memory: move preallocation code out of exec.c

So that backends can use it.

Since we need the page size for efficiency, move code to compute it
out of translate-all.c and into util/oslib-win32.c.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 73 insertions, 0 deletions

diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index 8e9c770d28..1524ead755 100644
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -46,6 +46,7 @@ extern int daemon(int, int);
 #else
 #  define QEMU_VMALLOC_ALIGN getpagesize()
 #endif
+#define HUGETLBFS_MAGIC       0x958458f6
 
 #include <termios.h>
 #include <unistd.h>
@@ -58,9 +59,12 @@ extern int daemon(int, int);
 #include "qemu/sockets.h"
 #include <sys/mman.h>
 #include <libgen.h>
+#include <setjmp.h>
+#include <sys/signal.h>
 
 #ifdef CONFIG_LINUX
 #include <sys/syscall.h>
+#include <sys/vfs.h>
 #endif
 
 #ifdef __FreeBSD__
@@ -332,3 +336,72 @@ char *qemu_get_exec_dir(void)
 {
     return g_strdup(exec_dir);
 }
+
+static sigjmp_buf sigjump;
+
+static void sigbus_handler(int signal)
+{
+    siglongjmp(sigjump, 1);
+}
+
+static size_t fd_getpagesize(int fd)
+{
+#ifdef CONFIG_LINUX
+    struct statfs fs;
+    int ret;
+
+    if (fd != -1) {
+        do {
+            ret = fstatfs(fd, &fs);
+        } while (ret != 0 && errno == EINTR);
+
+        if (ret == 0 && fs.f_type == HUGETLBFS_MAGIC) {
+            return fs.f_bsize;
+        }
+    }
+#endif
+
+    return getpagesize();
+}
+
+void os_mem_prealloc(int fd, char *area, size_t memory)
+{
+    int ret, i;
+    struct sigaction act, oldact;
+    sigset_t set, oldset;
+    size_t hpagesize = fd_getpagesize(fd);
+
+    memset(&act, 0, sizeof(act));
+    act.sa_handler = &sigbus_handler;
+    act.sa_flags = 0;
+
+    ret = sigaction(SIGBUS, &act, &oldact);
+    if (ret) {
+        perror("os_mem_prealloc: failed to install signal handler");
+        exit(1);
+    }
+
+    /* unblock SIGBUS */
+    sigemptyset(&set);
+    sigaddset(&set, SIGBUS);
+    pthread_sigmask(SIG_UNBLOCK, &set, &oldset);
+
+    if (sigsetjmp(sigjump, 1)) {
+        fprintf(stderr, "os_mem_prealloc: failed to preallocate pages\n");
+        exit(1);
+    }
+
+    /* MAP_POPULATE silently ignores failures */
+    memory = (memory + hpagesize - 1) & -hpagesize;
+    for (i = 0; i < (memory/hpagesize); i++) {
+        memset(area + (hpagesize*i), 0, 1);
+    }
+
+    ret = sigaction(SIGBUS, &oldact, NULL);
+    if (ret) {
+        perror("os_mem_prealloc: failed to reinstall signal handler");
+        exit(1);
+    }
+
+    pthread_sigmask(SIG_SETMASK, &oldset, NULL);
+}