Machine queue, 2019-03-11

* memfd fixes (Ilya Maximets)
 * Move nvdimms state into struct MachineState (Eric Auger)
 * hostmem-file: reject invalid pmem file sizes (Stefan Hajnoczi)
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Merge remote-tracking branch 'remotes/ehabkost/tags/machine-next-pull-request' into staging

Machine queue, 2019-03-11

* memfd fixes (Ilya Maximets)
* Move nvdimms state into struct MachineState (Eric Auger)
* hostmem-file: reject invalid pmem file sizes (Stefan Hajnoczi)

# gpg: Signature made Tue 12 Mar 2019 00:57:41 GMT
# gpg:                using RSA key 2807936F984DC5A6
# gpg: Good signature from "Eduardo Habkost <ehabkost@redhat.com>" [full]
# Primary key fingerprint: 5A32 2FD5 ABC4 D3DB ACCF  D1AA 2807 936F 984D C5A6

* remotes/ehabkost/tags/machine-next-pull-request:
  memfd: improve error messages
  memfd: set up correct errno if not supported
  memfd: always check for MFD_CLOEXEC
  hostmem-memfd: disable for systems without sealing support
  machine: Move nvdimms state into struct MachineState
  nvdimm: Rename AcpiNVDIMMState into NVDIMMState
  hostmem-file: reject invalid pmem file sizes

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

backends/hostmem-file.c

@@ -56,6 +56,29 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
         error_setg(errp, "mem-path property not set");
         return;
     }
+
+    /*
+     * Verify pmem file size since starting a guest with an incorrect size
+     * leads to confusing failures inside the guest.
+     */
+    if (fb->is_pmem) {
+        Error *local_err = NULL;
+        uint64_t size;
+
+        size = qemu_get_pmem_size(fb->mem_path, &local_err);
+        if (!size) {
+            error_propagate(errp, local_err);
+            return;
+        }
+
+        if (backend->size > size) {
+            error_setg(errp, "size property %" PRIu64 " is larger than "
+                       "pmem file \"%s\" size %" PRIu64, backend->size,
+                       fb->mem_path, size);
+            return;
+        }
+    }
+
     backend->force_prealloc = mem_prealloc;
     name = host_memory_backend_get_name(backend);
     memory_region_init_ram_from_file(&backend->mr, OBJECT(backend),

backends/hostmem-memfd.c

@@ -154,15 +154,13 @@ memfd_backend_class_init(ObjectClass *oc, void *data)
                                               "Huge pages size (ex: 2M, 1G)",
                                               &error_abort);
     }
-    if (qemu_memfd_check(MFD_ALLOW_SEALING)) {
+    object_class_property_add_bool(oc, "seal",
-        object_class_property_add_bool(oc, "seal",
+                                   memfd_backend_get_seal,
-                                       memfd_backend_get_seal,
+                                   memfd_backend_set_seal,
-                                       memfd_backend_set_seal,
+                                   &error_abort);
-                                       &error_abort);
+    object_class_property_set_description(oc, "seal",
-        object_class_property_set_description(oc, "seal",
+                                          "Seal growing & shrinking",
-                                              "Seal growing & shrinking",
+                                          &error_abort);
-                                              &error_abort);
-    }
 }
 
 static const TypeInfo memfd_backend_info = {
@@ -175,7 +173,7 @@ static const TypeInfo memfd_backend_info = {
 
 static void register_types(void)
 {
-    if (qemu_memfd_check(0)) {
+    if (qemu_memfd_check(MFD_ALLOW_SEALING)) {
         type_register_static(&memfd_backend_info);
     }
 }

hw/acpi/nvdimm.c

@@ -382,7 +382,7 @@ nvdimm_build_structure_caps(GArray *structures, uint32_t capabilities)
     nfit_caps->capabilities = cpu_to_le32(capabilities);
 }
 
-static GArray *nvdimm_build_device_structure(AcpiNVDIMMState *state)
+static GArray *nvdimm_build_device_structure(NVDIMMState *state)
 {
     GSList *device_list = nvdimm_get_device_list();
     GArray *structures = g_array_new(false, true /* clear */, 1);
@@ -416,7 +416,7 @@ static void nvdimm_init_fit_buffer(NvdimmFitBuffer *fit_buf)
     fit_buf->fit = g_array_new(false, true /* clear */, 1);
 }
 
-static void nvdimm_build_fit_buffer(AcpiNVDIMMState *state)
+static void nvdimm_build_fit_buffer(NVDIMMState *state)
 {
     NvdimmFitBuffer *fit_buf = &state->fit_buf;
 
@@ -425,12 +425,12 @@ static void nvdimm_build_fit_buffer(AcpiNVDIMMState *state)
     fit_buf->dirty = true;
 }
 
-void nvdimm_plug(AcpiNVDIMMState *state)
+void nvdimm_plug(NVDIMMState *state)
 {
     nvdimm_build_fit_buffer(state);
 }
 
-static void nvdimm_build_nfit(AcpiNVDIMMState *state, GArray *table_offsets,
+static void nvdimm_build_nfit(NVDIMMState *state, GArray *table_offsets,
                               GArray *table_data, BIOSLinker *linker)
 {
     NvdimmFitBuffer *fit_buf = &state->fit_buf;
@@ -570,7 +570,7 @@ nvdimm_dsm_no_payload(uint32_t func_ret_status, hwaddr dsm_mem_addr)
 #define NVDIMM_QEMU_RSVD_HANDLE_ROOT         0x10000
 
 /* Read FIT data, defined in docs/specs/acpi_nvdimm.txt. */
-static void nvdimm_dsm_func_read_fit(AcpiNVDIMMState *state, NvdimmDsmIn *in,
+static void nvdimm_dsm_func_read_fit(NVDIMMState *state, NvdimmDsmIn *in,
                                      hwaddr dsm_mem_addr)
 {
     NvdimmFitBuffer *fit_buf = &state->fit_buf;
@@ -619,7 +619,7 @@ exit:
 }
 
 static void
-nvdimm_dsm_handle_reserved_root_method(AcpiNVDIMMState *state,
+nvdimm_dsm_handle_reserved_root_method(NVDIMMState *state,
                                        NvdimmDsmIn *in, hwaddr dsm_mem_addr)
 {
     switch (in->function) {
@@ -863,7 +863,7 @@ nvdimm_dsm_read(void *opaque, hwaddr addr, unsigned size)
 static void
 nvdimm_dsm_write(void *opaque, hwaddr addr, uint64_t val, unsigned size)
 {
-    AcpiNVDIMMState *state = opaque;
+    NVDIMMState *state = opaque;
     NvdimmDsmIn *in;
     hwaddr dsm_mem_addr = val;
 
@@ -925,7 +925,7 @@ void nvdimm_acpi_plug_cb(HotplugHandler *hotplug_dev, DeviceState *dev)
     }
 }
 
-void nvdimm_init_acpi_state(AcpiNVDIMMState *state, MemoryRegion *io,
+void nvdimm_init_acpi_state(NVDIMMState *state, MemoryRegion *io,
                             FWCfgState *fw_cfg, Object *owner)
 {
     memory_region_init_io(&state->io_mr, owner, &nvdimm_dsm_ops, state,
@@ -1319,7 +1319,7 @@ static void nvdimm_build_ssdt(GArray *table_offsets, GArray *table_data,
 }
 
 void nvdimm_build_acpi(GArray *table_offsets, GArray *table_data,
-                       BIOSLinker *linker, AcpiNVDIMMState *state,
+                       BIOSLinker *linker, NVDIMMState *state,
                        uint32_t ram_slots)
 {
     GSList *device_list;

hw/core/machine.c

@@ -22,6 +22,7 @@
 #include "qemu/error-report.h"
 #include "sysemu/qtest.h"
 #include "hw/pci/pci.h"
+#include "hw/mem/nvdimm.h"
 
 GlobalProperty hw_compat_3_1[] = {
     { "pcie-root-port", "x-speed", "2_5" },
@@ -481,6 +482,47 @@ static void machine_set_memory_encryption(Object *obj, const char *value,
     ms->memory_encryption = g_strdup(value);
 }
 
+static bool machine_get_nvdimm(Object *obj, Error **errp)
+{
+    MachineState *ms = MACHINE(obj);
+
+    return ms->nvdimms_state->is_enabled;
+}
+
+static void machine_set_nvdimm(Object *obj, bool value, Error **errp)
+{
+    MachineState *ms = MACHINE(obj);
+
+    ms->nvdimms_state->is_enabled = value;
+}
+
+static char *machine_get_nvdimm_persistence(Object *obj, Error **errp)
+{
+    MachineState *ms = MACHINE(obj);
+
+    return g_strdup(ms->nvdimms_state->persistence_string);
+}
+
+static void machine_set_nvdimm_persistence(Object *obj, const char *value,
+                                           Error **errp)
+{
+    MachineState *ms = MACHINE(obj);
+    NVDIMMState *nvdimms_state = ms->nvdimms_state;
+
+    if (strcmp(value, "cpu") == 0) {
+        nvdimms_state->persistence = 3;
+    } else if (strcmp(value, "mem-ctrl") == 0) {
+        nvdimms_state->persistence = 2;
+    } else {
+        error_setg(errp, "-machine nvdimm-persistence=%s: unsupported option",
+                   value);
+        return;
+    }
+
+    g_free(nvdimms_state->persistence_string);
+    nvdimms_state->persistence_string = g_strdup(value);
+}
+
 void machine_class_allow_dynamic_sysbus_dev(MachineClass *mc, const char *type)
 {
     strList *item = g_new0(strList, 1);
@@ -791,6 +833,28 @@ static void machine_initfn(Object *obj)
     ms->mem_merge = true;
     ms->enable_graphics = true;
 
+    if (mc->nvdimm_supported) {
+        Object *obj = OBJECT(ms);
+
+        ms->nvdimms_state = g_new0(NVDIMMState, 1);
+        object_property_add_bool(obj, "nvdimm",
+                                 machine_get_nvdimm, machine_set_nvdimm,
+                                 &error_abort);
+        object_property_set_description(obj, "nvdimm",
+                                        "Set on/off to enable/disable "
+                                        "NVDIMM instantiation", NULL);
+
+        object_property_add_str(obj, "nvdimm-persistence",
+                                machine_get_nvdimm_persistence,
+                                machine_set_nvdimm_persistence,
+                                &error_abort);
+        object_property_set_description(obj, "nvdimm-persistence",
+                                        "Set NVDIMM persistence"
+                                        "Valid values are cpu, mem-ctrl",
+                                        NULL);
+    }
+
+
     /* Register notifier when init is done for sysbus sanity checks */
     ms->sysbus_notifier.notify = machine_init_notify;
     qemu_add_machine_init_done_notifier(&ms->sysbus_notifier);
@@ -809,6 +873,7 @@ static void machine_finalize(Object *obj)
     g_free(ms->dt_compatible);
     g_free(ms->firmware);
     g_free(ms->device_memory);
+    g_free(ms->nvdimms_state);
 }
 
 bool machine_usb(MachineState *machine)

hw/i386/acpi-build.c

@@ -1867,7 +1867,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
             aml_append(scope, method);
         }
 
-        if (pcms->acpi_nvdimm_state.is_enabled) {
+        if (machine->nvdimms_state->is_enabled) {
             method = aml_method("_E04", 0, AML_NOTSERIALIZED);
             aml_append(method, aml_notify(aml_name("\\_SB.NVDR"),
                                           aml_int(0x80)));
@@ -2704,9 +2704,9 @@ void acpi_build(AcpiBuildTables *tables, MachineState *machine)
             build_dmar_q35(tables_blob, tables->linker);
         }
     }
-    if (pcms->acpi_nvdimm_state.is_enabled) {
+    if (machine->nvdimms_state->is_enabled) {
         nvdimm_build_acpi(table_offsets, tables_blob, tables->linker,
-                          &pcms->acpi_nvdimm_state, machine->ram_slots);
+                          machine->nvdimms_state, machine->ram_slots);
     }
 
     /* Add tables supplied by user (if any) */

hw/i386/pc.c

@@ -2075,6 +2075,7 @@ static void pc_memory_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
 {
     const PCMachineState *pcms = PC_MACHINE(hotplug_dev);
     const PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
+    const MachineState *ms = MACHINE(hotplug_dev);
     const bool is_nvdimm = object_dynamic_cast(OBJECT(dev), TYPE_NVDIMM);
     const uint64_t legacy_align = TARGET_PAGE_SIZE;
 
@@ -2089,7 +2090,7 @@ static void pc_memory_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
         return;
     }
 
-    if (is_nvdimm && !pcms->acpi_nvdimm_state.is_enabled) {
+    if (is_nvdimm && !ms->nvdimms_state->is_enabled) {
         error_setg(errp, "nvdimm is not enabled: missing 'nvdimm' in '-M'");
         return;
     }
@@ -2103,6 +2104,7 @@ static void pc_memory_plug(HotplugHandler *hotplug_dev,
 {
     Error *local_err = NULL;
     PCMachineState *pcms = PC_MACHINE(hotplug_dev);
+    MachineState *ms = MACHINE(hotplug_dev);
     bool is_nvdimm = object_dynamic_cast(OBJECT(dev), TYPE_NVDIMM);
 
     pc_dimm_plug(PC_DIMM(dev), MACHINE(pcms), &local_err);
@@ -2111,7 +2113,7 @@ static void pc_memory_plug(HotplugHandler *hotplug_dev,
     }
 
     if (is_nvdimm) {
-        nvdimm_plug(&pcms->acpi_nvdimm_state);
+        nvdimm_plug(ms->nvdimms_state);
     }
 
     hotplug_handler_plug(HOTPLUG_HANDLER(pcms->acpi_dev), dev, &error_abort);
@@ -2552,47 +2554,6 @@ static void pc_machine_set_smm(Object *obj, Visitor *v, const char *name,
     visit_type_OnOffAuto(v, name, &pcms->smm, errp);
 }
 
-static bool pc_machine_get_nvdimm(Object *obj, Error **errp)
-{
-    PCMachineState *pcms = PC_MACHINE(obj);
-
-    return pcms->acpi_nvdimm_state.is_enabled;
-}
-
-static void pc_machine_set_nvdimm(Object *obj, bool value, Error **errp)
-{
-    PCMachineState *pcms = PC_MACHINE(obj);
-
-    pcms->acpi_nvdimm_state.is_enabled = value;
-}
-
-static char *pc_machine_get_nvdimm_persistence(Object *obj, Error **errp)
-{
-    PCMachineState *pcms = PC_MACHINE(obj);
-
-    return g_strdup(pcms->acpi_nvdimm_state.persistence_string);
-}
-
-static void pc_machine_set_nvdimm_persistence(Object *obj, const char *value,
-                                               Error **errp)
-{
-    PCMachineState *pcms = PC_MACHINE(obj);
-    AcpiNVDIMMState *nvdimm_state = &pcms->acpi_nvdimm_state;
-
-    if (strcmp(value, "cpu") == 0)
-        nvdimm_state->persistence = 3;
-    else if (strcmp(value, "mem-ctrl") == 0)
-        nvdimm_state->persistence = 2;
-    else {
-        error_setg(errp, "-machine nvdimm-persistence=%s: unsupported option",
-                   value);
-        return;
-    }
-
-    g_free(nvdimm_state->persistence_string);
-    nvdimm_state->persistence_string = g_strdup(value);
-}
-
 static bool pc_machine_get_smbus(Object *obj, Error **errp)
 {
     PCMachineState *pcms = PC_MACHINE(obj);
@@ -2642,8 +2603,6 @@ static void pc_machine_initfn(Object *obj)
     pcms->max_ram_below_4g = 0; /* use default */
     pcms->smm = ON_OFF_AUTO_AUTO;
     pcms->vmport = ON_OFF_AUTO_AUTO;
-    /* nvdimm is disabled on default. */
-    pcms->acpi_nvdimm_state.is_enabled = false;
     /* acpi build is enabled by default if machine supports it */
     pcms->acpi_build_enabled = PC_MACHINE_GET_CLASS(pcms)->has_acpi_build;
     pcms->smbus_enabled = true;
@@ -2782,6 +2741,7 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
     hc->unplug = pc_machine_device_unplug_cb;
     nc->nmi_monitor_handler = x86_nmi;
     mc->default_cpu_type = TARGET_DEFAULT_CPU_TYPE;
+    mc->nvdimm_supported = true;
 
     object_class_property_add(oc, PC_MACHINE_DEVMEM_REGION_SIZE, "int",
         pc_machine_get_device_memory_region_size, NULL,
@@ -2806,13 +2766,6 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
     object_class_property_set_description(oc, PC_MACHINE_VMPORT,
         "Enable vmport (pc & q35)", &error_abort);
 
-    object_class_property_add_bool(oc, PC_MACHINE_NVDIMM,
-        pc_machine_get_nvdimm, pc_machine_set_nvdimm, &error_abort);
-
-    object_class_property_add_str(oc, PC_MACHINE_NVDIMM_PERSIST,
-        pc_machine_get_nvdimm_persistence,
-        pc_machine_set_nvdimm_persistence, &error_abort);
-
     object_class_property_add_bool(oc, PC_MACHINE_SMBUS,
         pc_machine_get_smbus, pc_machine_set_smbus, &error_abort);
 

hw/i386/pc_piix.c

@@ -297,8 +297,8 @@ static void pc_init1(MachineState *machine,
                                  PC_MACHINE_ACPI_DEVICE_PROP, &error_abort);
     }
 
-    if (pcms->acpi_nvdimm_state.is_enabled) {
+    if (machine->nvdimms_state->is_enabled) {
-        nvdimm_init_acpi_state(&pcms->acpi_nvdimm_state, system_io,
+        nvdimm_init_acpi_state(machine->nvdimms_state, system_io,
                                pcms->fw_cfg, OBJECT(pcms));
     }
 }

hw/i386/pc_q35.c

@@ -329,8 +329,8 @@ static void pc_q35_init(MachineState *machine)
     pc_vga_init(isa_bus, host_bus);
     pc_nic_init(pcmc, isa_bus, host_bus);
 
-    if (pcms->acpi_nvdimm_state.is_enabled) {
+    if (machine->nvdimms_state->is_enabled) {
-        nvdimm_init_acpi_state(&pcms->acpi_nvdimm_state, system_io,
+        nvdimm_init_acpi_state(machine->nvdimms_state, system_io,
                                pcms->fw_cfg, OBJECT(pcms));
     }
 }

include/hw/boards.h

@@ -210,6 +210,7 @@ struct MachineClass {
                                  int nb_nodes, ram_addr_t size);
     bool ignore_boot_device_suffixes;
     bool smbus_no_migration_support;
+    bool nvdimm_supported;
 
     HotplugHandler *(*get_hotplug_handler)(MachineState *machine,
                                            DeviceState *dev);
@@ -272,6 +273,7 @@ struct MachineState {
     const char *cpu_type;
     AccelState *accelerator;
     CPUArchIdList *possible_cpus;
+    struct NVDIMMState *nvdimms_state;
 };
 
 #define DEFINE_MACHINE(namestr, machine_initfn) \

include/hw/i386/pc.h

@@ -47,8 +47,6 @@ struct PCMachineState {
     OnOffAuto vmport;
     OnOffAuto smm;
 
-    AcpiNVDIMMState acpi_nvdimm_state;
-
     bool acpi_build_enabled;
     bool smbus_enabled;
     bool sata_enabled;
@@ -76,8 +74,6 @@ struct PCMachineState {
 #define PC_MACHINE_MAX_RAM_BELOW_4G "max-ram-below-4g"
 #define PC_MACHINE_VMPORT           "vmport"
 #define PC_MACHINE_SMM              "smm"
-#define PC_MACHINE_NVDIMM           "nvdimm"
-#define PC_MACHINE_NVDIMM_PERSIST   "nvdimm-persistence"
 #define PC_MACHINE_SMBUS            "smbus"
 #define PC_MACHINE_SATA             "sata"
 #define PC_MACHINE_PIT              "pit"

include/hw/mem/nvdimm.h

@@ -123,7 +123,7 @@ struct NvdimmFitBuffer {
 };
 typedef struct NvdimmFitBuffer NvdimmFitBuffer;
 
-struct AcpiNVDIMMState {
+struct NVDIMMState {
     /* detect if NVDIMM support is enabled. */
     bool is_enabled;
 
@@ -141,13 +141,13 @@ struct AcpiNVDIMMState {
     int32_t persistence;
     char    *persistence_string;
 };
-typedef struct AcpiNVDIMMState AcpiNVDIMMState;
+typedef struct NVDIMMState NVDIMMState;
 
-void nvdimm_init_acpi_state(AcpiNVDIMMState *state, MemoryRegion *io,
+void nvdimm_init_acpi_state(NVDIMMState *state, MemoryRegion *io,
                             FWCfgState *fw_cfg, Object *owner);
 void nvdimm_build_acpi(GArray *table_offsets, GArray *table_data,
-                       BIOSLinker *linker, AcpiNVDIMMState *state,
+                       BIOSLinker *linker, NVDIMMState *state,
                        uint32_t ram_slots);
-void nvdimm_plug(AcpiNVDIMMState *state);
+void nvdimm_plug(NVDIMMState *state);
 void nvdimm_acpi_plug_cb(HotplugHandler *hotplug_dev, DeviceState *dev);
 #endif

include/qemu/osdep.h

@@ -570,6 +570,19 @@ void qemu_set_tty_echo(int fd, bool echo);
 void os_mem_prealloc(int fd, char *area, size_t sz, int smp_cpus,
                      Error **errp);
 
+/**
+ * qemu_get_pmem_size:
+ * @filename: path to a pmem file
+ * @errp: pointer to a NULL-initialized error object
+ *
+ * Determine the size of a persistent memory file.  Besides supporting files on
+ * DAX file systems, this function also supports Linux devdax character
+ * devices.
+ *
+ * Returns: the size or 0 on failure
+ */
+uint64_t qemu_get_pmem_size(const char *filename, Error **errp);
+
 /**
  * qemu_get_pid_name:
  * @pid: pid of a process

tests/vhost-user-test.c

@@ -178,7 +178,8 @@ static void append_mem_opts(TestServer *server, GString *cmd_line,
                             int size, enum test_memfd memfd)
 {
     if (memfd == TEST_MEMFD_AUTO) {
-        memfd = qemu_memfd_check(0) ? TEST_MEMFD_YES : TEST_MEMFD_NO;
+        memfd = qemu_memfd_check(MFD_ALLOW_SEALING) ? TEST_MEMFD_YES
+                                                    : TEST_MEMFD_NO;
     }
 
     if (memfd == TEST_MEMFD_YES) {
@@ -930,7 +931,7 @@ static void register_vhost_user_test(void)
                  "virtio-net",
                  test_read_guest_mem, &opts);
 
-    if (qemu_memfd_check(0)) {
+    if (qemu_memfd_check(MFD_ALLOW_SEALING)) {
         opts.before = vhost_user_test_setup_memfd;
         qos_add_test("vhost-user/read-guest-mem/memfd",
                      "virtio-net",

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);

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)
 {

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)
 {