3 files changed, 66 insertions, 2 deletions

diff --git a/util/memfd.c b/util/memfd.c
index 8debd0d037..00334e5b21 100644
--- a/util/memfd.c
+++ b/util/memfd.c
@@ -40,6 +40,7 @@ static int memfd_create(const char *name, unsigned int flags)
 #ifdef __NR_memfd_create
     return syscall(__NR_memfd_create, name, flags);
 #else
+    errno = ENOSYS;
     return -1;
 #endif
 }
@@ -70,14 +71,18 @@ int qemu_memfd_create(const char *name, size_t size, bool hugetlb,
     }
     mfd = memfd_create(name, flags);
     if (mfd < 0) {
+        error_setg_errno(errp, errno,
+                         "failed to create memfd with flags 0x%x", flags);
         goto err;
     }
 
     if (ftruncate(mfd, size) == -1) {
+        error_setg_errno(errp, errno, "failed to resize memfd to %zu", size);
         goto err;
     }
 
     if (seals && fcntl(mfd, F_ADD_SEALS, seals) == -1) {
+        error_setg_errno(errp, errno, "failed to add seals 0x%x", seals);
         goto err;
     }
 
@@ -87,8 +92,9 @@ err:
     if (mfd >= 0) {
         close(mfd);
     }
+#else
+    error_setg_errno(errp, ENOSYS, "failed to create memfd");
 #endif
-    error_setg_errno(errp, errno, "failed to create memfd");
     return -1;
 }
 
@@ -188,7 +194,7 @@ bool qemu_memfd_alloc_check(void)
 bool qemu_memfd_check(unsigned int flags)
 {
 #ifdef CONFIG_LINUX
-    int mfd = memfd_create("test", flags);
+    int mfd = memfd_create("test", flags | MFD_CLOEXEC);
 
     if (mfd >= 0) {
         close(mfd);
diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index 326d92dcd2..88dda9cd39 100644
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -512,6 +512,59 @@ void os_mem_prealloc(int fd, char *area, size_t memory, int smp_cpus,
     }
 }
 
+uint64_t qemu_get_pmem_size(const char *filename, Error **errp)
+{
+    struct stat st;
+
+    if (stat(filename, &st) < 0) {
+        error_setg(errp, "unable to stat pmem file \"%s\"", filename);
+        return 0;
+    }
+
+#if defined(__linux__)
+    /* Special handling for devdax character devices */
+    if (S_ISCHR(st.st_mode)) {
+        char *subsystem_path = NULL;
+        char *subsystem = NULL;
+        char *size_path = NULL;
+        char *size_str = NULL;
+        uint64_t ret = 0;
+
+        subsystem_path = g_strdup_printf("/sys/dev/char/%d:%d/subsystem",
+                                         major(st.st_rdev), minor(st.st_rdev));
+        subsystem = g_file_read_link(subsystem_path, NULL);
+        if (!subsystem) {
+            error_setg(errp, "unable to read subsystem for pmem file \"%s\"",
+                       filename);
+            goto devdax_err;
+        }
+
+        if (!g_str_has_suffix(subsystem, "/dax")) {
+            error_setg(errp, "pmem file \"%s\" is not a dax device", filename);
+            goto devdax_err;
+        }
+
+        size_path = g_strdup_printf("/sys/dev/char/%d:%d/size",
+                                    major(st.st_rdev), minor(st.st_rdev));
+        if (!g_file_get_contents(size_path, &size_str, NULL, NULL)) {
+            error_setg(errp, "unable to read size for pmem file \"%s\"",
+                       size_path);
+            goto devdax_err;
+        }
+
+        ret = g_ascii_strtoull(size_str, NULL, 0);
+
+devdax_err:
+        g_free(size_str);
+        g_free(size_path);
+        g_free(subsystem);
+        g_free(subsystem_path);
+        return ret;
+    }
+#endif /* defined(__linux__) */
+
+    return st.st_size;
+}
 
 char *qemu_get_pid_name(pid_t pid)
 {
diff --git a/util/oslib-win32.c b/util/oslib-win32.c
index b4c17f5dfa..bd633afab6 100644
--- a/util/oslib-win32.c
+++ b/util/oslib-win32.c
@@ -560,6 +560,11 @@ void os_mem_prealloc(int fd, char *area, size_t memory, int smp_cpus,
     }
 }
 
+uint64_t qemu_get_pmem_size(const char *filename, Error **errp)
+{
+    error_setg(errp, "pmem support not available");
+    return 0;
+}
 
 char *qemu_get_pid_name(pid_t pid)
 {