[Qemu-devel] [PATCH v2 0/6] migration: let pre_save fail

[Qemu-devel] [PATCH v2 0/6] migration: let pre_save fail

[Dr. David Alan Gilbert (git)]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

At the moment the pre-save method on VMStateDescription returns void
which means there's no sane way of a pre_save routine failing.  There
are quite a few pre_save's that abort or do other nasty things, and it
would be better if they could fail cleanly.

This patch series doesn't fix any of those pre_save's - it just changes
pre_save to return an error value and routes that back up so the
migration fails.  I'll leave that up to the individual device owners.

There are a bunch of corner cases that I've not fixed yet;  these are
mostly places that call vmstate_save_state which have been partially
converted to modern migration code;  often the functions they're called
from return void as well - they can get fixed later.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

v2
  test: Split assert/side effects [Fam]
  new patch 3: Changed to also check the return of the ->put methods
    that should have been checked previously. [Peter]

Dr. David Alan Gilbert (6):
  migration: pre_save return int
  migration: check pre_save return in vmstate_save_state
  migration: Check field save returns
  migration: wire vmstate_save_state errors up to
    vmstate_subsection_save
  migration: Route errors up through vmstate_save
  migration: Route more error paths

 docs/devel/migration.txt       |  2 +-
 hw/arm/pxa2xx.c                |  4 +++-
 hw/arm/strongarm.c             |  4 +++-
 hw/audio/wm8750.c              |  4 +++-
 hw/block/fdc.c                 |  4 +++-
 hw/block/m25p80.c              |  4 +++-
 hw/block/nand.c                |  4 +++-
 hw/block/onenand.c             |  4 +++-
 hw/char/serial.c               |  4 +++-
 hw/display/qxl.c               |  4 +++-
 hw/display/virtio-gpu.c        |  4 +---
 hw/i2c/core.c                  |  4 +++-
 hw/i386/kvm/clock.c            |  4 +++-
 hw/ide/core.c                  |  4 +++-
 hw/ide/pci.c                   |  4 +++-
 hw/input/ps2.c                 |  8 ++++++--
 hw/input/tsc210x.c             |  4 +++-
 hw/intc/apic_common.c          |  4 +++-
 hw/intc/arm_gic_common.c       |  4 +++-
 hw/intc/arm_gicv3_common.c     |  4 +++-
 hw/intc/arm_gicv3_its_common.c |  4 +++-
 hw/intc/i8259_common.c         |  4 +++-
 hw/intc/ioapic_common.c        |  4 +++-
 hw/intc/s390_flic_kvm.c        |  6 ++++--
 hw/intc/xics.c                 |  8 ++++++--
 hw/net/e1000.c                 |  4 +++-
 hw/net/e1000e.c                |  4 +++-
 hw/net/rtl8139.c               |  4 +++-
 hw/net/virtio-net.c            | 16 ++++++++++++----
 hw/net/vmxnet3.c               |  4 +++-
 hw/pci-host/piix.c             |  4 +++-
 hw/ppc/ppc.c                   |  4 +++-
 hw/ppc/spapr_iommu.c           |  4 +++-
 hw/ppc/spapr_pci.c             |  6 ++++--
 hw/s390x/css.c                 | 10 +++++++---
 hw/s390x/virtio-ccw.c          |  4 +++-
 hw/scsi/lsi53c895a.c           |  4 +++-
 hw/scsi/vmw_pvscsi.c           |  4 +++-
 hw/timer/cadence_ttc.c         |  4 +++-
 hw/timer/hpet.c                |  4 +++-
 hw/timer/i8254_common.c        |  4 +++-
 hw/timer/mc146818rtc.c         |  4 +++-
 hw/timer/pl031.c               |  4 +++-
 hw/timer/twl92230.c            |  4 +++-
 hw/usb/dev-smartcard-reader.c  |  4 +++-
 hw/usb/hcd-ehci.c              |  4 +++-
 hw/usb/redirect.c              |  4 +++-
 hw/virtio/vhost-vsock.c        |  4 +++-
 hw/virtio/virtio.c             | 13 +++++++------
 include/hw/virtio/virtio.h     |  2 +-
 include/migration/vmstate.h    |  6 +++---
 migration/colo-comm.c          |  4 +++-
 migration/global_state.c       |  4 +++-
 migration/savevm.c             | 23 ++++++++++++++++------
 migration/trace-events         |  1 +
 migration/vmstate-types.c      | 11 ++++++++---
 migration/vmstate.c            | 43 +++++++++++++++++++++++++++++++-----------
 replay/replay-snapshot.c       |  4 +++-
 slirp/slirp.c                  |  8 ++++++--
 target/arm/machine.c           |  4 +++-
 target/i386/machine.c          |  7 +++++--
 target/ppc/machine.c           |  4 +++-
 target/s390x/machine.c         |  4 +++-
 target/sparc/machine.c         |  4 +++-
 tests/test-vmstate.c           | 13 +++++++++----
 65 files changed, 271 insertions(+), 104 deletions(-)

-- 
2.13.5

[Qemu-devel] [PATCH v2 1/6] migration: pre_save return int

[Dr. David Alan Gilbert (git)]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Modify the pre_save method on VMStateDescription to return an int
rather than void so that it potentially can fail.

Changed zillions of devices to make them return 0; the only
case I've made it return non-0 is hw/intc/s390_flic_kvm.c that already
had an error_report/return case.

Note: If you add an error exit in your pre_save you must emit
an error_report to say why.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 docs/devel/migration.txt       |  2 +-
 hw/arm/pxa2xx.c                |  4 +++-
 hw/arm/strongarm.c             |  4 +++-
 hw/audio/wm8750.c              |  4 +++-
 hw/block/fdc.c                 |  4 +++-
 hw/block/m25p80.c              |  4 +++-
 hw/block/nand.c                |  4 +++-
 hw/block/onenand.c             |  4 +++-
 hw/char/serial.c               |  4 +++-
 hw/display/qxl.c               |  4 +++-
 hw/i2c/core.c                  |  4 +++-
 hw/i386/kvm/clock.c            |  4 +++-
 hw/ide/core.c                  |  4 +++-
 hw/ide/pci.c                   |  4 +++-
 hw/input/ps2.c                 |  8 ++++++--
 hw/input/tsc210x.c             |  4 +++-
 hw/intc/apic_common.c          |  4 +++-
 hw/intc/arm_gic_common.c       |  4 +++-
 hw/intc/arm_gicv3_common.c     |  4 +++-
 hw/intc/arm_gicv3_its_common.c |  4 +++-
 hw/intc/i8259_common.c         |  4 +++-
 hw/intc/ioapic_common.c        |  4 +++-
 hw/intc/s390_flic_kvm.c        |  6 ++++--
 hw/intc/xics.c                 |  8 ++++++--
 hw/net/e1000.c                 |  4 +++-
 hw/net/e1000e.c                |  4 +++-
 hw/net/rtl8139.c               |  4 +++-
 hw/net/virtio-net.c            | 16 ++++++++++++----
 hw/net/vmxnet3.c               |  4 +++-
 hw/pci-host/piix.c             |  4 +++-
 hw/ppc/ppc.c                   |  4 +++-
 hw/ppc/spapr_iommu.c           |  4 +++-
 hw/ppc/spapr_pci.c             |  6 ++++--
 hw/s390x/css.c                 | 10 +++++++---
 hw/s390x/virtio-ccw.c          |  4 +++-
 hw/scsi/lsi53c895a.c           |  4 +++-
 hw/scsi/vmw_pvscsi.c           |  4 +++-
 hw/timer/cadence_ttc.c         |  4 +++-
 hw/timer/hpet.c                |  4 +++-
 hw/timer/i8254_common.c        |  4 +++-
 hw/timer/mc146818rtc.c         |  4 +++-
 hw/timer/pl031.c               |  4 +++-
 hw/timer/twl92230.c            |  4 +++-
 hw/usb/dev-smartcard-reader.c  |  4 +++-
 hw/usb/hcd-ehci.c              |  4 +++-
 hw/usb/redirect.c              |  4 +++-
 hw/virtio/vhost-vsock.c        |  4 +++-
 include/migration/vmstate.h    |  2 +-
 migration/colo-comm.c          |  4 +++-
 migration/global_state.c       |  4 +++-
 migration/savevm.c             |  4 +++-
 replay/replay-snapshot.c       |  4 +++-
 slirp/slirp.c                  |  8 ++++++--
 target/arm/machine.c           |  4 +++-
 target/i386/machine.c          |  7 +++++--
 target/ppc/machine.c           |  4 +++-
 target/s390x/machine.c         |  4 +++-
 target/sparc/machine.c         |  4 +++-
 tests/test-vmstate.c           |  4 +++-
 59 files changed, 199 insertions(+), 70 deletions(-)

diff --git a/docs/devel/migration.txt b/docs/devel/migration.txt
index 1b940a829b..4030703726 100644
--- a/docs/devel/migration.txt
+++ b/docs/devel/migration.txt
@@ -202,7 +202,7 @@ The functions to do that are inside a vmstate definition, and are called:
 
   This function is called after we load the state of one device.
 
-- void (*pre_save)(void *opaque);
+- int (*pre_save)(void *opaque);
 
   This function is called before we save the state of one device.
 
diff --git a/hw/arm/pxa2xx.c b/hw/arm/pxa2xx.c
index cf07234578..ab691a7985 100644
--- a/hw/arm/pxa2xx.c
+++ b/hw/arm/pxa2xx.c
@@ -1143,13 +1143,15 @@ static void pxa2xx_rtc_init(Object *obj)
     sysbus_init_mmio(dev, &s->iomem);
 }
 
-static void pxa2xx_rtc_pre_save(void *opaque)
+static int pxa2xx_rtc_pre_save(void *opaque)
 {
     PXA2xxRTCState *s = (PXA2xxRTCState *) opaque;
 
     pxa2xx_rtc_hzupdate(s);
     pxa2xx_rtc_piupdate(s);
     pxa2xx_rtc_swupdate(s);
+
+    return 0;
 }
 
 static int pxa2xx_rtc_post_load(void *opaque, int version_id)
diff --git a/hw/arm/strongarm.c b/hw/arm/strongarm.c
index 3d1a231d9e..4cdb3a670b 100644
--- a/hw/arm/strongarm.c
+++ b/hw/arm/strongarm.c
@@ -406,11 +406,13 @@ static void strongarm_rtc_init(Object *obj)
     sysbus_init_mmio(dev, &s->iomem);
 }
 
-static void strongarm_rtc_pre_save(void *opaque)
+static int strongarm_rtc_pre_save(void *opaque)
 {
     StrongARMRTCState *s = opaque;
 
     strongarm_rtc_hzupdate(s);
+
+    return 0;
 }
 
 static int strongarm_rtc_post_load(void *opaque, int version_id)
diff --git a/hw/audio/wm8750.c b/hw/audio/wm8750.c
index d2bf2e1da1..8bb44a7cc1 100644
--- a/hw/audio/wm8750.c
+++ b/hw/audio/wm8750.c
@@ -567,11 +567,13 @@ static int wm8750_rx(I2CSlave *i2c)
     return 0x00;
 }
 
-static void wm8750_pre_save(void *opaque)
+static int wm8750_pre_save(void *opaque)
 {
     WM8750State *s = opaque;
 
     s->rate_vmstate = s->rate - wm_rate_table;
+
+    return 0;
 }
 
 static int wm8750_post_load(void *opaque, int version_id)
diff --git a/hw/block/fdc.c b/hw/block/fdc.c
index 2853cdc205..67f78ac702 100644
--- a/hw/block/fdc.c
+++ b/hw/block/fdc.c
@@ -1101,11 +1101,13 @@ static int reconstruct_phase(FDCtrl *fdctrl)
     }
 }
 
-static void fdc_pre_save(void *opaque)
+static int fdc_pre_save(void *opaque)
 {
     FDCtrl *s = opaque;
 
     s->dor_vmstate = s->dor | GET_CUR_DRV(s);
+
+    return 0;
 }
 
 static int fdc_pre_load(void *opaque)
diff --git a/hw/block/m25p80.c b/hw/block/m25p80.c
index 190573cefa..a2438b9ed2 100644
--- a/hw/block/m25p80.c
+++ b/hw/block/m25p80.c
@@ -1251,9 +1251,11 @@ static void m25p80_reset(DeviceState *d)
     reset_memory(s);
 }
 
-static void m25p80_pre_save(void *opaque)
+static int m25p80_pre_save(void *opaque)
 {
     flash_sync_dirty((Flash *)opaque, -1);
+
+    return 0;
 }
 
 static Property m25p80_properties[] = {
diff --git a/hw/block/nand.c b/hw/block/nand.c
index 0d33ac281f..76dcd3f76e 100644
--- a/hw/block/nand.c
+++ b/hw/block/nand.c
@@ -325,11 +325,13 @@ static void nand_command(NANDFlashState *s)
     }
 }
 
-static void nand_pre_save(void *opaque)
+static int nand_pre_save(void *opaque)
 {
     NANDFlashState *s = NAND(opaque);
 
     s->ioaddr_vmstate = s->ioaddr - s->io;
+
+    return 0;
 }
 
 static int nand_post_load(void *opaque, int version_id)
diff --git a/hw/block/onenand.c b/hw/block/onenand.c
index b7423607d9..30e40f3914 100644
--- a/hw/block/onenand.c
+++ b/hw/block/onenand.c
@@ -137,7 +137,7 @@ static void onenand_intr_update(OneNANDState *s)
     qemu_set_irq(s->intr, ((s->intstatus >> 15) ^ (~s->config[0] >> 6)) & 1);
 }
 
-static void onenand_pre_save(void *opaque)
+static int onenand_pre_save(void *opaque)
 {
     OneNANDState *s = opaque;
     if (s->current == s->otp) {
@@ -147,6 +147,8 @@ static void onenand_pre_save(void *opaque)
     } else {
         s->current_direction = 0;
     }
+
+    return 0;
 }
 
 static int onenand_post_load(void *opaque, int version_id)
diff --git a/hw/char/serial.c b/hw/char/serial.c
index 9aec6c60d8..376bd2f240 100644
--- a/hw/char/serial.c
+++ b/hw/char/serial.c
@@ -630,10 +630,12 @@ static void serial_event(void *opaque, int event)
         serial_receive_break(s);
 }
 
-static void serial_pre_save(void *opaque)
+static int serial_pre_save(void *opaque)
 {
     SerialState *s = opaque;
     s->fcr_vmstate = s->fcr;
+
+    return 0;
 }
 
 static int serial_pre_load(void *opaque)
diff --git a/hw/display/qxl.c b/hw/display/qxl.c
index ae3677fd1e..d92fe05f1a 100644
--- a/hw/display/qxl.c
+++ b/hw/display/qxl.c
@@ -2204,7 +2204,7 @@ static void qxl_realize_secondary(PCIDevice *dev, Error **errp)
     qxl_realize_common(qxl, errp);
 }
 
-static void qxl_pre_save(void *opaque)
+static int qxl_pre_save(void *opaque)
 {
     PCIQXLDevice* d = opaque;
     uint8_t *ram_start = d->vga.vram_ptr;
@@ -2216,6 +2216,8 @@ static void qxl_pre_save(void *opaque)
         d->last_release_offset = (uint8_t *)d->last_release - ram_start;
     }
     assert(d->last_release_offset < d->vga.vram_size);
+
+    return 0;
 }
 
 static int qxl_pre_load(void *opaque)
diff --git a/hw/i2c/core.c b/hw/i2c/core.c
index 2c1234cdff..59068f157e 100644
--- a/hw/i2c/core.c
+++ b/hw/i2c/core.c
@@ -41,7 +41,7 @@ static const TypeInfo i2c_bus_info = {
     .instance_size = sizeof(I2CBus),
 };
 
-static void i2c_bus_pre_save(void *opaque)
+static int i2c_bus_pre_save(void *opaque)
 {
     I2CBus *bus = opaque;
 
@@ -53,6 +53,8 @@ static void i2c_bus_pre_save(void *opaque)
             bus->saved_address = I2C_BROADCAST;
         }
     }
+
+    return 0;
 }
 
 static const VMStateDescription vmstate_i2c_bus = {
diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c
index 363d1b5743..75ad1ba6f0 100644
--- a/hw/i386/kvm/clock.c
+++ b/hw/i386/kvm/clock.c
@@ -254,11 +254,13 @@ static const VMStateDescription kvmclock_reliable_get_clock = {
  *  final pages of memory (which happens between vm_stop()
  *  and pre_save()) takes max_downtime.
  */
-static void kvmclock_pre_save(void *opaque)
+static int kvmclock_pre_save(void *opaque)
 {
     KVMClockState *s = opaque;
 
     kvm_update_clock(s);
+
+    return 0;
 }
 
 static const VMStateDescription kvmclock_vmsd = {
diff --git a/hw/ide/core.c b/hw/ide/core.c
index d63eb4a72e..5f1cd3b91f 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -2752,7 +2752,7 @@ static int ide_drive_pio_post_load(void *opaque, int version_id)
     return 0;
 }
 
-static void ide_drive_pio_pre_save(void *opaque)
+static int ide_drive_pio_pre_save(void *opaque)
 {
     IDEState *s = opaque;
     int idx;
@@ -2768,6 +2768,8 @@ static void ide_drive_pio_pre_save(void *opaque)
     } else {
         s->end_transfer_fn_idx = idx;
     }
+
+    return 0;
 }
 
 static bool ide_drive_pio_state_needed(void *opaque)
diff --git a/hw/ide/pci.c b/hw/ide/pci.c
index f2dcc0ed77..d53ff5341c 100644
--- a/hw/ide/pci.c
+++ b/hw/ide/pci.c
@@ -296,7 +296,7 @@ static bool ide_bmdma_status_needed(void *opaque)
     return ((bm->status & abused_bits) != 0);
 }
 
-static void ide_bmdma_pre_save(void *opaque)
+static int ide_bmdma_pre_save(void *opaque)
 {
     BMDMAState *bm = opaque;
     uint8_t abused_bits = BM_MIGRATION_COMPAT_STATUS_BITS;
@@ -310,6 +310,8 @@ static void ide_bmdma_pre_save(void *opaque)
     bm->migration_retry_nsector = bm->bus->retry_nsector;
     bm->migration_compat_status =
         (bm->status & ~abused_bits) | (bm->bus->error_status & abused_bits);
+
+    return 0;
 }
 
 /* This function accesses bm->bus->error_status which is loaded only after
diff --git a/hw/input/ps2.c b/hw/input/ps2.c
index 77906d5f46..dff3f1e024 100644
--- a/hw/input/ps2.c
+++ b/hw/input/ps2.c
@@ -1216,12 +1216,14 @@ static int ps2_kbd_post_load(void* opaque, int version_id)
     return 0;
 }
 
-static void ps2_kbd_pre_save(void *opaque)
+static int ps2_kbd_pre_save(void *opaque)
 {
     PS2KbdState *s = (PS2KbdState *)opaque;
     PS2State *ps2 = &s->common;
 
     ps2_common_post_load(ps2);
+
+    return 0;
 }
 
 static const VMStateDescription vmstate_ps2_keyboard = {
@@ -1254,12 +1256,14 @@ static int ps2_mouse_post_load(void *opaque, int version_id)
     return 0;
 }
 
-static void ps2_mouse_pre_save(void *opaque)
+static int ps2_mouse_pre_save(void *opaque)
 {
     PS2MouseState *s = (PS2MouseState *)opaque;
     PS2State *ps2 = &s->common;
 
     ps2_common_post_load(ps2);
+
+    return 0;
 }
 
 static const VMStateDescription vmstate_ps2_mouse = {
diff --git a/hw/input/tsc210x.c b/hw/input/tsc210x.c
index b068343771..75ac8c2ab5 100644
--- a/hw/input/tsc210x.c
+++ b/hw/input/tsc210x.c
@@ -976,10 +976,12 @@ static void tsc210x_i2s_set_rate(TSC210xState *s, int in, int out)
     s->i2s_rx_rate = in;
 }
 
-static void tsc210x_pre_save(void *opaque)
+static int tsc210x_pre_save(void *opaque)
 {
     TSC210xState *s = (TSC210xState *) opaque;
     s->now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+
+    return 0;
 }
 
 static int tsc210x_post_load(void *opaque, int version_id)
diff --git a/hw/intc/apic_common.c b/hw/intc/apic_common.c
index e1ac33042f..78903ea909 100644
--- a/hw/intc/apic_common.c
+++ b/hw/intc/apic_common.c
@@ -360,7 +360,7 @@ static int apic_pre_load(void *opaque)
     return 0;
 }
 
-static void apic_dispatch_pre_save(void *opaque)
+static int apic_dispatch_pre_save(void *opaque)
 {
     APICCommonState *s = APIC_COMMON(opaque);
     APICCommonClass *info = APIC_COMMON_GET_CLASS(s);
@@ -368,6 +368,8 @@ static void apic_dispatch_pre_save(void *opaque)
     if (info->pre_save) {
         info->pre_save(s);
     }
+
+    return 0;
 }
 
 static int apic_dispatch_post_load(void *opaque, int version_id)
diff --git a/hw/intc/arm_gic_common.c b/hw/intc/arm_gic_common.c
index 70f1134823..aee50a20e0 100644
--- a/hw/intc/arm_gic_common.c
+++ b/hw/intc/arm_gic_common.c
@@ -23,7 +23,7 @@
 #include "gic_internal.h"
 #include "hw/arm/linux-boot-if.h"
 
-static void gic_pre_save(void *opaque)
+static int gic_pre_save(void *opaque)
 {
     GICState *s = (GICState *)opaque;
     ARMGICCommonClass *c = ARM_GIC_COMMON_GET_CLASS(s);
@@ -31,6 +31,8 @@ static void gic_pre_save(void *opaque)
     if (c->pre_save) {
         c->pre_save(s);
     }
+
+    return 0;
 }
 
 static int gic_post_load(void *opaque, int version_id)
diff --git a/hw/intc/arm_gicv3_common.c b/hw/intc/arm_gicv3_common.c
index 410915a2ac..7b54d52376 100644
--- a/hw/intc/arm_gicv3_common.c
+++ b/hw/intc/arm_gicv3_common.c
@@ -28,7 +28,7 @@
 #include "gicv3_internal.h"
 #include "hw/arm/linux-boot-if.h"
 
-static void gicv3_pre_save(void *opaque)
+static int gicv3_pre_save(void *opaque)
 {
     GICv3State *s = (GICv3State *)opaque;
     ARMGICv3CommonClass *c = ARM_GICV3_COMMON_GET_CLASS(s);
@@ -36,6 +36,8 @@ static void gicv3_pre_save(void *opaque)
     if (c->pre_save) {
         c->pre_save(s);
     }
+
+    return 0;
 }
 
 static int gicv3_post_load(void *opaque, int version_id)
diff --git a/hw/intc/arm_gicv3_its_common.c b/hw/intc/arm_gicv3_its_common.c
index 68b20fccd1..f2cce597a9 100644
--- a/hw/intc/arm_gicv3_its_common.c
+++ b/hw/intc/arm_gicv3_its_common.c
@@ -23,7 +23,7 @@
 #include "hw/intc/arm_gicv3_its_common.h"
 #include "qemu/log.h"
 
-static void gicv3_its_pre_save(void *opaque)
+static int gicv3_its_pre_save(void *opaque)
 {
     GICv3ITSState *s = (GICv3ITSState *)opaque;
     GICv3ITSCommonClass *c = ARM_GICV3_ITS_COMMON_GET_CLASS(s);
@@ -31,6 +31,8 @@ static void gicv3_its_pre_save(void *opaque)
     if (c->pre_save) {
         c->pre_save(s);
     }
+
+    return 0;
 }
 
 static int gicv3_its_post_load(void *opaque, int version_id)
diff --git a/hw/intc/i8259_common.c b/hw/intc/i8259_common.c
index c2fd563b5b..18427b459a 100644
--- a/hw/intc/i8259_common.c
+++ b/hw/intc/i8259_common.c
@@ -46,7 +46,7 @@ void pic_reset_common(PICCommonState *s)
     /* Note: ELCR is not reset */
 }
 
-static void pic_dispatch_pre_save(void *opaque)
+static int pic_dispatch_pre_save(void *opaque)
 {
     PICCommonState *s = opaque;
     PICCommonClass *info = PIC_COMMON_GET_CLASS(s);
@@ -54,6 +54,8 @@ static void pic_dispatch_pre_save(void *opaque)
     if (info->pre_save) {
         info->pre_save(s);
     }
+
+    return 0;
 }
 
 static int pic_dispatch_post_load(void *opaque, int version_id)
diff --git a/hw/intc/ioapic_common.c b/hw/intc/ioapic_common.c
index 97c4f9c2df..3b3d0a7680 100644
--- a/hw/intc/ioapic_common.c
+++ b/hw/intc/ioapic_common.c
@@ -102,7 +102,7 @@ void ioapic_reset_common(DeviceState *dev)
     }
 }
 
-static void ioapic_dispatch_pre_save(void *opaque)
+static int ioapic_dispatch_pre_save(void *opaque)
 {
     IOAPICCommonState *s = IOAPIC_COMMON(opaque);
     IOAPICCommonClass *info = IOAPIC_COMMON_GET_CLASS(s);
@@ -110,6 +110,8 @@ static void ioapic_dispatch_pre_save(void *opaque)
     if (info->pre_save) {
         info->pre_save(s);
     }
+
+    return 0;
 }
 
 static int ioapic_dispatch_post_load(void *opaque, int version_id)
diff --git a/hw/intc/s390_flic_kvm.c b/hw/intc/s390_flic_kvm.c
index 7ead17ac3e..d208cb81c4 100644
--- a/hw/intc/s390_flic_kvm.c
+++ b/hw/intc/s390_flic_kvm.c
@@ -420,7 +420,7 @@ typedef struct KVMS390FLICStateMigTmp {
     uint8_t nimm;
 } KVMS390FLICStateMigTmp;
 
-static void kvm_flic_ais_pre_save(void *opaque)
+static int kvm_flic_ais_pre_save(void *opaque)
 {
     KVMS390FLICStateMigTmp *tmp = opaque;
     KVMS390FLICState *flic = tmp->parent;
@@ -433,11 +433,13 @@ static void kvm_flic_ais_pre_save(void *opaque)
 
     if (ioctl(flic->fd, KVM_GET_DEVICE_ATTR, &attr)) {
         error_report("Failed to retrieve kvm flic ais states");
-        return;
+        return -EINVAL;
     }
 
     tmp->simm = ais.simm;
     tmp->nimm = ais.nimm;
+
+    return 0;
 }
 
 static int kvm_flic_ais_post_load(void *opaque, int version_id)
diff --git a/hw/intc/xics.c b/hw/intc/xics.c
index 80c33be02e..cc9816e7f2 100644
--- a/hw/intc/xics.c
+++ b/hw/intc/xics.c
@@ -241,7 +241,7 @@ static void icp_irq(ICSState *ics, int server, int nr, uint8_t priority)
     }
 }
 
-static void icp_dispatch_pre_save(void *opaque)
+static int icp_dispatch_pre_save(void *opaque)
 {
     ICPState *icp = opaque;
     ICPStateClass *info = ICP_GET_CLASS(icp);
@@ -249,6 +249,8 @@ static void icp_dispatch_pre_save(void *opaque)
     if (info->pre_save) {
         info->pre_save(icp);
     }
+
+    return 0;
 }
 
 static int icp_dispatch_post_load(void *opaque, int version_id)
@@ -533,7 +535,7 @@ static void ics_simple_reset(void *dev)
     }
 }
 
-static void ics_simple_dispatch_pre_save(void *opaque)
+static int ics_simple_dispatch_pre_save(void *opaque)
 {
     ICSState *ics = opaque;
     ICSStateClass *info = ICS_BASE_GET_CLASS(ics);
@@ -541,6 +543,8 @@ static void ics_simple_dispatch_pre_save(void *opaque)
     if (info->pre_save) {
         info->pre_save(ics);
     }
+
+    return 0;
 }
 
 static int ics_simple_dispatch_post_load(void *opaque, int version_id)
diff --git a/hw/net/e1000.c b/hw/net/e1000.c
index eebe3a9c13..cae95185a5 100644
--- a/hw/net/e1000.c
+++ b/hw/net/e1000.c
@@ -1343,7 +1343,7 @@ static bool is_version_1(void *opaque, int version_id)
     return version_id == 1;
 }
 
-static void e1000_pre_save(void *opaque)
+static int e1000_pre_save(void *opaque)
 {
     E1000State *s = opaque;
     NetClientState *nc = qemu_get_queue(s->nic);
@@ -1361,6 +1361,8 @@ static void e1000_pre_save(void *opaque)
     if (nc->link_down && have_autoneg(s)) {
         s->phy_reg[PHY_STATUS] |= MII_SR_AUTONEG_COMPLETE;
     }
+
+    return 0;
 }
 
 static int e1000_post_load(void *opaque, int version_id)
diff --git a/hw/net/e1000e.c b/hw/net/e1000e.c
index 6c42b4478c..744f0f3b91 100644
--- a/hw/net/e1000e.c
+++ b/hw/net/e1000e.c
@@ -523,13 +523,15 @@ static void e1000e_qdev_reset(DeviceState *dev)
     e1000e_core_reset(&s->core);
 }
 
-static void e1000e_pre_save(void *opaque)
+static int e1000e_pre_save(void *opaque)
 {
     E1000EState *s = opaque;
 
     trace_e1000e_cb_pre_save();
 
     e1000e_core_pre_save(&s->core);
+
+    return 0;
 }
 
 static int e1000e_post_load(void *opaque, int version_id)
diff --git a/hw/net/rtl8139.c b/hw/net/rtl8139.c
index 3be24bbee7..d6c8188ae1 100644
--- a/hw/net/rtl8139.c
+++ b/hw/net/rtl8139.c
@@ -3162,7 +3162,7 @@ static const VMStateDescription vmstate_rtl8139_hotplug_ready ={
     }
 };
 
-static void rtl8139_pre_save(void *opaque)
+static int rtl8139_pre_save(void *opaque)
 {
     RTL8139State* s = opaque;
     int64_t current_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
@@ -3170,6 +3170,8 @@ static void rtl8139_pre_save(void *opaque)
     /* for migration to older versions */
     s->TCTR = (current_time - s->TCTR_base) / PCI_PERIOD;
     s->rtl8139_mmio_io_addr_dummy = 0;
+
+    return 0;
 }
 
 static const VMStateDescription vmstate_rtl8139 = {
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 148071a396..150fd0748e 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -1712,7 +1712,7 @@ struct VirtIONetMigTmp {
  * pointer and count and also validate the count.
  */
 
-static void virtio_net_tx_waiting_pre_save(void *opaque)
+static int virtio_net_tx_waiting_pre_save(void *opaque)
 {
     struct VirtIONetMigTmp *tmp = opaque;
 
@@ -1721,6 +1721,8 @@ static void virtio_net_tx_waiting_pre_save(void *opaque)
     if (tmp->parent->curr_queues == 0) {
         tmp->curr_queues_1 = 0;
     }
+
+    return 0;
 }
 
 static int virtio_net_tx_waiting_pre_load(void *opaque)
@@ -1768,11 +1770,13 @@ static int virtio_net_ufo_post_load(void *opaque, int version_id)
     return 0;
 }
 
-static void virtio_net_ufo_pre_save(void *opaque)
+static int virtio_net_ufo_pre_save(void *opaque)
 {
     struct VirtIONetMigTmp *tmp = opaque;
 
     tmp->has_ufo = tmp->parent->has_ufo;
+
+    return 0;
 }
 
 static const VMStateDescription vmstate_virtio_net_has_ufo = {
@@ -1800,11 +1804,13 @@ static int virtio_net_vnet_post_load(void *opaque, int version_id)
     return 0;
 }
 
-static void virtio_net_vnet_pre_save(void *opaque)
+static int virtio_net_vnet_pre_save(void *opaque)
 {
     struct VirtIONetMigTmp *tmp = opaque;
 
     tmp->has_vnet_hdr = tmp->parent->has_vnet_hdr;
+
+    return 0;
 }
 
 static const VMStateDescription vmstate_virtio_net_has_vnet = {
@@ -2079,13 +2085,15 @@ static void virtio_net_instance_init(Object *obj)
                                   DEVICE(n), NULL);
 }
 
-static void virtio_net_pre_save(void *opaque)
+static int virtio_net_pre_save(void *opaque)
 {
     VirtIONet *n = opaque;
 
     /* At this point, backend must be stopped, otherwise
      * it might keep writing to memory. */
     assert(!n->vhost_started);
+
+    return 0;
 }
 
 static const VMStateDescription vmstate_virtio_net = {
diff --git a/hw/net/vmxnet3.c b/hw/net/vmxnet3.c
index a19a7a31dd..b43b58be2b 100644
--- a/hw/net/vmxnet3.c
+++ b/hw/net/vmxnet3.c
@@ -2388,11 +2388,13 @@ static int vmxnet3_mcast_list_pre_load(void *opaque)
 }
 
 
-static void vmxnet3_pre_save(void *opaque)
+static int vmxnet3_pre_save(void *opaque)
 {
     VMXNET3State *s = opaque;
 
     s->mcast_list_buff_size = s->mcast_list_len * sizeof(MACAddr);
+
+    return 0;
 }
 
 static const VMStateDescription vmxstate_vmxnet3_mcast_list = {
diff --git a/hw/pci-host/piix.c b/hw/pci-host/piix.c
index 894e131c00..dec345fd24 100644
--- a/hw/pci-host/piix.c
+++ b/hw/pci-host/piix.c
@@ -579,7 +579,7 @@ static int piix3_post_load(void *opaque, int version_id)
     return 0;
 }
 
-static void piix3_pre_save(void *opaque)
+static int piix3_pre_save(void *opaque)
 {
     int i;
     PIIX3State *piix3 = opaque;
@@ -588,6 +588,8 @@ static void piix3_pre_save(void *opaque)
         piix3->pci_irq_levels_vmstate[i] =
             pci_bus_get_irq_level(piix3->dev.bus, i);
     }
+
+    return 0;
 }
 
 static bool piix3_rcr_needed(void *opaque)
diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c
index f76886f4d3..05da316e0b 100644
--- a/hw/ppc/ppc.c
+++ b/hw/ppc/ppc.c
@@ -937,11 +937,13 @@ void cpu_ppc_clock_vm_state_change(void *opaque, int running,
  *  final pages of memory (which happens between vm_stop()
  *  and pre_save()) takes max_downtime.
  */
-static void timebase_pre_save(void *opaque)
+static int timebase_pre_save(void *opaque)
 {
     PPCTimebase *tb = opaque;
 
     timebase_save(tb);
+
+    return 0;
 }
 
 const VMStateDescription vmstate_ppc_timebase = {
diff --git a/hw/ppc/spapr_iommu.c b/hw/ppc/spapr_iommu.c
index fa8b969840..5ccd785d5a 100644
--- a/hw/ppc/spapr_iommu.c
+++ b/hw/ppc/spapr_iommu.c
@@ -140,7 +140,7 @@ static IOMMUTLBEntry spapr_tce_translate_iommu(IOMMUMemoryRegion *iommu,
     return ret;
 }
 
-static void spapr_tce_table_pre_save(void *opaque)
+static int spapr_tce_table_pre_save(void *opaque)
 {
     sPAPRTCETable *tcet = SPAPR_TCE_TABLE(opaque);
 
@@ -149,6 +149,8 @@ static void spapr_tce_table_pre_save(void *opaque)
 
     trace_spapr_iommu_pre_save(tcet->liobn, tcet->mig_nb_table,
                                tcet->bus_offset, tcet->page_shift);
+
+    return 0;
 }
 
 static uint64_t spapr_tce_get_min_page_size(IOMMUMemoryRegion *iommu)
diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index cf54160526..8c2b6dc1dc 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -1844,7 +1844,7 @@ static const VMStateDescription vmstate_spapr_pci_msi = {
     },
 };
 
-static void spapr_pci_pre_save(void *opaque)
+static int spapr_pci_pre_save(void *opaque)
 {
     sPAPRPHBState *sphb = opaque;
     GHashTableIter iter;
@@ -1869,7 +1869,7 @@ static void spapr_pci_pre_save(void *opaque)
     sphb->msi_devs = NULL;
     sphb->msi_devs_num = g_hash_table_size(sphb->msi);
     if (!sphb->msi_devs_num) {
-        return;
+        return 0;
     }
     sphb->msi_devs = g_malloc(sphb->msi_devs_num * sizeof(spapr_pci_msi_mig));
 
@@ -1878,6 +1878,8 @@ static void spapr_pci_pre_save(void *opaque)
         sphb->msi_devs[i].key = *(uint32_t *) key;
         sphb->msi_devs[i].value = *(spapr_pci_msi *) value;
     }
+
+    return 0;
 }
 
 static int spapr_pci_post_load(void *opaque, int version_id)
diff --git a/hw/s390x/css.c b/hw/s390x/css.c
index 75d4f301fb..c59be1aad1 100644
--- a/hw/s390x/css.c
+++ b/hw/s390x/css.c
@@ -196,7 +196,7 @@ static const VMStateDescription vmstate_schdev_orb = {
 };
 
 static int subch_dev_post_load(void *opaque, int version_id);
-static void subch_dev_pre_save(void *opaque);
+static int subch_dev_pre_save(void *opaque);
 
 const char err_hint_devno[] = "Devno mismatch, tried to load wrong section!"
     " Likely reason: some sequences of plug and unplug  can break"
@@ -249,7 +249,7 @@ static int post_load_ind_addr(void *opaque, int version_id)
     return 0;
 }
 
-static void pre_save_ind_addr(void *opaque)
+static int pre_save_ind_addr(void *opaque)
 {
     IndAddrPtrTmp *ptmp = opaque;
     IndAddr *ind_addr = *(ptmp->parent);
@@ -261,6 +261,8 @@ static void pre_save_ind_addr(void *opaque)
         ptmp->len = 0;
         ptmp->addr = 0L;
     }
+
+    return 0;
 }
 
 const VMStateDescription vmstate_ind_addr_tmp = {
@@ -358,12 +360,14 @@ static ChannelSubSys channel_subsys = {
         QTAILQ_HEAD_INITIALIZER(channel_subsys.indicator_addresses),
 };
 
-static void subch_dev_pre_save(void *opaque)
+static int subch_dev_pre_save(void *opaque)
 {
     SubchDev *s = opaque;
 
     /* Prepare remote_schid for save */
     s->migrated_schid = s->schid;
+
+    return 0;
 }
 
 static int subch_dev_post_load(void *opaque, int version_id)
diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
index ff1bb1534c..62d69aa30b 100644
--- a/hw/s390x/virtio-ccw.c
+++ b/hw/s390x/virtio-ccw.c
@@ -62,13 +62,15 @@ typedef struct VirtioCcwDeviceTmp {
     uint16_t config_vector;
 } VirtioCcwDeviceTmp;
 
-static void virtio_ccw_dev_tmp_pre_save(void *opaque)
+static int virtio_ccw_dev_tmp_pre_save(void *opaque)
 {
     VirtioCcwDeviceTmp *tmp = opaque;
     VirtioCcwDevice *dev = tmp->parent;
     VirtIODevice *vdev = virtio_bus_get_device(&dev->bus);
 
     tmp->config_vector = vdev->config_vector;
+
+    return 0;
 }
 
 static int virtio_ccw_dev_tmp_post_load(void *opaque, int version_id)
diff --git a/hw/scsi/lsi53c895a.c b/hw/scsi/lsi53c895a.c
index 3e56ab267c..a67ee074d9 100644
--- a/hw/scsi/lsi53c895a.c
+++ b/hw/scsi/lsi53c895a.c
@@ -2083,7 +2083,7 @@ static void lsi_scsi_reset(DeviceState *dev)
     lsi_soft_reset(s);
 }
 
-static void lsi_pre_save(void *opaque)
+static int lsi_pre_save(void *opaque)
 {
     LSIState *s = opaque;
 
@@ -2092,6 +2092,8 @@ static void lsi_pre_save(void *opaque)
         assert(s->current->dma_len == 0);
     }
     assert(QTAILQ_EMPTY(&s->queue));
+
+    return 0;
 }
 
 static const VMStateDescription vmstate_lsi_scsi = {
diff --git a/hw/scsi/vmw_pvscsi.c b/hw/scsi/vmw_pvscsi.c
index 6d3f0bf11d..d8079158ac 100644
--- a/hw/scsi/vmw_pvscsi.c
+++ b/hw/scsi/vmw_pvscsi.c
@@ -1167,7 +1167,7 @@ pvscsi_reset(DeviceState *dev)
     pvscsi_reset_adapter(s);
 }
 
-static void
+static int
 pvscsi_pre_save(void *opaque)
 {
     PVSCSIState *s = (PVSCSIState *) opaque;
@@ -1176,6 +1176,8 @@ pvscsi_pre_save(void *opaque)
 
     assert(QTAILQ_EMPTY(&s->pending_queue));
     assert(QTAILQ_EMPTY(&s->completion_queue));
+
+    return 0;
 }
 
 static int
diff --git a/hw/timer/cadence_ttc.c b/hw/timer/cadence_ttc.c
index 03f5b9c206..5e65fdb5a0 100644
--- a/hw/timer/cadence_ttc.c
+++ b/hw/timer/cadence_ttc.c
@@ -421,9 +421,11 @@ static void cadence_ttc_init(Object *obj)
     sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->iomem);
 }
 
-static void cadence_timer_pre_save(void *opaque)
+static int cadence_timer_pre_save(void *opaque)
 {
     cadence_timer_sync((CadenceTimerState *)opaque);
+
+    return 0;
 }
 
 static int cadence_timer_post_load(void *opaque, int version_id)
diff --git a/hw/timer/hpet.c b/hw/timer/hpet.c
index a2c18b30c3..577371bc6d 100644
--- a/hw/timer/hpet.c
+++ b/hw/timer/hpet.c
@@ -216,12 +216,14 @@ static void update_irq(struct HPETTimer *timer, int set)
     }
 }
 
-static void hpet_pre_save(void *opaque)
+static int hpet_pre_save(void *opaque)
 {
     HPETState *s = opaque;
 
     /* save current counter value */
     s->hpet_counter = hpet_get_ticks(s);
+
+    return 0;
 }
 
 static int hpet_pre_load(void *opaque)
diff --git a/hw/timer/i8254_common.c b/hw/timer/i8254_common.c
index ee064aa819..b623c96198 100644
--- a/hw/timer/i8254_common.c
+++ b/hw/timer/i8254_common.c
@@ -237,7 +237,7 @@ static int pit_load_old(QEMUFile *f, void *opaque, int version_id)
     return 0;
 }
 
-static void pit_dispatch_pre_save(void *opaque)
+static int pit_dispatch_pre_save(void *opaque)
 {
     PITCommonState *s = opaque;
     PITCommonClass *c = PIT_COMMON_GET_CLASS(s);
@@ -245,6 +245,8 @@ static void pit_dispatch_pre_save(void *opaque)
     if (c->pre_save) {
         c->pre_save(s);
     }
+
+    return 0;
 }
 
 static int pit_dispatch_post_load(void *opaque, int version_id)
diff --git a/hw/timer/mc146818rtc.c b/hw/timer/mc146818rtc.c
index 82843ed03f..7764be25ec 100644
--- a/hw/timer/mc146818rtc.c
+++ b/hw/timer/mc146818rtc.c
@@ -795,11 +795,13 @@ static void rtc_set_date_from_host(ISADevice *dev)
     rtc_set_cmos(s, &tm);
 }
 
-static void rtc_pre_save(void *opaque)
+static int rtc_pre_save(void *opaque)
 {
     RTCState *s = opaque;
 
     rtc_update_time(s);
+
+    return 0;
 }
 
 static int rtc_post_load(void *opaque, int version_id)
diff --git a/hw/timer/pl031.c b/hw/timer/pl031.c
index dbbeb9b16b..d3aacce80d 100644
--- a/hw/timer/pl031.c
+++ b/hw/timer/pl031.c
@@ -211,7 +211,7 @@ static void pl031_init(Object *obj)
     s->timer = timer_new_ns(rtc_clock, pl031_interrupt, s);
 }
 
-static void pl031_pre_save(void *opaque)
+static int pl031_pre_save(void *opaque)
 {
     PL031State *s = opaque;
 
@@ -219,6 +219,8 @@ static void pl031_pre_save(void *opaque)
      * store the base time relative to the QEMU_CLOCK_VIRTUAL for backwards-compatibility.  */
     int64_t delta = qemu_clock_get_ns(rtc_clock) - qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
     s->tick_offset_vmstate = s->tick_offset + delta / NANOSECONDS_PER_SECOND;
+
+    return 0;
 }
 
 static int pl031_post_load(void *opaque, int version_id)
diff --git a/hw/timer/twl92230.c b/hw/timer/twl92230.c
index c0aa8ae3de..eb58c378e0 100644
--- a/hw/timer/twl92230.c
+++ b/hw/timer/twl92230.c
@@ -791,11 +791,13 @@ static const VMStateDescription vmstate_menelaus_tm = {
     }
 };
 
-static void menelaus_pre_save(void *opaque)
+static int menelaus_pre_save(void *opaque)
 {
     MenelausState *s = opaque;
     /* Should be <= 1000 */
     s->rtc_next_vmstate =  s->rtc.next - qemu_clock_get_ms(rtc_clock);
+
+    return 0;
 }
 
 static int menelaus_post_load(void *opaque, int version_id)
diff --git a/hw/usb/dev-smartcard-reader.c b/hw/usb/dev-smartcard-reader.c
index bef1f03c42..0c77d2a41d 100644
--- a/hw/usb/dev-smartcard-reader.c
+++ b/hw/usb/dev-smartcard-reader.c
@@ -1374,7 +1374,7 @@ static int ccid_post_load(void *opaque, int version_id)
     return 0;
 }
 
-static void ccid_pre_save(void *opaque)
+static int ccid_pre_save(void *opaque)
 {
     USBCCIDState *s = opaque;
 
@@ -1386,6 +1386,8 @@ static void ccid_pre_save(void *opaque)
          */
         s->migration_state = MIGRATION_MIGRATED;
     }
+
+    return 0;
 }
 
 static VMStateDescription bulk_in_vmstate = {
diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c
index 46fd30b075..0134232627 100644
--- a/hw/usb/hcd-ehci.c
+++ b/hw/usb/hcd-ehci.c
@@ -2381,7 +2381,7 @@ static USBBusOps ehci_bus_ops_standalone = {
     .wakeup_endpoint = ehci_wakeup_endpoint,
 };
 
-static void usb_ehci_pre_save(void *opaque)
+static int usb_ehci_pre_save(void *opaque)
 {
     EHCIState *ehci = opaque;
     uint32_t new_frindex;
@@ -2390,6 +2390,8 @@ static void usb_ehci_pre_save(void *opaque)
     new_frindex = ehci->frindex & ~7;
     ehci->last_run_ns -= (ehci->frindex - new_frindex) * UFRAME_TIMER_NS;
     ehci->frindex = new_frindex;
+
+    return 0;
 }
 
 static int usb_ehci_post_load(void *opaque, int version_id)
diff --git a/hw/usb/redirect.c b/hw/usb/redirect.c
index 5e42730449..ec174309db 100644
--- a/hw/usb/redirect.c
+++ b/hw/usb/redirect.c
@@ -2111,11 +2111,13 @@ static void usbredir_buffered_bulk_packet(void *priv, uint64_t id,
  * Migration code
  */
 
-static void usbredir_pre_save(void *priv)
+static int usbredir_pre_save(void *priv)
 {
     USBRedirDevice *dev = priv;
 
     usbredir_fill_already_in_flight(dev);
+
+    return 0;
 }
 
 static int usbredir_post_load(void *priv, int version_id)
diff --git a/hw/virtio/vhost-vsock.c b/hw/virtio/vhost-vsock.c
index 49e0022533..5ec1c6a2a2 100644
--- a/hw/virtio/vhost-vsock.c
+++ b/hw/virtio/vhost-vsock.c
@@ -254,13 +254,15 @@ static void vhost_vsock_post_load_timer_cb(void *opaque)
     vhost_vsock_send_transport_reset(vsock);
 }
 
-static void vhost_vsock_pre_save(void *opaque)
+static int vhost_vsock_pre_save(void *opaque)
 {
     VHostVSock *vsock = opaque;
 
     /* At this point, backend must be stopped, otherwise
      * it might keep writing to memory. */
     assert(!vsock->vhost_dev.started);
+
+    return 0;
 }
 
 static int vhost_vsock_post_load(void *opaque, int version_id)
diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
index 85e43da568..da46b1a36d 100644
--- a/include/migration/vmstate.h
+++ b/include/migration/vmstate.h
@@ -179,7 +179,7 @@ struct VMStateDescription {
     LoadStateHandler *load_state_old;
     int (*pre_load)(void *opaque);
     int (*post_load)(void *opaque, int version_id);
-    void (*pre_save)(void *opaque);
+    int (*pre_save)(void *opaque);
     bool (*needed)(void *opaque);
     VMStateField *fields;
     const VMStateDescription **subsections;
diff --git a/migration/colo-comm.c b/migration/colo-comm.c
index b61aa19a38..df26e4dfe7 100644
--- a/migration/colo-comm.c
+++ b/migration/colo-comm.c
@@ -34,11 +34,13 @@ COLOMode get_colo_mode(void)
     }
 }
 
-static void colo_info_pre_save(void *opaque)
+static int colo_info_pre_save(void *opaque)
 {
     COLOInfo *s = opaque;
 
     s->colo_requested = migrate_colo_enabled();
+
+    return 0;
 }
 
 static bool colo_info_need(void *opaque)
diff --git a/migration/global_state.c b/migration/global_state.c
index dfdaf63910..8e8ab5c51e 100644
--- a/migration/global_state.c
+++ b/migration/global_state.c
@@ -101,12 +101,14 @@ static int global_state_post_load(void *opaque, int version_id)
     return 0;
 }
 
-static void global_state_pre_save(void *opaque)
+static int global_state_pre_save(void *opaque)
 {
     GlobalState *s = opaque;
 
     trace_migrate_global_state_pre_save((char *)s->runstate);
     s->size = strlen((char *)s->runstate) + 1;
+
+    return 0;
 }
 
 static const VMStateDescription vmstate_globalstate = {
diff --git a/migration/savevm.c b/migration/savevm.c
index 2478352baf..e9feade46a 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -312,7 +312,7 @@ static SaveState savevm_state = {
     .global_section_id = 0,
 };
 
-static void configuration_pre_save(void *opaque)
+static int configuration_pre_save(void *opaque)
 {
     SaveState *state = opaque;
     const char *current_name = MACHINE_GET_CLASS(current_machine)->name;
@@ -320,6 +320,8 @@ static void configuration_pre_save(void *opaque)
     state->len = strlen(current_name);
     state->name = current_name;
     state->target_page_bits = qemu_target_page_bits();
+
+    return 0;
 }
 
 static int configuration_pre_load(void *opaque)
diff --git a/replay/replay-snapshot.c b/replay/replay-snapshot.c
index a4ded2956d..b2e10769a6 100644
--- a/replay/replay-snapshot.c
+++ b/replay/replay-snapshot.c
@@ -21,10 +21,12 @@
 #include "migration/vmstate.h"
 #include "migration/snapshot.h"
 
-static void replay_pre_save(void *opaque)
+static int replay_pre_save(void *opaque)
 {
     ReplayState *state = opaque;
     state->file_offset = ftell(replay_file);
+
+    return 0;
 }
 
 static int replay_post_load(void *opaque, int version_id)
diff --git a/slirp/slirp.c b/slirp/slirp.c
index 1d6756821c..1cb6b07004 100644
--- a/slirp/slirp.c
+++ b/slirp/slirp.c
@@ -1203,11 +1203,13 @@ struct sbuf_tmp {
     uint32_t roff, woff;
 };
 
-static void sbuf_tmp_pre_save(void *opaque)
+static int sbuf_tmp_pre_save(void *opaque)
 {
     struct sbuf_tmp *tmp = opaque;
     tmp->woff = tmp->parent->sb_wptr - tmp->parent->sb_data;
     tmp->roff = tmp->parent->sb_rptr - tmp->parent->sb_data;
+
+    return 0;
 }
 
 static int sbuf_tmp_post_load(void *opaque, int version)
@@ -1303,7 +1305,7 @@ typedef struct SS_FamilyTmpStruct {
 #define SS_FAMILY_MIG_IPV6  10  /* Linux */
 #define SS_FAMILY_MIG_OTHER 0xffff
 
-static void ss_family_pre_save(void *opaque)
+static int ss_family_pre_save(void *opaque)
 {
     SS_FamilyTmpStruct *tss = opaque;
 
@@ -1314,6 +1316,8 @@ static void ss_family_pre_save(void *opaque)
     } else if (tss->parent->ss.ss_family == AF_INET6) {
         tss->portable_family = SS_FAMILY_MIG_IPV6;
     }
+
+    return 0;
 }
 
 static int ss_family_post_load(void *opaque, int version_id)
diff --git a/target/arm/machine.c b/target/arm/machine.c
index e5fe083da4..29df7ac87d 100644
--- a/target/arm/machine.c
+++ b/target/arm/machine.c
@@ -394,7 +394,7 @@ static const VMStateInfo vmstate_powered_off = {
     .put = put_power,
 };
 
-static void cpu_pre_save(void *opaque)
+static int cpu_pre_save(void *opaque)
 {
     ARMCPU *cpu = opaque;
 
@@ -415,6 +415,8 @@ static void cpu_pre_save(void *opaque)
            cpu->cpreg_array_len * sizeof(uint64_t));
     memcpy(cpu->cpreg_vmstate_values, cpu->cpreg_values,
            cpu->cpreg_array_len * sizeof(uint64_t));
+
+    return 0;
 }
 
 static int cpu_post_load(void *opaque, int version_id)
diff --git a/target/i386/machine.c b/target/i386/machine.c
index 29cc58eda9..df5ec359eb 100644
--- a/target/i386/machine.c
+++ b/target/i386/machine.c
@@ -160,13 +160,15 @@ static floatx80 cpu_set_fp80(uint64_t mant, uint16_t upper)
     return temp.d;
 }
 
-static void fpreg_pre_save(void *opaque)
+static int fpreg_pre_save(void *opaque)
 {
     x86_FPReg_tmp *tmp = opaque;
 
     /* we save the real CPU data (in case of MMX usage only 'mant'
        contains the MMX register */
     cpu_get_fp80(&tmp->tmp_mant, &tmp->tmp_exp, tmp->parent->d);
+
+    return 0;
 }
 
 static int fpreg_post_load(void *opaque, int version)
@@ -196,7 +198,7 @@ static const VMStateDescription vmstate_fpreg = {
     }
 };
 
-static void cpu_pre_save(void *opaque)
+static int cpu_pre_save(void *opaque)
 {
     X86CPU *cpu = opaque;
     CPUX86State *env = &cpu->env;
@@ -228,6 +230,7 @@ static void cpu_pre_save(void *opaque)
         env->segs[R_SS].flags &= ~(env->segs[R_SS].flags & DESC_DPL_MASK);
     }
 
+    return 0;
 }
 
 static int cpu_post_load(void *opaque, int version_id)
diff --git a/target/ppc/machine.c b/target/ppc/machine.c
index e36b7100cb..384caee800 100644
--- a/target/ppc/machine.c
+++ b/target/ppc/machine.c
@@ -146,7 +146,7 @@ static bool cpu_pre_2_8_migration(void *opaque, int version_id)
     return cpu->pre_2_8_migration;
 }
 
-static void cpu_pre_save(void *opaque)
+static int cpu_pre_save(void *opaque)
 {
     PowerPCCPU *cpu = opaque;
     CPUPPCState *env = &cpu->env;
@@ -195,6 +195,8 @@ static void cpu_pre_save(void *opaque)
         cpu->mig_insns_flags2 = env->insns_flags2 & insns_compat_mask2;
         cpu->mig_nb_BATs = env->nb_BATs;
     }
+
+    return 0;
 }
 
 /*
diff --git a/target/s390x/machine.c b/target/s390x/machine.c
index 097a147dbb..e1b7015d20 100644
--- a/target/s390x/machine.c
+++ b/target/s390x/machine.c
@@ -37,13 +37,15 @@ static int cpu_post_load(void *opaque, int version_id)
     return 0;
 }
 
-static void cpu_pre_save(void *opaque)
+static int cpu_pre_save(void *opaque)
 {
     S390CPU *cpu = opaque;
 
     if (kvm_enabled()) {
         kvm_s390_vcpu_interrupt_pre_save(cpu);
     }
+
+    return 0;
 }
 
 static inline bool fpu_needed(void *opaque)
diff --git a/target/sparc/machine.c b/target/sparc/machine.c
index 6bd6b8ee3e..8ff9dea297 100644
--- a/target/sparc/machine.c
+++ b/target/sparc/machine.c
@@ -88,7 +88,7 @@ static const VMStateInfo vmstate_psr = {
     .put = put_psr,
 };
 
-static void cpu_pre_save(void *opaque)
+static int cpu_pre_save(void *opaque)
 {
     SPARCCPU *cpu = opaque;
     CPUSPARCState *env = &cpu->env;
@@ -97,6 +97,8 @@ static void cpu_pre_save(void *opaque)
      * window as the outs of the first window
      */
     cpu_set_cwp(env, env->cwp);
+
+    return 0;
 }
 
 /* 32-bit SPARC retains migration compatibility with older versions
diff --git a/tests/test-vmstate.c b/tests/test-vmstate.c
index ee292c7bee..e643ac662b 100644
--- a/tests/test-vmstate.c
+++ b/tests/test-vmstate.c
@@ -765,11 +765,13 @@ typedef struct TmpTestStruct {
     int64_t diff;
 } TmpTestStruct;
 
-static void tmp_child_pre_save(void *opaque)
+static int tmp_child_pre_save(void *opaque)
 {
     struct TmpTestStruct *tts = opaque;
 
     tts->diff = tts->parent->b - tts->parent->a;
+
+    return 0;
 }
 
 static int tmp_child_post_load(void *opaque, int version_id)
-- 
2.13.5

Re: [Qemu-devel] [PATCH v2 1/6] migration: pre_save return int

[Richard Henderson]

On 09/25/2017 06:29 AM, Dr. David Alan Gilbert (git) wrote:
> Modify the pre_save method on VMStateDescription to return an int
> rather than void so that it potentially can fail.

What does the int value signify?  Why not a bool?


r~

Re: [Qemu-devel] [PATCH v2 1/6] migration: pre_save return int

[Dr. David Alan Gilbert]

* Richard Henderson (rth@twiddle.net) wrote:
> On 09/25/2017 06:29 AM, Dr. David Alan Gilbert (git) wrote:
> > Modify the pre_save method on VMStateDescription to return an int
> > rather than void so that it potentially can fail.
> 
> What does the int value signify?

0 is success, anything else is a failure; typically -errno.

> Why not a bool?

Consistency with pre_load, post_load, put and get methods
that are already int.

Dave

> 
> r~
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Re: [Qemu-devel] [PATCH v2 1/6] migration: pre_save return int

[Richard Henderson]

On 09/25/2017 06:25 AM, Dr. David Alan Gilbert wrote:
>> Why not a bool?
> 
> Consistency with pre_load, post_load, put and get methods
> that are already int.

Fair enough, thanks.


r~

Re: [Qemu-devel] [PATCH v2 1/6] migration: pre_save return int

[Peter Xu]

On Mon, Sep 25, 2017 at 12:29:12PM +0100, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> 
> Modify the pre_save method on VMStateDescription to return an int
> rather than void so that it potentially can fail.
> 
> Changed zillions of devices to make them return 0; the only
> case I've made it return non-0 is hw/intc/s390_flic_kvm.c that already
> had an error_report/return case.
> 
> Note: If you add an error exit in your pre_save you must emit
> an error_report to say why.
> 
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Reviewed-by: Peter Xu <peterx@redhat.com>

-- 
Peter Xu

Re: [Qemu-devel] [PATCH v2 1/6] migration: pre_save return int

[Cornelia Huck]

On Mon, 25 Sep 2017 12:29:12 +0100
"Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote:

> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> 
> Modify the pre_save method on VMStateDescription to return an int
> rather than void so that it potentially can fail.
> 
> Changed zillions of devices to make them return 0; the only
> case I've made it return non-0 is hw/intc/s390_flic_kvm.c that already
> had an error_report/return case.
> 
> Note: If you add an error exit in your pre_save you must emit
> an error_report to say why.
> 
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
>  docs/devel/migration.txt       |  2 +-
>  hw/arm/pxa2xx.c                |  4 +++-
>  hw/arm/strongarm.c             |  4 +++-
>  hw/audio/wm8750.c              |  4 +++-
>  hw/block/fdc.c                 |  4 +++-
>  hw/block/m25p80.c              |  4 +++-
>  hw/block/nand.c                |  4 +++-
>  hw/block/onenand.c             |  4 +++-
>  hw/char/serial.c               |  4 +++-
>  hw/display/qxl.c               |  4 +++-
>  hw/i2c/core.c                  |  4 +++-
>  hw/i386/kvm/clock.c            |  4 +++-
>  hw/ide/core.c                  |  4 +++-
>  hw/ide/pci.c                   |  4 +++-
>  hw/input/ps2.c                 |  8 ++++++--
>  hw/input/tsc210x.c             |  4 +++-
>  hw/intc/apic_common.c          |  4 +++-
>  hw/intc/arm_gic_common.c       |  4 +++-
>  hw/intc/arm_gicv3_common.c     |  4 +++-
>  hw/intc/arm_gicv3_its_common.c |  4 +++-
>  hw/intc/i8259_common.c         |  4 +++-
>  hw/intc/ioapic_common.c        |  4 +++-
>  hw/intc/s390_flic_kvm.c        |  6 ++++--
>  hw/intc/xics.c                 |  8 ++++++--
>  hw/net/e1000.c                 |  4 +++-
>  hw/net/e1000e.c                |  4 +++-
>  hw/net/rtl8139.c               |  4 +++-
>  hw/net/virtio-net.c            | 16 ++++++++++++----
>  hw/net/vmxnet3.c               |  4 +++-
>  hw/pci-host/piix.c             |  4 +++-
>  hw/ppc/ppc.c                   |  4 +++-
>  hw/ppc/spapr_iommu.c           |  4 +++-
>  hw/ppc/spapr_pci.c             |  6 ++++--
>  hw/s390x/css.c                 | 10 +++++++---
>  hw/s390x/virtio-ccw.c          |  4 +++-
>  hw/scsi/lsi53c895a.c           |  4 +++-
>  hw/scsi/vmw_pvscsi.c           |  4 +++-
>  hw/timer/cadence_ttc.c         |  4 +++-
>  hw/timer/hpet.c                |  4 +++-
>  hw/timer/i8254_common.c        |  4 +++-
>  hw/timer/mc146818rtc.c         |  4 +++-
>  hw/timer/pl031.c               |  4 +++-
>  hw/timer/twl92230.c            |  4 +++-
>  hw/usb/dev-smartcard-reader.c  |  4 +++-
>  hw/usb/hcd-ehci.c              |  4 +++-
>  hw/usb/redirect.c              |  4 +++-
>  hw/virtio/vhost-vsock.c        |  4 +++-
>  include/migration/vmstate.h    |  2 +-
>  migration/colo-comm.c          |  4 +++-
>  migration/global_state.c       |  4 +++-
>  migration/savevm.c             |  4 +++-
>  replay/replay-snapshot.c       |  4 +++-
>  slirp/slirp.c                  |  8 ++++++--
>  target/arm/machine.c           |  4 +++-
>  target/i386/machine.c          |  7 +++++--
>  target/ppc/machine.c           |  4 +++-
>  target/s390x/machine.c         |  4 +++-
>  target/sparc/machine.c         |  4 +++-
>  tests/test-vmstate.c           |  4 +++-
>  59 files changed, 199 insertions(+), 70 deletions(-)

Reviewed-by: Cornelia Huck <cohuck@redhat.com>

Re: [Qemu-devel] [PATCH v2 1/6] migration: pre_save return int

[Juan Quintela]

"Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>
> Modify the pre_save method on VMStateDescription to return an int
> rather than void so that it potentially can fail.
>
> Changed zillions of devices to make them return 0; the only
> case I've made it return non-0 is hw/intc/s390_flic_kvm.c that already
> had an error_report/return case.
>
> Note: If you add an error exit in your pre_save you must emit
> an error_report to say why.
>
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Reviewed-by: Juan Quintela <quintela@redhat.com>

[Qemu-devel] [PATCH v2 2/6] migration: check pre_save return in vmstate_save_state

[Dr. David Alan Gilbert (git)]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Check the return value of pre_save state and fail vmstate_save_state
if the pre_save failed.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 include/migration/vmstate.h |  4 ++--
 migration/trace-events      |  1 +
 migration/vmstate.c         | 12 ++++++++++--
 3 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
index da46b1a36d..88b55df5ae 100644
--- a/include/migration/vmstate.h
+++ b/include/migration/vmstate.h
@@ -994,8 +994,8 @@ extern const VMStateInfo vmstate_info_qtailq;
 
 int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
                        void *opaque, int version_id);
-void vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
-                        void *opaque, QJSON *vmdesc);
+int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
+                       void *opaque, QJSON *vmdesc);
 
 bool vmstate_save_needed(const VMStateDescription *vmsd, void *opaque);
 
diff --git a/migration/trace-events b/migration/trace-events
index d2910a6e7b..6f29fcc686 100644
--- a/migration/trace-events
+++ b/migration/trace-events
@@ -40,6 +40,7 @@ savevm_state_iterate(void) ""
 savevm_state_cleanup(void) ""
 savevm_state_complete_precopy(void) ""
 vmstate_save(const char *idstr, const char *vmsd_name) "%s, %s"
+vmstate_save_state_pre_save_res(const char *name, int res) "%s/%d"
 vmstate_save_state_loop(const char *name, const char *field, int n_elems) "%s/%s[%d]"
 vmstate_save_state_top(const char *idstr) "%s"
 vmstate_subsection_save_loop(const char *name, const char *sub) "%s/%s"
diff --git a/migration/vmstate.c b/migration/vmstate.c
index 3226e8eb45..ae8abd3c32 100644
--- a/migration/vmstate.c
+++ b/migration/vmstate.c
@@ -308,15 +308,21 @@ bool vmstate_save_needed(const VMStateDescription *vmsd, void *opaque)
 }
 
 
-void vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
+int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
                         void *opaque, QJSON *vmdesc)
 {
+    int ret = 0;
     VMStateField *field = vmsd->fields;
 
     trace_vmstate_save_state_top(vmsd->name);
 
     if (vmsd->pre_save) {
-        vmsd->pre_save(opaque);
+        ret = vmsd->pre_save(opaque);
+        trace_vmstate_save_state_pre_save_res(vmsd->name, ret);
+        if (ret) {
+            error_report("pre-save failed: %s", vmsd->name);
+            return ret;
+        }
     }
 
     if (vmdesc) {
@@ -381,6 +387,8 @@ void vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
     }
 
     vmstate_subsection_save(f, vmsd, opaque, vmdesc);
+
+    return 0;
 }
 
 static const VMStateDescription *
-- 
2.13.5

Re: [Qemu-devel] [PATCH v2 2/6] migration: check pre_save return in vmstate_save_state

[Peter Xu]

On Mon, Sep 25, 2017 at 12:29:13PM +0100, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> 
> Check the return value of pre_save state and fail vmstate_save_state
> if the pre_save failed.
> 
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Reviewed-by: Peter Xu <peterx@redhat.com>

-- 
Peter Xu

Re: [Qemu-devel] [PATCH v2 2/6] migration: check pre_save return in vmstate_save_state

[Cornelia Huck]

On Mon, 25 Sep 2017 12:29:13 +0100
"Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote:

> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> 
> Check the return value of pre_save state and fail vmstate_save_state
> if the pre_save failed.
> 
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
>  include/migration/vmstate.h |  4 ++--
>  migration/trace-events      |  1 +
>  migration/vmstate.c         | 12 ++++++++++--
>  3 files changed, 13 insertions(+), 4 deletions(-)

Reviewed-by: Cornelia Huck <cohuck@redhat.com>

Re: [Qemu-devel] [PATCH v2 2/6] migration: check pre_save return in vmstate_save_state

[Juan Quintela]

"Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>
> Check the return value of pre_save state and fail vmstate_save_state
> if the pre_save failed.
>
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Reviewed-by: Juan Quintela <quintela@redhat.com>

[Qemu-devel] [PATCH v2 3/6] migration: Check field save returns

[Dr. David Alan Gilbert (git)]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Check the return values from vmstate_save_state for fields and also the
return values from 'put' for fields that use that.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 migration/vmstate.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/migration/vmstate.c b/migration/vmstate.c
index ae8abd3c32..848e8448c6 100644
--- a/migration/vmstate.c
+++ b/migration/vmstate.c
@@ -347,6 +347,7 @@ int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
             }
             for (i = 0; i < n_elems; i++) {
                 void *curr_elem = first_elem + size * i;
+                ret = 0;
 
                 vmsd_desc_field_start(vmsd, vmdesc_loop, field, i, n_elems);
                 old_offset = qemu_ftell_fast(f);
@@ -357,11 +358,19 @@ int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
                 if (!curr_elem && size) {
                     /* if null pointer write placeholder and do not follow */
                     assert(field->flags & VMS_ARRAY_OF_POINTER);
-                    vmstate_info_nullptr.put(f, curr_elem, size, NULL, NULL);
+                    ret = vmstate_info_nullptr.put(f, curr_elem, size, NULL,
+                                                   NULL);
                 } else if (field->flags & VMS_STRUCT) {
-                    vmstate_save_state(f, field->vmsd, curr_elem, vmdesc_loop);
+                    ret = vmstate_save_state(f, field->vmsd, curr_elem,
+                                             vmdesc_loop);
                 } else {
-                    field->info->put(f, curr_elem, size, field, vmdesc_loop);
+                    ret = field->info->put(f, curr_elem, size, field,
+                                     vmdesc_loop);
+                }
+                if (ret) {
+                    error_report("Save of field %s/%s failed",
+                                 vmsd->name, field->name);
+                    return ret;
                 }
 
                 written_bytes = qemu_ftell_fast(f) - old_offset;
-- 
2.13.5

Re: [Qemu-devel] [PATCH v2 3/6] migration: Check field save returns

[Peter Xu]

On Mon, Sep 25, 2017 at 12:29:14PM +0100, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> 
> Check the return values from vmstate_save_state for fields and also the
> return values from 'put' for fields that use that.
> 
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
>  migration/vmstate.c | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/migration/vmstate.c b/migration/vmstate.c
> index ae8abd3c32..848e8448c6 100644
> --- a/migration/vmstate.c
> +++ b/migration/vmstate.c
> @@ -347,6 +347,7 @@ int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
>              }
>              for (i = 0; i < n_elems; i++) {
>                  void *curr_elem = first_elem + size * i;
> +                ret = 0;
>  
>                  vmsd_desc_field_start(vmsd, vmdesc_loop, field, i, n_elems);
>                  old_offset = qemu_ftell_fast(f);
> @@ -357,11 +358,19 @@ int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
>                  if (!curr_elem && size) {
>                      /* if null pointer write placeholder and do not follow */
>                      assert(field->flags & VMS_ARRAY_OF_POINTER);
> -                    vmstate_info_nullptr.put(f, curr_elem, size, NULL, NULL);
> +                    ret = vmstate_info_nullptr.put(f, curr_elem, size, NULL,
> +                                                   NULL);
>                  } else if (field->flags & VMS_STRUCT) {
> -                    vmstate_save_state(f, field->vmsd, curr_elem, vmdesc_loop);
> +                    ret = vmstate_save_state(f, field->vmsd, curr_elem,
> +                                             vmdesc_loop);
>                  } else {
> -                    field->info->put(f, curr_elem, size, field, vmdesc_loop);
> +                    ret = field->info->put(f, curr_elem, size, field,
> +                                     vmdesc_loop);
> +                }
> +                if (ret) {
> +                    error_report("Save of field %s/%s failed",
> +                                 vmsd->name, field->name);

I would prefer to prefix the function name (also there is one
error_report in previous patch) but that's optional.

Reviewed-by: Peter Xu <peterx@redhat.com>

> +                    return ret;
>                  }
>  
>                  written_bytes = qemu_ftell_fast(f) - old_offset;
> -- 
> 2.13.5
> 

-- 
Peter Xu

Re: [Qemu-devel] [PATCH v2 3/6] migration: Check field save returns

[Cornelia Huck]

On Mon, 25 Sep 2017 12:29:14 +0100
"Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote:

> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> 
> Check the return values from vmstate_save_state for fields and also the
> return values from 'put' for fields that use that.
> 
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
>  migration/vmstate.c | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)

Reviewed-by: Cornelia Huck <cohuck@redhat.com>

Re: [Qemu-devel] [PATCH v2 3/6] migration: Check field save returns

[Juan Quintela]

"Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>
> Check the return values from vmstate_save_state for fields and also the
> return values from 'put' for fields that use that.
>
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Reviewed-by: Juan Quintela <quintela@redhat.com>

[Qemu-devel] [PATCH v2 4/6] migration: wire vmstate_save_state errors up to vmstate_subsection_save

[Dr. David Alan Gilbert (git)]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Route the errors from vmstate_subsection_save up through
vmstate_subsection_save (and back down, all rather recursive).

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 migration/vmstate.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/migration/vmstate.c b/migration/vmstate.c
index 848e8448c6..0b3282c9df 100644
--- a/migration/vmstate.c
+++ b/migration/vmstate.c
@@ -21,8 +21,8 @@
 #include "trace.h"
 #include "qjson.h"
 
-static void vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
-                                    void *opaque, QJSON *vmdesc);
+static int vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
+                                   void *opaque, QJSON *vmdesc);
 static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd,
                                    void *opaque);
 
@@ -395,9 +395,7 @@ int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
         json_end_array(vmdesc);
     }
 
-    vmstate_subsection_save(f, vmsd, opaque, vmdesc);
-
-    return 0;
+    return vmstate_subsection_save(f, vmsd, opaque, vmdesc);
 }
 
 static const VMStateDescription *
@@ -463,11 +461,12 @@ static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd,
     return 0;
 }
 
-static void vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
-                                    void *opaque, QJSON *vmdesc)
+static int vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
+                                   void *opaque, QJSON *vmdesc)
 {
     const VMStateDescription **sub = vmsd->subsections;
     bool subsection_found = false;
+    int ret = 0;
 
     trace_vmstate_subsection_save_top(vmsd->name);
     while (sub && *sub && (*sub)->needed) {
@@ -491,7 +490,10 @@ static void vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
             qemu_put_byte(f, len);
             qemu_put_buffer(f, (uint8_t *)vmsdsub->name, len);
             qemu_put_be32(f, vmsdsub->version_id);
-            vmstate_save_state(f, vmsdsub, opaque, vmdesc);
+            ret = vmstate_save_state(f, vmsdsub, opaque, vmdesc);
+            if (ret) {
+                return ret;
+            }
 
             if (vmdesc) {
                 json_end_object(vmdesc);
@@ -503,4 +505,6 @@ static void vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
     if (vmdesc && subsection_found) {
         json_end_array(vmdesc);
     }
+
+    return ret;
 }
-- 
2.13.5

Re: [Qemu-devel] [PATCH v2 4/6] migration: wire vmstate_save_state errors up to vmstate_subsection_save

[Peter Xu]

On Mon, Sep 25, 2017 at 12:29:15PM +0100, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> 
> Route the errors from vmstate_subsection_save up through
> vmstate_subsection_save (and back down, all rather recursive).

I guess here one of the "vmstate_subsection_save" should be replaced
by "vmstate_save_state"? :-)

> 
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Reviewed-by: Peter Xu <peterx@redhat.com>

-- 
Peter Xu

Re: [Qemu-devel] [PATCH v2 4/6] migration: wire vmstate_save_state errors up to vmstate_subsection_save

[Dr. David Alan Gilbert]

* Peter Xu (peterx@redhat.com) wrote:
> On Mon, Sep 25, 2017 at 12:29:15PM +0100, Dr. David Alan Gilbert (git) wrote:
> > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> > 
> > Route the errors from vmstate_subsection_save up through
> > vmstate_subsection_save (and back down, all rather recursive).
> 
> I guess here one of the "vmstate_subsection_save" should be replaced
> by "vmstate_save_state"? :-)

Ah yes, fixed.

> > 
> > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> 
> Reviewed-by: Peter Xu <peterx@redhat.com>

Thanks.

Dave

> 
> -- 
> Peter Xu
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Re: [Qemu-devel] [PATCH v2 4/6] migration: wire vmstate_save_state errors up to vmstate_subsection_save

[Cornelia Huck]

On Mon, 25 Sep 2017 12:29:15 +0100
"Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote:

> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> 
> Route the errors from vmstate_subsection_save up through
> vmstate_subsection_save (and back down, all rather recursive).
> 
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
>  migration/vmstate.c | 20 ++++++++++++--------
>  1 file changed, 12 insertions(+), 8 deletions(-)

With the patch description fixed up:

Reviewed-by: Cornelia Huck <cohuck@redhat.com>

Re: [Qemu-devel] [PATCH v2 4/6] migration: wire vmstate_save_state errors up to vmstate_subsection_save

[Juan Quintela]

"Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>
> Route the errors from vmstate_subsection_save up through
> vmstate_subsection_save (and back down, all rather recursive).
>
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Reviewed-by: Juan Quintela <quintela@redhat.com>

[Qemu-devel] [PATCH v2 5/6] migration: Route errors up through vmstate_save

[Dr. David Alan Gilbert (git)]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Route the errors from vsmtate_save_state back up through
vmstate_save and out to the normal device state path.
That's the normal error path done.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 migration/savevm.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/migration/savevm.c b/migration/savevm.c
index e9feade46a..4a88228614 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -768,14 +768,14 @@ static void vmstate_save_old_style(QEMUFile *f, SaveStateEntry *se, QJSON *vmdes
     }
 }
 
-static void vmstate_save(QEMUFile *f, SaveStateEntry *se, QJSON *vmdesc)
+static int vmstate_save(QEMUFile *f, SaveStateEntry *se, QJSON *vmdesc)
 {
     trace_vmstate_save(se->idstr, se->vmsd ? se->vmsd->name : "(old)");
     if (!se->vmsd) {
         vmstate_save_old_style(f, se, vmdesc);
-        return;
+        return 0;
     }
-    vmstate_save_state(f, se->vmsd, se->opaque, vmdesc);
+    return vmstate_save_state(f, se->vmsd, se->opaque, vmdesc);
 }
 
 /*
@@ -1171,7 +1171,11 @@ int qemu_savevm_state_complete_precopy(QEMUFile *f, bool iterable_only,
         json_prop_int(vmdesc, "instance_id", se->instance_id);
 
         save_section_header(f, se, QEMU_VM_SECTION_FULL);
-        vmstate_save(f, se, vmdesc);
+        ret = vmstate_save(f, se, vmdesc);
+        if (ret) {
+            qemu_file_set_error(f, ret);
+            return ret;
+        }
         trace_savevm_section_end(se->idstr, se->section_id, 0);
         save_section_footer(f, se);
 
@@ -1313,6 +1317,8 @@ static int qemu_save_device_state(QEMUFile *f)
     cpu_synchronize_all_states();
 
     QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
+        int ret;
+
         if (se->is_ram) {
             continue;
         }
@@ -1325,7 +1331,10 @@ static int qemu_save_device_state(QEMUFile *f)
 
         save_section_header(f, se, QEMU_VM_SECTION_FULL);
 
-        vmstate_save(f, se, NULL);
+        ret = vmstate_save(f, se, NULL);
+        if (ret) {
+            return ret;
+        }
 
         save_section_footer(f, se);
     }
-- 
2.13.5

Re: [Qemu-devel] [PATCH v2 5/6] migration: Route errors up through vmstate_save

[Peter Xu]

On Mon, Sep 25, 2017 at 12:29:16PM +0100, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> 
> Route the errors from vsmtate_save_state back up through
> vmstate_save and out to the normal device state path.
> That's the normal error path done.
> 
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Reviewed-by: Peter Xu <peterx@redhat.com>

-- 
Peter Xu

Re: [Qemu-devel] [PATCH v2 5/6] migration: Route errors up through vmstate_save

[Cornelia Huck]

On Mon, 25 Sep 2017 12:29:16 +0100
"Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote:

> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> 
> Route the errors from vsmtate_save_state back up through
> vmstate_save and out to the normal device state path.
> That's the normal error path done.
> 
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
>  migration/savevm.c | 19 ++++++++++++++-----
>  1 file changed, 14 insertions(+), 5 deletions(-)

Reviewed-by: Cornelia Huck <cohuck@redhat.com>

Re: [Qemu-devel] [PATCH v2 5/6] migration: Route errors up through vmstate_save

[Juan Quintela]

"Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>
> Route the errors from vsmtate_save_state back up through
> vmstate_save and out to the normal device state path.
> That's the normal error path done.
>
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Reviewed-by: Juan Quintela <quintela@redhat.com>

[Qemu-devel] [PATCH v2 6/6] migration: Route more error paths

[Dr. David Alan Gilbert (git)]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

vmstate_save is called in a few places, and vmstate_save_state is
called in lots of places.

Route error returns from the easier cases back up;  there are lots
of more complex cases where their own error paths need fixing.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 hw/display/virtio-gpu.c    |  4 +---
 hw/virtio/virtio.c         | 13 +++++++------
 include/hw/virtio/virtio.h |  2 +-
 migration/vmstate-types.c  | 11 ++++++++---
 tests/test-vmstate.c       |  9 ++++++---
 5 files changed, 23 insertions(+), 16 deletions(-)

diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
index 3a8f1e1a2d..2becbfda59 100644
--- a/hw/display/virtio-gpu.c
+++ b/hw/display/virtio-gpu.c
@@ -1050,9 +1050,7 @@ static int virtio_gpu_save(QEMUFile *f, void *opaque, size_t size,
     }
     qemu_put_be32(f, 0); /* end of list */
 
-    vmstate_save_state(f, &vmstate_virtio_gpu_scanouts, g, NULL);
-
-    return 0;
+    return vmstate_save_state(f, &vmstate_virtio_gpu_scanouts, g, NULL);
 }
 
 static int virtio_gpu_load(QEMUFile *f, void *opaque, size_t size,
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 3129d25c00..311929e9df 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -1897,7 +1897,7 @@ static const VMStateDescription vmstate_virtio = {
     }
 };
 
-void virtio_save(VirtIODevice *vdev, QEMUFile *f)
+int virtio_save(VirtIODevice *vdev, QEMUFile *f)
 {
     BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
@@ -1947,20 +1947,21 @@ void virtio_save(VirtIODevice *vdev, QEMUFile *f)
     }
 
     if (vdc->vmsd) {
-        vmstate_save_state(f, vdc->vmsd, vdev, NULL);
+        int ret = vmstate_save_state(f, vdc->vmsd, vdev, NULL);
+        if (ret) {
+            return ret;
+        }
     }
 
     /* Subsections */
-    vmstate_save_state(f, &vmstate_virtio, vdev, NULL);
+    return vmstate_save_state(f, &vmstate_virtio, vdev, NULL);
 }
 
 /* A wrapper for use as a VMState .put function */
 static int virtio_device_put(QEMUFile *f, void *opaque, size_t size,
                               VMStateField *field, QJSON *vmdesc)
 {
-    virtio_save(VIRTIO_DEVICE(opaque), f);
-
-    return 0;
+    return virtio_save(VIRTIO_DEVICE(opaque), f);
 }
 
 /* A wrapper for use as a VMState .get function */
diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index 80c45c321e..5abada6966 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -188,7 +188,7 @@ void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes,
 void virtio_notify_irqfd(VirtIODevice *vdev, VirtQueue *vq);
 void virtio_notify(VirtIODevice *vdev, VirtQueue *vq);
 
-void virtio_save(VirtIODevice *vdev, QEMUFile *f);
+int virtio_save(VirtIODevice *vdev, QEMUFile *f);
 
 extern const VMStateInfo virtio_vmstate_info;
 
diff --git a/migration/vmstate-types.c b/migration/vmstate-types.c
index c056c98bdb..48184c380d 100644
--- a/migration/vmstate-types.c
+++ b/migration/vmstate-types.c
@@ -550,13 +550,14 @@ static int put_tmp(QEMUFile *f, void *pv, size_t size, VMStateField *field,
 {
     const VMStateDescription *vmsd = field->vmsd;
     void *tmp = g_malloc(size);
+    int ret;
 
     /* Writes the parent field which is at the start of the tmp */
     *(void **)tmp = pv;
-    vmstate_save_state(f, vmsd, tmp, vmdesc);
+    ret = vmstate_save_state(f, vmsd, tmp, vmdesc);
     g_free(tmp);
 
-    return 0;
+    return ret;
 }
 
 const VMStateInfo vmstate_info_tmp = {
@@ -657,12 +658,16 @@ static int put_qtailq(QEMUFile *f, void *pv, size_t unused_size,
     /* offset of the QTAILQ entry in a QTAILQ element*/
     size_t entry_offset = field->start;
     void *elm;
+    int ret;
 
     trace_put_qtailq(vmsd->name, vmsd->version_id);
 
     QTAILQ_RAW_FOREACH(elm, pv, entry_offset) {
         qemu_put_byte(f, true);
-        vmstate_save_state(f, vmsd, elm, vmdesc);
+        ret = vmstate_save_state(f, vmsd, elm, vmdesc);
+        if (ret) {
+            return ret;
+        }
     }
     qemu_put_byte(f, false);
 
diff --git a/tests/test-vmstate.c b/tests/test-vmstate.c
index e643ac662b..087844b6c8 100644
--- a/tests/test-vmstate.c
+++ b/tests/test-vmstate.c
@@ -70,7 +70,8 @@ static void save_vmstate(const VMStateDescription *desc, void *obj)
     QEMUFile *f = open_test_file(true);
 
     /* Save file with vmstate */
-    vmstate_save_state(f, desc, obj, NULL);
+    int ret = vmstate_save_state(f, desc, obj, NULL);
+    g_assert(!ret);
     qemu_put_byte(f, QEMU_VM_EOF);
     g_assert(!qemu_file_get_error(f));
     qemu_fclose(f);
@@ -381,7 +382,8 @@ static void test_save_noskip(void)
     QEMUFile *fsave = open_test_file(true);
     TestStruct obj = { .a = 1, .b = 2, .c = 3, .d = 4, .e = 5, .f = 6,
                        .skip_c_e = false };
-    vmstate_save_state(fsave, &vmstate_skipping, &obj, NULL);
+    int ret = vmstate_save_state(fsave, &vmstate_skipping, &obj, NULL);
+    g_assert(!ret);
     g_assert(!qemu_file_get_error(fsave));
 
     uint8_t expected[] = {
@@ -402,7 +404,8 @@ static void test_save_skip(void)
     QEMUFile *fsave = open_test_file(true);
     TestStruct obj = { .a = 1, .b = 2, .c = 3, .d = 4, .e = 5, .f = 6,
                        .skip_c_e = true };
-    vmstate_save_state(fsave, &vmstate_skipping, &obj, NULL);
+    int ret = vmstate_save_state(fsave, &vmstate_skipping, &obj, NULL);
+    g_assert(!ret);
     g_assert(!qemu_file_get_error(fsave));
 
     uint8_t expected[] = {
-- 
2.13.5

Re: [Qemu-devel] [PATCH v2 6/6] migration: Route more error paths

[Peter Xu]

On Mon, Sep 25, 2017 at 12:29:17PM +0100, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> 
> vmstate_save is called in a few places, and vmstate_save_state is
> called in lots of places.

vmstate_save() should have been processed with previous patch?

> 
> Route error returns from the easier cases back up;  there are lots
> of more complex cases where their own error paths need fixing.
> 
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

The patch content wires quite a few vmstate_save_state() callers, so
the patch itself makes sense to me.

Reviewed-by: Peter Xu <peterx@redhat.com>

> ---
>  hw/display/virtio-gpu.c    |  4 +---
>  hw/virtio/virtio.c         | 13 +++++++------
>  include/hw/virtio/virtio.h |  2 +-
>  migration/vmstate-types.c  | 11 ++++++++---
>  tests/test-vmstate.c       |  9 ++++++---
>  5 files changed, 23 insertions(+), 16 deletions(-)
> 
> diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
> index 3a8f1e1a2d..2becbfda59 100644
> --- a/hw/display/virtio-gpu.c
> +++ b/hw/display/virtio-gpu.c
> @@ -1050,9 +1050,7 @@ static int virtio_gpu_save(QEMUFile *f, void *opaque, size_t size,
>      }
>      qemu_put_be32(f, 0); /* end of list */
>  
> -    vmstate_save_state(f, &vmstate_virtio_gpu_scanouts, g, NULL);
> -
> -    return 0;
> +    return vmstate_save_state(f, &vmstate_virtio_gpu_scanouts, g, NULL);
>  }
>  
>  static int virtio_gpu_load(QEMUFile *f, void *opaque, size_t size,
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 3129d25c00..311929e9df 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -1897,7 +1897,7 @@ static const VMStateDescription vmstate_virtio = {
>      }
>  };
>  
> -void virtio_save(VirtIODevice *vdev, QEMUFile *f)
> +int virtio_save(VirtIODevice *vdev, QEMUFile *f)
>  {
>      BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
>      VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
> @@ -1947,20 +1947,21 @@ void virtio_save(VirtIODevice *vdev, QEMUFile *f)
>      }
>  
>      if (vdc->vmsd) {
> -        vmstate_save_state(f, vdc->vmsd, vdev, NULL);
> +        int ret = vmstate_save_state(f, vdc->vmsd, vdev, NULL);
> +        if (ret) {
> +            return ret;
> +        }
>      }
>  
>      /* Subsections */
> -    vmstate_save_state(f, &vmstate_virtio, vdev, NULL);
> +    return vmstate_save_state(f, &vmstate_virtio, vdev, NULL);
>  }
>  
>  /* A wrapper for use as a VMState .put function */
>  static int virtio_device_put(QEMUFile *f, void *opaque, size_t size,
>                                VMStateField *field, QJSON *vmdesc)
>  {
> -    virtio_save(VIRTIO_DEVICE(opaque), f);
> -
> -    return 0;
> +    return virtio_save(VIRTIO_DEVICE(opaque), f);
>  }
>  
>  /* A wrapper for use as a VMState .get function */
> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> index 80c45c321e..5abada6966 100644
> --- a/include/hw/virtio/virtio.h
> +++ b/include/hw/virtio/virtio.h
> @@ -188,7 +188,7 @@ void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes,
>  void virtio_notify_irqfd(VirtIODevice *vdev, VirtQueue *vq);
>  void virtio_notify(VirtIODevice *vdev, VirtQueue *vq);
>  
> -void virtio_save(VirtIODevice *vdev, QEMUFile *f);
> +int virtio_save(VirtIODevice *vdev, QEMUFile *f);
>  
>  extern const VMStateInfo virtio_vmstate_info;
>  
> diff --git a/migration/vmstate-types.c b/migration/vmstate-types.c
> index c056c98bdb..48184c380d 100644
> --- a/migration/vmstate-types.c
> +++ b/migration/vmstate-types.c
> @@ -550,13 +550,14 @@ static int put_tmp(QEMUFile *f, void *pv, size_t size, VMStateField *field,
>  {
>      const VMStateDescription *vmsd = field->vmsd;
>      void *tmp = g_malloc(size);
> +    int ret;
>  
>      /* Writes the parent field which is at the start of the tmp */
>      *(void **)tmp = pv;
> -    vmstate_save_state(f, vmsd, tmp, vmdesc);
> +    ret = vmstate_save_state(f, vmsd, tmp, vmdesc);
>      g_free(tmp);
>  
> -    return 0;
> +    return ret;
>  }
>  
>  const VMStateInfo vmstate_info_tmp = {
> @@ -657,12 +658,16 @@ static int put_qtailq(QEMUFile *f, void *pv, size_t unused_size,
>      /* offset of the QTAILQ entry in a QTAILQ element*/
>      size_t entry_offset = field->start;
>      void *elm;
> +    int ret;
>  
>      trace_put_qtailq(vmsd->name, vmsd->version_id);
>  
>      QTAILQ_RAW_FOREACH(elm, pv, entry_offset) {
>          qemu_put_byte(f, true);
> -        vmstate_save_state(f, vmsd, elm, vmdesc);
> +        ret = vmstate_save_state(f, vmsd, elm, vmdesc);
> +        if (ret) {
> +            return ret;
> +        }
>      }
>      qemu_put_byte(f, false);
>  
> diff --git a/tests/test-vmstate.c b/tests/test-vmstate.c
> index e643ac662b..087844b6c8 100644
> --- a/tests/test-vmstate.c
> +++ b/tests/test-vmstate.c
> @@ -70,7 +70,8 @@ static void save_vmstate(const VMStateDescription *desc, void *obj)
>      QEMUFile *f = open_test_file(true);
>  
>      /* Save file with vmstate */
> -    vmstate_save_state(f, desc, obj, NULL);
> +    int ret = vmstate_save_state(f, desc, obj, NULL);
> +    g_assert(!ret);
>      qemu_put_byte(f, QEMU_VM_EOF);
>      g_assert(!qemu_file_get_error(f));
>      qemu_fclose(f);
> @@ -381,7 +382,8 @@ static void test_save_noskip(void)
>      QEMUFile *fsave = open_test_file(true);
>      TestStruct obj = { .a = 1, .b = 2, .c = 3, .d = 4, .e = 5, .f = 6,
>                         .skip_c_e = false };
> -    vmstate_save_state(fsave, &vmstate_skipping, &obj, NULL);
> +    int ret = vmstate_save_state(fsave, &vmstate_skipping, &obj, NULL);
> +    g_assert(!ret);
>      g_assert(!qemu_file_get_error(fsave));
>  
>      uint8_t expected[] = {
> @@ -402,7 +404,8 @@ static void test_save_skip(void)
>      QEMUFile *fsave = open_test_file(true);
>      TestStruct obj = { .a = 1, .b = 2, .c = 3, .d = 4, .e = 5, .f = 6,
>                         .skip_c_e = true };
> -    vmstate_save_state(fsave, &vmstate_skipping, &obj, NULL);
> +    int ret = vmstate_save_state(fsave, &vmstate_skipping, &obj, NULL);
> +    g_assert(!ret);
>      g_assert(!qemu_file_get_error(fsave));
>  
>      uint8_t expected[] = {
> -- 
> 2.13.5
> 

-- 
Peter Xu

Re: [Qemu-devel] [PATCH v2 6/6] migration: Route more error paths

[Dr. David Alan Gilbert]

* Peter Xu (peterx@redhat.com) wrote:
> On Mon, Sep 25, 2017 at 12:29:17PM +0100, Dr. David Alan Gilbert (git) wrote:
> > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> > 
> > vmstate_save is called in a few places, and vmstate_save_state is
> > called in lots of places.
> 
> vmstate_save() should have been processed with previous patch?

Ah yes, it was just vmstate_save_state in the end fixed in this one.

> > 
> > Route error returns from the easier cases back up;  there are lots
> > of more complex cases where their own error paths need fixing.
> > 
> > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> 
> The patch content wires quite a few vmstate_save_state() callers, so
> the patch itself makes sense to me.
> 
> Reviewed-by: Peter Xu <peterx@redhat.com>

Thanks!

Dave

> > ---
> >  hw/display/virtio-gpu.c    |  4 +---
> >  hw/virtio/virtio.c         | 13 +++++++------
> >  include/hw/virtio/virtio.h |  2 +-
> >  migration/vmstate-types.c  | 11 ++++++++---
> >  tests/test-vmstate.c       |  9 ++++++---
> >  5 files changed, 23 insertions(+), 16 deletions(-)
> > 
> > diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
> > index 3a8f1e1a2d..2becbfda59 100644
> > --- a/hw/display/virtio-gpu.c
> > +++ b/hw/display/virtio-gpu.c
> > @@ -1050,9 +1050,7 @@ static int virtio_gpu_save(QEMUFile *f, void *opaque, size_t size,
> >      }
> >      qemu_put_be32(f, 0); /* end of list */
> >  
> > -    vmstate_save_state(f, &vmstate_virtio_gpu_scanouts, g, NULL);
> > -
> > -    return 0;
> > +    return vmstate_save_state(f, &vmstate_virtio_gpu_scanouts, g, NULL);
> >  }
> >  
> >  static int virtio_gpu_load(QEMUFile *f, void *opaque, size_t size,
> > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> > index 3129d25c00..311929e9df 100644
> > --- a/hw/virtio/virtio.c
> > +++ b/hw/virtio/virtio.c
> > @@ -1897,7 +1897,7 @@ static const VMStateDescription vmstate_virtio = {
> >      }
> >  };
> >  
> > -void virtio_save(VirtIODevice *vdev, QEMUFile *f)
> > +int virtio_save(VirtIODevice *vdev, QEMUFile *f)
> >  {
> >      BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
> >      VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
> > @@ -1947,20 +1947,21 @@ void virtio_save(VirtIODevice *vdev, QEMUFile *f)
> >      }
> >  
> >      if (vdc->vmsd) {
> > -        vmstate_save_state(f, vdc->vmsd, vdev, NULL);
> > +        int ret = vmstate_save_state(f, vdc->vmsd, vdev, NULL);
> > +        if (ret) {
> > +            return ret;
> > +        }
> >      }
> >  
> >      /* Subsections */
> > -    vmstate_save_state(f, &vmstate_virtio, vdev, NULL);
> > +    return vmstate_save_state(f, &vmstate_virtio, vdev, NULL);
> >  }
> >  
> >  /* A wrapper for use as a VMState .put function */
> >  static int virtio_device_put(QEMUFile *f, void *opaque, size_t size,
> >                                VMStateField *field, QJSON *vmdesc)
> >  {
> > -    virtio_save(VIRTIO_DEVICE(opaque), f);
> > -
> > -    return 0;
> > +    return virtio_save(VIRTIO_DEVICE(opaque), f);
> >  }
> >  
> >  /* A wrapper for use as a VMState .get function */
> > diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> > index 80c45c321e..5abada6966 100644
> > --- a/include/hw/virtio/virtio.h
> > +++ b/include/hw/virtio/virtio.h
> > @@ -188,7 +188,7 @@ void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes,
> >  void virtio_notify_irqfd(VirtIODevice *vdev, VirtQueue *vq);
> >  void virtio_notify(VirtIODevice *vdev, VirtQueue *vq);
> >  
> > -void virtio_save(VirtIODevice *vdev, QEMUFile *f);
> > +int virtio_save(VirtIODevice *vdev, QEMUFile *f);
> >  
> >  extern const VMStateInfo virtio_vmstate_info;
> >  
> > diff --git a/migration/vmstate-types.c b/migration/vmstate-types.c
> > index c056c98bdb..48184c380d 100644
> > --- a/migration/vmstate-types.c
> > +++ b/migration/vmstate-types.c
> > @@ -550,13 +550,14 @@ static int put_tmp(QEMUFile *f, void *pv, size_t size, VMStateField *field,
> >  {
> >      const VMStateDescription *vmsd = field->vmsd;
> >      void *tmp = g_malloc(size);
> > +    int ret;
> >  
> >      /* Writes the parent field which is at the start of the tmp */
> >      *(void **)tmp = pv;
> > -    vmstate_save_state(f, vmsd, tmp, vmdesc);
> > +    ret = vmstate_save_state(f, vmsd, tmp, vmdesc);
> >      g_free(tmp);
> >  
> > -    return 0;
> > +    return ret;
> >  }
> >  
> >  const VMStateInfo vmstate_info_tmp = {
> > @@ -657,12 +658,16 @@ static int put_qtailq(QEMUFile *f, void *pv, size_t unused_size,
> >      /* offset of the QTAILQ entry in a QTAILQ element*/
> >      size_t entry_offset = field->start;
> >      void *elm;
> > +    int ret;
> >  
> >      trace_put_qtailq(vmsd->name, vmsd->version_id);
> >  
> >      QTAILQ_RAW_FOREACH(elm, pv, entry_offset) {
> >          qemu_put_byte(f, true);
> > -        vmstate_save_state(f, vmsd, elm, vmdesc);
> > +        ret = vmstate_save_state(f, vmsd, elm, vmdesc);
> > +        if (ret) {
> > +            return ret;
> > +        }
> >      }
> >      qemu_put_byte(f, false);
> >  
> > diff --git a/tests/test-vmstate.c b/tests/test-vmstate.c
> > index e643ac662b..087844b6c8 100644
> > --- a/tests/test-vmstate.c
> > +++ b/tests/test-vmstate.c
> > @@ -70,7 +70,8 @@ static void save_vmstate(const VMStateDescription *desc, void *obj)
> >      QEMUFile *f = open_test_file(true);
> >  
> >      /* Save file with vmstate */
> > -    vmstate_save_state(f, desc, obj, NULL);
> > +    int ret = vmstate_save_state(f, desc, obj, NULL);
> > +    g_assert(!ret);
> >      qemu_put_byte(f, QEMU_VM_EOF);
> >      g_assert(!qemu_file_get_error(f));
> >      qemu_fclose(f);
> > @@ -381,7 +382,8 @@ static void test_save_noskip(void)
> >      QEMUFile *fsave = open_test_file(true);
> >      TestStruct obj = { .a = 1, .b = 2, .c = 3, .d = 4, .e = 5, .f = 6,
> >                         .skip_c_e = false };
> > -    vmstate_save_state(fsave, &vmstate_skipping, &obj, NULL);
> > +    int ret = vmstate_save_state(fsave, &vmstate_skipping, &obj, NULL);
> > +    g_assert(!ret);
> >      g_assert(!qemu_file_get_error(fsave));
> >  
> >      uint8_t expected[] = {
> > @@ -402,7 +404,8 @@ static void test_save_skip(void)
> >      QEMUFile *fsave = open_test_file(true);
> >      TestStruct obj = { .a = 1, .b = 2, .c = 3, .d = 4, .e = 5, .f = 6,
> >                         .skip_c_e = true };
> > -    vmstate_save_state(fsave, &vmstate_skipping, &obj, NULL);
> > +    int ret = vmstate_save_state(fsave, &vmstate_skipping, &obj, NULL);
> > +    g_assert(!ret);
> >      g_assert(!qemu_file_get_error(fsave));
> >  
> >      uint8_t expected[] = {
> > -- 
> > 2.13.5
> > 
> 
> -- 
> Peter Xu
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Re: [Qemu-devel] [PATCH v2 6/6] migration: Route more error paths

[Cornelia Huck]

On Mon, 25 Sep 2017 12:29:17 +0100
"Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote:

> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> 
> vmstate_save is called in a few places, and vmstate_save_state is
> called in lots of places.
> 
> Route error returns from the easier cases back up;  there are lots
> of more complex cases where their own error paths need fixing.
> 
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
>  hw/display/virtio-gpu.c    |  4 +---
>  hw/virtio/virtio.c         | 13 +++++++------
>  include/hw/virtio/virtio.h |  2 +-
>  migration/vmstate-types.c  | 11 ++++++++---
>  tests/test-vmstate.c       |  9 ++++++---
>  5 files changed, 23 insertions(+), 16 deletions(-)

If you fix up the description to only refer to vmstate_save_state:

Reviewed-by: Cornelia Huck <cohuck@redhat.com>

Re: [Qemu-devel] [PATCH v2 6/6] migration: Route more error paths

[Juan Quintela]

"Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>
> vmstate_save is called in a few places, and vmstate_save_state is
> called in lots of places.
>
> Route error returns from the easier cases back up;  there are lots
> of more complex cases where their own error paths need fixing.
>
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Reviewed-by: Juan Quintela <quintela@redhat.com>

But .....

> -void virtio_save(VirtIODevice *vdev, QEMUFile *f)
> +int virtio_save(VirtIODevice *vdev, QEMUFile *f)
>  {
>      BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
>      VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
> @@ -1947,20 +1947,21 @@ void virtio_save(VirtIODevice *vdev, QEMUFile *f)
>      }
>  
>      if (vdc->vmsd) {
> -        vmstate_save_state(f, vdc->vmsd, vdev, NULL);
> +        int ret = vmstate_save_state(f, vdc->vmsd, vdev, NULL);
> +        if (ret) {
> +            return ret;
> +        }
>      }
>  
>      /* Subsections */
> -    vmstate_save_state(f, &vmstate_virtio, vdev, NULL);
> +    return vmstate_save_state(f, &vmstate_virtio, vdev, NULL);
>  }

We add error code, good.

>  
>  /* A wrapper for use as a VMState .put function */
>  static int virtio_device_put(QEMUFile *f, void *opaque, size_t size,
>                                VMStateField *field, QJSON *vmdesc)
>  {
> -    virtio_save(VIRTIO_DEVICE(opaque), f);
> -
> -    return 0;
> +    return virtio_save(VIRTIO_DEVICE(opaque), f);
>  }

And we add the error code.  But are the callers ready to use it?

...
                } else {
                    field->info->put(f, curr_elem, size, field, vmdesc_loop);
                }

No, we need to fix it on the callers also.  Yeap, that is can be fixed
in a posterios series.

Later, Juan.

Re: [Qemu-devel] [PATCH v2 0/6] migration: let pre_save fail

[Dr. David Alan Gilbert]

* Dr. David Alan Gilbert (git) (dgilbert@redhat.com) wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> 
> At the moment the pre-save method on VMStateDescription returns void
> which means there's no sane way of a pre_save routine failing.  There
> are quite a few pre_save's that abort or do other nasty things, and it
> would be better if they could fail cleanly.
> 
> This patch series doesn't fix any of those pre_save's - it just changes
> pre_save to return an error value and routes that back up so the
> migration fails.  I'll leave that up to the individual device owners.
> 
> There are a bunch of corner cases that I've not fixed yet;  these are
> mostly places that call vmstate_save_state which have been partially
> converted to modern migration code;  often the functions they're called
> from return void as well - they can get fixed later.
> 
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Queued.

> 
> v2
>   test: Split assert/side effects [Fam]
>   new patch 3: Changed to also check the return of the ->put methods
>     that should have been checked previously. [Peter]
> 
> Dr. David Alan Gilbert (6):
>   migration: pre_save return int
>   migration: check pre_save return in vmstate_save_state
>   migration: Check field save returns
>   migration: wire vmstate_save_state errors up to
>     vmstate_subsection_save
>   migration: Route errors up through vmstate_save
>   migration: Route more error paths
> 
>  docs/devel/migration.txt       |  2 +-
>  hw/arm/pxa2xx.c                |  4 +++-
>  hw/arm/strongarm.c             |  4 +++-
>  hw/audio/wm8750.c              |  4 +++-
>  hw/block/fdc.c                 |  4 +++-
>  hw/block/m25p80.c              |  4 +++-
>  hw/block/nand.c                |  4 +++-
>  hw/block/onenand.c             |  4 +++-
>  hw/char/serial.c               |  4 +++-
>  hw/display/qxl.c               |  4 +++-
>  hw/display/virtio-gpu.c        |  4 +---
>  hw/i2c/core.c                  |  4 +++-
>  hw/i386/kvm/clock.c            |  4 +++-
>  hw/ide/core.c                  |  4 +++-
>  hw/ide/pci.c                   |  4 +++-
>  hw/input/ps2.c                 |  8 ++++++--
>  hw/input/tsc210x.c             |  4 +++-
>  hw/intc/apic_common.c          |  4 +++-
>  hw/intc/arm_gic_common.c       |  4 +++-
>  hw/intc/arm_gicv3_common.c     |  4 +++-
>  hw/intc/arm_gicv3_its_common.c |  4 +++-
>  hw/intc/i8259_common.c         |  4 +++-
>  hw/intc/ioapic_common.c        |  4 +++-
>  hw/intc/s390_flic_kvm.c        |  6 ++++--
>  hw/intc/xics.c                 |  8 ++++++--
>  hw/net/e1000.c                 |  4 +++-
>  hw/net/e1000e.c                |  4 +++-
>  hw/net/rtl8139.c               |  4 +++-
>  hw/net/virtio-net.c            | 16 ++++++++++++----
>  hw/net/vmxnet3.c               |  4 +++-
>  hw/pci-host/piix.c             |  4 +++-
>  hw/ppc/ppc.c                   |  4 +++-
>  hw/ppc/spapr_iommu.c           |  4 +++-
>  hw/ppc/spapr_pci.c             |  6 ++++--
>  hw/s390x/css.c                 | 10 +++++++---
>  hw/s390x/virtio-ccw.c          |  4 +++-
>  hw/scsi/lsi53c895a.c           |  4 +++-
>  hw/scsi/vmw_pvscsi.c           |  4 +++-
>  hw/timer/cadence_ttc.c         |  4 +++-
>  hw/timer/hpet.c                |  4 +++-
>  hw/timer/i8254_common.c        |  4 +++-
>  hw/timer/mc146818rtc.c         |  4 +++-
>  hw/timer/pl031.c               |  4 +++-
>  hw/timer/twl92230.c            |  4 +++-
>  hw/usb/dev-smartcard-reader.c  |  4 +++-
>  hw/usb/hcd-ehci.c              |  4 +++-
>  hw/usb/redirect.c              |  4 +++-
>  hw/virtio/vhost-vsock.c        |  4 +++-
>  hw/virtio/virtio.c             | 13 +++++++------
>  include/hw/virtio/virtio.h     |  2 +-
>  include/migration/vmstate.h    |  6 +++---
>  migration/colo-comm.c          |  4 +++-
>  migration/global_state.c       |  4 +++-
>  migration/savevm.c             | 23 ++++++++++++++++------
>  migration/trace-events         |  1 +
>  migration/vmstate-types.c      | 11 ++++++++---
>  migration/vmstate.c            | 43 +++++++++++++++++++++++++++++++-----------
>  replay/replay-snapshot.c       |  4 +++-
>  slirp/slirp.c                  |  8 ++++++--
>  target/arm/machine.c           |  4 +++-
>  target/i386/machine.c          |  7 +++++--
>  target/ppc/machine.c           |  4 +++-
>  target/s390x/machine.c         |  4 +++-
>  target/sparc/machine.c         |  4 +++-
>  tests/test-vmstate.c           | 13 +++++++++----
>  65 files changed, 271 insertions(+), 104 deletions(-)
> 
> -- 
> 2.13.5
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK