[Qemu-devel] [PATCH v5 6/6] migration: Block migration while handling machine check

[Aravinda Prasad]

Block VM migration requests until the machine check
error handling is complete as (i) these errors are
specific to the source hardware and is irrelevant on
the target hardware, (ii) these errors cause data
corruption and should be handled before migration.

Signed-off-by: Aravinda Prasad <address@hidden>
---
 hw/ppc/spapr_rtas.c    |    3 +++
 include/hw/ppc/spapr.h |    2 ++
 target/ppc/kvm.c       |   17 +++++++++++++++++
 3 files changed, 22 insertions(+)

diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
index d017a67..17f6567 100644
--- a/hw/ppc/spapr_rtas.c
+++ b/hw/ppc/spapr_rtas.c
@@ -47,6 +47,7 @@
 #include "trace.h"
 #include "hw/ppc/fdt.h"
 #include "kvm_ppc.h"
+#include "migration/blocker.h"
 
 static void rtas_display_character(PowerPCCPU *cpu, sPAPRMachineState *spapr,
                                    uint32_t token, uint32_t nargs,
@@ -390,6 +391,8 @@ static void rtas_ibm_nmi_interlock(PowerPCCPU *cpu,
         spapr->mc_status = -1;
         qemu_cond_signal(&spapr->mc_delivery_cond);
         rtas_st(rets, 0, RTAS_OUT_SUCCESS);
+        migrate_del_blocker(spapr->migration_blocker);
+        error_free(spapr->migration_blocker);
     }
 }
 
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index a75e9cf..0890a44 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -7,6 +7,7 @@
 #include "hw/ppc/spapr_drc.h"
 #include "hw/mem/pc-dimm.h"
 #include "hw/ppc/spapr_ovec.h"
+#include "qapi/error.h"
 
 struct VIOsPAPRBus;
 struct sPAPRPHBState;
@@ -136,6 +137,7 @@ struct sPAPRMachineState {
     MemoryHotplugState hotplug_memory;
 
     const char *icp_type;
+    Error *migration_blocker;
 };
 
 #define H_SUCCESS         0
diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
index 59b3322..58de7ea 100644
--- a/target/ppc/kvm.c
+++ b/target/ppc/kvm.c
@@ -52,6 +52,7 @@
 #endif
 #include "elf.h"
 #include "sysemu/kvm_int.h"
+#include "migration/blocker.h"
 
 //#define DEBUG_KVM
 
@@ -2770,10 +2771,26 @@ int kvm_handle_nmi(PowerPCCPU *cpu, struct kvm_run *run)
     sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
     PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
     target_ulong msr = 0;
+    Error *local_err = NULL;
+    int ret;
     bool type, le;
 
     cpu_synchronize_state(CPU(cpu));
 
+    error_setg(&spapr->migration_blocker,
+            "Live migration not supported during machine check error 
handling");
+    ret = migrate_add_blocker(spapr->migration_blocker, &local_err);
+    if (ret < 0) {
+        /*
+         * We don't want to abort and let the migration to continue. In a
+         * rare case, the machine check handler will run on the target
+         * hardware. Though this is not preferable, it is better than aborting
+         * the migration or killing the VM.
+         */
+        error_free(spapr->migration_blocker);
+        fprintf(stderr, "Warning: Machine check during VM migration\n");
+    }
+
     /*
      * Properly set bits in MSR before we invoke the handler.
      * SRR0/1, DAR and DSISR are properly set by KVM