memory: expose alignment used for allocating RAM as MemoryRegion API

[qemu.git] / util / oslib-posix.c

diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index c2eeb4fe40676212e8acb9855e1b01cd4721236f..16fcec2f37e40b94ccc8f7af0ebdaa74f6657af2 100644 (file)
--- 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 +59,16 @@ 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__
+#include <sys/sysctl.h>
 #endif
 
 int qemu_get_thread_id(void)
@@ -86,7 +94,7 @@ void *qemu_oom_check(void *ptr)
     return ptr;
 }
 
-void *qemu_memalign(size_t alignment, size_t size)
+void *qemu_try_memalign(size_t alignment, size_t size)
 {
     void *ptr;
 
@@ -98,21 +106,25 @@ void *qemu_memalign(size_t alignment, size_t size)
     int ret;
     ret = posix_memalign(&ptr, alignment, size);
     if (ret != 0) {
-        fprintf(stderr, "Failed to allocate %zu B: %s\n",
-                size, strerror(ret));
-        abort();
+        errno = ret;
+        ptr = NULL;
     }
 #elif defined(CONFIG_BSD)
-    ptr = qemu_oom_check(valloc(size));
+    ptr = valloc(size);
 #else
-    ptr = qemu_oom_check(memalign(alignment, size));
+    ptr = memalign(alignment, size);
 #endif
     trace_qemu_memalign(alignment, size, ptr);
     return ptr;
 }
 
+void *qemu_memalign(size_t alignment, size_t size)
+{
+    return qemu_oom_check(qemu_try_memalign(alignment, size));
+}
+
 /* alloc shared memory pages */
-void *qemu_anon_ram_alloc(size_t size)
+void *qemu_anon_ram_alloc(size_t size, uint64_t *alignment)
 {
     size_t align = QEMU_VMALLOC_ALIGN;
     size_t total = size + align - getpagesize();
@@ -124,6 +136,9 @@ void *qemu_anon_ram_alloc(size_t size)
         return NULL;
     }
 
+    if (alignment) {
+        *alignment = align;
+    }
     ptr += offset;
     total -= offset;
 
@@ -328,3 +343,75 @@ 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;
+    struct sigaction act, oldact;
+    sigset_t set, oldset;
+
+    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: Insufficient free host memory "
+                        "pages available to allocate guest RAM\n");
+        exit(1);
+    } else {
+        int i;
+        size_t hpagesize = fd_getpagesize(fd);
+
+        /* 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);
+    }
+}