[PATCH 06/17] Use statfs to determine size of huge pages

[Anthony Liguori <aliguori@xxxxxxxxxx>]

From: Joerg Roedel <joerg.roedel@xxxxxxx>

The current method of finding out the size of huge pages does not work
reliably anymore. Current Linux supports more than one huge page size
but /proc/meminfo only show one of the supported sizes.
To find out the real page size used can be found by calling statfs. This
patch changes qemu to use statfs instead of parsing /proc/meminfo.

Signed-off-by: Joerg Roedel <joerg.roedel@xxxxxxx>
Signed-off-by: Avi Kivity <avi@xxxxxxxxxx>
Signed-off-by: Anthony Liguori <aliguori@xxxxxxxxxx>

diff --git a/sysemu.h b/sysemu.h
index 19464cf..4333495 100644
--- a/sysemu.h
+++ b/sysemu.h
@@ -99,7 +99,7 @@ extern int graphic_rotate;
 extern int no_quit;
 extern int semihosting_enabled;
 extern int old_param;
-extern int hpagesize;
+extern long hpagesize;
 extern const char *bootp_filename;
 
 #ifdef USE_KQEMU
diff --git a/vl.c b/vl.c
index 0437159..5d02e10 100644
--- a/vl.c
+++ b/vl.c
@@ -62,6 +62,7 @@
 #include <sys/ioctl.h>
 #include <sys/resource.h>
 #include <sys/socket.h>
+#include <sys/vfs.h>
 #include <netinet/in.h>
 #include <net/if.h>
 #if defined(__NetBSD__)
@@ -256,7 +257,7 @@ const char *mem_path = NULL;
 #ifdef MAP_POPULATE
 int mem_prealloc = 1;	/* force preallocation of physical target memory */
 #endif
-int hpagesize = 0;
+long hpagesize = 0;
 const char *cpu_vendor_string;
 #ifdef TARGET_ARM
 int old_param = 0;
@@ -4707,32 +4708,27 @@ void qemu_get_launch_info(int *argc, char ***argv, int *opt_daemonize, const cha
 }
 
 #ifdef USE_KVM
-static int gethugepagesize(void)
+
+#define HUGETLBFS_MAGIC       0x958458f6
+
+static long gethugepagesize(const char *path)
 {
-    int ret, fd;
-    char buf[4096];
-    const char *needle = "Hugepagesize:";
-    char *size;
-    unsigned long hugepagesize;
+    struct statfs fs;
+    int ret;
 
-    fd = open("/proc/meminfo", O_RDONLY);
-    if (fd < 0) {
-	perror("open");
-	exit(0);
-    }
+    do {
+	    ret = statfs(path, &fs);
+    } while (ret != 0 && errno == EINTR);
 
-    ret = read(fd, buf, sizeof(buf));
-    if (ret < 0) {
-	perror("read");
-	exit(0);
+    if (ret != 0) {
+	    perror("statfs");
+	    return 0;
     }
 
-    size = strstr(buf, needle);
-    if (!size)
-	return 0;
-    size += strlen(needle);
-    hugepagesize = strtol(size, NULL, 0);
-    return hugepagesize;
+    if (fs.f_type != HUGETLBFS_MAGIC)
+	    fprintf(stderr, "Warning: path not on HugeTLBFS: %s\n", path);
+
+    return fs.f_bsize;
 }
 
 static void *alloc_mem_area(size_t memory, unsigned long *len, const char *path)
@@ -4752,7 +4748,7 @@ static void *alloc_mem_area(size_t memory, unsigned long *len, const char *path)
     if (asprintf(&filename, "%s/kvm.XXXXXX", path) == -1)
 	return NULL;
 
-    hpagesize = gethugepagesize() * 1024;
+    hpagesize = gethugepagesize(path);
     if (!hpagesize)
 	return NULL;
 
-- 
1.6.0.6

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