Le 12/07/2022 à 03:33, Nicholas Piggin a écrit :
> 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 <nath...@linux.ibm.com>
>> Signed-off-by: Laurent Dufour <lduf...@linux.ibm.com>
>> ---
>> 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)
I tried to push one French word, but you caught it ;)
Will fix that and the other ones.
>> +
>> + /*
>> + * 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...
This is a bit empiric, the idea is to wait for the overall memory transfer
to be done. There is no real need to interact immediately after the
operation is terminated, so I pick that value to not make too many Hcalls
just for that. From the test I did, that seems to be a reasonable choice.
>
>> + }
>> +}
>> +
>> 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 <npig...@gmail.com>
Thanks Nick for reviewing this series.
>
>> + } else
>> pseries_cancel_migration(handle, ret);
>>
>> vas_migration_handler(VAS_RESUME);
>> --
>> 2.36.1
>>
>>
