On Fri, May 05, 2017 at 05:47:44PM -0300, Daniel Henrique Barboza wrote: > To allow for a DIMM unplug event to resume its work if a migration > occurs in the middle of it, this patch migrates the non-empty > pending_dimm_unplugs QTAILQ that stores the DIMM information > that the spapr_lmb_release() callback uses. > > It was considered an apprach where the DIMM states would be restored > on the post-_load after a migration. The problem is that there is > no way of knowing, from the sPAPRMachineState, if a given DIMM is going > through an unplug process and the callback needs the updated DIMM State. > > We could migrate a flag indicating that there is an unplug event going > on for a certain DIMM, fetching this information from the start of the > spapr_del_lmbs call. But this would also require a scan on post_load to > figure out how many nr_lmbs are left. At this point we can just > migrate the nr_lmbs information as well, given that it is being calculated > at spapr_del_lmbs already, and spare a scanning/discovery in the > post-load. All that we need is inside the sPAPRDIMMState structure > that is added to the pending_dimm_unplugs queue at the start of the > spapr_del_lmbs, so it's convenient to just migrated this queue it if it's > not empty. > > Signed-off-by: Daniel Henrique Barboza <danie...@linux.vnet.ibm.com>
NACK.
As I believe I suggested previously, you can reconstruct this state on
the receiving side by doing a full scan of the DIMM and LMB DRC states.
> ---
> hw/ppc/spapr.c | 31 +++++++++++++++++++++++++++++++
> 1 file changed, 31 insertions(+)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index e190eb9..30f0b7b 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1437,6 +1437,36 @@ static bool version_before_3(void *opaque, int
> version_id)
> return version_id < 3;
> }
>
> +static bool spapr_pending_dimm_unplugs_needed(void *opaque)
> +{
> + sPAPRMachineState *spapr = (sPAPRMachineState *)opaque;
> + return !QTAILQ_EMPTY(&spapr->pending_dimm_unplugs);
> +}
> +
> +static const VMStateDescription vmstate_spapr_dimmstate = {
> + .name = "spapr_dimm_state",
> + .version_id = 1,
> + .minimum_version_id = 1,
> + .fields = (VMStateField[]) {
> + VMSTATE_UINT64(addr, sPAPRDIMMState),
> + VMSTATE_UINT32(nr_lmbs, sPAPRDIMMState),
> + VMSTATE_END_OF_LIST()
> + },
> +};
> +
> +static const VMStateDescription vmstate_spapr_pending_dimm_unplugs = {
> + .name = "spapr_pending_dimm_unplugs",
> + .version_id = 1,
> + .minimum_version_id = 1,
> + .needed = spapr_pending_dimm_unplugs_needed,
> + .fields = (VMStateField[]) {
> + VMSTATE_QTAILQ_V(pending_dimm_unplugs, sPAPRMachineState, 1,
> + vmstate_spapr_dimmstate, sPAPRDIMMState,
> + next),
> + VMSTATE_END_OF_LIST()
> + },
> +};
> +
> static bool spapr_ov5_cas_needed(void *opaque)
> {
> sPAPRMachineState *spapr = opaque;
> @@ -1535,6 +1565,7 @@ static const VMStateDescription vmstate_spapr = {
> .subsections = (const VMStateDescription*[]) {
> &vmstate_spapr_ov5_cas,
> &vmstate_spapr_patb_entry,
> + &vmstate_spapr_pending_dimm_unplugs,
> NULL
> }
> };
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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