Merge remote-tracking branch 'remotes/armbru/tags/pull-error-2021-08-26' into staging

Error reporting patches for 2021-08-26

# gpg: Signature made Thu 26 Aug 2021 16:17:05 BST
# gpg:                using RSA key 354BC8B3D7EB2A6B68674E5F3870B400EB918653
# gpg:                issuer "armbru@redhat.com"
# gpg: Good signature from "Markus Armbruster <armbru@redhat.com>" [full]
# gpg:                 aka "Markus Armbruster <armbru@pond.sub.org>" [full]
# Primary key fingerprint: 354B C8B3 D7EB 2A6B 6867  4E5F 3870 B400 EB91 8653

* remotes/armbru/tags/pull-error-2021-08-26:
  vl: Clean up -smp error handling
  Remove superfluous ERRP_GUARD()
  vhost: Clean up how VhostOpts method vhost_backend_init() fails
  vhost: Clean up how VhostOpts method vhost_get_config() fails
  microvm: Drop dead error handling in microvm_machine_state_init()
  migration: Handle migration_incoming_setup() errors consistently
  migration: Unify failure check for migrate_add_blocker()
  whpx nvmm: Drop useless migrate_del_blocker()
  vfio: Avoid error_propagate() after migrate_add_blocker()
  i386: Never free migration blocker objects instead of sometimes
  vhost-scsi: Plug memory leak on migrate_add_blocker() failure
  multi-process: Fix pci_proxy_dev_realize() error handling
  spapr: Explain purpose of ->fwnmi_migration_blocker more clearly
  spapr: Plug memory leak when we can't add a migration blocker
  error: Use error_fatal to simplify obvious fatal errors (again)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 10 insertions, 10 deletions

diff --git a/hw/ppc/spapr_events.c b/hw/ppc/spapr_events.c
index 23e2e2fff1..630e86282c 100644
--- a/hw/ppc/spapr_events.c
+++ b/hw/ppc/spapr_events.c
@@ -872,7 +872,6 @@ void spapr_mce_req_event(PowerPCCPU *cpu, bool recovered)
     SpaprMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
     CPUState *cs = CPU(cpu);
     int ret;
-    Error *local_err = NULL;
 
     if (spapr->fwnmi_machine_check_addr == -1) {
         /* Non-FWNMI case, deliver it like an architected CPU interrupt. */
@@ -912,16 +911,17 @@ void spapr_mce_req_event(PowerPCCPU *cpu, bool recovered)
         }
     }
 
-    ret = migrate_add_blocker(spapr->fwnmi_migration_blocker, &local_err);
+    /*
+     * 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");
     }