Re: [PATCH v2 4/9] qemu: tpm: Pass --migration option to swtpm if supported

[Stefan Berger <stefanb@xxxxxxxxxxxxx>]

On 10/5/22 10:02, Stefan Berger wrote:
> Always pass the --migration option to swtpm, if swptm supports it (staring
> with v0.8). Always apply the 'release-lock-outgoing' parameter with this
> option and apply the 'incoming' parameter for incoming migration so that
> swtpm releases the file lock on the source side when the state is migrated
> and locks the file on the destination side when the state is received.
>
> If a started swtpm instance is capable of migrating with share storage
> then remember this with a flag in the virDomainTPMDef. This flag allows
> for modifications of the installed swtpm, such as installing a version
> that does not support migration with shared storage.
>
> Report an error if swtpm does not support the --migration option and an
> incoming migration across shared storage is requested.
>
> Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
> ---
>   src/conf/domain_conf.h    |  1 +
>   src/qemu/qemu_migration.c |  8 ++++++++
>   src/qemu/qemu_tpm.c       | 40 +++++++++++++++++++++++++++++++++++++++
>   src/qemu/qemu_tpm.h       |  3 +++
>   4 files changed, 52 insertions(+)
>
> diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
> index 352b88eae5..4f9b5c6686 100644
> --- a/src/conf/domain_conf.h
> +++ b/src/conf/domain_conf.h
> @@ -1461,6 +1461,7 @@ struct _virDomainTPMDef {
>               bool hassecretuuid;
>               bool persistent_state;
>               virBitmap *activePcrBanks;
> +            bool canMigrateWithSharedStorage;
>           } emulator;
>       } data;
>   };
> diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
> index efb27a24aa..431b1b0bcb 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"
> @@ -2789,6 +2790,13 @@ qemuMigrationSrcBegin(virConnectPtr conn,
>           goto cleanup;
>       }
>   
> +    if ((flags & VIR_MIGRATE_TPM_SHARED_STORAGE) &&
> +        !qemuTPMCanMigrateSharedStorage(vm->def)) {
> +        virReportError(VIR_ERR_NO_SUPPORT, "%s",
> +                       _("the running swtpm does not support migration with shared storage"));
> +        goto cleanup;
> +    }
> +
>       if (flags & VIR_MIGRATE_POSTCOPY_RESUME) {
>           ret = qemuMigrationSrcBeginResumePhase(conn, driver, vm, xmlin,
>                                                  cookieout, cookieoutlen, flags);
> diff --git a/src/qemu/qemu_tpm.c b/src/qemu/qemu_tpm.c
> index 07def3c840..fde15b7587 100644
> --- a/src/qemu/qemu_tpm.c
> +++ b/src/qemu/qemu_tpm.c
> @@ -644,6 +644,32 @@ qemuTPMEmulatorBuildCommand(virDomainTPMDef *tpm,
>           virCommandAddArgFormat(cmd, "pwdfd=%d,mode=aes-256-cbc", migpwdfile_fd);
>       }
>   
> +    /* If swtpm supports it, start it with --migration release-lock-outgoing
> +     * so it can migrate across shared storage if needed.
> +     */
> +    tpm->data.emulator.canMigrateWithSharedStorage = false;
> +    if (virTPMSwtpmCapsGet(VIR_TPM_SWTPM_FEATURE_CMDARG_MIGRATION)) {
> +        bool incoming = false;
> +
> +        if (incomingMigration && (flags & VIR_MIGRATE_TPM_SHARED_STORAGE))
> +            incoming = true;
> +        virCommandAddArg(cmd, "--migration");
> +        virCommandAddArgFormat(cmd, "release-lock-outgoing%s",
> +                               incoming ? ",incoming": "");
> +        tpm->data.emulator.canMigrateWithSharedStorage = true;



This flag  remembers the capability of swtpm that was started and allows to downgrade swtpm while the VM is running for example (which doesn't influence the running swtpm). When libvirt is restarted is unfortunately refuses to migrate the VM when --tpm-shared-storage is set up because this flag was forgotten. How would I persist this flag?


6/9 has wrong title... I will fix.

   Stefan