[PATCH v4 0/8] hw/nvme: add basic live migration support

[PATCH v4 0/8] hw/nvme: add basic live migration support

[Alexander Mikhalitsyn]

From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>

Dear friends,

This patchset adds basic live migration support for
QEMU emulated NVMe device.

Implementation has some limitations:
- only one NVMe namespace is supported
- SMART counters are not preserved
- CMB is not supported
- PMR is not supported
- SPDM is not supported
- SR-IOV is not supported

I believe this is something I can support in next patchset versions or
separately on-demand (when usecase appears).

Testing.

This patch series was manually tested on:
- Debian 13.3 VM (kernel 6.12.69+deb13-amd64) using fio on *non-root* NVMe disk
  (root disk was virtio-scsi):

time fio --name=nvme-verify \
    --filename=/dev/nvme0n1 \
    --size=5G \
    --rw=randwrite \
    --bs=4k \
    --iodepth=16 \
    --numjobs=1 \
    --direct=0 \
    --ioengine=io_uring \
    --verify=crc32c \
    --verify_fatal=1

- Windows Server 2022 VM (NVMe drive was a *root* disk) with opened browser
  playing video.

No defects were found.

Changelog for version 4:
- vmstate dynamic array support reworked as suggested by Peter Xu
  VMS_ARRAY_OF_POINTER_ALLOW_NULL flag was introduced
  qtests were added
- NVMe migration blockers were reworked as Klaus has requested earlier
  Now, instead of having "deny list" approach, we have more strict pattern
  of NVMe features filtering and it should be harded to break migration when
  adding new NVMe features.

Changelog for version 3:
- rebased
- simple functional test was added (in accordance with Klaus Jensen's review comment)
  $ meson test 'func-x86_64-nvme_migration' --setup thorough -C build

Changelog for version 2:
- full support for AERs (in-flight requests and queued events too)

Kind regards,
Alex

Alexander Mikhalitsyn (8):
  migration/vmstate: introduce vmstate_{load,save}_field helpers
  migration: add VMSTATE_VARRAY_OF_POINTER_TO_STRUCT_UINT{8, 32}_ALLOC
  tests/unit/test-vmstate: add tests for VMS_ARRAY_OF_POINTER_ALLOW_NULL
  tests/functional/migration: add VM launch/configure hooks
  hw/nvme: add migration blockers for non-supported cases
  hw/nvme: split nvme_init_sq/nvme_init_cq into helpers
  hw/nvme: add basic live migration support
  tests/functional/x86_64: add migration test for NVMe device

 hw/nvme/ctrl.c                                | 874 +++++++++++++++++-
 hw/nvme/ns.c                                  | 160 ++++
 hw/nvme/nvme.h                                |   8 +
 hw/nvme/trace-events                          |  11 +
 include/block/nvme.h                          |  12 +
 include/migration/vmstate.h                   |  81 +-
 migration/savevm.c                            |  26 +
 migration/vmstate-types.c                     | 102 ++
 migration/vmstate.c                           | 138 ++-
 tests/functional/migration.py                 |  22 +-
 tests/functional/x86_64/meson.build           |   1 +
 .../functional/x86_64/test_nvme_migration.py  | 159 ++++
 tests/unit/test-vmstate.c                     | 157 ++++
 13 files changed, 1674 insertions(+), 77 deletions(-)
 create mode 100755 tests/functional/x86_64/test_nvme_migration.py

-- 
2.47.3

[PATCH v4 1/8] migration/vmstate: introduce vmstate_{load, save}_field helpers

[Alexander Mikhalitsyn via qemu development]

From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>

Let's introduce vmstate_{load,save}_field() helpers, they will
be used in next patches to support fully-dynamic arrays with NULLs.

Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
---
 include/migration/vmstate.h |  4 ++
 migration/vmstate.c         | 84 +++++++++++++++++++++++--------------
 2 files changed, 56 insertions(+), 32 deletions(-)

diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
index 62c2abd0c49..5d7dfe70643 100644
--- a/include/migration/vmstate.h
+++ b/include/migration/vmstate.h
@@ -1240,8 +1240,12 @@ extern const VMStateInfo vmstate_info_qlist;
         .flags = VMS_END, \
     }
 
+int vmstate_load_field(QEMUFile *f, void *pv, size_t size,
+                       const VMStateField *field, Error **errp);
 int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
                        void *opaque, int version_id, Error **errp);
+int vmstate_save_field(QEMUFile *f, void *pv, size_t size,
+                       const VMStateField *field, JSONWriter *vmdesc, Error **errp);
 int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
                        void *opaque, JSONWriter *vmdesc, Error **errp);
 int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
diff --git a/migration/vmstate.c b/migration/vmstate.c
index 4d28364f7ba..8d192bcaa27 100644
--- a/migration/vmstate.c
+++ b/migration/vmstate.c
@@ -131,6 +131,32 @@ static void vmstate_handle_alloc(void *ptr, const VMStateField *field,
     }
 }
 
+int vmstate_load_field(QEMUFile *f, void *pv, size_t size,
+                       const VMStateField *field, Error **errp)
+{
+    int ret = 0;
+
+    if (field->flags & VMS_STRUCT) {
+        ret = vmstate_load_state(f, field->vmsd, pv,
+                                 field->vmsd->version_id,
+                                 errp);
+    } else if (field->flags & VMS_VSTRUCT) {
+        ret = vmstate_load_state(f, field->vmsd, pv,
+                                 field->struct_version_id,
+                                 errp);
+    } else {
+        ret = field->info->get(f, pv, size, field);
+        if (ret < 0) {
+            error_setg(errp,
+                       "Failed to load element of type %s for %s: "
+                       "%d", field->info->name,
+                       field->name, ret);
+        }
+    }
+
+    return ret;
+}
+
 int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
                        void *opaque, int version_id, Error **errp)
 {
@@ -203,24 +229,7 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
                     inner_field = field;
                 }
 
-                if (inner_field->flags & VMS_STRUCT) {
-                    ret = vmstate_load_state(f, inner_field->vmsd, curr_elem,
-                                             inner_field->vmsd->version_id,
-                                             errp);
-                } else if (inner_field->flags & VMS_VSTRUCT) {
-                    ret = vmstate_load_state(f, inner_field->vmsd, curr_elem,
-                                             inner_field->struct_version_id,
-                                             errp);
-                } else {
-                    ret = inner_field->info->get(f, curr_elem, size,
-                                                 inner_field);
-                    if (ret < 0) {
-                        error_setg(errp,
-                                   "Failed to load element of type %s for %s: "
-                                   "%d", inner_field->info->name,
-                                   inner_field->name, ret);
-                    }
-                }
+                ret = vmstate_load_field(f, curr_elem, size, inner_field, errp);
 
                 /* If we used a fake temp field.. free it now */
                 if (inner_field != field) {
@@ -427,6 +436,29 @@ int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
     return vmstate_save_state_v(f, vmsd, opaque, vmdesc_id, vmsd->version_id, errp);
 }
 
+int vmstate_save_field(QEMUFile *f, void *pv, size_t size,
+                       const VMStateField *field, JSONWriter *vmdesc, Error **errp)
+{
+    int ret = 0;
+
+    if (field->flags & VMS_STRUCT) {
+        ret = vmstate_save_state(f, field->vmsd, pv, vmdesc, errp);
+    } else if (field->flags & VMS_VSTRUCT) {
+        ret = vmstate_save_state_v(f, field->vmsd, pv, vmdesc,
+                                   field->struct_version_id, errp);
+    } else {
+        ret = field->info->put(f, pv, size, field, vmdesc);
+        if (ret < 0) {
+            error_setg(errp,
+                       "Failed to save element of type %s for %s: "
+                       "%d", field->info->name,
+                       field->name, ret);
+        }
+    }
+
+    return ret;
+}
+
 int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
                          void *opaque, JSONWriter *vmdesc, int version_id, Error **errp)
 {
@@ -528,19 +560,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
                 vmsd_desc_field_start(vmsd, vmdesc_loop, inner_field,
                                       i, max_elems);
 
-                if (inner_field->flags & VMS_STRUCT) {
-                    ret = vmstate_save_state(f, inner_field->vmsd,
-                                             curr_elem, vmdesc_loop, errp);
-                } else if (inner_field->flags & VMS_VSTRUCT) {
-                    ret = vmstate_save_state_v(f, inner_field->vmsd,
-                                               curr_elem, vmdesc_loop,
-                                               inner_field->struct_version_id,
-                                               errp);
-                } else {
-                    ret = inner_field->info->put(f, curr_elem, size,
-                                                 inner_field, vmdesc_loop);
-                }
-
+                ret = vmstate_save_field(f, curr_elem, size, inner_field, vmdesc_loop, errp);
                 written_bytes = qemu_file_transferred(f) - old_offset;
                 vmsd_desc_field_end(vmsd, vmdesc_loop, inner_field,
                                     written_bytes);
@@ -551,7 +571,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
                 }
 
                 if (ret) {
-                    error_setg(errp, "Save of field %s/%s failed",
+                    error_prepend(errp, "Save of field %s/%s failed: ",
                                 vmsd->name, field->name);
                     if (vmsd->post_save) {
                         vmsd->post_save(opaque);
-- 
2.47.3

Re: [PATCH v4 1/8] migration/vmstate: introduce vmstate_{load,save}_field helpers

[Peter Xu]

On Fri, Mar 13, 2026 at 03:12:14PM +0100, Alexander Mikhalitsyn wrote:
> From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
> 
> Let's introduce vmstate_{load,save}_field() helpers, they will
> be used in next patches to support fully-dynamic arrays with NULLs.
> 
> Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>

Feel free to rebase to Vladimir's series here, Fabiano already queued it:

https://lore.kernel.org/all/20260304212303.667141-11-vsementsov@yandex-team.ru/#t

These codes weren't touched that frequent, it's interesting to see such
coinsidence happens. :)

> ---
>  include/migration/vmstate.h |  4 ++
>  migration/vmstate.c         | 84 +++++++++++++++++++++++--------------
>  2 files changed, 56 insertions(+), 32 deletions(-)
> 
> diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
> index 62c2abd0c49..5d7dfe70643 100644
> --- a/include/migration/vmstate.h
> +++ b/include/migration/vmstate.h
> @@ -1240,8 +1240,12 @@ extern const VMStateInfo vmstate_info_qlist;
>          .flags = VMS_END, \
>      }
>  
> +int vmstate_load_field(QEMUFile *f, void *pv, size_t size,
> +                       const VMStateField *field, Error **errp);
>  int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
>                         void *opaque, int version_id, Error **errp);
> +int vmstate_save_field(QEMUFile *f, void *pv, size_t size,
> +                       const VMStateField *field, JSONWriter *vmdesc, Error **errp);
>  int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
>                         void *opaque, JSONWriter *vmdesc, Error **errp);
>  int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
> diff --git a/migration/vmstate.c b/migration/vmstate.c
> index 4d28364f7ba..8d192bcaa27 100644
> --- a/migration/vmstate.c
> +++ b/migration/vmstate.c
> @@ -131,6 +131,32 @@ static void vmstate_handle_alloc(void *ptr, const VMStateField *field,
>      }
>  }
>  
> +int vmstate_load_field(QEMUFile *f, void *pv, size_t size,
> +                       const VMStateField *field, Error **errp)
> +{
> +    int ret = 0;
> +
> +    if (field->flags & VMS_STRUCT) {
> +        ret = vmstate_load_state(f, field->vmsd, pv,
> +                                 field->vmsd->version_id,
> +                                 errp);
> +    } else if (field->flags & VMS_VSTRUCT) {
> +        ret = vmstate_load_state(f, field->vmsd, pv,
> +                                 field->struct_version_id,
> +                                 errp);
> +    } else {
> +        ret = field->info->get(f, pv, size, field);
> +        if (ret < 0) {
> +            error_setg(errp,
> +                       "Failed to load element of type %s for %s: "
> +                       "%d", field->info->name,
> +                       field->name, ret);
> +        }
> +    }
> +
> +    return ret;
> +}
> +
>  int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
>                         void *opaque, int version_id, Error **errp)
>  {
> @@ -203,24 +229,7 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
>                      inner_field = field;
>                  }
>  
> -                if (inner_field->flags & VMS_STRUCT) {
> -                    ret = vmstate_load_state(f, inner_field->vmsd, curr_elem,
> -                                             inner_field->vmsd->version_id,
> -                                             errp);
> -                } else if (inner_field->flags & VMS_VSTRUCT) {
> -                    ret = vmstate_load_state(f, inner_field->vmsd, curr_elem,
> -                                             inner_field->struct_version_id,
> -                                             errp);
> -                } else {
> -                    ret = inner_field->info->get(f, curr_elem, size,
> -                                                 inner_field);
> -                    if (ret < 0) {
> -                        error_setg(errp,
> -                                   "Failed to load element of type %s for %s: "
> -                                   "%d", inner_field->info->name,
> -                                   inner_field->name, ret);
> -                    }
> -                }
> +                ret = vmstate_load_field(f, curr_elem, size, inner_field, errp);
>  
>                  /* If we used a fake temp field.. free it now */
>                  if (inner_field != field) {
> @@ -427,6 +436,29 @@ int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
>      return vmstate_save_state_v(f, vmsd, opaque, vmdesc_id, vmsd->version_id, errp);
>  }
>  
> +int vmstate_save_field(QEMUFile *f, void *pv, size_t size,
> +                       const VMStateField *field, JSONWriter *vmdesc, Error **errp)
> +{
> +    int ret = 0;
> +
> +    if (field->flags & VMS_STRUCT) {
> +        ret = vmstate_save_state(f, field->vmsd, pv, vmdesc, errp);
> +    } else if (field->flags & VMS_VSTRUCT) {
> +        ret = vmstate_save_state_v(f, field->vmsd, pv, vmdesc,
> +                                   field->struct_version_id, errp);
> +    } else {
> +        ret = field->info->put(f, pv, size, field, vmdesc);
> +        if (ret < 0) {
> +            error_setg(errp,
> +                       "Failed to save element of type %s for %s: "
> +                       "%d", field->info->name,
> +                       field->name, ret);
> +        }
> +    }
> +
> +    return ret;
> +}
> +
>  int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
>                           void *opaque, JSONWriter *vmdesc, int version_id, Error **errp)
>  {
> @@ -528,19 +560,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
>                  vmsd_desc_field_start(vmsd, vmdesc_loop, inner_field,
>                                        i, max_elems);
>  
> -                if (inner_field->flags & VMS_STRUCT) {
> -                    ret = vmstate_save_state(f, inner_field->vmsd,
> -                                             curr_elem, vmdesc_loop, errp);
> -                } else if (inner_field->flags & VMS_VSTRUCT) {
> -                    ret = vmstate_save_state_v(f, inner_field->vmsd,
> -                                               curr_elem, vmdesc_loop,
> -                                               inner_field->struct_version_id,
> -                                               errp);
> -                } else {
> -                    ret = inner_field->info->put(f, curr_elem, size,
> -                                                 inner_field, vmdesc_loop);
> -                }
> -
> +                ret = vmstate_save_field(f, curr_elem, size, inner_field, vmdesc_loop, errp);
>                  written_bytes = qemu_file_transferred(f) - old_offset;
>                  vmsd_desc_field_end(vmsd, vmdesc_loop, inner_field,
>                                      written_bytes);
> @@ -551,7 +571,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
>                  }
>  
>                  if (ret) {
> -                    error_setg(errp, "Save of field %s/%s failed",
> +                    error_prepend(errp, "Save of field %s/%s failed: ",
>                                  vmsd->name, field->name);
>                      if (vmsd->post_save) {
>                          vmsd->post_save(opaque);
> -- 
> 2.47.3
> 

-- 
Peter Xu

Re: [PATCH v4 1/8] migration/vmstate: introduce vmstate_{load, save}_field helpers

[Alexander Mikhalitsyn via qemu development]

Am Fr., 13. März 2026 um 17:27 Uhr schrieb Peter Xu <peterx@redhat.com>:
>
> On Fri, Mar 13, 2026 at 03:12:14PM +0100, Alexander Mikhalitsyn wrote:
> > From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
> >
> > Let's introduce vmstate_{load,save}_field() helpers, they will
> > be used in next patches to support fully-dynamic arrays with NULLs.
> >
> > Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
>

Hi Peter,

> Feel free to rebase to Vladimir's series here, Fabiano already queued it:
>
> https://lore.kernel.org/all/20260304212303.667141-11-vsementsov@yandex-team.ru/#t

I've tried, but I can't see it anywhere
https://gitlab.com/farosas/qemu/-/commits/migration-next
doesn't contain it. As of now, last commit is
472f455cfbb0c5f84a7d48228d5226eaf6c7a61b.

Also, patchew tells that that series has conflicts with master:
https://patchew.org/QEMU/20260304212303.667141-1-vsementsov@yandex-team.ru/

Should I manually download mbox, apply/resolve conflicts with master,
then rebase my stuff and resend?

Kind regards,
Alex

>
> These codes weren't touched that frequent, it's interesting to see such
> coinsidence happens. :)
>
> > ---
> >  include/migration/vmstate.h |  4 ++
> >  migration/vmstate.c         | 84 +++++++++++++++++++++++--------------
> >  2 files changed, 56 insertions(+), 32 deletions(-)
> >
> > diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
> > index 62c2abd0c49..5d7dfe70643 100644
> > --- a/include/migration/vmstate.h
> > +++ b/include/migration/vmstate.h
> > @@ -1240,8 +1240,12 @@ extern const VMStateInfo vmstate_info_qlist;
> >          .flags = VMS_END, \
> >      }
> >
> > +int vmstate_load_field(QEMUFile *f, void *pv, size_t size,
> > +                       const VMStateField *field, Error **errp);
> >  int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
> >                         void *opaque, int version_id, Error **errp);
> > +int vmstate_save_field(QEMUFile *f, void *pv, size_t size,
> > +                       const VMStateField *field, JSONWriter *vmdesc, Error **errp);
> >  int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
> >                         void *opaque, JSONWriter *vmdesc, Error **errp);
> >  int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
> > diff --git a/migration/vmstate.c b/migration/vmstate.c
> > index 4d28364f7ba..8d192bcaa27 100644
> > --- a/migration/vmstate.c
> > +++ b/migration/vmstate.c
> > @@ -131,6 +131,32 @@ static void vmstate_handle_alloc(void *ptr, const VMStateField *field,
> >      }
> >  }
> >
> > +int vmstate_load_field(QEMUFile *f, void *pv, size_t size,
> > +                       const VMStateField *field, Error **errp)
> > +{
> > +    int ret = 0;
> > +
> > +    if (field->flags & VMS_STRUCT) {
> > +        ret = vmstate_load_state(f, field->vmsd, pv,
> > +                                 field->vmsd->version_id,
> > +                                 errp);
> > +    } else if (field->flags & VMS_VSTRUCT) {
> > +        ret = vmstate_load_state(f, field->vmsd, pv,
> > +                                 field->struct_version_id,
> > +                                 errp);
> > +    } else {
> > +        ret = field->info->get(f, pv, size, field);
> > +        if (ret < 0) {
> > +            error_setg(errp,
> > +                       "Failed to load element of type %s for %s: "
> > +                       "%d", field->info->name,
> > +                       field->name, ret);
> > +        }
> > +    }
> > +
> > +    return ret;
> > +}
> > +
> >  int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
> >                         void *opaque, int version_id, Error **errp)
> >  {
> > @@ -203,24 +229,7 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
> >                      inner_field = field;
> >                  }
> >
> > -                if (inner_field->flags & VMS_STRUCT) {
> > -                    ret = vmstate_load_state(f, inner_field->vmsd, curr_elem,
> > -                                             inner_field->vmsd->version_id,
> > -                                             errp);
> > -                } else if (inner_field->flags & VMS_VSTRUCT) {
> > -                    ret = vmstate_load_state(f, inner_field->vmsd, curr_elem,
> > -                                             inner_field->struct_version_id,
> > -                                             errp);
> > -                } else {
> > -                    ret = inner_field->info->get(f, curr_elem, size,
> > -                                                 inner_field);
> > -                    if (ret < 0) {
> > -                        error_setg(errp,
> > -                                   "Failed to load element of type %s for %s: "
> > -                                   "%d", inner_field->info->name,
> > -                                   inner_field->name, ret);
> > -                    }
> > -                }
> > +                ret = vmstate_load_field(f, curr_elem, size, inner_field, errp);
> >
> >                  /* If we used a fake temp field.. free it now */
> >                  if (inner_field != field) {
> > @@ -427,6 +436,29 @@ int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
> >      return vmstate_save_state_v(f, vmsd, opaque, vmdesc_id, vmsd->version_id, errp);
> >  }
> >
> > +int vmstate_save_field(QEMUFile *f, void *pv, size_t size,
> > +                       const VMStateField *field, JSONWriter *vmdesc, Error **errp)
> > +{
> > +    int ret = 0;
> > +
> > +    if (field->flags & VMS_STRUCT) {
> > +        ret = vmstate_save_state(f, field->vmsd, pv, vmdesc, errp);
> > +    } else if (field->flags & VMS_VSTRUCT) {
> > +        ret = vmstate_save_state_v(f, field->vmsd, pv, vmdesc,
> > +                                   field->struct_version_id, errp);
> > +    } else {
> > +        ret = field->info->put(f, pv, size, field, vmdesc);
> > +        if (ret < 0) {
> > +            error_setg(errp,
> > +                       "Failed to save element of type %s for %s: "
> > +                       "%d", field->info->name,
> > +                       field->name, ret);
> > +        }
> > +    }
> > +
> > +    return ret;
> > +}
> > +
> >  int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
> >                           void *opaque, JSONWriter *vmdesc, int version_id, Error **errp)
> >  {
> > @@ -528,19 +560,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
> >                  vmsd_desc_field_start(vmsd, vmdesc_loop, inner_field,
> >                                        i, max_elems);
> >
> > -                if (inner_field->flags & VMS_STRUCT) {
> > -                    ret = vmstate_save_state(f, inner_field->vmsd,
> > -                                             curr_elem, vmdesc_loop, errp);
> > -                } else if (inner_field->flags & VMS_VSTRUCT) {
> > -                    ret = vmstate_save_state_v(f, inner_field->vmsd,
> > -                                               curr_elem, vmdesc_loop,
> > -                                               inner_field->struct_version_id,
> > -                                               errp);
> > -                } else {
> > -                    ret = inner_field->info->put(f, curr_elem, size,
> > -                                                 inner_field, vmdesc_loop);
> > -                }
> > -
> > +                ret = vmstate_save_field(f, curr_elem, size, inner_field, vmdesc_loop, errp);
> >                  written_bytes = qemu_file_transferred(f) - old_offset;
> >                  vmsd_desc_field_end(vmsd, vmdesc_loop, inner_field,
> >                                      written_bytes);
> > @@ -551,7 +571,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
> >                  }
> >
> >                  if (ret) {
> > -                    error_setg(errp, "Save of field %s/%s failed",
> > +                    error_prepend(errp, "Save of field %s/%s failed: ",
> >                                  vmsd->name, field->name);
> >                      if (vmsd->post_save) {
> >                          vmsd->post_save(opaque);
> > --
> > 2.47.3
> >
>
> --
> Peter Xu
>

Re: [PATCH v4 1/8] migration/vmstate: introduce vmstate_{load, save}_field helpers

[Fabiano Rosas]

Alexander Mikhalitsyn via qemu development <qemu-devel@nongnu.org>
writes:

> Am Fr., 13. März 2026 um 17:27 Uhr schrieb Peter Xu <peterx@redhat.com>:
>>
>> On Fri, Mar 13, 2026 at 03:12:14PM +0100, Alexander Mikhalitsyn wrote:
>> > From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
>> >
>> > Let's introduce vmstate_{load,save}_field() helpers, they will
>> > be used in next patches to support fully-dynamic arrays with NULLs.
>> >
>> > Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
>>
>
> Hi Peter,
>
>> Feel free to rebase to Vladimir's series here, Fabiano already queued it:
>>
>> https://lore.kernel.org/all/20260304212303.667141-11-vsementsov@yandex-team.ru/#t
>
> I've tried, but I can't see it anywhere
> https://gitlab.com/farosas/qemu/-/commits/migration-next
> doesn't contain it. As of now, last commit is
> 472f455cfbb0c5f84a7d48228d5226eaf6c7a61b.
>

I think we usually just take the patches from the list and apply
directly instead of taking any branch*. I don't keep migration-next
stable.

I pushed migration-staging which you can use. It'll collect the patches
that will be merged at the start of the next development cycle, after
the release.

* I use:
b4 am -3 -c -o <patches/dir> <lore.kernel.org link>
(you'd need to solve any conflicts with the base branch yourself)

> Also, patchew tells that that series has conflicts with master:
> https://patchew.org/QEMU/20260304212303.667141-1-vsementsov@yandex-team.ru/
>
> Should I manually download mbox, apply/resolve conflicts with master,
> then rebase my stuff and resend?
>
> Kind regards,
> Alex
>
>>
>> These codes weren't touched that frequent, it's interesting to see such
>> coinsidence happens. :)
>>
>> > ---
>> >  include/migration/vmstate.h |  4 ++
>> >  migration/vmstate.c         | 84 +++++++++++++++++++++++--------------
>> >  2 files changed, 56 insertions(+), 32 deletions(-)
>> >
>> > diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
>> > index 62c2abd0c49..5d7dfe70643 100644
>> > --- a/include/migration/vmstate.h
>> > +++ b/include/migration/vmstate.h
>> > @@ -1240,8 +1240,12 @@ extern const VMStateInfo vmstate_info_qlist;
>> >          .flags = VMS_END, \
>> >      }
>> >
>> > +int vmstate_load_field(QEMUFile *f, void *pv, size_t size,
>> > +                       const VMStateField *field, Error **errp);
>> >  int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
>> >                         void *opaque, int version_id, Error **errp);
>> > +int vmstate_save_field(QEMUFile *f, void *pv, size_t size,
>> > +                       const VMStateField *field, JSONWriter *vmdesc, Error **errp);
>> >  int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
>> >                         void *opaque, JSONWriter *vmdesc, Error **errp);
>> >  int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
>> > diff --git a/migration/vmstate.c b/migration/vmstate.c
>> > index 4d28364f7ba..8d192bcaa27 100644
>> > --- a/migration/vmstate.c
>> > +++ b/migration/vmstate.c
>> > @@ -131,6 +131,32 @@ static void vmstate_handle_alloc(void *ptr, const VMStateField *field,
>> >      }
>> >  }
>> >
>> > +int vmstate_load_field(QEMUFile *f, void *pv, size_t size,
>> > +                       const VMStateField *field, Error **errp)
>> > +{
>> > +    int ret = 0;
>> > +
>> > +    if (field->flags & VMS_STRUCT) {
>> > +        ret = vmstate_load_state(f, field->vmsd, pv,
>> > +                                 field->vmsd->version_id,
>> > +                                 errp);
>> > +    } else if (field->flags & VMS_VSTRUCT) {
>> > +        ret = vmstate_load_state(f, field->vmsd, pv,
>> > +                                 field->struct_version_id,
>> > +                                 errp);
>> > +    } else {
>> > +        ret = field->info->get(f, pv, size, field);
>> > +        if (ret < 0) {
>> > +            error_setg(errp,
>> > +                       "Failed to load element of type %s for %s: "
>> > +                       "%d", field->info->name,
>> > +                       field->name, ret);
>> > +        }
>> > +    }
>> > +
>> > +    return ret;
>> > +}
>> > +
>> >  int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
>> >                         void *opaque, int version_id, Error **errp)
>> >  {
>> > @@ -203,24 +229,7 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
>> >                      inner_field = field;
>> >                  }
>> >
>> > -                if (inner_field->flags & VMS_STRUCT) {
>> > -                    ret = vmstate_load_state(f, inner_field->vmsd, curr_elem,
>> > -                                             inner_field->vmsd->version_id,
>> > -                                             errp);
>> > -                } else if (inner_field->flags & VMS_VSTRUCT) {
>> > -                    ret = vmstate_load_state(f, inner_field->vmsd, curr_elem,
>> > -                                             inner_field->struct_version_id,
>> > -                                             errp);
>> > -                } else {
>> > -                    ret = inner_field->info->get(f, curr_elem, size,
>> > -                                                 inner_field);
>> > -                    if (ret < 0) {
>> > -                        error_setg(errp,
>> > -                                   "Failed to load element of type %s for %s: "
>> > -                                   "%d", inner_field->info->name,
>> > -                                   inner_field->name, ret);
>> > -                    }
>> > -                }
>> > +                ret = vmstate_load_field(f, curr_elem, size, inner_field, errp);
>> >
>> >                  /* If we used a fake temp field.. free it now */
>> >                  if (inner_field != field) {
>> > @@ -427,6 +436,29 @@ int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
>> >      return vmstate_save_state_v(f, vmsd, opaque, vmdesc_id, vmsd->version_id, errp);
>> >  }
>> >
>> > +int vmstate_save_field(QEMUFile *f, void *pv, size_t size,
>> > +                       const VMStateField *field, JSONWriter *vmdesc, Error **errp)
>> > +{
>> > +    int ret = 0;
>> > +
>> > +    if (field->flags & VMS_STRUCT) {
>> > +        ret = vmstate_save_state(f, field->vmsd, pv, vmdesc, errp);
>> > +    } else if (field->flags & VMS_VSTRUCT) {
>> > +        ret = vmstate_save_state_v(f, field->vmsd, pv, vmdesc,
>> > +                                   field->struct_version_id, errp);
>> > +    } else {
>> > +        ret = field->info->put(f, pv, size, field, vmdesc);
>> > +        if (ret < 0) {
>> > +            error_setg(errp,
>> > +                       "Failed to save element of type %s for %s: "
>> > +                       "%d", field->info->name,
>> > +                       field->name, ret);
>> > +        }
>> > +    }
>> > +
>> > +    return ret;
>> > +}
>> > +
>> >  int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
>> >                           void *opaque, JSONWriter *vmdesc, int version_id, Error **errp)
>> >  {
>> > @@ -528,19 +560,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
>> >                  vmsd_desc_field_start(vmsd, vmdesc_loop, inner_field,
>> >                                        i, max_elems);
>> >
>> > -                if (inner_field->flags & VMS_STRUCT) {
>> > -                    ret = vmstate_save_state(f, inner_field->vmsd,
>> > -                                             curr_elem, vmdesc_loop, errp);
>> > -                } else if (inner_field->flags & VMS_VSTRUCT) {
>> > -                    ret = vmstate_save_state_v(f, inner_field->vmsd,
>> > -                                               curr_elem, vmdesc_loop,
>> > -                                               inner_field->struct_version_id,
>> > -                                               errp);
>> > -                } else {
>> > -                    ret = inner_field->info->put(f, curr_elem, size,
>> > -                                                 inner_field, vmdesc_loop);
>> > -                }
>> > -
>> > +                ret = vmstate_save_field(f, curr_elem, size, inner_field, vmdesc_loop, errp);
>> >                  written_bytes = qemu_file_transferred(f) - old_offset;
>> >                  vmsd_desc_field_end(vmsd, vmdesc_loop, inner_field,
>> >                                      written_bytes);
>> > @@ -551,7 +571,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
>> >                  }
>> >
>> >                  if (ret) {
>> > -                    error_setg(errp, "Save of field %s/%s failed",
>> > +                    error_prepend(errp, "Save of field %s/%s failed: ",
>> >                                  vmsd->name, field->name);
>> >                      if (vmsd->post_save) {
>> >                          vmsd->post_save(opaque);
>> > --
>> > 2.47.3
>> >
>>
>> --
>> Peter Xu
>>

Re: [PATCH v4 1/8] migration/vmstate: introduce vmstate_{load, save}_field helpers

[Alexander Mikhalitsyn]

Am Mo., 16. März 2026 um 15:57 Uhr schrieb Fabiano Rosas <farosas@suse.de>:
>
> Alexander Mikhalitsyn via qemu development <qemu-devel@nongnu.org>
> writes:
>
> > Am Fr., 13. März 2026 um 17:27 Uhr schrieb Peter Xu <peterx@redhat.com>:
> >>
> >> On Fri, Mar 13, 2026 at 03:12:14PM +0100, Alexander Mikhalitsyn wrote:
> >> > From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
> >> >
> >> > Let's introduce vmstate_{load,save}_field() helpers, they will
> >> > be used in next patches to support fully-dynamic arrays with NULLs.
> >> >
> >> > Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
> >>
> >
> > Hi Peter,
> >
> >> Feel free to rebase to Vladimir's series here, Fabiano already queued it:
> >>
> >> https://lore.kernel.org/all/20260304212303.667141-11-vsementsov@yandex-team.ru/#t
> >
> > I've tried, but I can't see it anywhere
> > https://gitlab.com/farosas/qemu/-/commits/migration-next
> > doesn't contain it. As of now, last commit is
> > 472f455cfbb0c5f84a7d48228d5226eaf6c7a61b.
> >

Hi Fabiano,

>
> I think we usually just take the patches from the list and apply
> directly instead of taking any branch*. I don't keep migration-next
> stable.

ah, makes sense.

>
> I pushed migration-staging which you can use. It'll collect the patches
> that will be merged at the start of the next development cycle, after
> the release.

Thank you!

>
> * I use:
> b4 am -3 -c -o <patches/dir> <lore.kernel.org link>
> (you'd need to solve any conflicts with the base branch yourself)

thanks for this, Fabiano! I'll try this out.

Kind regards,
Alex

>
> > Also, patchew tells that that series has conflicts with master:
> > https://patchew.org/QEMU/20260304212303.667141-1-vsementsov@yandex-team.ru/
> >
> > Should I manually download mbox, apply/resolve conflicts with master,
> > then rebase my stuff and resend?
> >
> > Kind regards,
> > Alex
> >
> >>
> >> These codes weren't touched that frequent, it's interesting to see such
> >> coinsidence happens. :)
> >>
> >> > ---
> >> >  include/migration/vmstate.h |  4 ++
> >> >  migration/vmstate.c         | 84 +++++++++++++++++++++++--------------
> >> >  2 files changed, 56 insertions(+), 32 deletions(-)
> >> >
> >> > diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
> >> > index 62c2abd0c49..5d7dfe70643 100644
> >> > --- a/include/migration/vmstate.h
> >> > +++ b/include/migration/vmstate.h
> >> > @@ -1240,8 +1240,12 @@ extern const VMStateInfo vmstate_info_qlist;
> >> >          .flags = VMS_END, \
> >> >      }
> >> >
> >> > +int vmstate_load_field(QEMUFile *f, void *pv, size_t size,
> >> > +                       const VMStateField *field, Error **errp);
> >> >  int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
> >> >                         void *opaque, int version_id, Error **errp);
> >> > +int vmstate_save_field(QEMUFile *f, void *pv, size_t size,
> >> > +                       const VMStateField *field, JSONWriter *vmdesc, Error **errp);
> >> >  int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
> >> >                         void *opaque, JSONWriter *vmdesc, Error **errp);
> >> >  int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
> >> > diff --git a/migration/vmstate.c b/migration/vmstate.c
> >> > index 4d28364f7ba..8d192bcaa27 100644
> >> > --- a/migration/vmstate.c
> >> > +++ b/migration/vmstate.c
> >> > @@ -131,6 +131,32 @@ static void vmstate_handle_alloc(void *ptr, const VMStateField *field,
> >> >      }
> >> >  }
> >> >
> >> > +int vmstate_load_field(QEMUFile *f, void *pv, size_t size,
> >> > +                       const VMStateField *field, Error **errp)
> >> > +{
> >> > +    int ret = 0;
> >> > +
> >> > +    if (field->flags & VMS_STRUCT) {
> >> > +        ret = vmstate_load_state(f, field->vmsd, pv,
> >> > +                                 field->vmsd->version_id,
> >> > +                                 errp);
> >> > +    } else if (field->flags & VMS_VSTRUCT) {
> >> > +        ret = vmstate_load_state(f, field->vmsd, pv,
> >> > +                                 field->struct_version_id,
> >> > +                                 errp);
> >> > +    } else {
> >> > +        ret = field->info->get(f, pv, size, field);
> >> > +        if (ret < 0) {
> >> > +            error_setg(errp,
> >> > +                       "Failed to load element of type %s for %s: "
> >> > +                       "%d", field->info->name,
> >> > +                       field->name, ret);
> >> > +        }
> >> > +    }
> >> > +
> >> > +    return ret;
> >> > +}
> >> > +
> >> >  int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
> >> >                         void *opaque, int version_id, Error **errp)
> >> >  {
> >> > @@ -203,24 +229,7 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
> >> >                      inner_field = field;
> >> >                  }
> >> >
> >> > -                if (inner_field->flags & VMS_STRUCT) {
> >> > -                    ret = vmstate_load_state(f, inner_field->vmsd, curr_elem,
> >> > -                                             inner_field->vmsd->version_id,
> >> > -                                             errp);
> >> > -                } else if (inner_field->flags & VMS_VSTRUCT) {
> >> > -                    ret = vmstate_load_state(f, inner_field->vmsd, curr_elem,
> >> > -                                             inner_field->struct_version_id,
> >> > -                                             errp);
> >> > -                } else {
> >> > -                    ret = inner_field->info->get(f, curr_elem, size,
> >> > -                                                 inner_field);
> >> > -                    if (ret < 0) {
> >> > -                        error_setg(errp,
> >> > -                                   "Failed to load element of type %s for %s: "
> >> > -                                   "%d", inner_field->info->name,
> >> > -                                   inner_field->name, ret);
> >> > -                    }
> >> > -                }
> >> > +                ret = vmstate_load_field(f, curr_elem, size, inner_field, errp);
> >> >
> >> >                  /* If we used a fake temp field.. free it now */
> >> >                  if (inner_field != field) {
> >> > @@ -427,6 +436,29 @@ int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
> >> >      return vmstate_save_state_v(f, vmsd, opaque, vmdesc_id, vmsd->version_id, errp);
> >> >  }
> >> >
> >> > +int vmstate_save_field(QEMUFile *f, void *pv, size_t size,
> >> > +                       const VMStateField *field, JSONWriter *vmdesc, Error **errp)
> >> > +{
> >> > +    int ret = 0;
> >> > +
> >> > +    if (field->flags & VMS_STRUCT) {
> >> > +        ret = vmstate_save_state(f, field->vmsd, pv, vmdesc, errp);
> >> > +    } else if (field->flags & VMS_VSTRUCT) {
> >> > +        ret = vmstate_save_state_v(f, field->vmsd, pv, vmdesc,
> >> > +                                   field->struct_version_id, errp);
> >> > +    } else {
> >> > +        ret = field->info->put(f, pv, size, field, vmdesc);
> >> > +        if (ret < 0) {
> >> > +            error_setg(errp,
> >> > +                       "Failed to save element of type %s for %s: "
> >> > +                       "%d", field->info->name,
> >> > +                       field->name, ret);
> >> > +        }
> >> > +    }
> >> > +
> >> > +    return ret;
> >> > +}
> >> > +
> >> >  int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
> >> >                           void *opaque, JSONWriter *vmdesc, int version_id, Error **errp)
> >> >  {
> >> > @@ -528,19 +560,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
> >> >                  vmsd_desc_field_start(vmsd, vmdesc_loop, inner_field,
> >> >                                        i, max_elems);
> >> >
> >> > -                if (inner_field->flags & VMS_STRUCT) {
> >> > -                    ret = vmstate_save_state(f, inner_field->vmsd,
> >> > -                                             curr_elem, vmdesc_loop, errp);
> >> > -                } else if (inner_field->flags & VMS_VSTRUCT) {
> >> > -                    ret = vmstate_save_state_v(f, inner_field->vmsd,
> >> > -                                               curr_elem, vmdesc_loop,
> >> > -                                               inner_field->struct_version_id,
> >> > -                                               errp);
> >> > -                } else {
> >> > -                    ret = inner_field->info->put(f, curr_elem, size,
> >> > -                                                 inner_field, vmdesc_loop);
> >> > -                }
> >> > -
> >> > +                ret = vmstate_save_field(f, curr_elem, size, inner_field, vmdesc_loop, errp);
> >> >                  written_bytes = qemu_file_transferred(f) - old_offset;
> >> >                  vmsd_desc_field_end(vmsd, vmdesc_loop, inner_field,
> >> >                                      written_bytes);
> >> > @@ -551,7 +571,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
> >> >                  }
> >> >
> >> >                  if (ret) {
> >> > -                    error_setg(errp, "Save of field %s/%s failed",
> >> > +                    error_prepend(errp, "Save of field %s/%s failed: ",
> >> >                                  vmsd->name, field->name);
> >> >                      if (vmsd->post_save) {
> >> >                          vmsd->post_save(opaque);
> >> > --
> >> > 2.47.3
> >> >
> >>
> >> --
> >> Peter Xu
> >>

[PATCH v4 2/8] migration: add VMSTATE_VARRAY_OF_POINTER_TO_STRUCT_UINT{8, 32}_ALLOC

[Alexander Mikhalitsyn]

From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>

Add VMSTATE_VARRAY_OF_POINTER_TO_STRUCT_UINT{8, 32}_ALLOC, which
helps to save/restore a dynamic array of pointers to
structures.

Suggested-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
v2:
- added VMSTATE_VARRAY_OF_POINTER_TO_STRUCT_UINT8_ALLOC
v4:
- almost completely reworked, new flag VMS_ARRAY_OF_POINTER_ALLOW_NULL
  was introduced as suggested by Peter
---
 include/migration/vmstate.h |  77 ++++++++++++++++++++++++++-
 migration/savevm.c          |  26 +++++++++
 migration/vmstate-types.c   | 102 ++++++++++++++++++++++++++++++++++++
 migration/vmstate.c         |  54 +++++++++++++++----
 4 files changed, 247 insertions(+), 12 deletions(-)

diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
index 5d7dfe70643..70588ed86d7 100644
--- a/include/migration/vmstate.h
+++ b/include/migration/vmstate.h
@@ -151,7 +151,19 @@ enum VMStateFlags {
     VMS_VSTRUCT           = 0x8000,
 
     /* Marker for end of list */
-    VMS_END = 0x10000
+    VMS_END                         = 0x10000,
+
+    /* The field is a (fixed-size or variable-size) array of pointers
+     * (e.g. struct a { uint8_t **b; }) that can contain NULL values.
+     * This instructs vmstate engine to:
+     * - Dereference each array entry before using it.
+     * - Assume that array is initialized with NULLs on load phase
+     * - Automatically allocate memory for array entries (with size
+     *   specified in (VMStateField).start) on load phase
+     * - Produce NULL/not-NULL markers in migration stream
+     *
+     * Note: Does not imply VMS_ARRAY_OF_POINTER; it needs to be set explicitly. */
+    VMS_ARRAY_OF_POINTER_ALLOW_NULL = 0x20000,
 };
 
 typedef enum {
@@ -184,6 +196,7 @@ struct VMStateField {
     int version_id;
     int struct_version_id;
     bool (*field_exists)(void *opaque, int version_id);
+    const struct VMStateField *real_field;
 };
 
 struct VMStateDescription {
@@ -252,8 +265,10 @@ extern const VMStateInfo vmstate_info_uint64;
 extern const VMStateInfo vmstate_info_fd;
 
 /** Put this in the stream when migrating a null pointer.*/
-#define VMS_NULLPTR_MARKER (0x30U) /* '0' */
+#define VMS_NULLPTR_MARKER    (0x30U) /* '0' */
+#define VMS_NOTNULLPTR_MARKER (0x31U) /* '1' */
 extern const VMStateInfo vmstate_info_nullptr;
+extern const VMStateInfo vmstate_info_maybeptr;
 
 extern const VMStateInfo vmstate_info_cpudouble;
 
@@ -265,6 +280,7 @@ extern const VMStateInfo vmstate_info_bitmap;
 extern const VMStateInfo vmstate_info_qtailq;
 extern const VMStateInfo vmstate_info_gtree;
 extern const VMStateInfo vmstate_info_qlist;
+extern const VMStateInfo vmstate_info_ptrs_array_entry;
 
 #define type_check_2darray(t1,t2,n,m) ((t1(*)[n][m])0 - (t2*)0)
 /*
@@ -547,6 +563,63 @@ extern const VMStateInfo vmstate_info_qlist;
     .offset     = vmstate_offset_array(_s, _f, _type*, _n),          \
 }
 
+/*
+ * For migrating a dynamically allocated uint{8,32}-indexed array
+ * of pointers to structures (with NULL entries and with auto memory allocation).
+ *
+ * _type: type of structure pointed to
+ * _vmsd: VMSD for structure _type (when VMS_STRUCT is set)
+ * _info: VMStateInfo for _type (when VMS_STRUCT is not set)
+ * start: size of (_type) pointed to (for auto memory allocation)
+ */
+#define VMSTATE_VARRAY_OF_POINTER_TO_STRUCT_UINT8_ALLOC(_field, _state, _field_num, _version, _vmsd, _type) { \
+    .name       = (stringify(_field)),                               \
+    .version_id = (_version),                                        \
+    .num_offset = vmstate_offset_value(_state, _field_num, uint8_t), \
+    .vmsd       = &(_vmsd),                                          \
+    .start      = sizeof(_type),                                     \
+    .size       = sizeof(_type *),                                   \
+    .flags      = VMS_POINTER|VMS_VARRAY_UINT8|VMS_ARRAY_OF_POINTER| \
+                  VMS_ARRAY_OF_POINTER_ALLOW_NULL|VMS_STRUCT,        \
+    .offset     = vmstate_offset_pointer(_state, _field, _type *),   \
+}
+
+#define VMSTATE_VARRAY_OF_POINTER_UINT8_ALLOC(_field, _state, _field_num, _version, _info, _type) { \
+    .name       = (stringify(_field)),                               \
+    .version_id = (_version),                                        \
+    .num_offset = vmstate_offset_value(_state, _field_num, uint8_t), \
+    .info       = &(_info),                                          \
+    .start      = sizeof(_type),                                     \
+    .size       = sizeof(_type *),                                   \
+    .flags      = VMS_POINTER|VMS_VARRAY_UINT8|VMS_ARRAY_OF_POINTER| \
+                  VMS_ARRAY_OF_POINTER_ALLOW_NULL,                   \
+    .offset     = vmstate_offset_pointer(_state, _field, _type *),   \
+}
+
+#define VMSTATE_VARRAY_OF_POINTER_TO_STRUCT_UINT32_ALLOC(_field, _state, _field_num, _version, _vmsd, _type) { \
+    .name       = (stringify(_field)),                                \
+    .version_id = (_version),                                         \
+    .num_offset = vmstate_offset_value(_state, _field_num, uint32_t), \
+    .vmsd       = &(_vmsd),                                           \
+    .start      = sizeof(_type),                                      \
+    .size       = sizeof(_type *),                                    \
+    .flags      = VMS_POINTER|VMS_VARRAY_UINT32|VMS_ARRAY_OF_POINTER| \
+                  VMS_ARRAY_OF_POINTER_ALLOW_NULL|VMS_STRUCT,         \
+    .offset     = vmstate_offset_pointer(_state, _field, _type *),    \
+}
+
+#define VMSTATE_VARRAY_OF_POINTER_UINT32_ALLOC(_field, _state, _field_num, _version, _info, _type) { \
+    .name       = (stringify(_field)),                                \
+    .version_id = (_version),                                         \
+    .num_offset = vmstate_offset_value(_state, _field_num, uint32_t), \
+    .info       = &(_info),                                           \
+    .start      = sizeof(_type),                                      \
+    .size       = sizeof(_type *),                                    \
+    .flags      = VMS_POINTER|VMS_VARRAY_UINT32|VMS_ARRAY_OF_POINTER| \
+                  VMS_ARRAY_OF_POINTER_ALLOW_NULL,                    \
+    .offset     = vmstate_offset_pointer(_state, _field, _type *),    \
+}
+
 #define VMSTATE_VARRAY_OF_POINTER_UINT32(_field, _state, _field_num, _version, _info, _type) { \
     .name       = (stringify(_field)),                                    \
     .version_id = (_version),                                             \
diff --git a/migration/savevm.c b/migration/savevm.c
index 197c89e0e65..1ce618d2e66 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -863,6 +863,32 @@ static void vmstate_check(const VMStateDescription *vmsd)
 
     if (field) {
         while (field->name) {
+            /*
+             * VMS_ARRAY_OF_POINTER must be used only together
+             * with one of VMS_(V)ARRAY* flags.
+             */
+            assert(!(field->flags & VMS_ARRAY_OF_POINTER) ||
+                   ((field->flags & (VMS_ARRAY | VMS_VARRAY_INT32 |
+                     VMS_VARRAY_UINT16 | VMS_VARRAY_UINT8 | VMS_VARRAY_UINT32))));
+
+            /*
+             * When VMS_ARRAY_OF_POINTER_ALLOW_NULL is used, we must:
+             * 1. have VMS_ARRAY_OF_POINTER set too;
+             * 2. have ->start field set and it should tell us a size
+             *    of memory chunk we should allocate for every array member.
+             */
+            assert(!(field->flags & VMS_ARRAY_OF_POINTER_ALLOW_NULL) ||
+                   (field->flags & VMS_ARRAY_OF_POINTER));
+            assert(!(field->flags & VMS_ARRAY_OF_POINTER_ALLOW_NULL) ||
+                   field->start);
+
+            /*
+             * (VMStateField).real_field is only for internal purposes
+             * and should never be used by any user-defined VMStateField.
+             * Currently, it is only used by vmsd_create_fake_nullptr_field().
+             */
+            assert(!field->real_field);
+
             if (field->flags & (VMS_STRUCT | VMS_VSTRUCT)) {
                 /* Recurse to sub structures */
                 vmstate_check(field->vmsd);
diff --git a/migration/vmstate-types.c b/migration/vmstate-types.c
index 89cb2114721..8e5431057db 100644
--- a/migration/vmstate-types.c
+++ b/migration/vmstate-types.c
@@ -377,6 +377,108 @@ const VMStateInfo vmstate_info_nullptr = {
     .put  = put_nullptr,
 };
 
+static int get_maybeptr(QEMUFile *f, void *ppv, size_t unused_size,
+                        const VMStateField *field)
+{
+    Error *local_err = NULL;
+    Error **errp = &local_err;
+    int ret = 0;
+    const VMStateField *real_field = field->real_field;
+    /* size of structure pointed to by elements of array */
+    size_t size = real_field->start;
+    int marker;
+
+    assert(size);
+
+    if (ppv == NULL) {
+        error_report("vmstate: get_maybeptr must be called with ppv != NULL");
+        return -EINVAL;
+    }
+
+    /*
+     * We start from a clean array, all elements must be NULL, unless
+     * something we haven't prepared for has changed in vmstate_save_state_v().
+     * Let's check for this just in case.
+     */
+    if (*(void **)ppv != NULL) {
+        error_report("vmstate: get_maybeptr must be called with *ppv == NULL");
+        return -EINVAL;
+    }
+
+    marker = qemu_get_byte(f);
+    assert(marker == VMS_NULLPTR_MARKER || marker == VMS_NOTNULLPTR_MARKER);
+
+    if (marker == VMS_NOTNULLPTR_MARKER) {
+        void *pv;
+
+        /* allocate memory for structure */
+        pv = g_malloc0(size);
+
+        ret = vmstate_load_field(f, pv, size, real_field, errp);
+        if (ret) {
+            error_report_err(local_err);
+            g_free(pv);
+            return ret;
+        }
+
+        *(void **)ppv = pv;
+    }
+
+    return ret;
+}
+
+static int put_maybeptr(QEMUFile *f, void *ppv, size_t unused_size,
+                        const VMStateField *field, JSONWriter *vmdesc)
+{
+    const VMStateField *real_field = field->real_field;
+    int ret = 0;
+    Error *local_err = NULL;
+    Error **errp = &local_err;
+    /* size of structure pointed to by elements of array */
+    size_t size = real_field->start;
+    void *pv;
+
+    assert(size);
+
+    /*
+     * (ppv) is an address of an i-th element of a dynamic array.
+     *
+     * (ppv) can not be NULL unless we have some regression/bug in
+     * vmstate_save_state_v(), because it is result of pointer arithemic like:
+     * first_elem + size * i.
+     */
+    if (ppv == NULL) {
+        error_report("vmstate: put_maybeptr must be called with ppv != NULL");
+        return -EINVAL;
+    }
+
+    /* get a pointer to a structure */
+    pv = *(void **)ppv;
+
+    if (pv == NULL) {
+        /* write a mark telling that there was a NULL pointer */
+        qemu_put_byte(f, VMS_NULLPTR_MARKER);
+        return 0;
+    }
+
+    /* if pv is not NULL, write a marker and save field using vmstate_save_field() */
+    qemu_put_byte(f, VMS_NOTNULLPTR_MARKER);
+
+    ret = vmstate_save_field(f, pv, size, real_field, vmdesc, errp);
+    if (ret) {
+        error_report_err(local_err);
+        return ret;
+    }
+
+    return 0;
+}
+
+const VMStateInfo vmstate_info_maybeptr = {
+    .name = "maybeptr",
+    .get  = get_maybeptr,
+    .put  = put_maybeptr,
+};
+
 /* 64 bit unsigned int. See that the received value is the same than the one
    in the field */
 
diff --git a/migration/vmstate.c b/migration/vmstate.c
index 8d192bcaa27..e52046f069d 100644
--- a/migration/vmstate.c
+++ b/migration/vmstate.c
@@ -71,10 +71,15 @@ vmsd_create_fake_nullptr_field(const VMStateField *field)
     /* Do not need "field_exists" check as it always exists (which is null) */
     fake->field_exists = NULL;
 
-    /* See vmstate_info_nullptr - use 1 byte to represent nullptr */
-    fake->size = 1;
-    fake->info = &vmstate_info_nullptr;
-    fake->flags = VMS_SINGLE;
+    if (!(field->flags & VMS_ARRAY_OF_POINTER_ALLOW_NULL)) {
+        /* See vmstate_info_nullptr - use 1 byte to represent nullptr */
+        fake->size = 1;
+        fake->info = &vmstate_info_nullptr;
+        fake->flags = VMS_SINGLE;
+    } else {
+        fake->real_field = field;
+        fake->info = &vmstate_info_maybeptr;
+    }
 
     /* All the rest fields shouldn't matter.. */
 
@@ -212,13 +217,28 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
             }
             for (i = 0; i < n_elems; i++) {
                 void *curr_elem = first_elem + size * i;
+                bool need_fake_field = false;
                 const VMStateField *inner_field;
 
                 if (field->flags & VMS_ARRAY_OF_POINTER) {
-                    curr_elem = *(void **)curr_elem;
+                    if (!(field->flags & VMS_ARRAY_OF_POINTER_ALLOW_NULL)) {
+                        assert(curr_elem);
+                        curr_elem = *(void **)curr_elem;
+                        need_fake_field = !curr_elem;
+                    } else {
+                        /*
+                         * We expect array of pointers to be initialized.
+                         * We don't want to overwrite curr_elem with it's
+                         * dereferenced value, because we may need to
+                         * allocate memory (depending on what is in the migration
+                         * stream) and write to it later.
+                         */
+                        assert(!*(void **)curr_elem);
+                        need_fake_field = true;
+                    }
                 }
 
-                if (!curr_elem && size) {
+                if (need_fake_field && size) {
                     /*
                      * If null pointer found (which should only happen in
                      * an array of pointers), use null placeholder and do
@@ -226,6 +246,7 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
                      */
                     inner_field = vmsd_create_fake_nullptr_field(field);
                 } else {
+                    assert(curr_elem || !size);
                     inner_field = field;
                 }
 
@@ -507,25 +528,38 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
 
             for (i = 0; i < n_elems; i++) {
                 void *curr_elem = first_elem + size * i;
+                bool need_fake_field = false;
                 const VMStateField *inner_field;
                 bool is_null;
                 int max_elems = n_elems - i;
 
                 old_offset = qemu_file_transferred(f);
                 if (field->flags & VMS_ARRAY_OF_POINTER) {
-                    assert(curr_elem);
-                    curr_elem = *(void **)curr_elem;
+                    if (!(field->flags & VMS_ARRAY_OF_POINTER_ALLOW_NULL)) {
+                        assert(curr_elem);
+                        curr_elem = *(void **)curr_elem;
+                        need_fake_field = !curr_elem;
+                    } else {
+                        /*
+                         * We always need a fake field to properly handle
+                         * VMS_ARRAY_OF_POINTER_ALLOW_NULL case, because
+                         * even if pointer is not NULL, we still want to
+                         * write a marker in the migration stream.
+                         */
+                        need_fake_field = true;
+                    }
                 }
 
-                if (!curr_elem && size) {
+                if (need_fake_field && size) {
                     /*
                      * If null pointer found (which should only happen in
                      * an array of pointers), use null placeholder and do
                      * not follow.
                      */
                     inner_field = vmsd_create_fake_nullptr_field(field);
-                    is_null = true;
+                    is_null = !curr_elem;
                 } else {
+                    assert(curr_elem || !size);
                     inner_field = field;
                     is_null = false;
                 }
-- 
2.47.3

[PATCH v4 3/8] tests/unit/test-vmstate: add tests for VMS_ARRAY_OF_POINTER_ALLOW_NULL

[Alexander Mikhalitsyn]

From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>

Add tests for VMSTATE_VARRAY_OF_POINTER{,_TO_STRUCT}_UINT32_ALLOC.

Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
---
 tests/unit/test-vmstate.c | 157 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 157 insertions(+)

diff --git a/tests/unit/test-vmstate.c b/tests/unit/test-vmstate.c
index cadbab3c5e2..d10cf34fc75 100644
--- a/tests/unit/test-vmstate.c
+++ b/tests/unit/test-vmstate.c
@@ -702,6 +702,155 @@ static void test_arr_ptr_prim_0_load(void)
     }
 }
 
+static uint8_t wire_arr_ptr_with_nulls[] = {
+    VMS_NOTNULLPTR_MARKER,
+    0x00, 0x00, 0x00, 0x00,
+    VMS_NULLPTR_MARKER,
+    VMS_NOTNULLPTR_MARKER,
+    0x00, 0x00, 0x00, 0x02,
+    VMS_NOTNULLPTR_MARKER,
+    0x00, 0x00, 0x00, 0x03,
+    QEMU_VM_EOF
+};
+
+typedef struct {
+    uint32_t       ar_items_num;
+    TestStructTriv **ar;
+} TestVArrayOfPtrToStuctWithNULLs;
+
+const VMStateDescription vmsd_arps_with_nulls = {
+    .name = "test/arps_with_nulls",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (const VMStateField[]) {
+        VMSTATE_VARRAY_OF_POINTER_TO_STRUCT_UINT32_ALLOC(
+            ar, TestVArrayOfPtrToStuctWithNULLs, ar_items_num, 0, vmsd_tst, TestStructTriv),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void test_arr_ptr_nulls_str_save(void)
+{
+    TestStructTriv ar[AR_SIZE] = { {.i = 0}, {.i = 1}, {.i = 2}, {.i = 3} };
+    TestVArrayOfPtrToStuctWithNULLs sample = {};
+    int idx;
+
+    sample.ar_items_num = AR_SIZE;
+    sample.ar = g_new0(TestStructTriv*, sample.ar_items_num);
+    sample.ar[0] = g_new0(TestStructTriv, 1);
+    *sample.ar[0] = ar[0];
+    /* note, sample.ar[1] remains NULL */
+    sample.ar[2] = g_new0(TestStructTriv, 1);
+    *sample.ar[2] = ar[2];
+    sample.ar[3] = g_new0(TestStructTriv, 1);
+    *sample.ar[3] = ar[3];
+
+    save_vmstate(&vmsd_arps_with_nulls, &sample);
+    compare_vmstate(wire_arr_ptr_with_nulls, sizeof(wire_arr_ptr_with_nulls));
+
+    for (idx = 0; idx < AR_SIZE; ++idx) {
+        g_free(sample.ar[idx]);
+    }
+    g_free(sample.ar);
+}
+
+static void test_arr_ptr_nulls_str_load(void)
+{
+    TestStructTriv ar_gt[AR_SIZE] = {{.i = 0}, {.i = 0}, {.i = 2}, {.i = 3} };
+    TestVArrayOfPtrToStuctWithNULLs obj = {};
+    int idx;
+
+    obj.ar_items_num = AR_SIZE;
+    obj.ar = g_new0(TestStructTriv*, obj.ar_items_num);
+
+    save_buffer(wire_arr_ptr_with_nulls, sizeof(wire_arr_ptr_with_nulls));
+    SUCCESS(load_vmstate_one(&vmsd_arps_with_nulls, &obj, 1,
+                          wire_arr_ptr_with_nulls, sizeof(wire_arr_ptr_with_nulls)));
+
+    for (idx = 0; idx < AR_SIZE; ++idx) {
+        if (idx == 1) {
+            g_assert_cmpint((uintptr_t)(obj.ar[idx]), ==, 0);
+        } else {
+            /* compare the target array ar with the ground truth array ar_gt */
+            g_assert_cmpint(ar_gt[idx].i, ==, obj.ar[idx]->i);
+        }
+    }
+
+    for (idx = 0; idx < AR_SIZE; ++idx) {
+        g_free(obj.ar[idx]);
+    }
+    g_free(obj.ar);
+}
+
+typedef struct {
+    uint32_t ar_items_num;
+    int32_t  **ar;
+} TestVArrayOfPtrToIntWithNULLs;
+
+const VMStateDescription vmsd_arpp_with_nulls = {
+    .name = "test/arpp_with_nulls",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (const VMStateField[]) {
+        VMSTATE_VARRAY_OF_POINTER_UINT32_ALLOC(
+            ar, TestVArrayOfPtrToIntWithNULLs, ar_items_num, 0, vmstate_info_int32, int32_t),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void test_arr_ptr_nulls_prim_save(void)
+{
+    int32_t ar[AR_SIZE] = { 0, 1, 2, 3 };
+    TestVArrayOfPtrToIntWithNULLs sample = {};
+    int idx;
+
+    sample.ar_items_num = AR_SIZE;
+    sample.ar = g_new0(int32_t*, sample.ar_items_num);
+    sample.ar[0] = g_new0(int32_t, 1);
+    *sample.ar[0] = ar[0];
+    /* note, sample.ar[1] remains NULL */
+    sample.ar[2] = g_new0(int32_t, 1);
+    *sample.ar[2] = ar[2];
+    sample.ar[3] = g_new0(int32_t, 1);
+    *sample.ar[3] = ar[3];
+
+    save_vmstate(&vmsd_arpp_with_nulls, &sample);
+    compare_vmstate(wire_arr_ptr_with_nulls, sizeof(wire_arr_ptr_with_nulls));
+
+    for (idx = 0; idx < AR_SIZE; ++idx) {
+        g_free(sample.ar[idx]);
+    }
+    g_free(sample.ar);
+}
+
+static void test_arr_ptr_nulls_prim_load(void)
+{
+    int32_t ar_gt[AR_SIZE] = { 0, 0, 2, 3 };
+    TestVArrayOfPtrToIntWithNULLs obj = {};
+    int idx;
+
+    obj.ar_items_num = AR_SIZE;
+    obj.ar = g_new0(int32_t*, obj.ar_items_num);
+
+    save_buffer(wire_arr_ptr_with_nulls, sizeof(wire_arr_ptr_with_nulls));
+    SUCCESS(load_vmstate_one(&vmsd_arpp_with_nulls, &obj, 1,
+                          wire_arr_ptr_with_nulls, sizeof(wire_arr_ptr_with_nulls)));
+
+    for (idx = 0; idx < AR_SIZE; ++idx) {
+        if (idx == 1) {
+            g_assert_cmpint((uintptr_t)(obj.ar[idx]), ==, 0);
+        } else {
+            /* compare the target array ar with the ground truth array ar_gt */
+            g_assert_cmpint(ar_gt[idx], ==, *obj.ar[idx]);
+        }
+    }
+
+    for (idx = 0; idx < AR_SIZE; ++idx) {
+        g_free(obj.ar[idx]);
+    }
+    g_free(obj.ar);
+}
+
 /* test QTAILQ migration */
 typedef struct TestQtailqElement TestQtailqElement;
 
@@ -1568,6 +1717,14 @@ int main(int argc, char **argv)
                     test_arr_ptr_prim_0_save);
     g_test_add_func("/vmstate/array/ptr/prim/0/load",
                     test_arr_ptr_prim_0_load);
+    g_test_add_func("/vmstate/array/ptr-nulls/str/save",
+                    test_arr_ptr_nulls_str_save);
+    g_test_add_func("/vmstate/array/ptr-nulls/str/load",
+                    test_arr_ptr_nulls_str_load);
+    g_test_add_func("/vmstate/array/ptr-nulls/prim/save",
+                    test_arr_ptr_nulls_prim_save);
+    g_test_add_func("/vmstate/array/ptr-nulls/prim/load",
+                    test_arr_ptr_nulls_prim_load);
     g_test_add_func("/vmstate/qtailq/save/saveq", test_save_q);
     g_test_add_func("/vmstate/qtailq/load/loadq", test_load_q);
     g_test_add_func("/vmstate/gtree/save/savedomain", test_gtree_save_domain);
-- 
2.47.3

[PATCH v4 4/8] tests/functional/migration: add VM launch/configure hooks

[Alexander Mikhalitsyn]

From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>

Introduce configure_machine, launch_source_vm and assert_dest_vm
methods to allow child classes to override some pieces of
source/dest VMs creation, start and check logic.

Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
---
 tests/functional/migration.py | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/tests/functional/migration.py b/tests/functional/migration.py
index e995328e833..40e9c094c46 100644
--- a/tests/functional/migration.py
+++ b/tests/functional/migration.py
@@ -40,19 +40,35 @@ def assert_migration(self, src_vm, dst_vm):
         self.assertEqual(dst_vm.cmd('query-status')['status'], 'running')
         self.assertEqual(src_vm.cmd('query-status')['status'],'postmigrate')
 
+    # Can be overridden by subclasses to configure both source/dest VMs.
+    def configure_machine(self, vm):
+        vm.add_args('-nodefaults')
+
+    # Can be overridden by subclasses to prepare the source VM before migration,
+    # e.g. by running some workload inside the source VM to see if it continues
+    # to run properly after migration.
+    def launch_source_vm(self, vm):
+        vm.launch()
+
+    # Can be overridden by subclasses to check the destination VM after migration,
+    # e.g. by checking if the workload is still running after migration.
+    def assert_dest_vm(self, vm):
+        pass
+
     def migrate_vms(self, dst_uri, src_uri, dst_vm, src_vm):
         dst_vm.qmp('migrate-incoming', uri=dst_uri)
         src_vm.qmp('migrate', uri=src_uri)
         self.assert_migration(src_vm, dst_vm)
+        self.assert_dest_vm(dst_vm)
 
     def migrate(self, dst_uri, src_uri=None):
         dst_vm = self.get_vm('-incoming', 'defer', name="dst-qemu")
-        dst_vm.add_args('-nodefaults')
+        self.configure_machine(dst_vm)
         dst_vm.launch()
 
         src_vm = self.get_vm(name="src-qemu")
-        src_vm.add_args('-nodefaults')
-        src_vm.launch()
+        self.configure_machine(src_vm)
+        self.launch_source_vm(src_vm)
 
         if src_uri is None:
             src_uri = dst_uri
-- 
2.47.3

[PATCH v4 5/8] hw/nvme: add migration blockers for non-supported cases

[Alexander Mikhalitsyn]

From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>

Let's block migration for cases we don't support:
- SR-IOV
- CMB
- PMR
- SPDM

No functional changes here, because NVMe migration is
not supported at all as of this commit.

Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
---
 hw/nvme/ctrl.c       | 206 +++++++++++++++++++++++++++++++++++++++++++
 hw/nvme/nvme.h       |   3 +
 include/block/nvme.h |  12 +++
 3 files changed, 221 insertions(+)

diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c
index cc4593cd427..9f9c9bcbead 100644
--- a/hw/nvme/ctrl.c
+++ b/hw/nvme/ctrl.c
@@ -207,6 +207,7 @@
 #include "hw/pci/msix.h"
 #include "hw/pci/pcie_sriov.h"
 #include "system/spdm-socket.h"
+#include "migration/blocker.h"
 #include "migration/vmstate.h"
 
 #include "nvme.h"
@@ -250,6 +251,7 @@ static const bool nvme_feature_support[NVME_FID_MAX] = {
     [NVME_COMMAND_SET_PROFILE]      = true,
     [NVME_FDP_MODE]                 = true,
     [NVME_FDP_EVENTS]               = true,
+    /* if you add something here, please update nvme_set_migration_blockers() */
 };
 
 static const uint32_t nvme_feature_cap[NVME_FID_MAX] = {
@@ -4601,6 +4603,7 @@ static uint16_t nvme_io_mgmt_send(NvmeCtrl *n, NvmeRequest *req)
         return 0;
     case NVME_IOMS_MO_RUH_UPDATE:
         return nvme_io_mgmt_send_ruh_update(n, req);
+    /* if you add something here, please update nvme_set_migration_blockers() */
     default:
         return NVME_INVALID_FIELD | NVME_DNR;
     };
@@ -7518,6 +7521,10 @@ static uint16_t nvme_security_receive(NvmeCtrl *n, NvmeRequest *req)
 
 static uint16_t nvme_directive_send(NvmeCtrl *n, NvmeRequest *req)
 {
+    /*
+     * When adding a new dtype handling here,
+     * please also update nvme_set_migration_blockers().
+     */
     return NVME_INVALID_FIELD | NVME_DNR;
 }
 
@@ -9208,6 +9215,199 @@ static void nvme_init_ctrl(NvmeCtrl *n, PCIDevice *pci_dev)
     }
 }
 
+#define BLOCKER_FEATURES_MAX_LEN 256
+
+static inline void nvme_add_blocker_feature(char *blocker_features, const char *feature)
+{
+    if (strlen(blocker_features) > 0) {
+        g_strlcat(blocker_features, ", ", BLOCKER_FEATURES_MAX_LEN);
+    }
+    g_strlcat(blocker_features, feature, BLOCKER_FEATURES_MAX_LEN);
+}
+
+static bool nvme_set_migration_blockers(NvmeCtrl *n, PCIDevice *pci_dev, Error **errp)
+{
+    uint64_t unsupported_cap, cap = ldq_le_p(&n->bar.cap);
+    char blocker_features[BLOCKER_FEATURES_MAX_LEN] = "";
+    bool adm_cmd_security_checked = false;
+    bool cmd_io_mgmt_checked = false;
+    bool cmd_zone_checked = false;
+
+    /*
+     * Idea of this function is simple, we iterate over all Command Sets and
+     * for each supported command we provide a special handling logic to
+     * determine if we should block migration or not.
+     *
+     * For instance, we have NVME_ADM_CMD_NS_ATTACHMENT and it is always
+     * available to the guest, but if there is only 1 namespace, then it is
+     * safe to allow migration, but if there are more, then we need to block
+     * migration because we don't handle this in migration code yet.
+     */
+    for (int opcode = 0; opcode < sizeof(n->cse.acs) / sizeof(n->cse.acs[0]); opcode++) {
+        /* Is command supported? */
+        if (!n->cse.acs[opcode]) {
+            continue;
+        }
+
+        switch (opcode) {
+        case NVME_ADM_CMD_DELETE_SQ:
+        case NVME_ADM_CMD_CREATE_SQ:
+        case NVME_ADM_CMD_GET_LOG_PAGE:
+        case NVME_ADM_CMD_DELETE_CQ:
+        case NVME_ADM_CMD_CREATE_CQ:
+        case NVME_ADM_CMD_IDENTIFY:
+        case NVME_ADM_CMD_ABORT:
+        case NVME_ADM_CMD_SET_FEATURES:
+        case NVME_ADM_CMD_GET_FEATURES:
+        case NVME_ADM_CMD_ASYNC_EV_REQ:
+        case NVME_ADM_CMD_DBBUF_CONFIG:
+        case NVME_ADM_CMD_FORMAT_NVM:
+        case NVME_ADM_CMD_DIRECTIVE_SEND:
+        case NVME_ADM_CMD_DIRECTIVE_RECV:
+            break;
+        case NVME_ADM_CMD_NS_ATTACHMENT:
+            int namespaces_num = 0;
+            for (int i = 1; i <= NVME_MAX_NAMESPACES; i++) {
+                NvmeNamespace *ns = nvme_subsys_ns(n->subsys, i);
+                if (!ns) {
+                    continue;
+                }
+
+                namespaces_num++;
+            }
+
+            if (namespaces_num > 1) {
+                nvme_add_blocker_feature(blocker_features, "Namespace Attachment");
+            }
+
+            break;
+        case NVME_ADM_CMD_VIRT_MNGMT:
+            if (n->params.sriov_max_vfs) {
+                nvme_add_blocker_feature(blocker_features, "SR-IOV");
+            }
+
+            break;
+        case NVME_ADM_CMD_SECURITY_SEND:
+        case NVME_ADM_CMD_SECURITY_RECV:
+            if (adm_cmd_security_checked) {
+                break;
+            }
+
+            if (pci_dev->spdm_port) {
+                nvme_add_blocker_feature(blocker_features, "SPDM");
+            }
+
+            adm_cmd_security_checked = true;
+
+            break;
+        default:
+            g_assert_not_reached();
+        }
+    }
+
+    for (int opcode = 0; opcode < sizeof(n->cse.iocs.nvm) / sizeof(n->cse.iocs.nvm[0]); opcode++) {
+        if (!n->cse.iocs.nvm[opcode]) {
+            continue;
+        }
+
+        switch (opcode) {
+        case NVME_CMD_FLUSH:
+        case NVME_CMD_WRITE:
+        case NVME_CMD_READ:
+        case NVME_CMD_COMPARE:
+        case NVME_CMD_WRITE_ZEROES:
+        case NVME_CMD_DSM:
+        case NVME_CMD_VERIFY:
+        case NVME_CMD_COPY:
+            break;
+        case NVME_CMD_IO_MGMT_RECV:
+        case NVME_CMD_IO_MGMT_SEND:
+            if (cmd_io_mgmt_checked) {
+                break;
+            }
+
+            /* check for NVME_IOMS_MO_RUH_UPDATE */
+            if (n->subsys->params.fdp.enabled) {
+                nvme_add_blocker_feature(blocker_features, "FDP");
+            }
+
+            cmd_io_mgmt_checked = true;
+
+            break;
+        default:
+            g_assert_not_reached();
+        }
+    }
+
+    for (int opcode = 0; opcode < sizeof(n->cse.iocs.zoned) / sizeof(n->cse.iocs.zoned[0]); opcode++) {
+        /*
+         * If command isn't supported or we have the same command
+         * in n->cse.iocs.nvm, then we can skip it here.
+         */
+        if (!n->cse.iocs.zoned[opcode] || n->cse.iocs.nvm[opcode]) {
+            continue;
+        }
+
+        switch (opcode) {
+        case NVME_CMD_ZONE_APPEND:
+        case NVME_CMD_ZONE_MGMT_SEND:
+        case NVME_CMD_ZONE_MGMT_RECV:
+            if (cmd_zone_checked) {
+                break;
+            }
+
+            for (int i = 1; i <= NVME_MAX_NAMESPACES; i++) {
+                NvmeNamespace *ns = nvme_subsys_ns(n->subsys, i);
+                if (!ns) {
+                    continue;
+                }
+
+                if (ns->params.zoned) {
+                    nvme_add_blocker_feature(blocker_features, "Zoned Namespace");
+                    break;
+                }
+            }
+
+            cmd_zone_checked = true;
+
+            break;
+        default:
+            g_assert_not_reached();
+        }
+    }
+
+    /*
+     * Try our best to explicitly detect all not supported caps,
+     * to let users know what features cause migration to be blocked,
+     * but in case we miss handling here, everything else will be
+     * covered by unsupported_cap check.
+     */
+    if (NVME_CAP_CMBS(cap)) {
+        nvme_add_blocker_feature(blocker_features, "CMB");
+        cap &= ~((uint64_t)CAP_CMBS_MASK << CAP_CMBS_SHIFT);
+    }
+
+    if (NVME_CAP_PMRS(cap)) {
+        nvme_add_blocker_feature(blocker_features, "PMR");
+        cap &= ~((uint64_t)CAP_PMRS_MASK << CAP_PMRS_SHIFT);
+    }
+
+    unsupported_cap = cap & ~NVME_MIGRATION_SUPPORTED_CAP_BITS;
+    if (unsupported_cap) {
+        nvme_add_blocker_feature(blocker_features, "unknown capability");
+    }
+
+    assert(n->migration_blocker == NULL);
+    if (strlen(blocker_features) > 0) {
+        error_setg(&n->migration_blocker, "Migration is not supported for %s", blocker_features);
+        if (migrate_add_blocker(&n->migration_blocker, errp) < 0) {
+            return false;
+        }
+    }
+
+    return true;
+}
+
 static int nvme_init_subsys(NvmeCtrl *n, Error **errp)
 {
     int cntlid;
@@ -9313,6 +9513,10 @@ static void nvme_realize(PCIDevice *pci_dev, Error **errp)
 
         n->subsys->namespaces[ns->params.nsid] = ns;
     }
+
+    if (!nvme_set_migration_blockers(n, pci_dev, errp)) {
+        return;
+    }
 }
 
 static void nvme_exit(PCIDevice *pci_dev)
@@ -9365,6 +9569,8 @@ static void nvme_exit(PCIDevice *pci_dev)
     }
 
     memory_region_del_subregion(&n->bar0, &n->iomem);
+
+    migrate_del_blocker(&n->migration_blocker);
 }
 
 static const Property nvme_props[] = {
diff --git a/hw/nvme/nvme.h b/hw/nvme/nvme.h
index d66f7dc82d5..457b6637249 100644
--- a/hw/nvme/nvme.h
+++ b/hw/nvme/nvme.h
@@ -666,6 +666,9 @@ typedef struct NvmeCtrl {
 
     /* Socket mapping to SPDM over NVMe Security In/Out commands */
     int spdm_socket;
+
+    /* Migration-related stuff */
+    Error *migration_blocker;
 } NvmeCtrl;
 
 typedef enum NvmeResetType {
diff --git a/include/block/nvme.h b/include/block/nvme.h
index 9d7159ed7a7..a7f586fc801 100644
--- a/include/block/nvme.h
+++ b/include/block/nvme.h
@@ -141,6 +141,18 @@ enum NvmeCapMask {
 #define NVME_CAP_SET_CMBS(cap, val)   \
     ((cap) |= (uint64_t)((val) & CAP_CMBS_MASK)   << CAP_CMBS_SHIFT)
 
+#define NVME_MIGRATION_SUPPORTED_CAP_BITS ( \
+      ((uint64_t)CAP_MQES_MASK   << CAP_MQES_SHIFT)   \
+    | ((uint64_t)CAP_CQR_MASK    << CAP_CQR_SHIFT)    \
+    | ((uint64_t)CAP_AMS_MASK    << CAP_AMS_SHIFT)    \
+    | ((uint64_t)CAP_TO_MASK     << CAP_TO_SHIFT)     \
+    | ((uint64_t)CAP_DSTRD_MASK  << CAP_DSTRD_SHIFT)  \
+    | ((uint64_t)CAP_NSSRS_MASK  << CAP_NSSRS_SHIFT)  \
+    | ((uint64_t)CAP_CSS_MASK    << CAP_CSS_SHIFT)    \
+    | ((uint64_t)CAP_MPSMIN_MASK << CAP_MPSMIN_SHIFT) \
+    | ((uint64_t)CAP_MPSMAX_MASK << CAP_MPSMAX_SHIFT) \
+)
+
 enum NvmeCapCss {
     NVME_CAP_CSS_NCSS    = 1 << 0,
     NVME_CAP_CSS_IOCSS   = 1 << 6,
-- 
2.47.3

[PATCH v4 6/8] hw/nvme: split nvme_init_sq/nvme_init_cq into helpers

[Alexander Mikhalitsyn]

From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>

Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
---
 hw/nvme/ctrl.c | 57 +++++++++++++++++++++++++++++++-------------------
 1 file changed, 36 insertions(+), 21 deletions(-)

diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c
index 9f9c9bcbead..68ce9802505 100644
--- a/hw/nvme/ctrl.c
+++ b/hw/nvme/ctrl.c
@@ -4854,18 +4854,14 @@ static uint16_t nvme_del_sq(NvmeCtrl *n, NvmeRequest *req)
     return NVME_SUCCESS;
 }
 
-static void nvme_init_sq(NvmeSQueue *sq, NvmeCtrl *n, uint64_t dma_addr,
-                         uint16_t sqid, uint16_t cqid, uint16_t size)
+static void __nvme_init_sq(NvmeSQueue *sq)
 {
+    NvmeCtrl *n = sq->ctrl;
+    uint16_t sqid = sq->sqid;
+    uint16_t cqid = sq->cqid;
     int i;
     NvmeCQueue *cq;
 
-    sq->ctrl = n;
-    sq->dma_addr = dma_addr;
-    sq->sqid = sqid;
-    sq->size = size;
-    sq->cqid = cqid;
-    sq->head = sq->tail = 0;
     sq->io_req = g_new0(NvmeRequest, sq->size);
 
     QTAILQ_INIT(&sq->req_list);
@@ -4895,6 +4891,18 @@ static void nvme_init_sq(NvmeSQueue *sq, NvmeCtrl *n, uint64_t dma_addr,
     n->sq[sqid] = sq;
 }
 
+static void nvme_init_sq(NvmeSQueue *sq, NvmeCtrl *n, uint64_t dma_addr,
+                         uint16_t sqid, uint16_t cqid, uint16_t size)
+{
+    sq->ctrl = n;
+    sq->dma_addr = dma_addr;
+    sq->sqid = sqid;
+    sq->size = size;
+    sq->cqid = cqid;
+    sq->head = sq->tail = 0;
+    __nvme_init_sq(sq);
+}
+
 static uint16_t nvme_create_sq(NvmeCtrl *n, NvmeRequest *req)
 {
     NvmeSQueue *sq;
@@ -5555,24 +5563,16 @@ static uint16_t nvme_del_cq(NvmeCtrl *n, NvmeRequest *req)
     return NVME_SUCCESS;
 }
 
-static void nvme_init_cq(NvmeCQueue *cq, NvmeCtrl *n, uint64_t dma_addr,
-                         uint16_t cqid, uint16_t vector, uint16_t size,
-                         uint16_t irq_enabled)
+static void __nvme_init_cq(NvmeCQueue *cq)
 {
+    NvmeCtrl *n = cq->ctrl;
     PCIDevice *pci = PCI_DEVICE(n);
+    uint16_t cqid = cq->cqid;
 
-    if (msix_enabled(pci) && irq_enabled) {
-        msix_vector_use(pci, vector);
+    if (msix_enabled(pci) && cq->irq_enabled) {
+        msix_vector_use(pci, cq->vector);
     }
 
-    cq->ctrl = n;
-    cq->cqid = cqid;
-    cq->size = size;
-    cq->dma_addr = dma_addr;
-    cq->phase = 1;
-    cq->irq_enabled = irq_enabled;
-    cq->vector = vector;
-    cq->head = cq->tail = 0;
     QTAILQ_INIT(&cq->req_list);
     QTAILQ_INIT(&cq->sq_list);
     if (n->dbbuf_enabled) {
@@ -5590,6 +5590,21 @@ static void nvme_init_cq(NvmeCQueue *cq, NvmeCtrl *n, uint64_t dma_addr,
                                  &DEVICE(cq->ctrl)->mem_reentrancy_guard);
 }
 
+static void nvme_init_cq(NvmeCQueue *cq, NvmeCtrl *n, uint64_t dma_addr,
+                         uint16_t cqid, uint16_t vector, uint16_t size,
+                         uint16_t irq_enabled)
+{
+    cq->ctrl = n;
+    cq->cqid = cqid;
+    cq->size = size;
+    cq->dma_addr = dma_addr;
+    cq->phase = 1;
+    cq->irq_enabled = irq_enabled;
+    cq->vector = vector;
+    cq->head = cq->tail = 0;
+    __nvme_init_cq(cq);
+}
+
 static uint16_t nvme_create_cq(NvmeCtrl *n, NvmeRequest *req)
 {
     NvmeCQueue *cq;
-- 
2.47.3

[PATCH v4 7/8] hw/nvme: add basic live migration support

[Alexander Mikhalitsyn]

From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>

It has some limitations:
- only one NVMe namespace is supported
- SMART counters are not preserved
- CMB is not supported
- PMR is not supported
- SPDM is not supported
- SR-IOV is not supported

Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
v2:
- AERs are now fully supported
---
 hw/nvme/ctrl.c       | 611 ++++++++++++++++++++++++++++++++++++++++++-
 hw/nvme/ns.c         | 160 +++++++++++
 hw/nvme/nvme.h       |   5 +
 hw/nvme/trace-events |  11 +
 4 files changed, 778 insertions(+), 9 deletions(-)

diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c
index 68ce9802505..e3030bfadcb 100644
--- a/hw/nvme/ctrl.c
+++ b/hw/nvme/ctrl.c
@@ -208,6 +208,7 @@
 #include "hw/pci/pcie_sriov.h"
 #include "system/spdm-socket.h"
 #include "migration/blocker.h"
+#include "migration/qemu-file-types.h"
 #include "migration/vmstate.h"
 
 #include "nvme.h"
@@ -4903,6 +4904,25 @@ static void nvme_init_sq(NvmeSQueue *sq, NvmeCtrl *n, uint64_t dma_addr,
     __nvme_init_sq(sq);
 }
 
+static void nvme_restore_sq(NvmeSQueue *sq_from)
+{
+    NvmeCtrl *n = sq_from->ctrl;
+    NvmeSQueue *sq = sq_from;
+
+    if (sq_from->sqid == 0) {
+        sq = &n->admin_sq;
+        sq->ctrl = n;
+        sq->dma_addr = sq_from->dma_addr;
+        sq->sqid = sq_from->sqid;
+        sq->size = sq_from->size;
+        sq->cqid = sq_from->cqid;
+        sq->head = sq_from->head;
+        sq->tail = sq_from->tail;
+    }
+
+    __nvme_init_sq(sq);
+}
+
 static uint16_t nvme_create_sq(NvmeCtrl *n, NvmeRequest *req)
 {
     NvmeSQueue *sq;
@@ -5605,6 +5625,27 @@ static void nvme_init_cq(NvmeCQueue *cq, NvmeCtrl *n, uint64_t dma_addr,
     __nvme_init_cq(cq);
 }
 
+static void nvme_restore_cq(NvmeCQueue *cq_from)
+{
+    NvmeCtrl *n = cq_from->ctrl;
+    NvmeCQueue *cq = cq_from;
+
+    if (cq_from->cqid == 0) {
+        cq = &n->admin_cq;
+        cq->ctrl = n;
+        cq->cqid = cq_from->cqid;
+        cq->size = cq_from->size;
+        cq->dma_addr = cq_from->dma_addr;
+        cq->phase = cq_from->phase;
+        cq->irq_enabled = cq_from->irq_enabled;
+        cq->vector = cq_from->vector;
+        cq->head = cq_from->head;
+        cq->tail = cq_from->tail;
+    }
+
+    __nvme_init_cq(cq);
+}
+
 static uint16_t nvme_create_cq(NvmeCtrl *n, NvmeRequest *req)
 {
     NvmeCQueue *cq;
@@ -7293,7 +7334,7 @@ static uint16_t nvme_dbbuf_config(NvmeCtrl *n, const NvmeRequest *req)
     n->dbbuf_eis = eis_addr;
     n->dbbuf_enabled = true;
 
-    for (i = 0; i < n->params.max_ioqpairs + 1; i++) {
+    for (i = 0; i < n->num_queues; i++) {
         NvmeSQueue *sq = n->sq[i];
         NvmeCQueue *cq = n->cq[i];
 
@@ -7737,7 +7778,7 @@ static int nvme_atomic_write_check(NvmeCtrl *n, NvmeCmd *cmd,
     /*
      * Walk the queues to see if there are any atomic conflicts.
      */
-    for (i = 1; i < n->params.max_ioqpairs + 1; i++) {
+    for (i = 1; i < n->num_queues; i++) {
         NvmeSQueue *sq;
         NvmeRequest *req;
         NvmeRwCmd *req_rw;
@@ -7807,6 +7848,10 @@ static void nvme_process_sq(void *opaque)
     NvmeCmd cmd;
     NvmeRequest *req;
 
+    if (qatomic_read(&n->stop_processing_sq)) {
+        return;
+    }
+
     if (n->dbbuf_enabled) {
         nvme_update_sq_tail(sq);
     }
@@ -7815,6 +7860,10 @@ static void nvme_process_sq(void *opaque)
         NvmeAtomic *atomic;
         bool cmd_is_atomic;
 
+        if (qatomic_read(&n->stop_processing_sq)) {
+            return;
+        }
+
         addr = sq->dma_addr + (sq->head << NVME_SQES);
         if (nvme_addr_read(n, addr, (void *)&cmd, sizeof(cmd))) {
             trace_pci_nvme_err_addr_read(addr);
@@ -7923,12 +7972,12 @@ static void nvme_ctrl_reset(NvmeCtrl *n, NvmeResetType rst)
         nvme_ns_drain(ns);
     }
 
-    for (i = 0; i < n->params.max_ioqpairs + 1; i++) {
+    for (i = 0; i < n->num_queues; i++) {
         if (n->sq[i] != NULL) {
             nvme_free_sq(n->sq[i], n);
         }
     }
-    for (i = 0; i < n->params.max_ioqpairs + 1; i++) {
+    for (i = 0; i < n->num_queues; i++) {
         if (n->cq[i] != NULL) {
             nvme_free_cq(n->cq[i], n);
         }
@@ -8598,6 +8647,8 @@ static bool nvme_check_params(NvmeCtrl *n, Error **errp)
         params->max_ioqpairs = params->num_queues - 1;
     }
 
+    n->num_queues = params->max_ioqpairs + 1;
+
     if (n->namespace.blkconf.blk && n->subsys) {
         error_setg(errp, "subsystem support is unavailable with legacy "
                    "namespace ('drive' property)");
@@ -8752,8 +8803,8 @@ static void nvme_init_state(NvmeCtrl *n)
         n->conf_msix_qsize = n->params.msix_qsize;
     }
 
-    n->sq = g_new0(NvmeSQueue *, n->params.max_ioqpairs + 1);
-    n->cq = g_new0(NvmeCQueue *, n->params.max_ioqpairs + 1);
+    n->sq = g_new0(NvmeSQueue *, n->num_queues);
+    n->cq = g_new0(NvmeCQueue *, n->num_queues);
     n->temperature = NVME_TEMPERATURE;
     n->features.temp_thresh_hi = NVME_TEMPERATURE_WARNING;
     n->starttime_ms = qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL);
@@ -8988,7 +9039,7 @@ static bool nvme_init_pci(NvmeCtrl *n, PCIDevice *pci_dev, Error **errp)
     }
 
     if (n->params.msix_exclusive_bar && !pci_is_vf(pci_dev)) {
-        bar_size = nvme_mbar_size(n->params.max_ioqpairs + 1, 0, NULL, NULL);
+        bar_size = nvme_mbar_size(n->num_queues, 0, NULL, NULL);
         memory_region_init_io(&n->iomem, OBJECT(n), &nvme_mmio_ops, n, "nvme",
                               bar_size);
         pci_register_bar(pci_dev, 0, PCI_BASE_ADDRESS_SPACE_MEMORY |
@@ -9000,7 +9051,7 @@ static bool nvme_init_pci(NvmeCtrl *n, PCIDevice *pci_dev, Error **errp)
         /* add one to max_ioqpairs to account for the admin queue pair */
         if (!pci_is_vf(pci_dev)) {
             nr_vectors = n->params.msix_qsize;
-            bar_size = nvme_mbar_size(n->params.max_ioqpairs + 1,
+            bar_size = nvme_mbar_size(n->num_queues,
                                       nr_vectors, &msix_table_offset,
                                       &msix_pba_offset);
         } else {
@@ -9723,9 +9774,551 @@ static uint32_t nvme_pci_read_config(PCIDevice *dev, uint32_t address, int len)
     return pci_default_read_config(dev, address, len);
 }
 
+static bool nvme_ctrl_pre_save(void *opaque, Error **errp)
+{
+    NvmeCtrl *n = opaque;
+    int i;
+
+    trace_pci_nvme_pre_save_enter(n);
+
+    /* ask SQ processing code not to take new requests */
+    qatomic_set(&n->stop_processing_sq, true);
+
+    /* prevent new in-flight IO from appearing */
+    for (i = 0; i < n->num_queues; i++) {
+        NvmeSQueue *sq = n->sq[i];
+
+        if (!sq)
+            continue;
+
+        qemu_bh_cancel(sq->bh);
+    }
+
+    /* drain all IO */
+    for (i = 1; i <= NVME_MAX_NAMESPACES; i++) {
+        NvmeNamespace *ns;
+
+        ns = nvme_ns(n, i);
+        if (!ns) {
+            continue;
+        }
+
+        trace_pci_nvme_pre_save_ns_drain(n, i);
+        nvme_ns_drain(ns);
+    }
+
+    /*
+     * Now, we should take care of AERs.
+     *
+     * 1. Save all queued events (n->aer_queue).
+     *    This is done automatically, see nvme_vmstate VMStateDescription.
+     *    Here we only need to print them for debugging purpose.
+     * 2. Go over outstanding AER requests (n->aer_reqs) and check they are
+     *    all have expected opcode (NVME_ADM_CMD_ASYNC_EV_REQ) and other fields.
+     *
+     * We must be really careful here, because in case of further QEMU NVMe changes,
+     * we may break migration without noticing it, or worse, introduce silent
+     * data corruption during migration.
+     */
+    if (n->aer_queued) {
+        NvmeAsyncEvent *event;
+
+        QTAILQ_FOREACH(event, &n->aer_queue, entry) {
+            trace_pci_nvme_pre_save_aer(event->result.event_type, event->result.event_info,
+                                        event->result.log_page);
+        }
+    }
+
+    for (i = 0; i < n->outstanding_aers; i++) {
+        NvmeRequest *re = n->aer_reqs[i];
+
+        /*
+         * Can't use assert() here, because we don't want
+         * to just crash QEMU when user requests a migration.
+         */
+        if (!(re->cmd.opcode == NVME_ADM_CMD_ASYNC_EV_REQ)) {
+            error_setg(errp, "re->cmd.opcode (%u) != NVME_ADM_CMD_ASYNC_EV_REQ", re->cmd.opcode);
+            goto err;
+        }
+
+        if (!(re->ns == NULL)) {
+            error_setg(errp, "re->ns != NULL");
+            goto err;
+        }
+
+        if (!(re->sq == &n->admin_sq)) {
+            error_setg(errp, "re->sq != &n->admin_sq");
+            goto err;
+        }
+
+        if (!(re->aiocb == NULL)) {
+            error_setg(errp, "re->aiocb != NULL");
+            goto err;
+        }
+
+        if (!(re->opaque == NULL)) {
+            error_setg(errp, "re->opaque != NULL");
+            goto err;
+        }
+
+        if (!(re->atomic_write == false)) {
+            error_setg(errp, "re->atomic_write != false");
+            goto err;
+        }
+
+        if (re->sg.flags & NVME_SG_ALLOC) {
+            error_setg(errp, "unexpected NVME_SG_ALLOC flag in re->sg.flags");
+            goto err;
+        }
+    }
+
+    /* wait when all in-flight IO requests (except NVME_ADM_CMD_ASYNC_EV_REQ) are processed */
+    for (i = 0; i < n->num_queues; i++) {
+        NvmeRequest *req;
+        NvmeSQueue *sq = n->sq[i];
+
+        if (!sq)
+            continue;
+
+        trace_pci_nvme_pre_save_sq_out_req_drain_wait(n, i, sq->head, sq->tail, sq->size);
+
+wait_out_reqs:
+        QTAILQ_FOREACH(req, &sq->out_req_list, entry) {
+            if (req->cmd.opcode != NVME_ADM_CMD_ASYNC_EV_REQ) {
+                cpu_relax();
+                goto wait_out_reqs;
+            }
+        }
+
+        trace_pci_nvme_pre_save_sq_out_req_drain_wait_end(n, i, sq->head, sq->tail);
+    }
+
+    /* wait when all IO requests completions are written to guest memory */
+    for (i = 0; i < n->num_queues; i++) {
+        NvmeCQueue *cq = n->cq[i];
+
+        if (!cq)
+            continue;
+
+        trace_pci_nvme_pre_save_cq_req_drain_wait(n, i, cq->head, cq->tail, cq->size);
+
+        while (!QTAILQ_EMPTY(&cq->req_list)) {
+            /*
+             * nvme_post_cqes() can't do its job of cleaning cq->req_list
+             * when CQ is full, it means that we need to save what we have in
+             * cq->req_list and restore it back on VM resume.
+             *
+             * Good thing is that this can only happen when guest hasn't
+             * processed CQ for a long time and at the same time, many SQEs
+             * are in flight.
+             *
+             * For now, let's just block migration in this rare case.
+             */
+            if (nvme_cq_full(cq)) {
+                error_setg(errp, "no free space in CQ (not supported)");
+                goto err;
+            }
+
+            cpu_relax();
+        }
+
+        trace_pci_nvme_pre_save_cq_req_drain_wait_end(n, i, cq->head, cq->tail);
+    }
+
+    for (uint32_t nsid = 0; nsid <= NVME_MAX_NAMESPACES; nsid++) {
+        NvmeNamespace *ns = n->namespaces[nsid];
+
+        if (!ns)
+            continue;
+
+        if (ns != &n->namespace) {
+            error_setg(errp, "only one NVMe namespace is supported for migration");
+            goto err;
+        }
+    }
+
+    return true;
+
+err:
+    /* restore sq processing back to normal */
+    qatomic_set(&n->stop_processing_sq, false);
+    return false;
+}
+
+static bool nvme_ctrl_post_load(void *opaque, int version_id, Error **errp)
+{
+    NvmeCtrl *n = opaque;
+    int i;
+
+    trace_pci_nvme_post_load_enter(n);
+
+    /* restore CQs first */
+    for (i = 0; i < n->num_queues; i++) {
+        NvmeCQueue *cq = n->cq[i];
+
+        if (!cq)
+            continue;
+
+        cq->ctrl = n;
+        nvme_restore_cq(cq);
+        trace_pci_nvme_post_load_restore_cq(n, i, cq->head, cq->tail, cq->size);
+
+        if (i == 0) {
+            /*
+             * Admin CQ lives in n->admin_cq, we don't need
+             * memory allocated for it in get_ptrs_array_entry() anymore.
+             *
+             * nvme_restore_cq() also takes care of:
+             * n->cq[0] = &n->admin_cq;
+             * so n->cq[0] remains valid.
+             */
+            g_free(cq);
+        }
+    }
+
+    for (i = 0; i < n->num_queues; i++) {
+        NvmeSQueue *sq = n->sq[i];
+
+        if (!sq)
+            continue;
+
+        sq->ctrl = n;
+        nvme_restore_sq(sq);
+        trace_pci_nvme_post_load_restore_sq(n, i, sq->head, sq->tail, sq->size);
+
+        if (i == 0) {
+            /* same as for CQ */
+            g_free(sq);
+        }
+    }
+
+    if (n->aer_queued) {
+        NvmeAsyncEvent *event;
+
+        QTAILQ_FOREACH(event, &n->aer_queue, entry) {
+            trace_pci_nvme_post_load_aer(event->result.event_type, event->result.event_info,
+                                         event->result.log_page);
+        }
+    }
+
+    for (i = 0; i < n->outstanding_aers; i++) {
+        NvmeSQueue *sq = &n->admin_sq;
+        NvmeRequest *req_from = n->aer_reqs[i];
+        NvmeRequest *req;
+
+        /*
+         * We use nvme_vmstate VMStateDescription to save/restore
+         * NvmeRequest structures, but tricky thing here is that
+         * memory for each n->aer_reqs[i] will be allocated separately
+         * during restore. It doesn't work for us. We need to take
+         * an existing NvmeRequest structure from SQ's req_list
+         * and fill it with data from the newly allocated one (req_from).
+         * Then, we can safely release allocated memory for it.
+         */
+
+        /* take an NvmeRequest struct from SQ */
+        req = QTAILQ_FIRST(&sq->req_list);
+        QTAILQ_REMOVE(&sq->req_list, req, entry);
+        QTAILQ_INSERT_TAIL(&sq->out_req_list, req, entry);
+        nvme_req_clear(req);
+
+        /* copy data from the source NvmeRequest */
+        req->status = req_from->status;
+        memcpy(&req->cqe, &req_from->cqe, sizeof(NvmeCqe));
+        memcpy(&req->cmd, &req_from->cmd, sizeof(NvmeCmd));
+
+        n->aer_reqs[i] = req;
+        g_free(req_from);
+    }
+
+    /*
+     * We need to attach namespaces (currently, only one namespace is
+     * supported for migration).
+     * This logic comes from nvme_start_ctrl().
+     */
+    for (i = 1; i <= NVME_MAX_NAMESPACES; i++) {
+        NvmeNamespace *ns = nvme_subsys_ns(n->subsys, i);
+
+        if (!ns || (!ns->params.shared && ns->ctrl != n)) {
+            continue;
+        }
+
+        if (nvme_csi_supported(n, ns->csi) && !ns->params.detached) {
+            if (!ns->attached || ns->params.shared) {
+                nvme_attach_ns(n, ns);
+            }
+        }
+    }
+
+    /* schedule SQ processing */
+    for (i = 0; i < n->num_queues; i++) {
+        NvmeSQueue *sq = n->sq[i];
+
+        if (!sq)
+            continue;
+
+        qemu_bh_schedule(sq->bh);
+    }
+
+    /*
+     * We ensured in pre_save() that cq->req_list was empty,
+     * so we don't need to schedule BH for CQ processing.
+     */
+
+    return true;
+}
+
+static const VMStateDescription nvme_vmstate_bar = {
+    .name = "nvme-bar",
+    .minimum_version_id = 1,
+    .version_id = 1,
+    .fields = (const VMStateField[]) {
+        VMSTATE_UINT64(cap, NvmeBar),
+        VMSTATE_UINT32(vs, NvmeBar),
+        VMSTATE_UINT32(intms, NvmeBar),
+        VMSTATE_UINT32(intmc, NvmeBar),
+        VMSTATE_UINT32(cc, NvmeBar),
+        VMSTATE_UINT8_ARRAY(rsvd24, NvmeBar, 4),
+        VMSTATE_UINT32(csts, NvmeBar),
+        VMSTATE_UINT32(nssr, NvmeBar),
+        VMSTATE_UINT32(aqa, NvmeBar),
+        VMSTATE_UINT64(asq, NvmeBar),
+        VMSTATE_UINT64(acq, NvmeBar),
+        VMSTATE_UINT32(cmbloc, NvmeBar),
+        VMSTATE_UINT32(cmbsz, NvmeBar),
+        VMSTATE_UINT32(bpinfo, NvmeBar),
+        VMSTATE_UINT32(bprsel, NvmeBar),
+        VMSTATE_UINT64(bpmbl, NvmeBar),
+        VMSTATE_UINT64(cmbmsc, NvmeBar),
+        VMSTATE_UINT32(cmbsts, NvmeBar),
+        VMSTATE_UINT8_ARRAY(rsvd92, NvmeBar, 3492),
+        VMSTATE_UINT32(pmrcap, NvmeBar),
+        VMSTATE_UINT32(pmrctl, NvmeBar),
+        VMSTATE_UINT32(pmrsts, NvmeBar),
+        VMSTATE_UINT32(pmrebs, NvmeBar),
+        VMSTATE_UINT32(pmrswtp, NvmeBar),
+        VMSTATE_UINT32(pmrmscl, NvmeBar),
+        VMSTATE_UINT32(pmrmscu, NvmeBar),
+        VMSTATE_UINT8_ARRAY(css, NvmeBar, 484),
+        VMSTATE_END_OF_LIST()
+    },
+};
+
+static const VMStateDescription nvme_vmstate_cqueue = {
+    .name = "nvme-cq",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (const VMStateField[]) {
+        VMSTATE_UINT8(phase, NvmeCQueue),
+        VMSTATE_UINT16(cqid, NvmeCQueue),
+        VMSTATE_UINT16(irq_enabled, NvmeCQueue),
+        VMSTATE_UINT32(head, NvmeCQueue),
+        VMSTATE_UINT32(tail, NvmeCQueue),
+        VMSTATE_UINT32(vector, NvmeCQueue),
+        VMSTATE_UINT32(size, NvmeCQueue),
+        VMSTATE_UINT64(dma_addr, NvmeCQueue),
+        /* db_addr, ei_addr, etc will be recalculated */
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static const VMStateDescription nvme_vmstate_squeue = {
+    .name = "nvme-sq",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (const VMStateField[]) {
+        VMSTATE_UINT16(sqid, NvmeSQueue),
+        VMSTATE_UINT16(cqid, NvmeSQueue),
+        VMSTATE_UINT32(head, NvmeSQueue),
+        VMSTATE_UINT32(tail, NvmeSQueue),
+        VMSTATE_UINT32(size, NvmeSQueue),
+        VMSTATE_UINT64(dma_addr, NvmeSQueue),
+        /* db_addr, ei_addr, etc will be recalculated */
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static const VMStateDescription nvme_vmstate_async_event_result = {
+    .name = "nvme-async-event-result",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (const VMStateField[]) {
+        VMSTATE_UINT8(event_type, NvmeAerResult),
+        VMSTATE_UINT8(event_info, NvmeAerResult),
+        VMSTATE_UINT8(log_page, NvmeAerResult),
+        VMSTATE_UINT8(resv, NvmeAerResult),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static const VMStateDescription nvme_vmstate_async_event = {
+    .name = "nvme-async-event",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (const VMStateField[]) {
+        VMSTATE_STRUCT(result, NvmeAsyncEvent, 0, nvme_vmstate_async_event_result, NvmeAerResult),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static const VMStateDescription nvme_vmstate_cqe = {
+    .name = "nvme-cqe",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (const VMStateField[]) {
+        VMSTATE_UINT32(result, NvmeCqe),
+        VMSTATE_UINT32(dw1, NvmeCqe),
+        VMSTATE_UINT16(sq_head, NvmeCqe),
+        VMSTATE_UINT16(sq_id, NvmeCqe),
+        VMSTATE_UINT16(cid, NvmeCqe),
+        VMSTATE_UINT16(status, NvmeCqe),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static const VMStateDescription nvme_vmstate_cmd_dptr_sgl = {
+    .name = "nvme-request-cmd-dptr-sgl",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (const VMStateField[]) {
+        VMSTATE_UINT64(addr, NvmeSglDescriptor),
+        VMSTATE_UINT32(len, NvmeSglDescriptor),
+        VMSTATE_UINT8_ARRAY(rsvd, NvmeSglDescriptor, 3),
+        VMSTATE_UINT8(type, NvmeSglDescriptor),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static const VMStateDescription nvme_vmstate_cmd_dptr = {
+    .name = "nvme-request-cmd-dptr",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (const VMStateField[]) {
+        VMSTATE_UINT64(prp1, NvmeCmdDptr),
+        VMSTATE_UINT64(prp2, NvmeCmdDptr),
+        VMSTATE_STRUCT(sgl, NvmeCmdDptr, 0, nvme_vmstate_cmd_dptr_sgl, NvmeSglDescriptor),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static const VMStateDescription nvme_vmstate_cmd = {
+    .name = "nvme-request-cmd",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (const VMStateField[]) {
+        VMSTATE_UINT8(opcode, NvmeCmd),
+        VMSTATE_UINT8(flags, NvmeCmd),
+        VMSTATE_UINT16(cid, NvmeCmd),
+        VMSTATE_UINT32(nsid, NvmeCmd),
+        VMSTATE_UINT64(res1, NvmeCmd),
+        VMSTATE_UINT64(mptr, NvmeCmd),
+        VMSTATE_STRUCT(dptr, NvmeCmd, 0, nvme_vmstate_cmd_dptr, NvmeCmdDptr),
+        VMSTATE_UINT32(cdw10, NvmeCmd),
+        VMSTATE_UINT32(cdw11, NvmeCmd),
+        VMSTATE_UINT32(cdw12, NvmeCmd),
+        VMSTATE_UINT32(cdw13, NvmeCmd),
+        VMSTATE_UINT32(cdw14, NvmeCmd),
+        VMSTATE_UINT32(cdw15, NvmeCmd),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static const VMStateDescription nvme_vmstate_request = {
+    .name = "nvme-request",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (const VMStateField[]) {
+        VMSTATE_UINT16(status, NvmeRequest),
+        VMSTATE_STRUCT(cqe, NvmeRequest, 0, nvme_vmstate_cqe, NvmeCqe),
+        VMSTATE_STRUCT(cmd, NvmeRequest, 0, nvme_vmstate_cmd, NvmeCmd),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static const VMStateDescription nvme_vmstate_hbs = {
+    .name = "nvme-hbs",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (const VMStateField[]) {
+        VMSTATE_UINT8(acre, NvmeHostBehaviorSupport),
+        VMSTATE_UINT8(etdas, NvmeHostBehaviorSupport),
+        VMSTATE_UINT8(lbafee, NvmeHostBehaviorSupport),
+        VMSTATE_UINT8(rsvd3, NvmeHostBehaviorSupport),
+        VMSTATE_UINT16(cdfe, NvmeHostBehaviorSupport),
+        VMSTATE_UINT8_ARRAY(rsvd6, NvmeHostBehaviorSupport, 506),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+const VMStateDescription nvme_vmstate_atomic = {
+    .name = "nvme-atomic",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (const VMStateField[]) {
+        VMSTATE_UINT32(atomic_max_write_size, NvmeAtomic),
+        VMSTATE_UINT64(atomic_boundary, NvmeAtomic),
+        VMSTATE_UINT64(atomic_nabo, NvmeAtomic),
+        VMSTATE_BOOL(atomic_writes, NvmeAtomic),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static const VMStateDescription nvme_vmstate = {
     .name = "nvme",
-    .unmigratable = 1,
+    .minimum_version_id = 1,
+    .version_id = 1,
+    .pre_save_errp = nvme_ctrl_pre_save,
+    .post_load_errp = nvme_ctrl_post_load,
+    .fields = (const VMStateField[]) {
+        VMSTATE_PCI_DEVICE(parent_obj, NvmeCtrl),
+        VMSTATE_MSIX(parent_obj, NvmeCtrl),
+        VMSTATE_STRUCT(bar, NvmeCtrl, 0, nvme_vmstate_bar, NvmeBar),
+
+        VMSTATE_BOOL(qs_created, NvmeCtrl),
+        VMSTATE_UINT32(page_size, NvmeCtrl),
+        VMSTATE_UINT16(page_bits, NvmeCtrl),
+        VMSTATE_UINT16(max_prp_ents, NvmeCtrl),
+        VMSTATE_UINT32(max_q_ents, NvmeCtrl),
+        VMSTATE_UINT8(outstanding_aers, NvmeCtrl),
+        VMSTATE_UINT32(irq_status, NvmeCtrl),
+        VMSTATE_INT32(cq_pending, NvmeCtrl),
+
+        VMSTATE_UINT64(host_timestamp, NvmeCtrl),
+        VMSTATE_UINT64(timestamp_set_qemu_clock_ms, NvmeCtrl),
+        VMSTATE_UINT64(starttime_ms, NvmeCtrl),
+        VMSTATE_UINT16(temperature, NvmeCtrl),
+        VMSTATE_UINT8(smart_critical_warning, NvmeCtrl),
+
+        VMSTATE_UINT32(conf_msix_qsize, NvmeCtrl),
+        VMSTATE_UINT32(conf_ioqpairs, NvmeCtrl),
+        VMSTATE_UINT64(dbbuf_dbs, NvmeCtrl),
+        VMSTATE_UINT64(dbbuf_eis, NvmeCtrl),
+        VMSTATE_BOOL(dbbuf_enabled, NvmeCtrl),
+
+        VMSTATE_UINT8(aer_mask, NvmeCtrl),
+        VMSTATE_VARRAY_OF_POINTER_TO_STRUCT_UINT8_ALLOC(
+            aer_reqs, NvmeCtrl, outstanding_aers, 0, nvme_vmstate_request, NvmeRequest),
+        VMSTATE_QTAILQ_V(aer_queue, NvmeCtrl, 1, nvme_vmstate_async_event,
+                         NvmeAsyncEvent, entry),
+        VMSTATE_INT32(aer_queued, NvmeCtrl),
+
+        VMSTATE_STRUCT(namespace, NvmeCtrl, 0, nvme_vmstate_ns, NvmeNamespace),
+
+        VMSTATE_VARRAY_OF_POINTER_TO_STRUCT_UINT32_ALLOC(
+            sq, NvmeCtrl, num_queues, 0, nvme_vmstate_squeue, NvmeSQueue),
+        VMSTATE_VARRAY_OF_POINTER_TO_STRUCT_UINT32_ALLOC(
+            cq, NvmeCtrl, num_queues, 0, nvme_vmstate_cqueue, NvmeCQueue),
+
+        VMSTATE_UINT16(features.temp_thresh_hi, NvmeCtrl),
+        VMSTATE_UINT16(features.temp_thresh_low, NvmeCtrl),
+        VMSTATE_UINT32(features.async_config, NvmeCtrl),
+        VMSTATE_STRUCT(features.hbs, NvmeCtrl, 0, nvme_vmstate_hbs, NvmeHostBehaviorSupport),
+
+        VMSTATE_UINT32(dn, NvmeCtrl),
+        VMSTATE_STRUCT(atomic, NvmeCtrl, 0, nvme_vmstate_atomic, NvmeAtomic),
+
+        VMSTATE_END_OF_LIST()
+    },
 };
 
 static void nvme_class_init(ObjectClass *oc, const void *data)
diff --git a/hw/nvme/ns.c b/hw/nvme/ns.c
index 38f86a17268..dd374677078 100644
--- a/hw/nvme/ns.c
+++ b/hw/nvme/ns.c
@@ -20,6 +20,7 @@
 #include "qemu/bitops.h"
 #include "system/system.h"
 #include "system/block-backend.h"
+#include "migration/vmstate.h"
 
 #include "nvme.h"
 #include "trace.h"
@@ -886,6 +887,164 @@ static void nvme_ns_realize(DeviceState *dev, Error **errp)
     }
 }
 
+static const VMStateDescription nvme_vmstate_lbaf = {
+    .name = "nvme_lbaf",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (const VMStateField[]) {
+        VMSTATE_UINT16(ms, NvmeLBAF),
+        VMSTATE_UINT8(ds, NvmeLBAF),
+        VMSTATE_UINT8(rp, NvmeLBAF),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static const VMStateDescription nvme_vmstate_id_ns = {
+    .name = "nvme_id_ns",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (const VMStateField[]) {
+        VMSTATE_UINT64(nsze, NvmeIdNs),
+        VMSTATE_UINT64(ncap, NvmeIdNs),
+        VMSTATE_UINT64(nuse, NvmeIdNs),
+        VMSTATE_UINT8(nsfeat, NvmeIdNs),
+        VMSTATE_UINT8(nlbaf, NvmeIdNs),
+        VMSTATE_UINT8(flbas, NvmeIdNs),
+        VMSTATE_UINT8(mc, NvmeIdNs),
+        VMSTATE_UINT8(dpc, NvmeIdNs),
+        VMSTATE_UINT8(dps, NvmeIdNs),
+        VMSTATE_UINT8(nmic, NvmeIdNs),
+        VMSTATE_UINT8(rescap, NvmeIdNs),
+        VMSTATE_UINT8(fpi, NvmeIdNs),
+        VMSTATE_UINT8(dlfeat, NvmeIdNs),
+        VMSTATE_UINT16(nawun, NvmeIdNs),
+        VMSTATE_UINT16(nawupf, NvmeIdNs),
+        VMSTATE_UINT16(nacwu, NvmeIdNs),
+        VMSTATE_UINT16(nabsn, NvmeIdNs),
+        VMSTATE_UINT16(nabo, NvmeIdNs),
+        VMSTATE_UINT16(nabspf, NvmeIdNs),
+        VMSTATE_UINT16(noiob, NvmeIdNs),
+        VMSTATE_UINT8_ARRAY(nvmcap, NvmeIdNs, 16),
+        VMSTATE_UINT16(npwg, NvmeIdNs),
+        VMSTATE_UINT16(npwa, NvmeIdNs),
+        VMSTATE_UINT16(npdg, NvmeIdNs),
+        VMSTATE_UINT16(npda, NvmeIdNs),
+        VMSTATE_UINT16(nows, NvmeIdNs),
+        VMSTATE_UINT16(mssrl, NvmeIdNs),
+        VMSTATE_UINT32(mcl, NvmeIdNs),
+        VMSTATE_UINT8(msrc, NvmeIdNs),
+        VMSTATE_UINT8_ARRAY(rsvd81, NvmeIdNs, 18),
+        VMSTATE_UINT8(nsattr, NvmeIdNs),
+        VMSTATE_UINT16(nvmsetid, NvmeIdNs),
+        VMSTATE_UINT16(endgid, NvmeIdNs),
+        VMSTATE_UINT8_ARRAY(nguid, NvmeIdNs, 16),
+        VMSTATE_UINT64(eui64, NvmeIdNs),
+        VMSTATE_STRUCT_ARRAY(lbaf, NvmeIdNs, NVME_MAX_NLBAF, 1,
+                             nvme_vmstate_lbaf, NvmeLBAF),
+        VMSTATE_UINT8_ARRAY(vs, NvmeIdNs, 3712),
+
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static const VMStateDescription nvme_vmstate_id_ns_nvm = {
+    .name = "nvme_id_ns_nvm",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (const VMStateField[]) {
+        VMSTATE_UINT64(lbstm, NvmeIdNsNvm),
+        VMSTATE_UINT8(pic, NvmeIdNsNvm),
+        VMSTATE_UINT8_ARRAY(rsvd9, NvmeIdNsNvm, 3),
+        VMSTATE_UINT32_ARRAY(elbaf, NvmeIdNsNvm, NVME_MAX_NLBAF),
+        VMSTATE_UINT32(npdgl, NvmeIdNsNvm),
+        VMSTATE_UINT32(nprg, NvmeIdNsNvm),
+        VMSTATE_UINT32(npra, NvmeIdNsNvm),
+        VMSTATE_UINT32(nors, NvmeIdNsNvm),
+        VMSTATE_UINT32(npdal, NvmeIdNsNvm),
+        VMSTATE_UINT8_ARRAY(rsvd288, NvmeIdNsNvm, 3808),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static const VMStateDescription nvme_vmstate_id_ns_ind = {
+    .name = "nvme_id_ns_ind",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (const VMStateField[]) {
+        VMSTATE_UINT8(nsfeat, NvmeIdNsInd),
+        VMSTATE_UINT8(nmic, NvmeIdNsInd),
+        VMSTATE_UINT8(rescap, NvmeIdNsInd),
+        VMSTATE_UINT8(fpi, NvmeIdNsInd),
+        VMSTATE_UINT32(anagrpid, NvmeIdNsInd),
+        VMSTATE_UINT8(nsattr, NvmeIdNsInd),
+        VMSTATE_UINT8(rsvd9, NvmeIdNsInd),
+        VMSTATE_UINT16(nvmsetid, NvmeIdNsInd),
+        VMSTATE_UINT16(endgrpid, NvmeIdNsInd),
+        VMSTATE_UINT8(nstat, NvmeIdNsInd),
+        VMSTATE_UINT8_ARRAY(rsvd15, NvmeIdNsInd, 4081),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+typedef struct TmpNvmeNamespace {
+    NvmeNamespace *parent;
+    bool enable_write_cache;
+} TmpNvmeNamespace;
+
+static bool nvme_ns_tmp_pre_save(void *opaque, Error **errp)
+{
+    struct TmpNvmeNamespace *tns = opaque;
+
+    tns->enable_write_cache = blk_enable_write_cache(tns->parent->blkconf.blk);
+
+    return true;
+}
+
+static bool nvme_ns_tmp_post_load(void *opaque, int version_id, Error **errp)
+{
+    struct TmpNvmeNamespace *tns = opaque;
+
+    blk_set_enable_write_cache(tns->parent->blkconf.blk, tns->enable_write_cache);
+
+    return true;
+}
+
+static const VMStateDescription nvme_vmstate_ns_tmp = {
+    .name = "nvme_ns_tmp",
+    .pre_save_errp = nvme_ns_tmp_pre_save,
+    .post_load_errp = nvme_ns_tmp_post_load,
+    .fields = (const VMStateField[]) {
+        VMSTATE_BOOL(enable_write_cache, TmpNvmeNamespace),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+const VMStateDescription nvme_vmstate_ns = {
+    .name = "nvme_ns",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (const VMStateField[]) {
+        VMSTATE_WITH_TMP(NvmeNamespace, TmpNvmeNamespace, nvme_vmstate_ns_tmp),
+
+        VMSTATE_STRUCT(id_ns, NvmeNamespace, 0, nvme_vmstate_id_ns, NvmeIdNs),
+        VMSTATE_STRUCT(id_ns_nvm, NvmeNamespace, 0, nvme_vmstate_id_ns_nvm, NvmeIdNsNvm),
+        VMSTATE_STRUCT(id_ns_ind, NvmeNamespace, 0, nvme_vmstate_id_ns_ind, NvmeIdNsInd),
+        VMSTATE_STRUCT(lbaf, NvmeNamespace, 0, nvme_vmstate_lbaf, NvmeLBAF),
+        VMSTATE_UINT32(nlbaf, NvmeNamespace),
+        VMSTATE_UINT8(csi, NvmeNamespace),
+        VMSTATE_UINT16(status, NvmeNamespace),
+        VMSTATE_UINT8(pif, NvmeNamespace),
+
+        VMSTATE_UINT16(zns.zrwas, NvmeNamespace),
+        VMSTATE_UINT16(zns.zrwafg, NvmeNamespace),
+        VMSTATE_UINT32(zns.numzrwa, NvmeNamespace),
+
+        VMSTATE_UINT32(features.err_rec, NvmeNamespace),
+        VMSTATE_STRUCT(atomic, NvmeNamespace, 0, nvme_vmstate_atomic, NvmeAtomic),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static const Property nvme_ns_props[] = {
     DEFINE_BLOCK_PROPERTIES(NvmeNamespace, blkconf),
     DEFINE_PROP_BOOL("detached", NvmeNamespace, params.detached, false),
@@ -937,6 +1096,7 @@ static void nvme_ns_class_init(ObjectClass *oc, const void *data)
     dc->bus_type = TYPE_NVME_BUS;
     dc->realize = nvme_ns_realize;
     dc->unrealize = nvme_ns_unrealize;
+    dc->vmsd = &nvme_vmstate_ns;
     device_class_set_props(dc, nvme_ns_props);
     dc->desc = "Virtual NVMe namespace";
 }
diff --git a/hw/nvme/nvme.h b/hw/nvme/nvme.h
index 457b6637249..03d6aecb7d7 100644
--- a/hw/nvme/nvme.h
+++ b/hw/nvme/nvme.h
@@ -638,6 +638,7 @@ typedef struct NvmeCtrl {
 
     NvmeNamespace   namespace;
     NvmeNamespace   *namespaces[NVME_MAX_NAMESPACES + 1];
+    uint32_t        num_queues;
     NvmeSQueue      **sq;
     NvmeCQueue      **cq;
     NvmeSQueue      admin_sq;
@@ -669,6 +670,7 @@ typedef struct NvmeCtrl {
 
     /* Migration-related stuff */
     Error *migration_blocker;
+    bool stop_processing_sq;
 } NvmeCtrl;
 
 typedef enum NvmeResetType {
@@ -749,4 +751,7 @@ void nvme_atomic_configure_max_write_size(bool dn, uint16_t awun,
 void nvme_ns_atomic_configure_boundary(bool dn, uint16_t nabsn,
                                        uint16_t nabspf, NvmeAtomic *atomic);
 
+extern const VMStateDescription nvme_vmstate_atomic;
+extern const VMStateDescription nvme_vmstate_ns;
+
 #endif /* HW_NVME_NVME_H */
diff --git a/hw/nvme/trace-events b/hw/nvme/trace-events
index 6be0bfa1c1f..8e5544e0008 100644
--- a/hw/nvme/trace-events
+++ b/hw/nvme/trace-events
@@ -7,6 +7,17 @@ pci_nvme_dbbuf_config(uint64_t dbs_addr, uint64_t eis_addr) "dbs_addr=0x%"PRIx64
 pci_nvme_map_addr(uint64_t addr, uint64_t len) "addr 0x%"PRIx64" len %"PRIu64""
 pci_nvme_map_addr_cmb(uint64_t addr, uint64_t len) "addr 0x%"PRIx64" len %"PRIu64""
 pci_nvme_map_prp(uint64_t trans_len, uint32_t len, uint64_t prp1, uint64_t prp2, int num_prps) "trans_len %"PRIu64" len %"PRIu32" prp1 0x%"PRIx64" prp2 0x%"PRIx64" num_prps %d"
+pci_nvme_pre_save_enter(void *n) "n=%p"
+pci_nvme_pre_save_ns_drain(void *n, int i) "n=%p i=%d"
+pci_nvme_pre_save_sq_out_req_drain_wait(void *n, int i, uint32_t head, uint32_t tail, uint32_t size) "n=%p i=%d head=0x%"PRIx32" tail=0x%"PRIx32" size=0x%"PRIx32""
+pci_nvme_pre_save_sq_out_req_drain_wait_end(void *n, int i, uint32_t head, uint32_t tail) "n=%p i=%d head=0x%"PRIx32" tail=0x%"PRIx32""
+pci_nvme_pre_save_cq_req_drain_wait(void *n, int i, uint32_t head, uint32_t tail, uint32_t size) "n=%p i=%d head=0x%"PRIx32" tail=0x%"PRIx32" size=0x%"PRIx32""
+pci_nvme_pre_save_cq_req_drain_wait_end(void *n, int i, uint32_t head, uint32_t tail) "n=%p i=%d head=0x%"PRIx32" tail=0x%"PRIx32""
+pci_nvme_pre_save_aer(uint8_t typ, uint8_t info, uint8_t log_page) "type 0x%"PRIx8" info 0x%"PRIx8" lid 0x%"PRIx8""
+pci_nvme_post_load_enter(void *n) "n=%p"
+pci_nvme_post_load_restore_cq(void *n, int i, uint32_t head, uint32_t tail, uint32_t size) "n=%p i=%d head=0x%"PRIx32" tail=0x%"PRIx32" size=0x%"PRIx32""
+pci_nvme_post_load_restore_sq(void *n, int i, uint32_t head, uint32_t tail, uint32_t size) "n=%p i=%d head=0x%"PRIx32" tail=0x%"PRIx32" size=0x%"PRIx32""
+pci_nvme_post_load_aer(uint8_t typ, uint8_t info, uint8_t log_page) "type 0x%"PRIx8" info 0x%"PRIx8" lid 0x%"PRIx8""
 pci_nvme_map_sgl(uint8_t typ, uint64_t len) "type 0x%"PRIx8" len %"PRIu64""
 pci_nvme_io_cmd(uint16_t cid, uint32_t nsid, uint16_t sqid, uint8_t opcode, const char *opname) "cid %"PRIu16" nsid 0x%"PRIx32" sqid %"PRIu16" opc 0x%"PRIx8" opname '%s'"
 pci_nvme_admin_cmd(uint16_t cid, uint16_t sqid, uint8_t opcode, const char *opname) "cid %"PRIu16" sqid %"PRIu16" opc 0x%"PRIx8" opname '%s'"
-- 
2.47.3

[PATCH v4 8/8] tests/functional/x86_64: add migration test for NVMe device

[Alexander Mikhalitsyn]

From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>

Introduce a very simple test to ensure that NVMe device
migration works fine.

Test plan is simple:
1. prepare VM with NVMe device
2. run workload that produces relatively heavy IO on the device
3. migrate VM
4. ensure that workload is alive and finishes without errors

Test can be run as simple as:
$ meson test 'func-x86_64-nvme_migration' --setup thorough -C build

In the future we can extend this approach, and introduce some
fio-based tests. And probably, it makes sense to make this test
to apply not only to NVMe device, but also virtio-{blk,scsi},
ide, sata and other migratable devices.

Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@futurfusion.io>
---
 tests/functional/x86_64/meson.build           |   1 +
 .../functional/x86_64/test_nvme_migration.py  | 159 ++++++++++++++++++
 2 files changed, 160 insertions(+)
 create mode 100755 tests/functional/x86_64/test_nvme_migration.py

diff --git a/tests/functional/x86_64/meson.build b/tests/functional/x86_64/meson.build
index 1ed10ad6c29..fd77f19d726 100644
--- a/tests/functional/x86_64/meson.build
+++ b/tests/functional/x86_64/meson.build
@@ -37,6 +37,7 @@ tests_x86_64_system_thorough = [
   'linux_initrd',
   'multiprocess',
   'netdev_ethtool',
+  'nvme_migration',
   'replay',
   'reverse_debug',
   'tuxrun',
diff --git a/tests/functional/x86_64/test_nvme_migration.py b/tests/functional/x86_64/test_nvme_migration.py
new file mode 100755
index 00000000000..3788a8e3473
--- /dev/null
+++ b/tests/functional/x86_64/test_nvme_migration.py
@@ -0,0 +1,159 @@
+#!/usr/bin/env python3
+#
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+# x86_64 NVMe migration test
+
+from migration import MigrationTest
+from qemu_test import QemuSystemTest, Asset
+from qemu_test import wait_for_console_pattern
+from qemu_test import exec_command, exec_command_and_wait_for_pattern
+
+
+class X8664NVMeMigrationTest(MigrationTest):
+    ASSET_KERNEL = Asset(
+        ('https://archives.fedoraproject.org/pub/archive/fedora/linux/releases'
+         '/31/Server/x86_64/os/images/pxeboot/vmlinuz'),
+        'd4738d03dbbe083ca610d0821d0a8f1488bebbdccef54ce33e3adb35fda00129')
+
+    ASSET_INITRD = Asset(
+        ('https://archives.fedoraproject.org/pub/archive/fedora/linux/releases'
+         '/31/Server/x86_64/os/images/pxeboot/initrd.img'),
+        '277cd6c7adf77c7e63d73bbb2cded8ef9e2d3a2f100000e92ff1f8396513cd8b')
+
+    ASSET_DISKIMAGE = Asset(
+        ('https://archives.fedoraproject.org/pub/archive/fedora/linux/releases'
+         '/31/Cloud/x86_64/images/Fedora-Cloud-Base-31-1.9.x86_64.qcow2'),
+        'e3c1b309d9203604922d6e255c2c5d098a309c2d46215d8fc026954f3c5c27a0')
+
+    DEFAULT_KERNEL_PARAMS = ('root=/dev/nvme0n1p1 console=ttyS0 net.ifnames=0 '
+                             'rd.rescue quiet')
+
+    def wait_for_console_pattern(self, success_message, vm):
+        wait_for_console_pattern(
+            self,
+            success_message,
+            failure_message="Kernel panic - not syncing",
+            vm=vm,
+        )
+
+    def exec_command_and_check(self, command, vm):
+        prompt = '# '
+        exec_command_and_wait_for_pattern(self,
+                                        f"{command} && echo OK || echo FAIL",
+                                        'FAIL', vm=vm)
+        # Note, that commands we send to the console are echo-ed back, so if we have a word "FAIL"
+        # in the command itself, we should expect to see it once.
+        wait_for_console_pattern(self, 'OK', failure_message="FAIL", vm=vm)
+        self.wait_for_console_pattern(prompt, vm)
+
+    def configure_machine(self, vm):
+        kernel_path = self.ASSET_KERNEL.fetch()
+        initrd_path = self.ASSET_INITRD.fetch()
+        diskimage_path = self.ASSET_DISKIMAGE.fetch()
+
+        vm.set_console()
+        vm.add_args("-cpu", "max")
+        vm.add_args("-m", "2G")
+        vm.add_args("-accel", "kvm")
+
+        vm.add_args('-drive',
+                         f'file={diskimage_path},if=none,id=drv0,snapshot=on')
+        vm.add_args('-device', 'nvme,bus=pcie.0,' +
+                         'drive=drv0,id=nvme-disk0,serial=nvmemigratetest,bootindex=1')
+
+        vm.add_args(
+            "-kernel",
+            kernel_path,
+            "-initrd",
+            initrd_path,
+            "-append",
+            self.DEFAULT_KERNEL_PARAMS
+        )
+
+    def launch_source_vm(self, vm):
+        vm.launch()
+
+        self.wait_for_console_pattern('Entering emergency mode.', vm)
+        prompt = '# '
+        self.wait_for_console_pattern(prompt, vm)
+
+        # Synchronize on NVMe driver creating the root device
+        exec_command_and_wait_for_pattern(self,
+                        "while ! (dmesg -c | grep nvme0n1:) ; do sleep 1 ; done",
+                        "nvme0n1", vm=vm)
+        self.wait_for_console_pattern(prompt, vm)
+
+        # prepare system
+        exec_command_and_wait_for_pattern(self, 'mount /dev/nvme0n1p1 /sysroot',
+                                          prompt, vm=vm)
+        exec_command_and_wait_for_pattern(self, 'chroot /sysroot',
+                                          prompt, vm=vm)
+        exec_command_and_wait_for_pattern(self, 'mount -t proc proc /proc',
+                                          prompt, vm=vm)
+        exec_command_and_wait_for_pattern(self, 'mount -t sysfs sysfs /sys',
+                                          prompt, vm=vm)
+
+        # Run workload before migration to check if it continues to run properly after migration
+        #
+        # Workload is simple: it continuously calculates checksums of all files in /usr/bin
+        # to generate some I/O load on the NVMe disk and at the same time it drops caches to
+        # make sure that we have some read I/O on the disk as well.
+        # If there are any issues with the migration of the NVMe device, we should see errors
+        # in dmesg and consequently in the workload log.
+        exec_command_and_wait_for_pattern(self,
+                                        "(while [ ! -f /tmp/test_nvme_migration_workload.stop ]; do \
+                                            rm -f /tmp/test_nvme_migration_workload.iteration_finished; \
+                                            echo 3 > /proc/sys/vm/drop_caches; \
+                                            find /usr/bin -type f -exec cksum {} \\;; \
+                                            touch /tmp/test_nvme_migration_workload.iteration_finished; \
+                                        done) > /dev/null 2> /tmp/test_nvme_migration_workload.errors &",
+                                        prompt, vm=vm)
+        exec_command_and_wait_for_pattern(self, 'echo $! > /tmp/test_nvme_migration_workload.pid',
+                                          prompt, vm=vm)
+
+        # check if process is alive and running
+        self.exec_command_and_check("kill -0 $(cat /tmp/test_nvme_migration_workload.pid)", vm)
+
+    def assert_dest_vm(self, vm):
+        prompt = '# '
+
+        # check if process is alive and running after migration, if not - fail the test
+        self.exec_command_and_check("kill -0 $(cat /tmp/test_nvme_migration_workload.pid)", vm)
+
+        # signal workload to stop
+        exec_command_and_wait_for_pattern(self, 'touch /tmp/test_nvme_migration_workload.stop',
+                                          prompt, vm=vm)
+
+        # wait workload to finish, because we want to examine log to see if there are any errors
+        exec_command_and_wait_for_pattern(self,
+                                        "while [ ! -f /tmp/test_nvme_migration_workload.iteration_finished ]; do sleep 1; done;",
+                                        prompt, vm=vm)
+
+        exec_command_and_wait_for_pattern(self, 'cat /tmp/test_nvme_migration_workload.errors',
+                                          prompt, vm=vm)
+
+        # fail the test if non-empty
+        self.exec_command_and_check("[ ! -s /tmp/test_nvme_migration_workload.errors ]", vm)
+
+    def test_migration_with_tcp_localhost(self):
+        self.set_machine('q35')
+        self.require_accelerator("kvm")
+
+        self.migration_with_tcp_localhost()
+
+    def test_migration_with_unix(self):
+        self.set_machine('q35')
+        self.require_accelerator("kvm")
+
+        self.migration_with_unix()
+
+    def test_migration_with_exec(self):
+        self.set_machine('q35')
+        self.require_accelerator("kvm")
+
+        self.migration_with_exec()
+
+
+if __name__ == '__main__':
+    MigrationTest.main()
-- 
2.47.3