[PATCH v6 03/24] migration: push Error **errp into qemu_loadvm_state_header()

Arun Menon posted 24 patches 3 months, 3 weeks ago
Maintainers: Stefan Berger <stefanb@linux.vnet.ibm.com>, "Alex Bennée" <alex.bennee@linaro.org>, Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>, Dmitry Osipenko <dmitry.osipenko@collabora.com>, "Michael S. Tsirkin" <mst@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Cornelia Huck <cohuck@redhat.com>, Halil Pasic <pasic@linux.ibm.com>, Eric Farman <farman@linux.ibm.com>, Richard Henderson <richard.henderson@linaro.org>, David Hildenbrand <david@redhat.com>, Ilya Leoshkevich <iii@linux.ibm.com>, Thomas Huth <thuth@redhat.com>, Christian Borntraeger <borntraeger@linux.ibm.com>, Matthew Rosato <mjrosato@linux.ibm.com>, Paolo Bonzini <pbonzini@redhat.com>, Fam Zheng <fam@euphon.net>, Nicholas Piggin <npiggin@gmail.com>, Daniel Henrique Barboza <danielhb413@gmail.com>, Harsh Prateek Bora <harshpb@linux.ibm.com>, Alex Williamson <alex.williamson@redhat.com>, "Cédric Le Goater" <clg@redhat.com>, Hailiang Zhang <zhanghailiang@xfusion.com>, Peter Xu <peterx@redhat.com>, Fabiano Rosas <farosas@suse.de>, Steve Sistare <steven.sistare@oracle.com>, "Marc-André Lureau" <marcandre.lureau@redhat.com>
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[PATCH v6 03/24] migration: push Error **errp into qemu_loadvm_state_header()
Posted by Arun Menon 3 months, 3 weeks ago
This is an incremental step in converting vmstate loading
code to report error via Error objects instead of directly
printing it to console/monitor.
It is ensured that qemu_loadvm_state_header() must report an error
in errp, in case of failure.

Signed-off-by: Arun Menon <armenon@redhat.com>
---
 migration/savevm.c | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/migration/savevm.c b/migration/savevm.c
index ab947620f724874f325fb9fb59bef50b7c16fb51..162fb05933fae5993eeef107811f97cb08726ac3 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2814,35 +2814,42 @@ qemu_loadvm_section_part_end(QEMUFile *f, uint8_t type)
     return 0;
 }
 
-static int qemu_loadvm_state_header(QEMUFile *f)
+static int qemu_loadvm_state_header(QEMUFile *f, Error **errp)
 {
     unsigned int v;
     int ret;
 
     v = qemu_get_be32(f);
     if (v != QEMU_VM_FILE_MAGIC) {
-        error_report("Not a migration stream");
+        error_setg(errp, "Not a migration stream, "
+                   "magic: %x != %x", v, QEMU_VM_FILE_MAGIC);
         return -EINVAL;
     }
 
     v = qemu_get_be32(f);
     if (v == QEMU_VM_FILE_VERSION_COMPAT) {
-        error_report("SaveVM v2 format is obsolete and don't work anymore");
+        error_setg(errp, "SaveVM v2 format is obsolete and no"
+                   "longer supported, file version %x != %x",
+                   v, QEMU_VM_FILE_VERSION_COMPAT);
+
         return -ENOTSUP;
     }
     if (v != QEMU_VM_FILE_VERSION) {
-        error_report("Unsupported migration stream version");
+        error_setg(errp, "Unsupported migration stream "
+                   "version, file version %x != %x", v, QEMU_VM_FILE_VERSION);
         return -ENOTSUP;
     }
 
     if (migrate_get_current()->send_configuration) {
-        if (qemu_get_byte(f) != QEMU_VM_CONFIGURATION) {
-            error_report("Configuration section missing");
+        v = qemu_get_byte(f);
+        if (v != QEMU_VM_CONFIGURATION) {
+            error_setg(errp, "Configuration section missing,"
+                       "%x != %x", v, QEMU_VM_CONFIGURATION);
             return -EINVAL;
         }
-        ret = vmstate_load_state(f, &vmstate_configuration, &savevm_state, 0,
-                                 NULL);
 
+        ret = vmstate_load_state(f, &vmstate_configuration, &savevm_state, 0,
+                                 errp);
         if (ret) {
             return ret;
         }
@@ -3119,7 +3126,7 @@ int qemu_loadvm_state(QEMUFile *f)
 
     qemu_loadvm_thread_pool_create(mis);
 
-    ret = qemu_loadvm_state_header(f);
+    ret = qemu_loadvm_state_header(f, NULL);
     if (ret) {
         return ret;
     }

-- 
2.50.0
Re: [PATCH v6 03/24] migration: push Error **errp into qemu_loadvm_state_header()
Posted by Marc-André Lureau 3 months, 3 weeks ago
Hi

On Mon, Jul 21, 2025 at 3:30 PM Arun Menon <armenon@redhat.com> wrote:

> This is an incremental step in converting vmstate loading
> code to report error via Error objects instead of directly
> printing it to console/monitor.
> It is ensured that qemu_loadvm_state_header() must report an error
> in errp, in case of failure.
>
> Signed-off-by: Arun Menon <armenon@redhat.com>
> ---
>  migration/savevm.c | 25 ++++++++++++++++---------
>  1 file changed, 16 insertions(+), 9 deletions(-)
>
> diff --git a/migration/savevm.c b/migration/savevm.c
> index
> ab947620f724874f325fb9fb59bef50b7c16fb51..162fb05933fae5993eeef107811f97cb08726ac3
> 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -2814,35 +2814,42 @@ qemu_loadvm_section_part_end(QEMUFile *f, uint8_t
> type)
>      return 0;
>  }
>
> -static int qemu_loadvm_state_header(QEMUFile *f)
> +static int qemu_loadvm_state_header(QEMUFile *f, Error **errp)
>  {
>      unsigned int v;
>      int ret;
>
>      v = qemu_get_be32(f);
>      if (v != QEMU_VM_FILE_MAGIC) {
> -        error_report("Not a migration stream");
> +        error_setg(errp, "Not a migration stream, "
> +                   "magic: %x != %x", v, QEMU_VM_FILE_MAGIC);
>          return -EINVAL;
>      }
>
>      v = qemu_get_be32(f);
>      if (v == QEMU_VM_FILE_VERSION_COMPAT) {
> -        error_report("SaveVM v2 format is obsolete and don't work
> anymore");
> +        error_setg(errp, "SaveVM v2 format is obsolete and no"
> +                   "longer supported, file version %x != %x",
>

As Akihiko said in patch 2 review, better "not to have line breaks in
string literals" .. here, there is a missing space now.

+                   v, QEMU_VM_FILE_VERSION_COMPAT);
> +
>          return -ENOTSUP;
>      }
>      if (v != QEMU_VM_FILE_VERSION) {
> -        error_report("Unsupported migration stream version");
> +        error_setg(errp, "Unsupported migration stream "
> +                   "version, file version %x != %x", v,
> QEMU_VM_FILE_VERSION);
>          return -ENOTSUP;
>      }
>
>      if (migrate_get_current()->send_configuration) {
> -        if (qemu_get_byte(f) != QEMU_VM_CONFIGURATION) {
> -            error_report("Configuration section missing");
> +        v = qemu_get_byte(f);
> +        if (v != QEMU_VM_CONFIGURATION) {
> +            error_setg(errp, "Configuration section missing,"
>

here too


> +                       "%x != %x", v, QEMU_VM_CONFIGURATION);
>              return -EINVAL;
>          }
> -        ret = vmstate_load_state(f, &vmstate_configuration,
> &savevm_state, 0,
> -                                 NULL);
>
> +        ret = vmstate_load_state(f, &vmstate_configuration,
> &savevm_state, 0,
> +                                 errp);
>          if (ret) {
>              return ret;
>          }
> @@ -3119,7 +3126,7 @@ int qemu_loadvm_state(QEMUFile *f)
>
>      qemu_loadvm_thread_pool_create(mis);
>
> -    ret = qemu_loadvm_state_header(f);
> +    ret = qemu_loadvm_state_header(f, NULL);
>      if (ret) {
>          return ret;
>      }
>
> --
> 2.50.0
>
>
Re: [PATCH v6 03/24] migration: push Error **errp into qemu_loadvm_state_header()
Posted by Arun Menon 3 months, 3 weeks ago
Hi,
Thanks for the review.

On Mon, Jul 21, 2025 at 04:34:12PM +0400, Marc-André Lureau wrote:
> Hi
> 
> On Mon, Jul 21, 2025 at 3:30 PM Arun Menon <armenon@redhat.com> wrote:
> 
> > This is an incremental step in converting vmstate loading
> > code to report error via Error objects instead of directly
> > printing it to console/monitor.
> > It is ensured that qemu_loadvm_state_header() must report an error
> > in errp, in case of failure.
> >
> > Signed-off-by: Arun Menon <armenon@redhat.com>
> > ---
> >  migration/savevm.c | 25 ++++++++++++++++---------
> >  1 file changed, 16 insertions(+), 9 deletions(-)
> >
> > diff --git a/migration/savevm.c b/migration/savevm.c
> > index
> > ab947620f724874f325fb9fb59bef50b7c16fb51..162fb05933fae5993eeef107811f97cb08726ac3
> > 100644
> > --- a/migration/savevm.c
> > +++ b/migration/savevm.c
> > @@ -2814,35 +2814,42 @@ qemu_loadvm_section_part_end(QEMUFile *f, uint8_t
> > type)
> >      return 0;
> >  }
> >
> > -static int qemu_loadvm_state_header(QEMUFile *f)
> > +static int qemu_loadvm_state_header(QEMUFile *f, Error **errp)
> >  {
> >      unsigned int v;
> >      int ret;
> >
> >      v = qemu_get_be32(f);
> >      if (v != QEMU_VM_FILE_MAGIC) {
> > -        error_report("Not a migration stream");
> > +        error_setg(errp, "Not a migration stream, "
> > +                   "magic: %x != %x", v, QEMU_VM_FILE_MAGIC);
> >          return -EINVAL;
> >      }
> >
> >      v = qemu_get_be32(f);
> >      if (v == QEMU_VM_FILE_VERSION_COMPAT) {
> > -        error_report("SaveVM v2 format is obsolete and don't work
> > anymore");
> > +        error_setg(errp, "SaveVM v2 format is obsolete and no"
> > +                   "longer supported, file version %x != %x",
> >
> 
> As Akihiko said in patch 2 review, better "not to have line breaks in
> string literals" .. here, there is a missing space now.

Agreed. I am going to amend all the commits once and check for these kind of
breaks. However, I do not want to have the line too long also (more than 100 chars).

I will try to find a way in which I can use minimum breaks, while keeping in mind
that a grep search should be able to find the line in the codebase, if that is ok.
> 
> +                   v, QEMU_VM_FILE_VERSION_COMPAT);
> > +
> >          return -ENOTSUP;
> >      }
> >      if (v != QEMU_VM_FILE_VERSION) {
> > -        error_report("Unsupported migration stream version");
> > +        error_setg(errp, "Unsupported migration stream "
> > +                   "version, file version %x != %x", v,
> > QEMU_VM_FILE_VERSION);
> >          return -ENOTSUP;
> >      }
> >
> >      if (migrate_get_current()->send_configuration) {
> > -        if (qemu_get_byte(f) != QEMU_VM_CONFIGURATION) {
> > -            error_report("Configuration section missing");
> > +        v = qemu_get_byte(f);
> > +        if (v != QEMU_VM_CONFIGURATION) {
> > +            error_setg(errp, "Configuration section missing,"
> >
> 
> here too
yes
> 
> 
> > +                       "%x != %x", v, QEMU_VM_CONFIGURATION);
> >              return -EINVAL;
> >          }
> > -        ret = vmstate_load_state(f, &vmstate_configuration,
> > &savevm_state, 0,
> > -                                 NULL);
> >
> > +        ret = vmstate_load_state(f, &vmstate_configuration,
> > &savevm_state, 0,
> > +                                 errp);
> >          if (ret) {
> >              return ret;
> >          }
> > @@ -3119,7 +3126,7 @@ int qemu_loadvm_state(QEMUFile *f)
> >
> >      qemu_loadvm_thread_pool_create(mis);
> >
> > -    ret = qemu_loadvm_state_header(f);
> > +    ret = qemu_loadvm_state_header(f, NULL);
> >      if (ret) {
> >          return ret;
> >      }
> >
> > --
> > 2.50.0
> >
> >
Regards,
Arun