[Qemu-devel] [PATCH v9 6/6] migration: Include migration support for machine check handling

[Aravinda Prasad]

This patch includes migration support for machine check
handling. Especially this patch blocks 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.c         |   20 ++++++++++++++++++++
 hw/ppc/spapr_events.c  |   17 +++++++++++++++++
 hw/ppc/spapr_rtas.c    |    4 ++++
 include/hw/ppc/spapr.h |    2 ++
 4 files changed, 43 insertions(+)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index e8a77636..31c4850 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -2104,6 +2104,25 @@ static const VMStateDescription vmstate_spapr_dtb = {
     },
 };
 
+static bool spapr_fwnmi_needed(void *opaque)
+{
+    SpaprMachineState *spapr = (SpaprMachineState *)opaque;
+
+    return (spapr->guest_machine_check_addr == -1) ? 0 : 1;
+}
+
+static const VMStateDescription vmstate_spapr_machine_check = {
+    .name = "spapr_machine_check",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = spapr_fwnmi_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT64(guest_machine_check_addr, SpaprMachineState),
+        VMSTATE_INT32(mc_status, SpaprMachineState),
+        VMSTATE_END_OF_LIST()
+    },
+};
+
 static const VMStateDescription vmstate_spapr = {
     .name = "spapr",
     .version_id = 3,
@@ -2137,6 +2156,7 @@ static const VMStateDescription vmstate_spapr = {
         &vmstate_spapr_dtb,
         &vmstate_spapr_cap_large_decr,
         &vmstate_spapr_cap_ccf_assist,
+        &vmstate_spapr_machine_check,
         NULL
     }
 };
diff --git a/hw/ppc/spapr_events.c b/hw/ppc/spapr_events.c
index 573c0b7..35e21e4 100644
--- a/hw/ppc/spapr_events.c
+++ b/hw/ppc/spapr_events.c
@@ -41,6 +41,7 @@
 #include "qemu/bcd.h"
 #include "hw/ppc/spapr_ovec.h"
 #include <libfdt.h>
+#include "migration/blocker.h"
 
 #define RTAS_LOG_VERSION_MASK                   0xff000000
 #define   RTAS_LOG_VERSION_6                    0x06000000
@@ -855,6 +856,22 @@ static void spapr_mce_dispatch_elog(PowerPCCPU *cpu, bool 
recovered)
 void spapr_mce_req_event(PowerPCCPU *cpu, bool recovered)
 {
     SpaprMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
+    int ret;
+    Error *local_err = NULL;
+
+    error_setg(&spapr->fwnmi_migration_blocker,
+            "Live migration not supported during machine check handling");
+    ret = migrate_add_blocker(spapr->fwnmi_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->fwnmi_migration_blocker);
+        warn_report_err(local_err);
+    }
 
     while (spapr->mc_status != -1) {
         /*
diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
index 91a7ab9..c849223 100644
--- a/hw/ppc/spapr_rtas.c
+++ b/hw/ppc/spapr_rtas.c
@@ -50,6 +50,7 @@
 #include "target/ppc/mmu-hash64.h"
 #include "target/ppc/mmu-book3s-v3.h"
 #include "kvm_ppc.h"
+#include "migration/blocker.h"
 
 static void rtas_display_character(PowerPCCPU *cpu, SpaprMachineState *spapr,
                                    uint32_t token, uint32_t nargs,
@@ -404,6 +405,9 @@ 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->fwnmi_migration_blocker);
+        error_free(spapr->fwnmi_migration_blocker);
+        spapr->fwnmi_migration_blocker = NULL;
     }
 }
 
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index bd75d4b..6c0cfd8 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -214,6 +214,8 @@ struct SpaprMachineState {
     SpaprCapabilities def, eff, mig;
 
     unsigned gpu_numa_id;
+
+    Error *fwnmi_migration_blocker;
 };
 
 #define H_SUCCESS         0