[PATCH v1] s390x: kvm-unit-tests: a PONG device for Sub Channels tests

[Pierre Morel <pmorel@linux.ibm.com>]

The PONG device accept two commands: PONG_READ and PONG_WRITE
which allow to read from and write to an internal buffer of
1024 bytes.

The QEMU device is named ccw-pong.

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
---
 hw/s390x/Makefile.objs  |   1 +
 hw/s390x/ccw-pong.c     | 186 ++++++++++++++++++++++++++++++++++++++++++++++++
 include/hw/s390x/pong.h |  47 ++++++++++++
 3 files changed, 234 insertions(+)
 create mode 100644 hw/s390x/ccw-pong.c
 create mode 100644 include/hw/s390x/pong.h

diff --git a/hw/s390x/Makefile.objs b/hw/s390x/Makefile.objs
index ee91152..3a83438 100644
--- a/hw/s390x/Makefile.objs
+++ b/hw/s390x/Makefile.objs
@@ -32,6 +32,7 @@ obj-$(CONFIG_KVM) += tod-kvm.o
 obj-$(CONFIG_KVM) += s390-skeys-kvm.o
 obj-$(CONFIG_KVM) += s390-stattrib-kvm.o s390-mchk.o
 obj-y += s390-ccw.o
+obj-y += ccw-pong.o
 obj-y += ap-device.o
 obj-y += ap-bridge.o
 obj-y += s390-sei.o
diff --git a/hw/s390x/ccw-pong.c b/hw/s390x/ccw-pong.c
new file mode 100644
index 0000000..e7439d5
--- /dev/null
+++ b/hw/s390x/ccw-pong.c
@@ -0,0 +1,186 @@
+/*
+ * CCW PING-PONG
+ *
+ * Copyright 2019 IBM Corp.
+ * Author(s): Pierre Morel <pmorel@linux.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or (at
+ * your option) any later version. See the COPYING file in the top-level
+ * directory.
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qemu/module.h"
+#include "cpu.h"
+#include "exec/address-spaces.h"
+#include "hw/s390x/css.h"
+#include "hw/s390x/css-bridge.h"
+#include "hw/qdev-properties.h"
+#include "hw/s390x/pong.h"
+
+#define PONG_BUF_SIZE 0x1000
+static char buf[PONG_BUF_SIZE] = "Hello world\n";
+
+static inline int pong_rw(CCW1 *ccw, char *p, int len, bool dir)
+{
+    int ret;
+
+    ret = address_space_rw(&address_space_memory, ccw->cda,
+                           MEMTXATTRS_UNSPECIFIED,
+                           (unsigned char *)buf, len, dir);
+
+    return (ret == MEMTX_OK) ? -EIO : 0;
+}
+
+/* Handle READ ccw commands from guest */
+static int handle_payload_read(CcwPONGDevice *dev, CCW1 *ccw)
+{
+    CcwDevice *ccw_dev = CCW_DEVICE(dev);
+    int len;
+
+    if (!ccw->cda) {
+        return -EFAULT;
+    }
+
+    if (ccw->count > PONG_BUF_SIZE) {
+        len = PONG_BUF_SIZE;
+        ccw_dev->sch->curr_status.scsw.count = ccw->count - PONG_BUF_SIZE;
+    } else {
+        len = ccw->count;
+        ccw_dev->sch->curr_status.scsw.count = 0;
+    }
+
+    return pong_rw(ccw, buf, len, 1);
+}
+
+/*
+ * Handle WRITE ccw commands to write data to client
+ * The SCSW count is set to the number of bytes not transfered.
+ */
+static int handle_payload_write(CcwPONGDevice *dev, CCW1 *ccw)
+{
+    CcwDevice *ccw_dev = CCW_DEVICE(dev);
+    int len;
+
+    if (!ccw->cda) {
+        ccw_dev->sch->curr_status.scsw.count = ccw->count;
+        return -EFAULT;
+    }
+
+    if (ccw->count > PONG_BUF_SIZE) {
+        len = PONG_BUF_SIZE;
+        ccw_dev->sch->curr_status.scsw.count = ccw->count - PONG_BUF_SIZE;
+    } else {
+        len = ccw->count;
+        ccw_dev->sch->curr_status.scsw.count = 0;
+    }
+
+    return pong_rw(ccw, buf, len, 0);
+}
+
+static int pong_ccw_cb(SubchDev *sch, CCW1 ccw)
+{
+    int rc = 0;
+    CcwPONGDevice *dev = sch->driver_data;
+
+    switch (ccw.cmd_code) {
+    case PONG_WRITE:
+        rc = handle_payload_write(dev, &ccw);
+        break;
+    case PONG_READ:
+        rc = handle_payload_read(dev, &ccw);
+        break;
+    default:
+        rc = -ENOSYS;
+        break;
+    }
+
+    if (rc == -EIO) {
+        /* I/O error, specific devices generate specific conditions */
+        SCHIB *schib = &sch->curr_status;
+
+        sch->curr_status.scsw.dstat = SCSW_DSTAT_UNIT_CHECK;
+        sch->sense_data[0] = 0x40;    /* intervention-req */
+        schib->scsw.ctrl &= ~SCSW_ACTL_START_PEND;
+        schib->scsw.ctrl &= ~SCSW_CTRL_MASK_STCTL;
+        schib->scsw.ctrl |= SCSW_STCTL_PRIMARY | SCSW_STCTL_SECONDARY |
+                   SCSW_STCTL_ALERT | SCSW_STCTL_STATUS_PEND;
+    }
+    return rc;
+}
+
+static void pong_ccw_realize(DeviceState *ds, Error **errp)
+{
+    uint16_t chpid;
+    CcwPONGDevice *dev = CCW_PONG(ds);
+    CcwDevice *cdev = CCW_DEVICE(ds);
+    CCWDeviceClass *cdk = CCW_DEVICE_GET_CLASS(cdev);
+    SubchDev *sch;
+    Error *err = NULL;
+
+    sch = css_create_sch(cdev->devno, 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 = CCW_PONG_CU_TYPE;
+    css_sch_build_virtual_schib(sch, (uint8_t)chpid,
+                                CCW_PONG_CHPID_TYPE);
+    sch->do_subchannel_work = do_subchannel_work_virtual;
+    sch->ccw_cb = pong_ccw_cb;
+
+    cdk->realize(cdev, &err);
+    if (err) {
+        goto out_err;
+    }
+
+    css_reset_sch(sch);
+    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 pong_ccw_properties[] = {
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void pong_ccw_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->props = pong_ccw_properties;
+    dc->bus_type = TYPE_VIRTUAL_CSS_BUS;
+    dc->realize = pong_ccw_realize;
+    dc->hotpluggable = false;
+    set_bit(DEVICE_CATEGORY_DISPLAY, dc->categories);
+}
+
+static const TypeInfo pong_ccw_info = {
+    .name = TYPE_CCW_PONG,
+    .parent = TYPE_CCW_DEVICE,
+    .instance_size = sizeof(CcwPONGDevice),
+    .class_init = pong_ccw_class_init,
+    .class_size = sizeof(CcwPONGClass),
+};
+
+static void pong_ccw_register(void)
+{
+    type_register_static(&pong_ccw_info);
+}
+
+type_init(pong_ccw_register)
diff --git a/include/hw/s390x/pong.h b/include/hw/s390x/pong.h
new file mode 100644
index 0000000..6358e2d
--- /dev/null
+++ b/include/hw/s390x/pong.h
@@ -0,0 +1,47 @@
+/*
+ *  ccw-attached PONG definitions
+ *
+ * Copyright 2019 IBM Corp.
+ * Author(s): Pierre Morel <pmorel@linux.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or (at
+ * your option) any later version. See the COPYING file in the top-level
+ * directory.
+ */
+
+#ifndef HW_S390X_PONG_CCW_H
+#define HW_S390X_PONG_CCW_H
+
+#include "hw/sysbus.h"
+#include "hw/s390x/css.h"
+#include "hw/s390x/ccw-device.h"
+
+#define CCW_PONG_CU_TYPE 0x0007
+#define CCW_PONG_CHPID_TYPE 0x09
+
+#define TYPE_CCW_PONG "ccw-pong"
+
+/* Local Channel Commands */
+#define PONG_WRITE 0x21         /* Write */
+#define PONG_READ  0x22         /* Read buffer */
+
+#define CCW_PONG(obj) \
+     OBJECT_CHECK(CcwPONGDevice, (obj), TYPE_CCW_PONG)
+#define CCW_PONG_CLASS(klass) \
+     OBJECT_CLASS_CHECK(CcwPONGClass, (klass), TYPE_CCW_PONG)
+#define CCW_PONG_GET_CLASS(obj) \
+     OBJECT_GET_CLASS(CcwPONGClass, (obj), TYPE_CCW_PONG)
+
+typedef struct CcwPONGDevice {
+    CcwDevice parent_obj;
+} CcwPONGDevice;
+
+typedef struct CcwPONGClass {
+    CCWDeviceClass parent_class;
+
+    void (*init)(CcwPONGDevice *, Error **);
+    int (*read_payload)(CcwPONGDevice *);
+    int (*write_payload)(CcwPONGDevice *, uint8_t);
+} CcwPONGClass;
+
+#endif
-- 
2.7.4