[PATCH v2] NUMA: replace phys_to_nid()

[Jan Beulich <jbeulich@xxxxxxxx>]

All callers convert frame numbers (perhaps in turn derived from struct
page_info pointers) to an address, just for the function to convert it
back to a frame number (as the first step of paddr_to_pdx()). Replace
the function by mfn_to_nid() plus a page_to_nid() wrapper macro. Replace
call sites by the respectively most suitable one.

While there also
- introduce a !NUMA stub, eliminating the need for Arm (and potentially
  other ports) to carry one individually,
- drop the (strictly speaking wrong) "pure" attribute from the function,
- extend a condition in dump_numa() to make sure that none of the
  assertions would trigger for empty or (unlikely) single-page nodes (at
  the same time this also prevents the warning printk() to be issued for
  every empty [e.g. CPU-only] node).

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
v2: Refine guarding in dump_numa(). Drop __attribute_pure__. Use
    mfn_to_nid() in free_heap_pages().

--- a/xen/arch/arm/include/asm/numa.h
+++ b/xen/arch/arm/include/asm/numa.h
@@ -11,11 +11,6 @@ typedef u8 nodeid_t;
 #define cpu_to_node(cpu) 0
 #define node_to_cpumask(node)   (cpu_online_map)
 
-static inline __attribute__((pure)) nodeid_t phys_to_nid(paddr_t addr)
-{
-    return 0;
-}
-
 /*
  * TODO: make first_valid_mfn static when NUMA is supported on Arm, this
  * is required because the dummy helpers are using it.
--- a/xen/arch/x86/mm/p2m-pod.c
+++ b/xen/arch/x86/mm/p2m-pod.c
@@ -492,7 +492,7 @@ p2m_pod_offline_or_broken_replace(struct
 {
     struct domain *d;
     struct p2m_domain *p2m;
-    nodeid_t node = phys_to_nid(page_to_maddr(p));
+    nodeid_t node = page_to_nid(p);
 
     if ( !(d = page_get_owner(p)) || !(p2m = p2m_get_hostp2m(d)) )
         return;
--- a/xen/arch/x86/x86_64/mm.c
+++ b/xen/arch/x86/x86_64/mm.c
@@ -565,7 +565,7 @@ void __init paging_init(void)
                 if ( n == CNT )
                     ++holes;
                 else if ( k == holes )
-                    memflags = MEMF_node(phys_to_nid(mfn_to_maddr(mfn)));
+                    memflags = MEMF_node(mfn_to_nid(mfn));
             }
             if ( k == holes )
             {
@@ -600,7 +600,7 @@ void __init paging_init(void)
             mfn = _mfn(MFN(i) + n * PDX_GROUP_COUNT);
             if ( mfn_valid(mfn) )
             {
-                memflags = MEMF_node(phys_to_nid(mfn_to_maddr(mfn)));
+                memflags = MEMF_node(mfn_to_nid(mfn));
                 break;
             }
         }
@@ -677,7 +677,7 @@ void __init paging_init(void)
             mfn = _mfn(MFN(i) + n * PDX_GROUP_COUNT);
             if ( mfn_valid(mfn) )
             {
-                memflags = MEMF_node(phys_to_nid(mfn_to_maddr(mfn)));
+                memflags = MEMF_node(mfn_to_nid(mfn));
                 break;
             }
         }
--- a/xen/common/numa.c
+++ b/xen/common/numa.c
@@ -671,15 +671,15 @@ static void cf_check dump_numa(unsigned
 
     for_each_online_node ( i )
     {
-        paddr_t pa = pfn_to_paddr(node_start_pfn(i) + 1);
+        mfn_t mfn = _mfn(node_start_pfn(i) + 1);
 
         printk("NODE%u start->%lu size->%lu free->%lu\n",
                i, node_start_pfn(i), node_spanned_pages(i),
                avail_node_heap_pages(i));
-        /* Sanity check phys_to_nid() */
-        if ( phys_to_nid(pa) != i )
-            printk("phys_to_nid(%"PRIpaddr") -> %d should be %u\n",
-                   pa, phys_to_nid(pa), i);
+        /* Sanity check mfn_to_nid() */
+        if ( node_spanned_pages(i) > 1 && mfn_to_nid(mfn) != i )
+            printk("mfn_to_nid(%"PRI_mfn") -> %d should be %u\n",
+                   mfn_x(mfn), mfn_to_nid(mfn), i);
     }
 
     j = cpumask_first(&cpu_online_map);
@@ -721,7 +721,7 @@ static void cf_check dump_numa(unsigned
         spin_lock(&d->page_alloc_lock);
         page_list_for_each ( page, &d->page_list )
         {
-            i = phys_to_nid(page_to_maddr(page));
+            i = page_to_nid(page);
             page_num_node[i]++;
         }
         spin_unlock(&d->page_alloc_lock);
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -971,7 +971,7 @@ static struct page_info *alloc_heap_page
         return NULL;
     }
 
-    node = phys_to_nid(page_to_maddr(pg));
+    node = page_to_nid(pg);
     zone = page_to_zone(pg);
     buddy_order = PFN_ORDER(pg);
 
@@ -1078,7 +1078,7 @@ static struct page_info *alloc_heap_page
 /* Remove any offlined page in the buddy pointed to by head. */
 static int reserve_offlined_page(struct page_info *head)
 {
-    unsigned int node = phys_to_nid(page_to_maddr(head));
+    unsigned int node = page_to_nid(head);
     int zone = page_to_zone(head), i, head_order = PFN_ORDER(head), count = 0;
     struct page_info *cur_head;
     unsigned int cur_order, first_dirty;
@@ -1443,7 +1443,7 @@ static void free_heap_pages(
 {
     unsigned long mask;
     mfn_t mfn = page_to_mfn(pg);
-    unsigned int i, node = phys_to_nid(mfn_to_maddr(mfn));
+    unsigned int i, node = mfn_to_nid(mfn);
     unsigned int zone = page_to_zone(pg);
     bool pg_offlined = false;
 
@@ -1487,7 +1487,7 @@ static void free_heap_pages(
                  !page_state_is(predecessor, free) ||
                  (predecessor->count_info & PGC_static) ||
                  (PFN_ORDER(predecessor) != order) ||
-                 (phys_to_nid(page_to_maddr(predecessor)) != node) )
+                 (page_to_nid(predecessor) != node) )
                 break;
 
             check_and_stop_scrub(predecessor);
@@ -1511,7 +1511,7 @@ static void free_heap_pages(
                  !page_state_is(successor, free) ||
                  (successor->count_info & PGC_static) ||
                  (PFN_ORDER(successor) != order) ||
-                 (phys_to_nid(page_to_maddr(successor)) != node) )
+                 (page_to_nid(successor) != node) )
                 break;
 
             check_and_stop_scrub(successor);
@@ -1574,7 +1574,7 @@ static unsigned long mark_page_offline(s
 static int reserve_heap_page(struct page_info *pg)
 {
     struct page_info *head = NULL;
-    unsigned int i, node = phys_to_nid(page_to_maddr(pg));
+    unsigned int i, node = page_to_nid(pg);
     unsigned int zone = page_to_zone(pg);
 
     for ( i = 0; i <= MAX_ORDER; i++ )
@@ -1794,7 +1794,7 @@ static void _init_heap_pages(const struc
                              bool need_scrub)
 {
     unsigned long s, e;
-    unsigned int nid = phys_to_nid(page_to_maddr(pg));
+    unsigned int nid = page_to_nid(pg);
 
     s = mfn_x(page_to_mfn(pg));
     e = mfn_x(mfn_add(page_to_mfn(pg + nr_pages - 1), 1));
@@ -1869,7 +1869,7 @@ static void init_heap_pages(
 #ifdef CONFIG_SEPARATE_XENHEAP
         unsigned int zone = page_to_zone(pg);
 #endif
-        unsigned int nid = phys_to_nid(page_to_maddr(pg));
+        unsigned int nid = page_to_nid(pg);
         unsigned long left = nr_pages - i;
         unsigned long contig_pages;
 
@@ -1893,7 +1893,7 @@ static void init_heap_pages(
                 break;
 #endif
 
-            if ( nid != (phys_to_nid(page_to_maddr(pg + contig_pages))) )
+            if ( nid != (page_to_nid(pg + contig_pages)) )
                 break;
         }
 
@@ -1934,7 +1934,7 @@ void __init end_boot_allocator(void)
     {
         struct bootmem_region *r = &bootmem_region_list[i];
         if ( (r->s < r->e) &&
-             (phys_to_nid(pfn_to_paddr(r->s)) == cpu_to_node(0)) )
+             (mfn_to_nid(_mfn(r->s)) == cpu_to_node(0)) )
         {
             init_heap_pages(mfn_to_page(_mfn(r->s)), r->e - r->s);
             r->e = r->s;
--- a/xen/include/xen/numa.h
+++ b/xen/include/xen/numa.h
@@ -1,6 +1,7 @@
 #ifndef _XEN_NUMA_H
 #define _XEN_NUMA_H
 
+#include <xen/mm-frame.h>
 #include <asm/numa.h>
 
 #define NUMA_NO_NODE     0xFF
@@ -68,12 +69,15 @@ struct node_data {
 
 extern struct node_data node_data[];
 
-static inline nodeid_t __attribute_pure__ phys_to_nid(paddr_t addr)
+static inline nodeid_t mfn_to_nid(mfn_t mfn)
 {
     nodeid_t nid;
-    ASSERT((paddr_to_pdx(addr) >> memnode_shift) < memnodemapsize);
-    nid = memnodemap[paddr_to_pdx(addr) >> memnode_shift];
+    unsigned long pdx = mfn_to_pdx(mfn);
+
+    ASSERT((pdx >> memnode_shift) < memnodemapsize);
+    nid = memnodemap[pdx >> memnode_shift];
     ASSERT(nid < MAX_NUMNODES && node_data[nid].node_spanned_pages);
+
     return nid;
 }
 
@@ -102,6 +106,15 @@ extern bool numa_update_node_memblks(nod
                                      paddr_t start, paddr_t size, bool 
hotplug);
 extern void numa_set_processor_nodes_parsed(nodeid_t node);
 
+#else
+
+static inline nodeid_t mfn_to_nid(mfn_t mfn)
+{
+    return 0;
+}
+
 #endif
 
+#define page_to_nid(pg) mfn_to_nid(page_to_mfn(pg))
+
 #endif /* _XEN_NUMA_H */