[Qemu-devel] [PATCH/RFC 2/3] s390x/ais: enable ais when migration is available

[Christian Borntraeger]

Instead of unconditionally enabling the KVM AIS capability
in the kvm arch init function, do this in the flic realize function
when we know if migration is available. This requires to initialize
flic before the CPUs.

Signed-off-by: Christian Borntraeger <address@hidden>
---
 hw/intc/s390_flic.c          | 11 +++++++++--
 hw/intc/s390_flic_kvm.c      |  8 +++++++-
 hw/s390x/s390-virtio-ccw.c   |  8 ++++++--
 include/hw/s390x/s390_flic.h |  1 +
 target/s390x/cpu_models.c    |  6 ++++++
 target/s390x/kvm.c           |  8 +-------
 6 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/hw/intc/s390_flic.c b/hw/intc/s390_flic.c
index 6eaf178..08040fe 100644
--- a/hw/intc/s390_flic.c
+++ b/hw/intc/s390_flic.c
@@ -1,7 +1,7 @@
 /*
  * QEMU S390x floating interrupt controller (flic)
  *
- * Copyright 2014 IBM Corp.
+ * Copyright 2014,2017 IBM Corp.
  * Author(s): Jens Freimann <address@hidden>
  *            Cornelia Huck <address@hidden>
  *
@@ -49,6 +49,13 @@ void s390_flic_init(void)
     qdev_init_nofail(dev);
 }
 
+void s390_flic_enable_ais(void)
+{
+    S390FLICState *fs = s390_get_flic();
+
+    fs->ais_supported = true;
+}
+
 static int qemu_s390_register_io_adapter(S390FLICState *fs, uint32_t id,
                                          uint8_t isc, bool swap,
                                          bool is_maskable, uint8_t flags)
@@ -186,7 +193,7 @@ static void s390_flic_common_realize(DeviceState *dev, 
Error **errp)
         return;
     }
 
-    fs->ais_supported = s390_has_feat(S390_FEAT_ADAPTER_INT_SUPPRESSION);
+    fs->ais_supported = false;
 }
 
 static void s390_flic_class_init(ObjectClass *oc, void *data)
diff --git a/hw/intc/s390_flic_kvm.c b/hw/intc/s390_flic_kvm.c
index 7ead17a..a655567 100644
--- a/hw/intc/s390_flic_kvm.c
+++ b/hw/intc/s390_flic_kvm.c
@@ -1,7 +1,7 @@
 /*
  * QEMU S390x KVM floating interrupt controller (flic)
  *
- * Copyright 2014 IBM Corp.
+ * Copyright 2014,2017 IBM Corp.
  * Author(s): Jens Freimann <address@hidden>
  *            Cornelia Huck <address@hidden>
  *
@@ -557,6 +557,12 @@ static void kvm_s390_flic_realize(DeviceState *dev, Error 
**errp)
     test_attr.group = KVM_DEV_FLIC_CLEAR_IO_IRQ;
     flic_state->clear_io_supported = !ioctl(flic_state->fd,
                                             KVM_HAS_DEVICE_ATTR, test_attr);
+    /* try enable the AIS facility */
+    test_attr.group = KVM_DEV_FLIC_AISM_ALL;
+    if (!ioctl(flic_state->fd, KVM_HAS_DEVICE_ATTR, test_attr)) {
+            kvm_vm_enable_cap(kvm_state, KVM_CAP_S390_AIS, 0);
+    }
+
     return;
 fail:
     error_propagate(errp, errp_local);
diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
index fafbc6d..11d4dc4 100644
--- a/hw/s390x/s390-virtio-ccw.c
+++ b/hw/s390x/s390-virtio-ccw.c
@@ -279,11 +279,15 @@ static void ccw_init(MachineState *machine)
     s390_sclp_init();
     s390_memory_init(machine->ram_size);
 
+    /*
+     * This might also enable some KVM features like AIS, so it must
+     * be called before the CPU model
+     */
+    s390_flic_init();
+
     /* init CPUs (incl. CPU model) early so s390_has_feature() works */
     s390_init_cpus(machine);
 
-    s390_flic_init();
-
     /* get a BUS */
     css_bus = virtual_css_bus_init();
     s390_init_ipl_dev(machine->kernel_filename, machine->kernel_cmdline,
diff --git a/include/hw/s390x/s390_flic.h b/include/hw/s390x/s390_flic.h
index 7aab6ef..ac4e170 100644
--- a/include/hw/s390x/s390_flic.h
+++ b/include/hw/s390x/s390_flic.h
@@ -90,6 +90,7 @@ void s390_flic_init(void);
 
 S390FLICState *s390_get_flic(void);
 bool ais_needed(void *opaque);
+void s390_flic_enable_ais(void);
 
 #ifdef CONFIG_KVM
 DeviceState *s390_flic_kvm_create(void);
diff --git a/target/s390x/cpu_models.c b/target/s390x/cpu_models.c
index 5169379..03ff583 100644
--- a/target/s390x/cpu_models.c
+++ b/target/s390x/cpu_models.c
@@ -23,6 +23,7 @@
 #include "qapi/qobject-input-visitor.h"
 #include "qapi/qmp/qbool.h"
 #ifndef CONFIG_USER_ONLY
+#include "hw/s390x/s390_flic.h"
 #include "sysemu/arch_init.h"
 #endif
 
@@ -901,6 +902,11 @@ static inline void apply_cpu_model(const S390CPUModel 
*model, Error **errp)
             applied_model = *model;
         }
     }
+
+    if (model &&
+        test_bit(S390_FEAT_ADAPTER_INT_SUPPRESSION, model->features)) {
+        s390_flic_enable_ais();
+    }
 #endif
 }
 
diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
index ebb75ca..6c5c57e 100644
--- a/target/s390x/kvm.c
+++ b/target/s390x/kvm.c
@@ -311,13 +311,7 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
         }
     }
 
-    /*
-     * The migration interface for ais was introduced with kernel 4.13
-     * but the capability itself had been active since 4.12. As migration
-     * support is considered necessary let's disable ais in the 2.10
-     * machine.
-     */
-    /* kvm_vm_enable_cap(s, KVM_CAP_S390_AIS, 0); */
+    /* The AIS enablement happens in the flic realize */
 
     qemu_mutex_init(&qemu_sigp_mutex);
 
-- 
2.9.4