pmalloc: don't lock 4K pages if we don't have access to pagemap

Without pagemap access only way to do DMA to physmem is by
using IOMMU. In such case VFIO will take care for preventing
paging of such memory so we don't need to lock here.

Change-Id: Ica9c20659fba3ea3c96202eb5f7d29c43b313fa9
Signed-off-by: Damjan Marion <damarion@cisco.com>

2 files changed, 30 insertions, 6 deletions

diff --git a/src/vppinfra/pmalloc.c b/src/vppinfra/pmalloc.c
index 5812f9fa120..98e3369bbca 100644
--- a/src/vppinfra/pmalloc.c
+++ b/src/vppinfra/pmalloc.c
@@ -62,6 +62,7 @@ int
 clib_pmalloc_init (clib_pmalloc_main_t * pm, uword size)
 {
   uword off, pagesize;
+  u64 *pt = 0;
 
   ASSERT (pm->error == 0);
 
@@ -70,6 +71,11 @@ clib_pmalloc_init (clib_pmalloc_main_t * pm, uword size)
   pm->sys_log2_page_sz = min_log2 (sysconf (_SC_PAGESIZE));
   pm->lookup_log2_page_sz = pm->def_log2_page_sz;
 
+  /* check if pagemap is accessible */
+  pt = clib_mem_vm_get_paddr (&pt, pm->sys_log2_page_sz, 1);
+  if (pt == 0 || pt[0] == 0)
+    pm->flags |= CLIB_PMALLOC_F_NO_PAGEMAP;
+
   size = size ? size : ((u64) DEFAULT_RESERVED_MB) << 20;
   size = round_pow2 (size, pagesize);
 
@@ -206,9 +212,19 @@ pmalloc_update_lookup_table (clib_pmalloc_main_t * pm, u32 first, u32 count)
   vec_validate_aligned (pm->lookup_table, vec_len (pm->pages) *
 			elts_per_page - 1, CLIB_CACHE_LINE_BYTES);
 
-  fd = open ((char *) "/proc/self/pagemap", O_RDONLY);
-
   p = first * elts_per_page;
+  if (pm->flags & CLIB_PMALLOC_F_NO_PAGEMAP)
+    {
+      while (p < elts_per_page * count)
+	{
+	  pm->lookup_table[p] = pointer_to_uword (pm->base) +
+	    (p << pm->lookup_log2_page_sz);
+	  p++;
+	}
+      return;
+    }
+
+  fd = open ((char *) "/proc/self/pagemap", O_RDONLY);
   while (p < elts_per_page * count)
     {
       va = pointer_to_uword (pm->base) + (p << pm->lookup_log2_page_sz);
@@ -273,10 +289,13 @@ pmalloc_map_pages (clib_pmalloc_main_t * pm, clib_pmalloc_arena_t * a,
       return 0;
     }
 
-  mmap_flags = MAP_FIXED | MAP_ANONYMOUS | MAP_LOCKED;
+  mmap_flags = MAP_FIXED | MAP_ANONYMOUS;
+
+  if ((pm->flags & CLIB_PMALLOC_F_NO_PAGEMAP) == 0)
+    mmap_flags |= MAP_LOCKED;
 
   if (a->log2_subpage_sz != pm->sys_log2_page_sz)
-    mmap_flags |= MAP_HUGETLB;
+    mmap_flags |= MAP_HUGETLB | MAP_LOCKED;
 
   if (a->flags & CLIB_PMALLOC_ARENA_F_SHARED_MEM)
     {
@@ -628,9 +647,10 @@ format_pmalloc (u8 * s, va_list * va)
   clib_pmalloc_arena_t *a;
 
   s = format (s, "used-pages %u reserved-pages %u default-page-size %U "
-	      "lookup-page-size %U", vec_len (pm->pages), pm->max_pages,
+	      "lookup-page-size %U%s", vec_len (pm->pages), pm->max_pages,
 	      format_log2_page_size, pm->def_log2_page_sz,
-	      format_log2_page_size, pm->lookup_log2_page_sz);
+	      format_log2_page_size, pm->lookup_log2_page_sz,
+	      pm->flags & CLIB_PMALLOC_F_NO_PAGEMAP ? " no-pagemap" : "");
 
 
   if (verbose >= 2)
diff --git a/src/vppinfra/pmalloc.h b/src/vppinfra/pmalloc.h
index 41b85e0c517..9cd652971a6 100644
--- a/src/vppinfra/pmalloc.h
+++ b/src/vppinfra/pmalloc.h
@@ -60,6 +60,10 @@ typedef struct
 
 typedef struct
 {
+  /* flags */
+  u32 flags;
+#define CLIB_PMALLOC_F_NO_PAGEMAP (1 << 0)
+
   /* base VA address */
   u8 *base;