {
+               /* Skip itself */
+               if (i == nid)
+                       continue;
+
+               nd = &nodes[i];
+               if (start < nd->start && nd->end < end) {
+                       printk(KERN_ERR
+                              "Node %u: (%"PRIpaddr"-%"PRIpaddr") interleaves with node %u 
(%"PRIpaddr"-%"PRIpaddr")\n",
+                              nid, start, end, i, nd->start, nd->end);
+                       return true;
+               }
+       }
+
+       return false;
+}
+
  /* Callback for parsing of the Proximity Domain <-> Memory Area mappings */
  void __init
  acpi_numa_memory_affinity_init(const struct acpi_srat_mem_affinity *ma)
@@ -340,10 +369,22 @@ acpi_numa_memory_affinity_init(const struct 
acpi_srat_mem_affinity *ma)

Just up from here there already is overlap detection (via a call to
conflicting_memblks(), and you even mention that in the earlier
comment). If that doesn't cover all cases, I think it wants fixing
there rather than introducing a 2nd checking function. But afaics
that code covers the "fully contains" case.


Yes, that makes sense, I will try to add this case check in 
conflicting_memblks.

Thanks,
Wei Chen

Jan

                        nd->start = start;
                        nd->end = end;
                } else {
-                       if (start < nd->start)
-                               nd->start = start;
-                       if (nd->end < end)
-                               nd->end = end;
+                       paddr_t new_start = nd->start;
+                       paddr_t new_end = nd->end;
+
+                       if (start < new_start)
+                               new_start = start;
+                       if (new_end < end)
+                               new_end = end;
+
+                       /* Check whether new range contains memory for other 
nodes */
+                       if (check_node_memory_interleave(node, new_start, 
new_end)) {
+                               bad_srat();
+                               return;
+                       }
+
+                       nd->start = new_start;
+                       nd->end = new_end;
                }
        }
        printk(KERN_INFO "SRAT: Node %u PXM %u %"PRIpaddr"-%"PRIpaddr"%s\n",