Excerpts from Laurent Dufour's message of June 27, 2022 11:53 pm:
> In pseries_migration_partition(), loop until the memory transfer is
> complete. This way the calling drmgr process will not exit earlier,
> allowing callbacks to be run only once the migration is fully completed.
>
> If reading the VASI state is done after the hypervisor has completed the
> migration, the HCALL is returning H_PARAMETER. We can safely assume that
> the memory transfer is achieved if this happens.
>
> This will also allow to manage the NMI watchdog state in the next commits.
>
> Reviewed-by: Nathan Lynch <nathanl@xxxxxxxxxxxxx>
> Signed-off-by: Laurent Dufour <ldufour@xxxxxxxxxxxxx>
> ---
> arch/powerpc/platforms/pseries/mobility.c | 42 +++++++++++++++++++++--
> 1 file changed, 40 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
> index 78f3f74c7056..907a779074d6 100644
> --- a/arch/powerpc/platforms/pseries/mobility.c
> +++ b/arch/powerpc/platforms/pseries/mobility.c
> @@ -427,6 +427,43 @@ static int wait_for_vasi_session_suspending(u64 handle)
> return ret;
> }
>
> +static void wait_for_vasi_session_completed(u64 handle)
> +{
> + unsigned long state = 0;
> + int ret;
> +
> + pr_info("waiting for memory transfert to complete...\n");
^ extra t (also below)
> +
> + /*
> + * Wait for transition from H_VASI_RESUMED to H_VASI_COMPLETED.
> + */
> + while (true) {
> + ret = poll_vasi_state(handle, &state);
> +
> + /*
> + * If the memory transfer is already complete and the migration
> + * has been cleaned up by the hypervisor, H_PARAMETER is return,
> + * which is translate in EINVAL by poll_vasi_state().
> + */
> + if (ret == -EINVAL || (!ret && state == H_VASI_COMPLETED)) {
> + pr_info("memory transfert completed.\n");
> + break;
> + }
> +
> + if (ret) {
> + pr_err("H_VASI_STATE return error (%d)\n", ret);
> + break;
> + }
> +
> + if (state != H_VASI_RESUMED) {
> + pr_err("unexpected H_VASI_STATE result %lu\n", state);
> + break;
> + }
> +
> + msleep(500);
Is 500 specified anywhere? Another caller uses 1000, and the other one
uses some backoff interval starting at 1ms...
> + }
> +}
> +
> static void prod_single(unsigned int target_cpu)
> {
> long hvrc;
> @@ -673,9 +710,10 @@ static int pseries_migrate_partition(u64 handle)
> vas_migration_handler(VAS_SUSPEND);
>
> ret = pseries_suspend(handle);
> - if (ret == 0)
> + if (ret == 0) {
> post_mobility_fixup();
> - else
> + wait_for_vasi_session_completed(handle);
If this wasn't required until later patches, maybe a comment about why
it's here? Could call it wait_for_migration() or similar too.
Looks okay though from my basic reading of PAPR.
Reviewed-by: Nicholas Piggin <npiggin@xxxxxxxxx>
> + } else
> pseries_cancel_migration(handle, ret);
>
> vas_migration_handler(VAS_RESUME);
> --
> 2.36.1
>
>
