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author | Markus Armbruster <armbru@redhat.com> | 2021-07-20 14:53:55 +0200 |
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committer | Markus Armbruster <armbru@redhat.com> | 2021-08-26 17:15:28 +0200 |
commit | d7f5013e122e14c6f5ac8d973e6567413cfa3790 (patch) | |
tree | c1a5034cf601d4f8eb19570dddba5963ea17b33d /hw/ppc | |
parent | e2ef4fc7aeb7e5856594f3172e08e6650011084a (diff) | |
download | qemu-d7f5013e122e14c6f5ac8d973e6567413cfa3790.zip qemu-d7f5013e122e14c6f5ac8d973e6567413cfa3790.tar.gz qemu-d7f5013e122e14c6f5ac8d973e6567413cfa3790.tar.bz2 |
spapr: Explain purpose of ->fwnmi_migration_blocker more clearly
spapr_mce_req_event() makes an effort to prevent migration from
degrading the reporting of FWNMIs. It adds a migration blocker when
it receives one, and deletes it when it's done handling it. This is a
best effort.
Commit 2500fb423a "migration: Include migration support for machine
check handling" tried to explain this in a comment. Rewrite the
comment for clarity, and reposition it to make it clear it applies to
all failure modes, not just "migration already in progress".
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Aravinda Prasad <arawinda.p@gmail.com>
Cc: Ganesh Goudar <ganeshgr@linux.ibm.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20210720125408.387910-4-armbru@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'hw/ppc')
-rw-r--r-- | hw/ppc/spapr_events.c | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/hw/ppc/spapr_events.c b/hw/ppc/spapr_events.c index 690533c..630e862 100644 --- a/hw/ppc/spapr_events.c +++ b/hw/ppc/spapr_events.c @@ -911,16 +911,17 @@ void spapr_mce_req_event(PowerPCCPU *cpu, bool recovered) } } + /* + * Try to block migration while FWNMI is being handled, so the + * machine check handler runs where the information passed to it + * actually makes sense. This shouldn't actually block migration, + * only delay it slightly, assuming migration is retried. If the + * attempt to block fails, carry on. Unfortunately, it always + * fails when running with -only-migrate. A proper interface to + * delay migration completion for a bit could avoid that. + */ ret = migrate_add_blocker(spapr->fwnmi_migration_blocker, NULL); if (ret == -EBUSY) { - /* - * We don't want to abort so we let the migration to continue. - * In a rare case, the machine check handler will run on the target. - * Though this is not preferable, it is better than aborting - * the migration or killing the VM. It is okay to call - * migrate_del_blocker on a blocker that was not added (which the - * nmi-interlock handler would do when it's called after this). - */ warn_report("Received a fwnmi while migration was in progress"); } |