x86: don't blindly create L3 tables for the direct map

Now that the direct map area can extend all the way up to almost the
end of address space, this is wasteful.

Also fold two almost redundant messages in SRAT parsing into one.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Tested-by: Malcolm Crossley <malcolm.crossley@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Keir Fraser <keir@xen.org>
master commit: ca145fe70bad3a25ad54c6ded1ef237e45a2311e
master date: 2013-09-30 15:28:12 +0200

4 files changed, 20 insertions, 28 deletions

diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index f151dec2b2..1db363e610 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -137,7 +137,7 @@ l1_pgentry_t __attribute__ ((__section__ (".bss.page_aligned")))
 #define PTE_UPDATE_WITH_CMPXCHG
 #endif
 
-bool_t __read_mostly mem_hotplug = 0;
+paddr_t __read_mostly mem_hotplug;
 
 /* Private domain structs for DOMID_XEN and DOMID_IO. */
 struct domain *dom_xen, *dom_io, *dom_cow;
diff --git a/xen/arch/x86/srat.c b/xen/arch/x86/srat.c
index ff73881652..2b052721c4 100644
--- a/xen/arch/x86/srat.c
+++ b/xen/arch/x86/srat.c
@@ -113,6 +113,7 @@ static __init void bad_srat(void)
 		apicid_to_node[i] = NUMA_NO_NODE;
 	for (i = 0; i < ARRAY_SIZE(pxm2node); i++)
 		pxm2node[i] = NUMA_NO_NODE;
+	mem_hotplug = 0;
 }
 
 /*
@@ -257,13 +258,6 @@ acpi_numa_memory_affinity_init(struct acpi_srat_mem_affinity *ma)
 		return;
 	}
 	/* It is fine to add this area to the nodes data it will be used later*/
-	if (ma->flags & ACPI_SRAT_MEM_HOT_PLUGGABLE)
-	{
-		printk(KERN_INFO "SRAT: hot plug zone found %"PRIx64" - %"PRIx64" \n",
-				start, end);
-		mem_hotplug = 1;
-	}
-
 	i = conflicting_memblks(start, end);
 	if (i == node) {
 		printk(KERN_WARNING
@@ -287,8 +281,11 @@ acpi_numa_memory_affinity_init(struct acpi_srat_mem_affinity *ma)
 		if (nd->end < end)
 			nd->end = end;
 	}
-	printk(KERN_INFO "SRAT: Node %u PXM %u %"PRIx64"-%"PRIx64"\n", node, pxm,
-	       start, end);
+	if ((ma->flags & ACPI_SRAT_MEM_HOT_PLUGGABLE) && end > mem_hotplug)
+		mem_hotplug = end;
+	printk(KERN_INFO "SRAT: Node %u PXM %u %"PRIx64"-%"PRIx64"%s\n",
+	       node, pxm, start, end,
+	       ma->flags & ACPI_SRAT_MEM_HOT_PLUGGABLE ? " (hotplug)" : "");
 
 	node_memblk_range[num_node_memblks].start = start;
 	node_memblk_range[num_node_memblks].end = end;
diff --git a/xen/arch/x86/x86_64/mm.c b/xen/arch/x86/x86_64/mm.c
index 96a033bf88..d1a1c02855 100644
--- a/xen/arch/x86/x86_64/mm.c
+++ b/xen/arch/x86/x86_64/mm.c
@@ -621,25 +621,20 @@ void __init paging_init(void)
      * We setup the L3s for 1:1 mapping if host support memory hotplug
      * to avoid sync the 1:1 mapping on page fault handler
      */
-    if ( mem_hotplug )
+    for ( va = DIRECTMAP_VIRT_START;
+          va < DIRECTMAP_VIRT_END && (void *)va < __va(mem_hotplug);
+          va += (1UL << L4_PAGETABLE_SHIFT) )
     {
-        unsigned long va;
-
-        for ( va = DIRECTMAP_VIRT_START;
-              va < DIRECTMAP_VIRT_END;
-              va += (1UL << L4_PAGETABLE_SHIFT) )
+        if ( !(l4e_get_flags(idle_pg_table[l4_table_offset(va)]) &
+              _PAGE_PRESENT) )
         {
-            if ( !(l4e_get_flags(idle_pg_table[l4_table_offset(va)]) &
-                  _PAGE_PRESENT) )
-            {
-                l3_pg = alloc_domheap_page(NULL, 0);
-                if ( !l3_pg )
-                    goto nomem;
-                l3_ro_mpt = page_to_virt(l3_pg);
-                clear_page(l3_ro_mpt);
-                l4e_write(&idle_pg_table[l4_table_offset(va)],
-                  l4e_from_page(l3_pg, __PAGE_HYPERVISOR));
-            }
+            l3_pg = alloc_domheap_page(NULL, 0);
+            if ( !l3_pg )
+                goto nomem;
+            l3_ro_mpt = page_to_virt(l3_pg);
+            clear_page(l3_ro_mpt);
+            l4e_write(&idle_pg_table[l4_table_offset(va)],
+                      l4e_from_page(l3_pg, __PAGE_HYPERVISOR));
         }
     }
 
diff --git a/xen/include/asm-x86/mm.h b/xen/include/asm-x86/mm.h
index 213fc9cb37..5f0387528b 100644
--- a/xen/include/asm-x86/mm.h
+++ b/xen/include/asm-x86/mm.h
@@ -399,7 +399,7 @@ static inline int get_page_and_type(struct page_info *page,
 int check_descriptor(const struct domain *, struct desc_struct *d);
 
 extern bool_t opt_allow_superpage;
-extern bool_t mem_hotplug;
+extern paddr_t mem_hotplug;
 
 /******************************************************************************
  * With shadow pagetables, the different kinds of address start