[PATCH 2/2] qemu: tpm: Remove TPM state after successful migration

[Michal Prívozník]

On 8/23/22 18:28, Stefan Berger wrote:
> This patch 'fixes' the behavior of the persistent_state TPM domain XML
> attribute that intends to preserve the state of the TPM but should not
> keep the state around on all the hosts a VM has been migrated to. It
> removes the TPM state directory structure from the source host upon
> successful migration when non-shared storage is used. Similarly, it
> removes it from the destination host upon migration failure when
> non-shared storage is used.
> 
> Signed-off-by: Stefan Berger <stefanb at linux.ibm.com>
> ---
>  src/qemu/qemu_migration.c | 14 +++++++++++---
>  src/qemu/qemu_tpm.h       | 12 ++++++++++++
>  2 files changed, 23 insertions(+), 3 deletions(-)
> 
> diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
> index 7f69991e2b..355a2cb5c7 100644
> --- a/src/qemu/qemu_migration.c
> +++ b/src/qemu/qemu_migration.c
> @@ -38,6 +38,7 @@
>  #include "qemu_security.h"
>  #include "qemu_slirp.h"
>  #include "qemu_block.h"
> +#include "qemu_tpm.h"
>  
>  #include "domain_audit.h"
>  #include "virlog.h"
> @@ -4006,6 +4007,7 @@ qemuMigrationSrcConfirm(virQEMUDriver *driver,
>      qemuMigrationJobPhase phase;
>      g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(driver);
>      qemuDomainObjPrivate *priv = vm->privateData;
> +    virDomainUndefineFlagsValues undefFlags = 0;
>      int ret = -1;
>  
>      VIR_DEBUG("vm=%p, flags=0x%x, cancelled=%d", vm, flags, cancelled);
> @@ -4054,7 +4056,9 @@ qemuMigrationSrcConfirm(virQEMUDriver *driver,
>              virDomainDeleteConfig(cfg->configDir, cfg->autostartDir, vm);
>              vm->persistent = 0;
>          }
> -        qemuDomainRemoveInactive(driver, vm, 0);
> +        if (!qemuTPMCheckKeepTPMStateMigrationSrcSuccess(vm))
> +            undefFlags |= VIR_DOMAIN_UNDEFINE_TPM;
> +        qemuDomainRemoveInactive(driver, vm, undefFlags);
>      }
>  
>   cleanup:
> @@ -6590,6 +6594,7 @@ qemuMigrationDstFinishActive(virQEMUDriver *driver,
>      virObjectEvent *event;
>      bool inPostCopy = false;
>      bool doKill = priv->job.phase != QEMU_MIGRATION_PHASE_FINISH_RESUME;
> +    virDomainUndefineFlagsValues undefFlags = 0;
>      int rc;
>  
>      VIR_DEBUG("vm=%p, flags=0x%lx, retcode=%d",
> @@ -6666,8 +6671,11 @@ qemuMigrationDstFinishActive(virQEMUDriver *driver,
>                                   jobPriv->migParams, priv->job.apiFlags);
>      }
>  
> -    if (!virDomainObjIsActive(vm))
> -        qemuDomainRemoveInactive(driver, vm, 0);
> +    if (!virDomainObjIsActive(vm)) {
> +        if (!qemuTPMCheckKeepTPMStateMigrationDstFailure(vm))
> +            undefFlags |= VIR_DOMAIN_UNDEFINE_TPM;
> +        qemuDomainRemoveInactive(driver, vm, undefFlags);
> +    }
>  
>      virErrorRestore(&orig_err);
>      return NULL;
> diff --git a/src/qemu/qemu_tpm.h b/src/qemu/qemu_tpm.h
> index f068f3ca5a..c5d8774f07 100644
> --- a/src/qemu/qemu_tpm.h
> +++ b/src/qemu/qemu_tpm.h
> @@ -56,3 +56,15 @@ int qemuExtTPMSetupCgroup(virQEMUDriver *driver,
>                            virCgroup *cgroup)
>      ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(3)
>      G_GNUC_WARN_UNUSED_RESULT;
> +
> +static inline bool
> +qemuTPMCheckKeepTPMStateMigrationSrcSuccess(virDomainObj *vm G_GNUC_UNUSED)
> +{
> +    return false;
> +}
> +
> +static inline bool
> +qemuTPMCheckKeepTPMStateMigrationDstFailure(virDomainObj *vm G_GNUC_UNUSED)
> +{
> +    return false;
> +}

Yeah, I know where you're headed with these two, but G_GNUC_UNUSED
breaks syntax-check. And they can be added in shared storage state series.

Michal