Hello, Currently, when a migration of a VM with an encrypted vTPM fails on the destination host (e.g., due to a mismatch in secret values), the error message displayed on the source host is generic and unhelpful.
For example, a typical error looks like this: "operation failed: job 'migration out' failed: Sibling indicated error 1. operation failed: job 'migration in' failed: load of migration failed: Input/output error" This message does not provide any specific indication of a vTPM failure. Such generic errors are logged using error_report(), which prints to the console/monitor but does not make the detailed error accessible via the QMP query-migrate command. This series addresses the issue, by ensuring that specific TPM error messages are propagated via the QEMU Error object. To make this possible, - A set of functions in the call stack is changed to incorporate an Error object as an additional parameter. - Also, the TPM backend makes use of a new hook called post_load_errp() that explicitly passes an Error object. It is organized as follows, - Patches 1-23 focuses on pushing Error object into the functions that are important in the call stack where TPM errors are observed. We still need to make changes in rest of the functions in savevm.c such that they also incorporate the errp object for propagating errors. - Patches 12, 13, 20, are minor refactoring changes. - Patch 24 removes error variant of vmstate_save_state() function. - Patch 25 renames post_save() to cleanup_save() - Patch 26 introduces the new variants of the hooks in VMStateDescription structure. These hooks should be used in future implementations. - Patch 27 focuses on changing the TPM backend such that the errors are set in the Error object. While this series focuses specifically on TPM error reporting during live migration, it lays the groundwork for broader improvements. A lot of methods in savevm.c that previously returned an integer now capture errors in the Error object, enabling other modules to adopt the post_load_errp hook in the future. One such change previously attempted: https://lists.gnu.org/archive/html/qemu-devel/2021-02/msg01727.html Resolves: https://issues.redhat.com/browse/RHEL-82826 Signed-off-by: Arun Menon <arme...@redhat.com> --- Changes in v12: - Remove error_prepend() calls where no additional information is appended to the error string. This also allows us to remove unnecessary ERRP_GUARD(). - Avoid ambiguity by propagating clear messages in errp. - Add clarity to commit messages throughout the series. - Link to v11: https://lore.kernel.org/qemu-devel/20250813-propagate_tpm_error-v11-0-b470a374b...@redhat.com Changes in v11: - Remove unnecessary NULL check in postcopy_ram_listen_thread. - Change error_warn to error_fatal or pass local_err wherever appropriate, because, https://lore.kernel.org/qemu-devel/20250808080823.2638861-13-arm...@redhat.com/ Most changes are in patches 2,24. - Link to v10: https://lore.kernel.org/qemu-devel/20250808-propagate_tpm_error-v10-0-3e81a1d41...@redhat.com Changes in v10: - Remove the patch to propagate most recent error and the patch of refactoring vmstate_save_state_v(): 23,24. They are not required because we intend to keep the design as is. - Added 2 new patches - patch 25: Rename post_save() to cleanup_save() and make it void - patch 20: Return -1 on memory allocation failure in ram.c - Pass &error_warn or &error_fatal to capture error or exit on error. - Link to v9: https://lore.kernel.org/qemu-devel/20250805-propagate_tpm_error-v9-0-123450810...@redhat.com Changes in v9: - Re ordering patches such that error is reported in each one of them. - format specifier enclosed in '' changed i.e. '%d' changed to %d - Reporting errors where they were missed before. Setting errp to NULL in case of retry. - Link to v8: https://lore.kernel.org/qemu-devel/20250731-propagate_tpm_error-v8-0-28fd82fdf...@redhat.com Changes in v8: - 3 new patches added: - patch 23: - Changes the error propagation by returning the most recent error to the caller when both save device state and post_save fails. - patch 24: - Refactors the vmstate_save_state_v() function by adding wrapper functions to separate concerns. - patch 25: - Removes the error variant of the vmstate_save_state() function introduced in commit 969298f9d7. - Use ERRP_GUARD() where there is an errp dereference or an error_prepend call. - Pass &error_warn in place of NULL, in vmstate_load_state() calls so that the caller knows about the error. - Remove unnecessary null check before setting errp. Dereferencing it is not required. - Documentation for the new variants of post/pre save/load hooks added. - Some patches, although they received a 'Reviewed-by' tag, have undergone few minor changes, Patch 1 : removed extra space Patch 2 : Commit message changed, refactoring the function to always set errp and return. Patch 8 : Commit message changed. Patch 9 : use error_setg_errno instead of error_setg. Patch 27 : use error_setg_errno instead of error_setg. - Link to v7: https://lore.kernel.org/qemu-devel/20250725-propagate_tpm_error-v7-0-d52704443...@redhat.com Changes in v7: - Fix propagating errors in post_save_errp. The latest error encountered is propagated. - user-strings in error_prepend() calls now end with a ': ' so that the print is pretty. - Change the order of one of the patches. - Link to v6: https://lore.kernel.org/qemu-devel/20250721-propagate_tpm_error-v6-0-fef740e15...@redhat.com Changes in v6: - Incorporated review comments from Daniel and Akihiko, related to few semantic errors and improve error logging. - Add one more patch that removes NULL checks after calling qemu_file_get_return_path() because it does not fail. - Link to v5: https://lore.kernel.org/qemu-devel/20250717-propagate_tpm_error-v5-0-1f406f88e...@redhat.com Changes in v5: - Solve a bug that set errp even though it was not NULL, pointed out by Fabiano in v4. - Link to v4: https://lore.kernel.org/qemu-devel/20250716-propagate_tpm_error-v4-0-714190207...@redhat.com Changes in v4: - Split the patches into smaller ones based on functions. Pass NULL in the caller until errp is made available. Every function that has an Error **errp object passed to it, ensures that it sets the errp object in case of failure. - A few more functions within loadvm_process_command() now handle errors using the errp object. I've converted these for consistency, taking Daniel's patches (link above) as a reference. - Along with the post_load_errp() hook, other duplicate hooks are also introduced. This will enable us to migrate to the newer versions eventually. - Fix some semantic errors, like using error_propagate_prepend() in places where we need to preserve existing behaviour of accumulating the error in local_err and then propagating it to errp. This can be refactored in a later commit. - Add more information in commit messages explaining the changes. - Link to v3: https://lore.kernel.org/qemu-devel/20250702-propagate_tpm_error-v3-0-986d94540...@redhat.com Changes in v3: - Split the 2nd patch into 2. Introducing post_load_with_error() hook has been separated from using it in the backends TPM module. This is so that it can be acknowledged. - Link to v2: https://lore.kernel.org/qemu-devel/20250627-propagate_tpm_error-v2-0-85990c89d...@redhat.com Changes in v2: - Combine the first two changes into one, focusing on passing the Error object (errp) consistently through functions involved in loading the VM's state. Other functions are not yet changed. - As suggested in the review comment, add null checks for errp before adding error messages, preventing crashes. We also now correctly set errors when post-copy migration fails. - In process_incoming_migration_co(), switch to error_prepend instead of error_setg. This means we now null-check local_err in the "fail" section before using it, preventing dereferencing issues. - Link to v1: https://lore.kernel.org/qemu-devel/20250624-propagate_tpm_error-v1-0-2171487a5...@redhat.com --- Arun Menon (27): migration: push Error **errp into vmstate_subsection_load() migration: push Error **errp into vmstate_load_state() migration: push Error **errp into qemu_loadvm_state_header() migration: push Error **errp into vmstate_load() migration: push Error **errp into loadvm_process_command() migration: push Error **errp into loadvm_handle_cmd_packaged() migration: push Error **errp into qemu_loadvm_state() migration: push Error **errp into qemu_load_device_state() migration: push Error **errp into qemu_loadvm_state_main() migration: push Error **errp into qemu_loadvm_section_start_full() migration: push Error **errp into qemu_loadvm_section_part_end() migration: Update qemu_file_get_return_path() docs and remove dead checks migration: make loadvm_postcopy_handle_resume() void migration: push Error **errp into ram_postcopy_incoming_init() migration: push Error **errp into loadvm_postcopy_handle_advise() migration: push Error **errp into loadvm_postcopy_handle_listen() migration: push Error **errp into loadvm_postcopy_handle_run() migration: push Error **errp into loadvm_postcopy_ram_handle_discard() migration: push Error **errp into loadvm_handle_recv_bitmap() migration: Return -1 on memory allocation failure in ram.c migration: push Error **errp into loadvm_process_enable_colo() migration: push Error **errp into loadvm_postcopy_handle_switchover_start() migration: Capture error in postcopy_ram_listen_thread() migration: Remove error variant of vmstate_save_state() function migration: Rename post_save() to cleanup_save() and make it void migration: Add error-parameterized function variants in VMSD struct backends/tpm: Propagate vTPM error on migration failure backends/tpm/tpm_emulator.c | 40 ++--- docs/devel/migration/main.rst | 21 ++- hw/display/virtio-gpu.c | 5 +- hw/pci/pci.c | 5 +- hw/ppc/spapr_pci.c | 5 +- hw/s390x/virtio-ccw.c | 4 +- hw/scsi/spapr_vscsi.c | 6 +- hw/vfio/pci.c | 9 +- hw/virtio/virtio-mmio.c | 5 +- hw/virtio/virtio-pci.c | 4 +- hw/virtio/virtio.c | 13 +- include/migration/colo.h | 2 +- include/migration/vmstate.h | 20 ++- migration/colo.c | 10 +- migration/cpr.c | 6 +- migration/migration.c | 33 ++--- migration/postcopy-ram.c | 9 +- migration/postcopy-ram.h | 2 +- migration/qemu-file.c | 1 - migration/ram.c | 16 +- migration/ram.h | 4 +- migration/savevm.c | 337 ++++++++++++++++++++++++------------------ migration/savevm.h | 7 +- migration/vmstate-types.c | 45 ++++-- migration/vmstate.c | 118 ++++++++++----- target/arm/machine.c | 6 +- tests/unit/test-vmstate.c | 83 +++++++++-- ui/vdagent.c | 8 +- 28 files changed, 522 insertions(+), 302 deletions(-) --- base-commit: e0006a86615baa70bc9d8b183e528aed91c1ac90 change-id: 20250624-propagate_tpm_error-bf4ae6c23d30 Best regards, -- Arun Menon <arme...@redhat.com>
