Re: [PATCH 18/20] qemu: Add support for parallel save and restore

On Thu, Aug 08, 2024 at 05:38:11PM -0600, Jim Fehlig via Devel wrote: > Add support for parallel save and restore by mapping libvirt's > "parallel-connections" parameter to QEMU's "multifd-channels" > migration parameter. > > Signed-off-by: Jim Fehlig <jfehlig(a)suse.com&gt; > --- > src/qemu/qemu_driver.c | 31 ++++++++++++++++++++----------- > src/qemu/qemu_migration_params.c | 25 +++++++++++++++++++++++-- > src/qemu/qemu_migration_params.h | 5 ++++- > 3 files changed, 47 insertions(+), 14 deletions(-) Unless I'm missing something, nothing in this patch is validating the the image is about to be written in v3 format with MAPPED_RAM set. We must reject VIR_DOMAIN_SAVE_PARALLEL if we're not using MAPPED_RAM. Likewise when restoring we must reject PARALLEL if the loaded image doesnt have MAPPED_RAM feature set.

> diff --git a/src/qemu/qemu_migration_params.c b/src/qemu/qemu_migration_params.c > index 8f6003005c..8c656af163 100644 > --- a/src/qemu/qemu_migration_params.c > +++ b/src/qemu/qemu_migration_params.c > @@ -788,7 +788,10 @@ qemuMigrationParamsFromFlags(virTypedParameterPtr params, > > > qemuMigrationParams * > -qemuMigrationParamsForSave(bool mappedRam, unsigned int flags) > +qemuMigrationParamsForSave(virTypedParameterPtr params, > + int nparams, > + bool mappedRam, > + unsigned int flags) > { > g_autoptr(qemuMigrationParams) saveParams = NULL; > > @@ -800,7 +803,25 @@ qemuMigrationParamsForSave(bool mappedRam, unsigned int flags) > return NULL; > if (virBitmapSetBit(saveParams->caps, QEMU_MIGRATION_CAP_MULTIFD) < 0) > return NULL; > - saveParams->params[QEMU_MIGRATION_PARAM_MULTIFD_CHANNELS].value.i = 1; > + > + if (flags & VIR_DOMAIN_SAVE_PARALLEL) { > + int nchannels; > + > + if (params && virTypedParamsGetInt(params, nparams, > + VIR_DOMAIN_SAVE_PARAM_PARALLEL_CONNECTIONS, > + &nchannels) < 0) > + return NULL; > + > + if (nchannels < 1) { > + virReportError(VIR_ERR_INVALID_ARG, "%s", > + _("number of parallel save channels cannot be less than 1")); > + return NULL; > + } > + > + saveParams->params[QEMU_MIGRATION_PARAM_MULTIFD_CHANNELS].value.i = nchannels; > + } else { > + saveParams->params[QEMU_MIGRATION_PARAM_MULTIFD_CHANNELS].value.i = 1; > + }