s390x/flic: introduce modify_ais_mode callback

In order to emulate the adapter interruption suppression (AIS)
facility properly, the guest needs to be able to modify the AIS mask.
Interrupt suppression will be handled via the flic (for kvm, via a
recently introduced kernel backend; for !kvm, in the flic code), so
let's introduce a method to change the mode via the flic interface.

We introduce the 'simm' and 'nimm' fields to QEMUS390FLICState
to store interruption modes for each ISC. Each bit in 'simm' and
'nimm' targets one ISC, and collaboratively indicate three modes:
ALL-Interruptions, SINGLE-Interruption and NO-Interruptions. This
interface can initiate most transitions between the states; transition
from SINGLE-Interruption to NO-Interruptions via adapter interrupt
injection will be introduced in a following patch. The meaningful
combinations are as follows:

    interruption mode | simm bit | nimm bit
    ------------------|----------|----------
             ALL      |    0     |     0
           SINGLE     |    1     |     0
             NO       |    1     |     1

Co-authored-by: Yi Min Zhao <zyimin@linux.vnet.ibm.com>
Signed-off-by: Yi Min Zhao <zyimin@linux.vnet.ibm.com>
Signed-off-by: Fei Li <sherrylf@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

3 files changed, 80 insertions, 2 deletions

diff --git a/hw/intc/s390_flic.c b/hw/intc/s390_flic.c
index d3938b332b..ce7f355248 100644
--- a/hw/intc/s390_flic.c
+++ b/hw/intc/s390_flic.c
@@ -79,15 +79,47 @@ static int qemu_s390_clear_io_flic(S390FLICState *fs, uint16_t subchannel_id,
     return -ENOSYS;
 }
 
+static int qemu_s390_modify_ais_mode(S390FLICState *fs, uint8_t isc,
+                                     uint16_t mode)
+{
+    QEMUS390FLICState *flic  = QEMU_S390_FLIC(fs);
+
+    switch (mode) {
+    case SIC_IRQ_MODE_ALL:
+        flic->simm &= ~AIS_MODE_MASK(isc);
+        flic->nimm &= ~AIS_MODE_MASK(isc);
+        break;
+    case SIC_IRQ_MODE_SINGLE:
+        flic->simm |= AIS_MODE_MASK(isc);
+        flic->nimm &= ~AIS_MODE_MASK(isc);
+        break;
+    default:
+        return -EINVAL;
+    }
+
+    return 0;
+}
+
+static void qemu_s390_flic_reset(DeviceState *dev)
+{
+    QEMUS390FLICState *flic = QEMU_S390_FLIC(dev);
+
+    flic->simm = 0;
+    flic->nimm = 0;
+}
+
 static void qemu_s390_flic_class_init(ObjectClass *oc, void *data)
 {
+    DeviceClass *dc = DEVICE_CLASS(oc);
     S390FLICStateClass *fsc = S390_FLIC_COMMON_CLASS(oc);
 
+    dc->reset = qemu_s390_flic_reset;
     fsc->register_io_adapter = qemu_s390_register_io_adapter;
     fsc->io_adapter_map = qemu_s390_io_adapter_map;
     fsc->add_adapter_routes = qemu_s390_add_adapter_routes;
     fsc->release_adapter_routes = qemu_s390_release_adapter_routes;
     fsc->clear_io_irq = qemu_s390_clear_io_flic;
+    fsc->modify_ais_mode = qemu_s390_modify_ais_mode;
 }
 
 static Property s390_flic_common_properties[] = {
@@ -98,12 +130,15 @@ static Property s390_flic_common_properties[] = {
 
 static void s390_flic_common_realize(DeviceState *dev, Error **errp)
 {
-    uint32_t max_batch = S390_FLIC_COMMON(dev)->adapter_routes_max_batch;
+    S390FLICState *fs = S390_FLIC_COMMON(dev);
+    uint32_t max_batch = fs->adapter_routes_max_batch;
 
     if (max_batch > ADAPTER_ROUTES_MAX_GSI) {
         error_setg(errp, "flic property adapter_routes_max_batch too big"
                    " (%d > %d)", max_batch, ADAPTER_ROUTES_MAX_GSI);
     }
+
+    fs->ais_supported = true;
 }
 
 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 15ff534fd1..55aa35fc6a 100644
--- a/hw/intc/s390_flic_kvm.c
+++ b/hw/intc/s390_flic_kvm.c
@@ -20,6 +20,7 @@
 #include "sysemu/kvm.h"
 #include "hw/s390x/s390_flic.h"
 #include "hw/s390x/adapter.h"
+#include "hw/s390x/css.h"
 #include "trace.h"
 
 #define FLIC_SAVE_INITIAL_SIZE getpagesize()
@@ -149,6 +150,26 @@ static int kvm_s390_clear_io_flic(S390FLICState *fs, uint16_t subchannel_id,
     return rc ? -errno : 0;
 }
 
+static int kvm_s390_modify_ais_mode(S390FLICState *fs, uint8_t isc,
+                                    uint16_t mode)
+{
+    KVMS390FLICState *flic = KVM_S390_FLIC(fs);
+    struct kvm_s390_ais_req req = {
+        .isc = isc,
+        .mode = mode,
+    };
+    struct kvm_device_attr attr = {
+        .group = KVM_DEV_FLIC_AISM,
+        .addr = (uint64_t)&req,
+    };
+
+    if (!fs->ais_supported) {
+        return -ENOSYS;
+    }
+
+    return ioctl(flic->fd, KVM_SET_DEVICE_ATTR, &attr) ? -errno : 0;
+}
+
 /**
  * __get_all_irqs - store all pending irqs in buffer
  * @flic: pointer to flic device state
@@ -406,6 +427,7 @@ typedef struct KVMS390FLICStateClass {
 
 static void kvm_s390_flic_realize(DeviceState *dev, Error **errp)
 {
+    S390FLICState *fs = S390_FLIC_COMMON(dev);
     KVMS390FLICState *flic_state = KVM_S390_FLIC(dev);
     struct kvm_create_device cd = {0};
     struct kvm_device_attr test_attr = {0};
@@ -438,6 +460,7 @@ static void kvm_s390_flic_realize(DeviceState *dev, Error **errp)
     flic_state->clear_io_supported = !ioctl(flic_state->fd,
                                             KVM_HAS_DEVICE_ATTR, test_attr);
 
+    fs->ais_supported = false;
     return;
 fail:
     error_propagate(errp, errp_local);
@@ -446,10 +469,12 @@ fail:
 static void kvm_s390_flic_reset(DeviceState *dev)
 {
     KVMS390FLICState *flic = KVM_S390_FLIC(dev);
+    S390FLICState *fs = S390_FLIC_COMMON(dev);
     struct kvm_device_attr attr = {
         .group = KVM_DEV_FLIC_CLEAR_IRQS,
     };
     int rc = 0;
+    uint8_t isc;
 
     if (flic->fd == -1) {
         return;
@@ -457,6 +482,16 @@ static void kvm_s390_flic_reset(DeviceState *dev)
 
     flic_disable_wait_pfault(flic);
 
+    if (fs->ais_supported) {
+        for (isc = 0; isc <= MAX_ISC; isc++) {
+            rc = kvm_s390_modify_ais_mode(fs, isc, SIC_IRQ_MODE_ALL);
+            if (rc) {
+                error_report("Failed to reset ais mode for isc %d: %s",
+                             isc, strerror(-rc));
+            }
+        }
+    }
+
     rc = ioctl(flic->fd, KVM_SET_DEVICE_ATTR, &attr);
     if (rc) {
         trace_flic_reset_failed(errno);
@@ -479,6 +514,7 @@ static void kvm_s390_flic_class_init(ObjectClass *oc, void *data)
     fsc->add_adapter_routes = kvm_s390_add_adapter_routes;
     fsc->release_adapter_routes = kvm_s390_release_adapter_routes;
     fsc->clear_io_irq = kvm_s390_clear_io_flic;
+    fsc->modify_ais_mode = kvm_s390_modify_ais_mode;
 }
 
 static const TypeInfo kvm_s390_flic_info = {
diff --git a/include/hw/s390x/s390_flic.h b/include/hw/s390x/s390_flic.h
index d4145ad8eb..f500184794 100644
--- a/include/hw/s390x/s390_flic.h
+++ b/include/hw/s390x/s390_flic.h
@@ -44,7 +44,7 @@ typedef struct S390FLICState {
     SysBusDevice parent_obj;
     /* to limit AdapterRoutes.num_routes for compat */
     uint32_t adapter_routes_max_batch;
-
+    bool ais_supported;
 } S390FLICState;
 
 #define S390_FLIC_COMMON_CLASS(klass) \
@@ -63,6 +63,7 @@ typedef struct S390FLICStateClass {
     void (*release_adapter_routes)(S390FLICState *fs, AdapterRoutes *routes);
     int (*clear_io_irq)(S390FLICState *fs, uint16_t subchannel_id,
                         uint16_t subchannel_nr);
+    int (*modify_ais_mode)(S390FLICState *fs, uint8_t isc, uint16_t mode);
 } S390FLICStateClass;
 
 #define TYPE_KVM_S390_FLIC "s390-flic-kvm"
@@ -73,8 +74,14 @@ typedef struct S390FLICStateClass {
 #define QEMU_S390_FLIC(obj) \
     OBJECT_CHECK(QEMUS390FLICState, (obj), TYPE_QEMU_S390_FLIC)
 
+#define SIC_IRQ_MODE_ALL 0
+#define SIC_IRQ_MODE_SINGLE 1
+#define AIS_MODE_MASK(isc) (0x80 >> isc)
+
 typedef struct QEMUS390FLICState {
     S390FLICState parent_obj;
+    uint8_t simm;
+    uint8_t nimm;
 } QEMUS390FLICState;
 
 void s390_flic_init(void);