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 1-21 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. - Patch 22 introduces the new variants of the hooks in VMStateDescription structure. These hooks should be used in future implementations. - Patch 23 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 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 (23): 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 qemu_loadvm_section_start_full() migration: push Error **errp into qemu_loadvm_section_part_end() migration: push Error **errp into loadvm_process_command() migration: push Error **errp into loadvm_handle_cmd_packaged() 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: make loadvm_postcopy_handle_resume() void migration: push Error **errp into loadvm_handle_recv_bitmap() migration: push Error **errp into loadvm_process_enable_colo() migration: push Error **errp into loadvm_postcopy_handle_switchover_start() migration: push Error **errp into qemu_loadvm_state_main() migration: push Error **errp into qemu_loadvm_state() migration: push Error **errp into qemu_load_device_state() migration: Capture error in postcopy_ram_listen_thread() migration: Add error-parameterized function variants in VMSD struct backends/tpm: Propagate vTPM error on migration failure backends/tpm/tpm_emulator.c | 39 +++--- hw/display/virtio-gpu.c | 2 +- hw/pci/pci.c | 2 +- hw/s390x/virtio-ccw.c | 2 +- hw/scsi/spapr_vscsi.c | 2 +- hw/vfio/pci.c | 2 +- hw/virtio/virtio-mmio.c | 2 +- hw/virtio/virtio-pci.c | 2 +- hw/virtio/virtio.c | 4 +- include/migration/colo.h | 2 +- include/migration/vmstate.h | 13 +- migration/colo.c | 10 +- migration/cpr.c | 4 +- migration/migration.c | 19 +-- migration/postcopy-ram.c | 9 +- migration/postcopy-ram.h | 2 +- migration/ram.c | 14 +-- migration/ram.h | 4 +- migration/savevm.c | 293 +++++++++++++++++++++++++------------------- migration/savevm.h | 7 +- migration/vmstate-types.c | 10 +- migration/vmstate.c | 83 +++++++++---- tests/unit/test-vmstate.c | 18 +-- ui/vdagent.c | 2 +- 24 files changed, 321 insertions(+), 226 deletions(-) --- base-commit: f96b157ebb93f94cd56ebbc99bc20982b8fd86ef change-id: 20250624-propagate_tpm_error-bf4ae6c23d30 Best regards, -- Arun Menon <arme...@redhat.com>
