[Qemu-devel] [PATCH 5/5] s390x/ccs: add ccw-tester emulated device

[Halil Pasic <pasic@linux.vnet.ibm.com>]

Add a fake device meant for testing the correctness of our css emulation.

What we currently have is writing a Fibonacci sequence of uint32_t to the
device via ccw write. The write is going to fail if it ain't a Fibonacci
and indicate a device exception in scsw together with the proper residual
count.

Of course lot's of invalid inputs (besides basic data processing) can be
tested with that as well.

Usage:
1) fire up a qemu with something like -device ccw-tester,devno=fe.0.0001
   on the command line
2) exercise the device from the guest

Signed-off-by: Halil Pasic <pasic@linux.vnet.ibm.com>
---

It may not make sense to merge this work in the current form, as it is
solely for test purposes.
---
 hw/s390x/Makefile.objs |   1 +
 hw/s390x/ccw-tester.c  | 179 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 180 insertions(+)
 create mode 100644 hw/s390x/ccw-tester.c

diff --git a/hw/s390x/Makefile.objs b/hw/s390x/Makefile.objs
index b2aade2466..44a07431da 100644
--- a/hw/s390x/Makefile.objs
+++ b/hw/s390x/Makefile.objs
@@ -17,3 +17,4 @@ obj-y += s390-stattrib.o
 obj-$(CONFIG_KVM) += s390-skeys-kvm.o
 obj-$(CONFIG_KVM) += s390-stattrib-kvm.o
 obj-y += s390-ccw.o
+obj-y += ccw-tester.o
diff --git a/hw/s390x/ccw-tester.c b/hw/s390x/ccw-tester.c
new file mode 100644
index 0000000000..c8017818c4
--- /dev/null
+++ b/hw/s390x/ccw-tester.c
@@ -0,0 +1,179 @@
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qemu/module.h"
+#include "cpu.h"
+#include "hw/s390x/css.h"
+#include "hw/s390x/css-bridge.h"
+#include "hw/s390x/3270-ccw.h"
+#include "exec/address-spaces.h"
+#include <error.h>
+
+typedef struct CcwTesterDevice {
+    CcwDevice parent_obj;
+    uint16_t cu_type;
+    uint8_t chpid_type;
+    struct {
+        uint32_t ring[4];
+        unsigned int next;
+    } fib;
+} CcwTesterDevice;
+
+
+typedef struct CcwTesterClass {
+    CCWDeviceClass parent_class;
+    DeviceRealize parent_realize;
+} CcwTesterClass;
+
+#define TYPE_CCW_TESTER "ccw-tester"
+
+#define CCW_TESTER(obj) \
+     OBJECT_CHECK(CcwTesterDevice, (obj), TYPE_CCW_TESTER)
+#define CCW_TESTER_CLASS(klass) \
+     OBJECT_CLASS_CHECK(CcwTesterClass, (klass), TYPE_CCW_TESTER)
+#define CCW_TESTER_GET_CLASS(obj) \
+     OBJECT_GET_CLASS(CcwTesterClass, (obj), TYPE_CCW_TESTER)
+
+#define CCW_CMD_READ 0x01U
+#define CCW_CMD_WRITE 0x02U
+
+static unsigned int abs_to_ring(unsigned int i)
+{
+    return i & 0x3;
+}
+
+static int  ccw_tester_write_fib(SubchDev *sch, CCW1 ccw)
+{
+    CcwTesterDevice *d = sch->driver_data;
+    bool is_fib = true;
+    uint32_t sum;
+    int ret = 0;
+
+    ccw_dstream_init(&sch->cds, &ccw, &sch->orb);
+    d->fib.next = 0;
+    while (ccw_dstream_avail(&sch->cds) > 0) {
+        ret = ccw_dstream_read(&sch->cds,
+                               d->fib.ring[abs_to_ring(d->fib.next)]);
+        if (ret) {
+            error(0, -ret, "fib");
+            break;
+        }
+        if (d->fib.next > 2) {
+            sum = (d->fib.ring[abs_to_ring(d->fib.next - 1)]
+                  + d->fib.ring[abs_to_ring(d->fib.next - 2)]);
+            is_fib = sum ==  d->fib.ring[abs_to_ring(d->fib.next)];
+            if (!is_fib) {
+                break;
+            }
+        }
+        ++(d->fib.next);
+    }
+    if (!is_fib) {
+        sch->curr_status.scsw.ctrl &= ~SCSW_ACTL_START_PEND;
+        sch->curr_status.scsw.ctrl |= SCSW_STCTL_PRIMARY |
+                                      SCSW_STCTL_SECONDARY |
+                                      SCSW_STCTL_ALERT |
+                                      SCSW_STCTL_STATUS_PEND;
+        sch->curr_status.scsw.count = ccw_dstream_residual_count(&sch->cds);
+        sch->curr_status.scsw.cpa = sch->channel_prog + 8;
+        sch->curr_status.scsw.dstat =  SCSW_DSTAT_UNIT_EXCEP;
+        return -EIO;
+    }
+    return ret;
+}
+
+static int ccw_tester_ccw_cb_impl(SubchDev *sch, CCW1 ccw)
+{
+    switch (ccw.cmd_code) {
+    case CCW_CMD_READ:
+        break;
+    case CCW_CMD_WRITE:
+        return ccw_tester_write_fib(sch, ccw);
+    default:
+        return -EINVAL;
+    }
+    return 0;
+}
+
+static void ccw_tester_realize(DeviceState *ds, Error **errp)
+{
+    uint16_t chpid;
+    CcwTesterDevice *dev = CCW_TESTER(ds);
+    CcwTesterClass *ctc = CCW_TESTER_GET_CLASS(dev);
+    CcwDevice *cdev = CCW_DEVICE(ds);
+    BusState *qbus = qdev_get_parent_bus(ds);
+    VirtualCssBus *cbus = VIRTUAL_CSS_BUS(qbus);
+    SubchDev *sch;
+    Error *err = NULL;
+
+    sch = css_create_sch(cdev->devno, true, cbus->squash_mcss, errp);
+    if (!sch) {
+        return;
+    }
+
+    sch->driver_data = dev;
+    cdev->sch = sch;
+    chpid = css_find_free_chpid(sch->cssid);
+
+    if (chpid > MAX_CHPID) {
+        error_setg(&err, "No available chpid to use.");
+        goto out_err;
+    }
+
+    sch->id.reserved = 0xff;
+    sch->id.cu_type = dev->cu_type;
+    css_sch_build_virtual_schib(sch, (uint8_t)chpid,
+                                dev->chpid_type);
+    sch->ccw_cb = ccw_tester_ccw_cb_impl;
+    sch->do_subchannel_work = do_subchannel_work_virtual;
+
+
+    ctc->parent_realize(ds, &err);
+    if (err) {
+        goto out_err;
+    }
+
+    css_generate_sch_crws(sch->cssid, sch->ssid, sch->schid,
+                          ds->hotplugged, 1);
+    return;
+
+out_err:
+    error_propagate(errp, err);
+    css_subch_assign(sch->cssid, sch->ssid, sch->schid, sch->devno, NULL);
+    cdev->sch = NULL;
+    g_free(sch);
+}
+
+static Property ccw_tester_properties[] = {
+    DEFINE_PROP_UINT16("cu_type", CcwTesterDevice, cu_type,
+                        0x3831),
+    DEFINE_PROP_UINT8("chpid_type", CcwTesterDevice, chpid_type,
+                       0x98),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void ccw_tester_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    CcwTesterClass *ctc = CCW_TESTER_CLASS(klass);
+
+    dc->props = ccw_tester_properties;
+    dc->bus_type = TYPE_VIRTUAL_CSS_BUS;
+    ctc->parent_realize = dc->realize;
+    dc->realize = ccw_tester_realize;
+    dc->hotpluggable = false;
+}
+
+static const TypeInfo ccw_tester_info = {
+    .name = TYPE_CCW_TESTER,
+    .parent = TYPE_CCW_DEVICE,
+    .instance_size = sizeof(CcwTesterDevice),
+    .class_init = ccw_tester_class_init,
+    .class_size = sizeof(CcwTesterClass),
+};
+
+static void ccw_tester_register(void)
+{
+    type_register_static(&ccw_tester_info);
+}
+
+type_init(ccw_tester_register)
-- 
2.13.5