From 40de712a89d8fe26af398dd23c24e94834ca442b Mon Sep 17 00:00:00 2001 From: Arun Menon Date: Thu, 18 Sep 2025 20:53:43 +0530 Subject: [PATCH] migration: Add error-parameterized function variants in VMSD struct - We need to have good error reporting in the callbacks in VMStateDescription struct. Specifically pre_save, pre_load and post_load callbacks. - It is not possible to change these functions everywhere in one patch, therefore, we introduce a duplicate set of callbacks with Error object passed to them. - So, in this commit, we implement 'errp' variants of these callbacks, introducing an explicit Error object parameter. - This is a functional step towards transitioning the entire codebase to the new error-parameterized functions. - Deliberately called in mutual exclusion from their counterparts, to prevent conflicts during the transition. - New impls should preferentally use 'errp' variants of these methods, and existing impls incrementally converted. The variants without 'errp' are intended to be removed once all usage is converted. Reviewed-by: Fabiano Rosas Signed-off-by: Arun Menon Tested-by: Fabiano Rosas Reviewed-by: Akihiko Odaki Link: https://lore.kernel.org/r/20250918-propagate_tpm_error-v14-26-36f11a6fb9d3@redhat.com Signed-off-by: Peter Xu --- docs/devel/migration/main.rst | 19 +++++++++++++++++++ include/migration/vmstate.h | 14 ++++++++++++++ migration/vmstate.c | 31 ++++++++++++++++++++++++++++--- 3 files changed, 61 insertions(+), 3 deletions(-) diff --git a/docs/devel/migration/main.rst b/docs/devel/migration/main.rst index 6493c1d2bca..1afe7b9689b 100644 --- a/docs/devel/migration/main.rst +++ b/docs/devel/migration/main.rst @@ -444,6 +444,25 @@ The functions to do that are inside a vmstate definition, and are called: This function is called after we save the state of one device (even upon failure, unless the call to pre_save returned an error). +Following are the errp variants of these functions. + +- ``int (*pre_load_errp)(void *opaque, Error **errp);`` + + This function is called before we load the state of one device. + +- ``int (*post_load_errp)(void *opaque, int version_id, Error **errp);`` + + This function is called after we load the state of one device. + +- ``int (*pre_save_errp)(void *opaque, Error **errp);`` + + This function is called before we save the state of one device. + +New impls should preferentally use 'errp' variants of these +methods and existing impls incrementally converted. +The variants without 'errp' are intended to be removed +once all usage is converted. + Example: You can look at hpet.c, that uses the first three functions to massage the state that is transferred. diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h index 5fe9bbf3905..5567fd78d04 100644 --- a/include/migration/vmstate.h +++ b/include/migration/vmstate.h @@ -200,14 +200,28 @@ struct VMStateDescription { * exclusive. For this reason, also early_setup VMSDs are migrated in a * QEMU_VM_SECTION_FULL section, while save_setup() data is migrated in * a QEMU_VM_SECTION_START section. + * + * There are duplicate impls of the post/pre save/load hooks. + * New impls should preferentally use 'errp' variants of these + * methods and existing impls incrementally converted. + * The variants without 'errp' are intended to be removed + * once all usage is converted. + * + * For the errp variants, + * Returns: 0 on success, + * <0 on error where -value is an error number from errno.h */ + bool early_setup; int version_id; int minimum_version_id; MigrationPriority priority; int (*pre_load)(void *opaque); + int (*pre_load_errp)(void *opaque, Error **errp); int (*post_load)(void *opaque, int version_id); + int (*post_load_errp)(void *opaque, int version_id, Error **errp); int (*pre_save)(void *opaque); + int (*pre_save_errp)(void *opaque, Error **errp); int (*post_save)(void *opaque); bool (*needed)(void *opaque); bool (*dev_unplug_pending)(void *opaque); diff --git a/migration/vmstate.c b/migration/vmstate.c index ad8e5b71ae2..81eadde553d 100644 --- a/migration/vmstate.c +++ b/migration/vmstate.c @@ -134,6 +134,7 @@ static void vmstate_handle_alloc(void *ptr, const VMStateField *field, int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd, void *opaque, int version_id, Error **errp) { + ERRP_GUARD(); const VMStateField *field = vmsd->fields; int ret = 0; @@ -152,7 +153,16 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd, trace_vmstate_load_state_end(vmsd->name, "too old", -EINVAL); return -EINVAL; } - if (vmsd->pre_load) { + if (vmsd->pre_load_errp) { + ret = vmsd->pre_load_errp(opaque, errp); + if (ret < 0) { + error_prepend(errp, "pre load hook failed for: '%s', " + "version_id: %d, minimum version_id: %d, " + "ret: %d: ", vmsd->name, vmsd->version_id, + vmsd->minimum_version_id, ret); + return ret; + } + } else if (vmsd->pre_load) { ret = vmsd->pre_load(opaque); if (ret) { error_setg(errp, "pre load hook failed for: '%s', " @@ -245,7 +255,14 @@ 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_errp) { + ret = vmsd->post_load_errp(opaque, version_id, errp); + if (ret < 0) { + error_prepend(errp, "post load hook failed for: %s, version_id: " + "%d, minimum_version: %d, ret: %d: ", vmsd->name, + vmsd->version_id, vmsd->minimum_version_id, ret); + } + } else if (vmsd->post_load) { ret = vmsd->post_load(opaque, version_id); if (ret < 0) { error_setg(errp, @@ -414,12 +431,20 @@ int vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd, int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd, void *opaque, JSONWriter *vmdesc, int version_id, Error **errp) { + ERRP_GUARD(); int ret = 0; const VMStateField *field = vmsd->fields; trace_vmstate_save_state_top(vmsd->name); - if (vmsd->pre_save) { + if (vmsd->pre_save_errp) { + ret = vmsd->pre_save_errp(opaque, errp); + trace_vmstate_save_state_pre_save_res(vmsd->name, ret); + if (ret < 0) { + error_prepend(errp, "pre-save for %s failed, ret: %d: ", + vmsd->name, ret); + } + } else if (vmsd->pre_save) { ret = vmsd->pre_save(opaque); trace_vmstate_save_state_pre_save_res(vmsd->name, ret); if (ret) { -- 2.47.3