[PATCH 3/3] backends/tpm: Propagate vTPM error on migration failure

Arun Menon posted 3 patches 4 months, 3 weeks ago
Maintainers: Stefan Berger <stefanb@linux.vnet.ibm.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>, Thomas Huth <thuth@redhat.com>, Richard Henderson <richard.henderson@linaro.org>, David Hildenbrand <david@redhat.com>, Ilya Leoshkevich <iii@linux.ibm.com>, Christian Borntraeger <borntraeger@linux.ibm.com>, Nicholas Piggin <npiggin@gmail.com>, Daniel Henrique Barboza <danielhb413@gmail.com>, Harsh Prateek Bora <harshpb@linux.ibm.com>, Paolo Bonzini <pbonzini@redhat.com>, Fam Zheng <fam@euphon.net>, Alex Williamson <alex.williamson@redhat.com>, "Cédric Le Goater" <clg@redhat.com>, Peter Xu <peterx@redhat.com>, Fabiano Rosas <farosas@suse.de>, Hailiang Zhang <zhanghailiang@xfusion.com>, Steve Sistare <steven.sistare@oracle.com>
There is a newer version of this series
[PATCH 3/3] backends/tpm: Propagate vTPM error on migration failure
Posted by Arun Menon 4 months, 3 weeks ago
- Introduce a new post_load_with_error() hook that will
  take in the Error object as a parameter.
- This error object is set if the loading of state fails.
- The error can then be retrieved using QMP command
  {"execute" : "query-migrate"}

Buglink: https://issues.redhat.com/browse/RHEL-82826

Signed-off-by: Arun Menon <armenon@redhat.com>
---
 backends/tpm/tpm_emulator.c | 39 ++++++++++++++++++++-------------------
 include/migration/vmstate.h |  1 +
 migration/vmstate.c         |  4 +++-
 3 files changed, 24 insertions(+), 20 deletions(-)

diff --git a/backends/tpm/tpm_emulator.c b/backends/tpm/tpm_emulator.c
index 4a234ab2c0b19b2604bf0dd8cb5f4540c72a9438..816134d7b4de00a75a3d0b928d160595b17be810 100644
--- a/backends/tpm/tpm_emulator.c
+++ b/backends/tpm/tpm_emulator.c
@@ -819,7 +819,8 @@ static int tpm_emulator_get_state_blobs(TPMEmulator *tpm_emu)
 static int tpm_emulator_set_state_blob(TPMEmulator *tpm_emu,
                                        uint32_t type,
                                        TPMSizedBuffer *tsb,
-                                       uint32_t flags)
+                                       uint32_t flags,
+                                       Error **errp)
 {
     ssize_t n;
     ptm_setstate pss;
@@ -838,17 +839,17 @@ static int tpm_emulator_set_state_blob(TPMEmulator *tpm_emu,
     /* write the header only */
     if (tpm_emulator_ctrlcmd(tpm_emu, CMD_SET_STATEBLOB, &pss,
                              offsetof(ptm_setstate, u.req.data), 0, 0) < 0) {
-        error_report("tpm-emulator: could not set state blob type %d : %s",
-                     type, strerror(errno));
+        error_setg(errp, "tpm-emulator: could not set state blob type %d : %s",
+                   type, strerror(errno));
         return -1;
     }
 
     /* now the body */
     n = qemu_chr_fe_write_all(&tpm_emu->ctrl_chr, tsb->buffer, tsb->size);
     if (n != tsb->size) {
-        error_report("tpm-emulator: Writing the stateblob (type %d) "
-                     "failed; could not write %u bytes, but only %zd",
-                     type, tsb->size, n);
+        error_setg(errp, "tpm-emulator: Writing the stateblob (type %d) "
+                   "failed; could not write %u bytes, but only %zd",
+                   type, tsb->size, n);
         return -1;
     }
 
@@ -856,17 +857,17 @@ static int tpm_emulator_set_state_blob(TPMEmulator *tpm_emu,
     n = qemu_chr_fe_read_all(&tpm_emu->ctrl_chr,
                              (uint8_t *)&pss, sizeof(pss.u.resp));
     if (n != sizeof(pss.u.resp)) {
-        error_report("tpm-emulator: Reading response from writing stateblob "
-                     "(type %d) failed; expected %zu bytes, got %zd", type,
-                     sizeof(pss.u.resp), n);
+        error_setg(errp, "tpm-emulator: Reading response from writing "
+                   "stateblob (type %d) failed; expected %zu bytes, "
+                   "got %zd", type, sizeof(pss.u.resp), n);
         return -1;
     }
 
     tpm_result = be32_to_cpu(pss.u.resp.tpm_result);
     if (tpm_result != 0) {
-        error_report("tpm-emulator: Setting the stateblob (type %d) failed "
-                     "with a TPM error 0x%x %s", type, tpm_result,
-                     tpm_emulator_strerror(tpm_result));
+        error_setg(errp, "tpm-emulator: Setting the stateblob (type %d) "
+                   "failed with a TPM error 0x%x %s", type, tpm_result,
+                   tpm_emulator_strerror(tpm_result));
         return -1;
     }
 
@@ -880,7 +881,7 @@ static int tpm_emulator_set_state_blob(TPMEmulator *tpm_emu,
  *
  * Returns a negative errno code in case of error.
  */
-static int tpm_emulator_set_state_blobs(TPMBackend *tb)
+static int tpm_emulator_set_state_blobs(TPMBackend *tb, Error **errp)
 {
     TPMEmulator *tpm_emu = TPM_EMULATOR(tb);
     TPMBlobBuffers *state_blobs = &tpm_emu->state_blobs;
@@ -894,13 +895,13 @@ static int tpm_emulator_set_state_blobs(TPMBackend *tb)
 
     if (tpm_emulator_set_state_blob(tpm_emu, PTM_BLOB_TYPE_PERMANENT,
                                     &state_blobs->permanent,
-                                    state_blobs->permanent_flags) < 0 ||
+                                    state_blobs->permanent_flags, errp) < 0 ||
         tpm_emulator_set_state_blob(tpm_emu, PTM_BLOB_TYPE_VOLATILE,
                                     &state_blobs->volatil,
-                                    state_blobs->volatil_flags) < 0 ||
+                                    state_blobs->volatil_flags, errp) < 0 ||
         tpm_emulator_set_state_blob(tpm_emu, PTM_BLOB_TYPE_SAVESTATE,
                                     &state_blobs->savestate,
-                                    state_blobs->savestate_flags) < 0) {
+                                    state_blobs->savestate_flags, errp) < 0) {
         return -EIO;
     }
 
@@ -948,12 +949,12 @@ static void tpm_emulator_vm_state_change(void *opaque, bool running,
  *
  * Returns negative errno codes in case of error.
  */
-static int tpm_emulator_post_load(void *opaque, int version_id)
+static int tpm_emulator_post_load(void *opaque, int version_id, Error **errp)
 {
     TPMBackend *tb = opaque;
     int ret;
 
-    ret = tpm_emulator_set_state_blobs(tb);
+    ret = tpm_emulator_set_state_blobs(tb, errp);
     if (ret < 0) {
         return ret;
     }
@@ -969,7 +970,7 @@ static const VMStateDescription vmstate_tpm_emulator = {
     .name = "tpm-emulator",
     .version_id = 0,
     .pre_save = tpm_emulator_pre_save,
-    .post_load = tpm_emulator_post_load,
+    .post_load_with_error = tpm_emulator_post_load,
     .fields = (const VMStateField[]) {
         VMSTATE_UINT32(state_blobs.permanent_flags, TPMEmulator),
         VMSTATE_UINT32(state_blobs.permanent.size, TPMEmulator),
diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
index 056781b1c21e737583f081594d9f88b32adfd674..1c6e89c3b08a3914cde6dce3be5955978b6b7d0b 100644
--- a/include/migration/vmstate.h
+++ b/include/migration/vmstate.h
@@ -207,6 +207,7 @@ struct VMStateDescription {
     MigrationPriority priority;
     int (*pre_load)(void *opaque);
     int (*post_load)(void *opaque, int version_id);
+    int (*post_load_with_error)(void *opaque, int version_id, Error **errp);
     int (*pre_save)(void *opaque);
     int (*post_save)(void *opaque);
     bool (*needed)(void *opaque);
diff --git a/migration/vmstate.c b/migration/vmstate.c
index 3f8c3d3c1dcfe14d70bab1f43b827244eb4bb385..c5dfffd9bad7285e819d4769e055d47157caab34 100644
--- a/migration/vmstate.c
+++ b/migration/vmstate.c
@@ -232,7 +232,9 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
         qemu_file_set_error(f, ret);
         return ret;
     }
-    if (vmsd->post_load) {
+    if (vmsd->post_load_with_error) {
+        ret = vmsd->post_load_with_error(opaque, version_id, errp);
+    } else if (vmsd->post_load) {
         ret = vmsd->post_load(opaque, version_id);
     }
     trace_vmstate_load_state_end(vmsd->name, "end", ret);

-- 
2.49.0
Re: [PATCH 3/3] backends/tpm: Propagate vTPM error on migration failure
Posted by Marc-André Lureau 4 months, 2 weeks ago
Hi

On Tue, Jun 24, 2025 at 4:26 PM Arun Menon <armenon@redhat.com> wrote:
>
> - Introduce a new post_load_with_error() hook that will
>   take in the Error object as a parameter.

You should make this a different patch. I wonder if adding another
callback is the right approach, as only one of the two is called. I
would rather change the existing callback.

> - This error object is set if the loading of state fails.
> - The error can then be retrieved using QMP command
>   {"execute" : "query-migrate"}
>
> Buglink: https://issues.redhat.com/browse/RHEL-82826
>
> Signed-off-by: Arun Menon <armenon@redhat.com>
> ---
>  backends/tpm/tpm_emulator.c | 39 ++++++++++++++++++++-------------------
>  include/migration/vmstate.h |  1 +
>  migration/vmstate.c         |  4 +++-
>  3 files changed, 24 insertions(+), 20 deletions(-)
>
> diff --git a/backends/tpm/tpm_emulator.c b/backends/tpm/tpm_emulator.c
> index 4a234ab2c0b19b2604bf0dd8cb5f4540c72a9438..816134d7b4de00a75a3d0b928d160595b17be810 100644
> --- a/backends/tpm/tpm_emulator.c
> +++ b/backends/tpm/tpm_emulator.c
> @@ -819,7 +819,8 @@ static int tpm_emulator_get_state_blobs(TPMEmulator *tpm_emu)
>  static int tpm_emulator_set_state_blob(TPMEmulator *tpm_emu,
>                                         uint32_t type,
>                                         TPMSizedBuffer *tsb,
> -                                       uint32_t flags)
> +                                       uint32_t flags,
> +                                       Error **errp)
>  {
>      ssize_t n;
>      ptm_setstate pss;
> @@ -838,17 +839,17 @@ static int tpm_emulator_set_state_blob(TPMEmulator *tpm_emu,
>      /* write the header only */
>      if (tpm_emulator_ctrlcmd(tpm_emu, CMD_SET_STATEBLOB, &pss,
>                               offsetof(ptm_setstate, u.req.data), 0, 0) < 0) {
> -        error_report("tpm-emulator: could not set state blob type %d : %s",
> -                     type, strerror(errno));
> +        error_setg(errp, "tpm-emulator: could not set state blob type %d : %s",
> +                   type, strerror(errno));
>          return -1;
>      }
>
>      /* now the body */
>      n = qemu_chr_fe_write_all(&tpm_emu->ctrl_chr, tsb->buffer, tsb->size);
>      if (n != tsb->size) {
> -        error_report("tpm-emulator: Writing the stateblob (type %d) "
> -                     "failed; could not write %u bytes, but only %zd",
> -                     type, tsb->size, n);
> +        error_setg(errp, "tpm-emulator: Writing the stateblob (type %d) "
> +                   "failed; could not write %u bytes, but only %zd",
> +                   type, tsb->size, n);
>          return -1;
>      }
>
> @@ -856,17 +857,17 @@ static int tpm_emulator_set_state_blob(TPMEmulator *tpm_emu,
>      n = qemu_chr_fe_read_all(&tpm_emu->ctrl_chr,
>                               (uint8_t *)&pss, sizeof(pss.u.resp));
>      if (n != sizeof(pss.u.resp)) {
> -        error_report("tpm-emulator: Reading response from writing stateblob "
> -                     "(type %d) failed; expected %zu bytes, got %zd", type,
> -                     sizeof(pss.u.resp), n);
> +        error_setg(errp, "tpm-emulator: Reading response from writing "
> +                   "stateblob (type %d) failed; expected %zu bytes, "
> +                   "got %zd", type, sizeof(pss.u.resp), n);
>          return -1;
>      }
>
>      tpm_result = be32_to_cpu(pss.u.resp.tpm_result);
>      if (tpm_result != 0) {
> -        error_report("tpm-emulator: Setting the stateblob (type %d) failed "
> -                     "with a TPM error 0x%x %s", type, tpm_result,
> -                     tpm_emulator_strerror(tpm_result));
> +        error_setg(errp, "tpm-emulator: Setting the stateblob (type %d) "
> +                   "failed with a TPM error 0x%x %s", type, tpm_result,
> +                   tpm_emulator_strerror(tpm_result));
>          return -1;
>      }
>
> @@ -880,7 +881,7 @@ static int tpm_emulator_set_state_blob(TPMEmulator *tpm_emu,
>   *
>   * Returns a negative errno code in case of error.
>   */
> -static int tpm_emulator_set_state_blobs(TPMBackend *tb)
> +static int tpm_emulator_set_state_blobs(TPMBackend *tb, Error **errp)
>  {
>      TPMEmulator *tpm_emu = TPM_EMULATOR(tb);
>      TPMBlobBuffers *state_blobs = &tpm_emu->state_blobs;
> @@ -894,13 +895,13 @@ static int tpm_emulator_set_state_blobs(TPMBackend *tb)
>
>      if (tpm_emulator_set_state_blob(tpm_emu, PTM_BLOB_TYPE_PERMANENT,
>                                      &state_blobs->permanent,
> -                                    state_blobs->permanent_flags) < 0 ||
> +                                    state_blobs->permanent_flags, errp) < 0 ||
>          tpm_emulator_set_state_blob(tpm_emu, PTM_BLOB_TYPE_VOLATILE,
>                                      &state_blobs->volatil,
> -                                    state_blobs->volatil_flags) < 0 ||
> +                                    state_blobs->volatil_flags, errp) < 0 ||
>          tpm_emulator_set_state_blob(tpm_emu, PTM_BLOB_TYPE_SAVESTATE,
>                                      &state_blobs->savestate,
> -                                    state_blobs->savestate_flags) < 0) {
> +                                    state_blobs->savestate_flags, errp) < 0) {
>          return -EIO;
>      }
>
> @@ -948,12 +949,12 @@ static void tpm_emulator_vm_state_change(void *opaque, bool running,
>   *
>   * Returns negative errno codes in case of error.
>   */
> -static int tpm_emulator_post_load(void *opaque, int version_id)
> +static int tpm_emulator_post_load(void *opaque, int version_id, Error **errp)
>  {
>      TPMBackend *tb = opaque;
>      int ret;
>
> -    ret = tpm_emulator_set_state_blobs(tb);
> +    ret = tpm_emulator_set_state_blobs(tb, errp);
>      if (ret < 0) {
>          return ret;
>      }
> @@ -969,7 +970,7 @@ static const VMStateDescription vmstate_tpm_emulator = {
>      .name = "tpm-emulator",
>      .version_id = 0,
>      .pre_save = tpm_emulator_pre_save,
> -    .post_load = tpm_emulator_post_load,
> +    .post_load_with_error = tpm_emulator_post_load,
>      .fields = (const VMStateField[]) {
>          VMSTATE_UINT32(state_blobs.permanent_flags, TPMEmulator),
>          VMSTATE_UINT32(state_blobs.permanent.size, TPMEmulator),
> diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
> index 056781b1c21e737583f081594d9f88b32adfd674..1c6e89c3b08a3914cde6dce3be5955978b6b7d0b 100644
> --- a/include/migration/vmstate.h
> +++ b/include/migration/vmstate.h
> @@ -207,6 +207,7 @@ struct VMStateDescription {
>      MigrationPriority priority;
>      int (*pre_load)(void *opaque);
>      int (*post_load)(void *opaque, int version_id);
> +    int (*post_load_with_error)(void *opaque, int version_id, Error **errp);
>      int (*pre_save)(void *opaque);
>      int (*post_save)(void *opaque);
>      bool (*needed)(void *opaque);
> diff --git a/migration/vmstate.c b/migration/vmstate.c
> index 3f8c3d3c1dcfe14d70bab1f43b827244eb4bb385..c5dfffd9bad7285e819d4769e055d47157caab34 100644
> --- a/migration/vmstate.c
> +++ b/migration/vmstate.c
> @@ -232,7 +232,9 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
>          qemu_file_set_error(f, ret);
>          return ret;
>      }
> -    if (vmsd->post_load) {
> +    if (vmsd->post_load_with_error) {
> +        ret = vmsd->post_load_with_error(opaque, version_id, errp);
> +    } else if (vmsd->post_load) {
>          ret = vmsd->post_load(opaque, version_id);
>      }
>      trace_vmstate_load_state_end(vmsd->name, "end", ret);
>
> --
> 2.49.0
>
>


-- 
Marc-André Lureau
Re: [PATCH 3/3] backends/tpm: Propagate vTPM error on migration failure
Posted by Arun Menon 4 months, 2 weeks ago
Hi Marc-André,

Thank you for the review.

On Tue, Jul 01, 2025 at 04:21:23PM +0400, Marc-André Lureau wrote:
> Hi
> 
> On Tue, Jun 24, 2025 at 4:26 PM Arun Menon <armenon@redhat.com> wrote:
> >
> > - Introduce a new post_load_with_error() hook that will
> >   take in the Error object as a parameter.
> 
> You should make this a different patch.

Agreed. Updated in version 3.

> I wonder if adding another
> callback is the right approach, as only one of the two is called. I
> would rather change the existing callback.

This was briefly discussed in the ticket comment section.
https://issues.redhat.com/browse/RHEL-82826
The idea is to gradually introduce convert the codebase to using
post_load_with_error() hook. Therefore, the call is kept in mutual
exclusion to post_load().

> 
> > - This error object is set if the loading of state fails.
> > - The error can then be retrieved using QMP command
> >   {"execute" : "query-migrate"}
> >
> > Buglink: https://issues.redhat.com/browse/RHEL-82826
> >
> > Signed-off-by: Arun Menon <armenon@redhat.com>
> > ---
> >  backends/tpm/tpm_emulator.c | 39 ++++++++++++++++++++-------------------
> >  include/migration/vmstate.h |  1 +
> >  migration/vmstate.c         |  4 +++-
> >  3 files changed, 24 insertions(+), 20 deletions(-)
> >
> > diff --git a/backends/tpm/tpm_emulator.c b/backends/tpm/tpm_emulator.c
> > index 4a234ab2c0b19b2604bf0dd8cb5f4540c72a9438..816134d7b4de00a75a3d0b928d160595b17be810 100644
> > --- a/backends/tpm/tpm_emulator.c
> > +++ b/backends/tpm/tpm_emulator.c
> > @@ -819,7 +819,8 @@ static int tpm_emulator_get_state_blobs(TPMEmulator *tpm_emu)
> >  static int tpm_emulator_set_state_blob(TPMEmulator *tpm_emu,
> >                                         uint32_t type,
> >                                         TPMSizedBuffer *tsb,
> > -                                       uint32_t flags)
> > +                                       uint32_t flags,
> > +                                       Error **errp)
> >  {
> >      ssize_t n;
> >      ptm_setstate pss;
> > @@ -838,17 +839,17 @@ static int tpm_emulator_set_state_blob(TPMEmulator *tpm_emu,
> >      /* write the header only */
> >      if (tpm_emulator_ctrlcmd(tpm_emu, CMD_SET_STATEBLOB, &pss,
> >                               offsetof(ptm_setstate, u.req.data), 0, 0) < 0) {
> > -        error_report("tpm-emulator: could not set state blob type %d : %s",
> > -                     type, strerror(errno));
> > +        error_setg(errp, "tpm-emulator: could not set state blob type %d : %s",
> > +                   type, strerror(errno));
> >          return -1;
> >      }
> >
> >      /* now the body */
> >      n = qemu_chr_fe_write_all(&tpm_emu->ctrl_chr, tsb->buffer, tsb->size);
> >      if (n != tsb->size) {
> > -        error_report("tpm-emulator: Writing the stateblob (type %d) "
> > -                     "failed; could not write %u bytes, but only %zd",
> > -                     type, tsb->size, n);
> > +        error_setg(errp, "tpm-emulator: Writing the stateblob (type %d) "
> > +                   "failed; could not write %u bytes, but only %zd",
> > +                   type, tsb->size, n);
> >          return -1;
> >      }
> >
> > @@ -856,17 +857,17 @@ static int tpm_emulator_set_state_blob(TPMEmulator *tpm_emu,
> >      n = qemu_chr_fe_read_all(&tpm_emu->ctrl_chr,
> >                               (uint8_t *)&pss, sizeof(pss.u.resp));
> >      if (n != sizeof(pss.u.resp)) {
> > -        error_report("tpm-emulator: Reading response from writing stateblob "
> > -                     "(type %d) failed; expected %zu bytes, got %zd", type,
> > -                     sizeof(pss.u.resp), n);
> > +        error_setg(errp, "tpm-emulator: Reading response from writing "
> > +                   "stateblob (type %d) failed; expected %zu bytes, "
> > +                   "got %zd", type, sizeof(pss.u.resp), n);
> >          return -1;
> >      }
> >
> >      tpm_result = be32_to_cpu(pss.u.resp.tpm_result);
> >      if (tpm_result != 0) {
> > -        error_report("tpm-emulator: Setting the stateblob (type %d) failed "
> > -                     "with a TPM error 0x%x %s", type, tpm_result,
> > -                     tpm_emulator_strerror(tpm_result));
> > +        error_setg(errp, "tpm-emulator: Setting the stateblob (type %d) "
> > +                   "failed with a TPM error 0x%x %s", type, tpm_result,
> > +                   tpm_emulator_strerror(tpm_result));
> >          return -1;
> >      }
> >
> > @@ -880,7 +881,7 @@ static int tpm_emulator_set_state_blob(TPMEmulator *tpm_emu,
> >   *
> >   * Returns a negative errno code in case of error.
> >   */
> > -static int tpm_emulator_set_state_blobs(TPMBackend *tb)
> > +static int tpm_emulator_set_state_blobs(TPMBackend *tb, Error **errp)
> >  {
> >      TPMEmulator *tpm_emu = TPM_EMULATOR(tb);
> >      TPMBlobBuffers *state_blobs = &tpm_emu->state_blobs;
> > @@ -894,13 +895,13 @@ static int tpm_emulator_set_state_blobs(TPMBackend *tb)
> >
> >      if (tpm_emulator_set_state_blob(tpm_emu, PTM_BLOB_TYPE_PERMANENT,
> >                                      &state_blobs->permanent,
> > -                                    state_blobs->permanent_flags) < 0 ||
> > +                                    state_blobs->permanent_flags, errp) < 0 ||
> >          tpm_emulator_set_state_blob(tpm_emu, PTM_BLOB_TYPE_VOLATILE,
> >                                      &state_blobs->volatil,
> > -                                    state_blobs->volatil_flags) < 0 ||
> > +                                    state_blobs->volatil_flags, errp) < 0 ||
> >          tpm_emulator_set_state_blob(tpm_emu, PTM_BLOB_TYPE_SAVESTATE,
> >                                      &state_blobs->savestate,
> > -                                    state_blobs->savestate_flags) < 0) {
> > +                                    state_blobs->savestate_flags, errp) < 0) {
> >          return -EIO;
> >      }
> >
> > @@ -948,12 +949,12 @@ static void tpm_emulator_vm_state_change(void *opaque, bool running,
> >   *
> >   * Returns negative errno codes in case of error.
> >   */
> > -static int tpm_emulator_post_load(void *opaque, int version_id)
> > +static int tpm_emulator_post_load(void *opaque, int version_id, Error **errp)
> >  {
> >      TPMBackend *tb = opaque;
> >      int ret;
> >
> > -    ret = tpm_emulator_set_state_blobs(tb);
> > +    ret = tpm_emulator_set_state_blobs(tb, errp);
> >      if (ret < 0) {
> >          return ret;
> >      }
> > @@ -969,7 +970,7 @@ static const VMStateDescription vmstate_tpm_emulator = {
> >      .name = "tpm-emulator",
> >      .version_id = 0,
> >      .pre_save = tpm_emulator_pre_save,
> > -    .post_load = tpm_emulator_post_load,
> > +    .post_load_with_error = tpm_emulator_post_load,
> >      .fields = (const VMStateField[]) {
> >          VMSTATE_UINT32(state_blobs.permanent_flags, TPMEmulator),
> >          VMSTATE_UINT32(state_blobs.permanent.size, TPMEmulator),
> > diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
> > index 056781b1c21e737583f081594d9f88b32adfd674..1c6e89c3b08a3914cde6dce3be5955978b6b7d0b 100644
> > --- a/include/migration/vmstate.h
> > +++ b/include/migration/vmstate.h
> > @@ -207,6 +207,7 @@ struct VMStateDescription {
> >      MigrationPriority priority;
> >      int (*pre_load)(void *opaque);
> >      int (*post_load)(void *opaque, int version_id);
> > +    int (*post_load_with_error)(void *opaque, int version_id, Error **errp);
> >      int (*pre_save)(void *opaque);
> >      int (*post_save)(void *opaque);
> >      bool (*needed)(void *opaque);
> > diff --git a/migration/vmstate.c b/migration/vmstate.c
> > index 3f8c3d3c1dcfe14d70bab1f43b827244eb4bb385..c5dfffd9bad7285e819d4769e055d47157caab34 100644
> > --- a/migration/vmstate.c
> > +++ b/migration/vmstate.c
> > @@ -232,7 +232,9 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
> >          qemu_file_set_error(f, ret);
> >          return ret;
> >      }
> > -    if (vmsd->post_load) {
> > +    if (vmsd->post_load_with_error) {
> > +        ret = vmsd->post_load_with_error(opaque, version_id, errp);
> > +    } else if (vmsd->post_load) {
> >          ret = vmsd->post_load(opaque, version_id);
> >      }
> >      trace_vmstate_load_state_end(vmsd->name, "end", ret);
> >
> > --
> > 2.49.0
> >
> >
> 
> 
> -- 
> Marc-André Lureau
> 


Regards,
Arun Menon


Re: [PATCH 3/3] backends/tpm: Propagate vTPM error on migration failure
Posted by Stefan Berger 4 months, 3 weeks ago

On 6/24/25 8:23 AM, Arun Menon wrote:
> - Introduce a new post_load_with_error() hook that will
>    take in the Error object as a parameter.
> - This error object is set if the loading of state fails.
> - The error can then be retrieved using QMP command
>    {"execute" : "query-migrate"}
> 
> Buglink: https://issues.redhat.com/browse/RHEL-82826
> 
> Signed-off-by: Arun Menon <armenon@redhat.com>

Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>

> ---
>   backends/tpm/tpm_emulator.c | 39 ++++++++++++++++++++-------------------
>   include/migration/vmstate.h |  1 +
>   migration/vmstate.c         |  4 +++-
>   3 files changed, 24 insertions(+), 20 deletions(-)
> 
> diff --git a/backends/tpm/tpm_emulator.c b/backends/tpm/tpm_emulator.c
> index 4a234ab2c0b19b2604bf0dd8cb5f4540c72a9438..816134d7b4de00a75a3d0b928d160595b17be810 100644
> --- a/backends/tpm/tpm_emulator.c
> +++ b/backends/tpm/tpm_emulator.c
> @@ -819,7 +819,8 @@ static int tpm_emulator_get_state_blobs(TPMEmulator *tpm_emu)
>   static int tpm_emulator_set_state_blob(TPMEmulator *tpm_emu,
>                                          uint32_t type,
>                                          TPMSizedBuffer *tsb,
> -                                       uint32_t flags)
> +                                       uint32_t flags,
> +                                       Error **errp)
>   {
>       ssize_t n;
>       ptm_setstate pss;
> @@ -838,17 +839,17 @@ static int tpm_emulator_set_state_blob(TPMEmulator *tpm_emu,
>       /* write the header only */
>       if (tpm_emulator_ctrlcmd(tpm_emu, CMD_SET_STATEBLOB, &pss,
>                                offsetof(ptm_setstate, u.req.data), 0, 0) < 0) {
> -        error_report("tpm-emulator: could not set state blob type %d : %s",
> -                     type, strerror(errno));
> +        error_setg(errp, "tpm-emulator: could not set state blob type %d : %s",
> +                   type, strerror(errno));
>           return -1;
>       }
> 
>       /* now the body */
>       n = qemu_chr_fe_write_all(&tpm_emu->ctrl_chr, tsb->buffer, tsb->size);
>       if (n != tsb->size) {
> -        error_report("tpm-emulator: Writing the stateblob (type %d) "
> -                     "failed; could not write %u bytes, but only %zd",
> -                     type, tsb->size, n);
> +        error_setg(errp, "tpm-emulator: Writing the stateblob (type %d) "
> +                   "failed; could not write %u bytes, but only %zd",
> +                   type, tsb->size, n);
>           return -1;
>       }
> 
> @@ -856,17 +857,17 @@ static int tpm_emulator_set_state_blob(TPMEmulator *tpm_emu,
>       n = qemu_chr_fe_read_all(&tpm_emu->ctrl_chr,
>                                (uint8_t *)&pss, sizeof(pss.u.resp));
>       if (n != sizeof(pss.u.resp)) {
> -        error_report("tpm-emulator: Reading response from writing stateblob "
> -                     "(type %d) failed; expected %zu bytes, got %zd", type,
> -                     sizeof(pss.u.resp), n);
> +        error_setg(errp, "tpm-emulator: Reading response from writing "
> +                   "stateblob (type %d) failed; expected %zu bytes, "
> +                   "got %zd", type, sizeof(pss.u.resp), n);
>           return -1;
>       }
> 
>       tpm_result = be32_to_cpu(pss.u.resp.tpm_result);
>       if (tpm_result != 0) {
> -        error_report("tpm-emulator: Setting the stateblob (type %d) failed "
> -                     "with a TPM error 0x%x %s", type, tpm_result,
> -                     tpm_emulator_strerror(tpm_result));
> +        error_setg(errp, "tpm-emulator: Setting the stateblob (type %d) "
> +                   "failed with a TPM error 0x%x %s", type, tpm_result,
> +                   tpm_emulator_strerror(tpm_result));
>           return -1;
>       }
> 
> @@ -880,7 +881,7 @@ static int tpm_emulator_set_state_blob(TPMEmulator *tpm_emu,
>    *
>    * Returns a negative errno code in case of error.
>    */
> -static int tpm_emulator_set_state_blobs(TPMBackend *tb)
> +static int tpm_emulator_set_state_blobs(TPMBackend *tb, Error **errp)
>   {
>       TPMEmulator *tpm_emu = TPM_EMULATOR(tb);
>       TPMBlobBuffers *state_blobs = &tpm_emu->state_blobs;
> @@ -894,13 +895,13 @@ static int tpm_emulator_set_state_blobs(TPMBackend *tb)
> 
>       if (tpm_emulator_set_state_blob(tpm_emu, PTM_BLOB_TYPE_PERMANENT,
>                                       &state_blobs->permanent,
> -                                    state_blobs->permanent_flags) < 0 ||
> +                                    state_blobs->permanent_flags, errp) < 0 ||
>           tpm_emulator_set_state_blob(tpm_emu, PTM_BLOB_TYPE_VOLATILE,
>                                       &state_blobs->volatil,
> -                                    state_blobs->volatil_flags) < 0 ||
> +                                    state_blobs->volatil_flags, errp) < 0 ||
>           tpm_emulator_set_state_blob(tpm_emu, PTM_BLOB_TYPE_SAVESTATE,
>                                       &state_blobs->savestate,
> -                                    state_blobs->savestate_flags) < 0) {
> +                                    state_blobs->savestate_flags, errp) < 0) {
>           return -EIO;
>       }
> 
> @@ -948,12 +949,12 @@ static void tpm_emulator_vm_state_change(void *opaque, bool running,
>    *
>    * Returns negative errno codes in case of error.
>    */
> -static int tpm_emulator_post_load(void *opaque, int version_id)
> +static int tpm_emulator_post_load(void *opaque, int version_id, Error **errp)
>   {
>       TPMBackend *tb = opaque;
>       int ret;
> 
> -    ret = tpm_emulator_set_state_blobs(tb);
> +    ret = tpm_emulator_set_state_blobs(tb, errp);
>       if (ret < 0) {
>           return ret;
>       }
> @@ -969,7 +970,7 @@ static const VMStateDescription vmstate_tpm_emulator = {
>       .name = "tpm-emulator",
>       .version_id = 0,
>       .pre_save = tpm_emulator_pre_save,
> -    .post_load = tpm_emulator_post_load,
> +    .post_load_with_error = tpm_emulator_post_load,
>       .fields = (const VMStateField[]) {
>           VMSTATE_UINT32(state_blobs.permanent_flags, TPMEmulator),
>           VMSTATE_UINT32(state_blobs.permanent.size, TPMEmulator),
> diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
> index 056781b1c21e737583f081594d9f88b32adfd674..1c6e89c3b08a3914cde6dce3be5955978b6b7d0b 100644
> --- a/include/migration/vmstate.h
> +++ b/include/migration/vmstate.h
> @@ -207,6 +207,7 @@ struct VMStateDescription {
>       MigrationPriority priority;
>       int (*pre_load)(void *opaque);
>       int (*post_load)(void *opaque, int version_id);
> +    int (*post_load_with_error)(void *opaque, int version_id, Error **errp);
>       int (*pre_save)(void *opaque);
>       int (*post_save)(void *opaque);
>       bool (*needed)(void *opaque);
> diff --git a/migration/vmstate.c b/migration/vmstate.c
> index 3f8c3d3c1dcfe14d70bab1f43b827244eb4bb385..c5dfffd9bad7285e819d4769e055d47157caab34 100644
> --- a/migration/vmstate.c
> +++ b/migration/vmstate.c
> @@ -232,7 +232,9 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
>           qemu_file_set_error(f, ret);
>           return ret;
>       }
> -    if (vmsd->post_load) {
> +    if (vmsd->post_load_with_error) {
> +        ret = vmsd->post_load_with_error(opaque, version_id, errp);
> +    } else if (vmsd->post_load) {
>           ret = vmsd->post_load(opaque, version_id);
>       }
>       trace_vmstate_load_state_end(vmsd->name, "end", ret);
>