Re: [PATCH v3 1/4] powerpc/mobility: wait for memory transfer to complete
From: Nicholas Piggin <npiggin@gmail.com>
Date: 2022-07-12 01:33:24
Also in:
linux-watchdog, lkml
Excerpts from Laurent Dufour's message of June 27, 2022 11:53 pm:
quoted hunk ↗ jump to hunk
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 <redacted> Signed-off-by: Laurent Dufour <redacted> --- 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...
quoted hunk ↗ jump to hunk
+ } +} + 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@gmail.com>
+ } else pseries_cancel_migration(handle, ret); vas_migration_handler(VAS_RESUME); -- 2.36.1