[Qemu-devel] [PATCH V12 10/17] xen: Adds a cap to the number of map cache entries.

[anthony.perard@citrix.com]

From: John Baboval <john.baboval@virtualcomputer.com>

Adds a cap to the number of map cache entries. This prevents the map
cache from overwhelming system memory.

I also removed the bitmap macros and #included bitmap.h instead.

Signed-off-By: John Baboval <john.baboval@virtualcomputer.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
---
 xen-mapcache.c |   21 ++++++++++-----------
 1 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/xen-mapcache.c b/xen-mapcache.c
index d7f44a7..eab97bc 100644
--- a/xen-mapcache.c
+++ b/xen-mapcache.c
@@ -12,6 +12,7 @@
 
 #include "hw/xen_backend.h"
 #include "blockdev.h"
+#include "bitmap.h"
 
 #include <xen/hvm/params.h>
 #include <sys/mman.h>
@@ -31,15 +32,13 @@
 
 #if defined(__i386__)
 #  define MCACHE_BUCKET_SHIFT 16
+#  define MCACHE_MAX_SIZE     (1UL<<31) /* 2GB Cap */
 #elif defined(__x86_64__)
 #  define MCACHE_BUCKET_SHIFT 20
+#  define MCACHE_MAX_SIZE     (1UL<<35) /* 32GB Cap */
 #endif
 #define MCACHE_BUCKET_SIZE (1UL << MCACHE_BUCKET_SHIFT)
 
-#define BITS_PER_LONG (sizeof(long) * 8)
-#define BITS_TO_LONGS(bits) (((bits) + BITS_PER_LONG - 1) / BITS_PER_LONG)
-#define DECLARE_BITMAP(name, bits) unsigned long name[BITS_TO_LONGS(bits)]
-
 typedef struct MapCacheEntry {
     target_phys_addr_t paddr_index;
     uint8_t *vaddr_base;
@@ -68,11 +67,6 @@ typedef struct MapCache {
 
 static MapCache *mapcache;
 
-static inline int test_bit(unsigned int bit, const unsigned long *map)
-{
-    return !!((map)[(bit) / BITS_PER_LONG] & (1UL << ((bit) % BITS_PER_LONG)));
-}
-
 void qemu_map_cache_init(void)
 {
     unsigned long size;
@@ -84,9 +78,14 @@ void qemu_map_cache_init(void)
     mapcache->last_address_index = -1;
 
     getrlimit(RLIMIT_AS, &rlimit_as);
-    rlimit_as.rlim_cur = rlimit_as.rlim_max;
+    if (rlimit_as.rlim_max < MCACHE_MAX_SIZE) {
+        rlimit_as.rlim_cur = rlimit_as.rlim_max;
+    } else {
+        rlimit_as.rlim_cur = MCACHE_MAX_SIZE;
+    }
+
     setrlimit(RLIMIT_AS, &rlimit_as);
-    mapcache->max_mcache_size = rlimit_as.rlim_max;
+    mapcache->max_mcache_size = rlimit_as.rlim_cur;
 
     mapcache->nr_buckets =
         (((mapcache->max_mcache_size >> XC_PAGE_SHIFT) +
-- 
1.7.2.3