[Qemu-devel] [PATCH v4 06/16] vfio: ccw: register vfio_ccw to the mediated device framework

[Dong Jia Shi]

To make vfio support subchannel devices, we need to leverage the
mediated device framework to create a mediated device for the
subchannel device.

This registers the subchannel device to the mediated device
framework during probe to enable mediated device creation.

Reviewed-by: Pierre Morel <address@hidden>
Signed-off-by: Dong Jia Shi <address@hidden>
---
 arch/s390/Kconfig                   |   2 +-
 drivers/s390/cio/Makefile           |   2 +-
 drivers/s390/cio/vfio_ccw_drv.c     |  12 ++-
 drivers/s390/cio/vfio_ccw_ops.c     | 147 ++++++++++++++++++++++++++++++++++++
 drivers/s390/cio/vfio_ccw_private.h |  11 +++
 5 files changed, 171 insertions(+), 3 deletions(-)
 create mode 100644 drivers/s390/cio/vfio_ccw_ops.c

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index b53f0359..f1317cb 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -675,7 +675,7 @@ config EADM_SCH
 config VFIO_CCW
        def_tristate n
        prompt "Support for VFIO-CCW subchannels"
-       depends on S390_CCW_IOMMU && VFIO
+       depends on S390_CCW_IOMMU && VFIO_MDEV
        help
          This driver allows usage of I/O subchannels via VFIO-CCW.
 
diff --git a/drivers/s390/cio/Makefile b/drivers/s390/cio/Makefile
index 1bec279..b0586b2 100644
--- a/drivers/s390/cio/Makefile
+++ b/drivers/s390/cio/Makefile
@@ -18,5 +18,5 @@ obj-$(CONFIG_CCWGROUP) += ccwgroup.o
 qdio-objs := qdio_main.o qdio_thinint.o qdio_debug.o qdio_setup.o
 obj-$(CONFIG_QDIO) += qdio.o
 
-vfio_ccw-objs += vfio_ccw_drv.o vfio_ccw_cp.o
+vfio_ccw-objs += vfio_ccw_drv.o vfio_ccw_cp.o vfio_ccw_ops.o
 obj-$(CONFIG_VFIO_CCW) += vfio_ccw.o
diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c
index de4f4f1..b1f430a 100644
--- a/drivers/s390/cio/vfio_ccw_drv.c
+++ b/drivers/s390/cio/vfio_ccw_drv.c
@@ -19,7 +19,7 @@
 /*
  * Helpers
  */
-static int vfio_ccw_sch_quiesce(struct subchannel *sch)
+int vfio_ccw_sch_quiesce(struct subchannel *sch)
 {
        struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
        DECLARE_COMPLETION_ONSTACK(completion);
@@ -152,8 +152,16 @@ static int vfio_ccw_sch_probe(struct subchannel *sch)
        if (ret)
                goto out_disable;
 
+       ret = vfio_ccw_mdev_reg(sch);
+       if (ret)
+               goto out_rm_group;
+
+       atomic_set(&private->avail, 1);
+
        return 0;
 
+out_rm_group:
+       sysfs_remove_group(&sch->dev.kobj, &vfio_subchannel_attr_group);
 out_disable:
        cio_disable_subchannel(sch);
 out_free:
@@ -168,6 +176,8 @@ static int vfio_ccw_sch_remove(struct subchannel *sch)
 
        vfio_ccw_sch_quiesce(sch);
 
+       vfio_ccw_mdev_unreg(sch);
+
        sysfs_remove_group(&sch->dev.kobj, &vfio_subchannel_attr_group);
 
        dev_set_drvdata(&sch->dev, NULL);
diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
new file mode 100644
index 0000000..b8a2fed
--- /dev/null
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -0,0 +1,147 @@
+/*
+ * Physical device callbacks for vfio_ccw
+ *
+ * Copyright IBM Corp. 2017
+ *
+ * Author(s): Dong Jia Shi <address@hidden>
+ *            Xiao Feng Ren <address@hidden>
+ */
+
+#include <linux/vfio.h>
+#include <linux/mdev.h>
+
+#include "vfio_ccw_private.h"
+
+static int vfio_ccw_mdev_notifier(struct notifier_block *nb,
+                                 unsigned long action,
+                                 void *data)
+{
+       struct vfio_ccw_private *private =
+               container_of(nb, struct vfio_ccw_private, nb);
+
+       if (!private)
+               return NOTIFY_STOP;
+
+       /*
+        * TODO:
+        * Vendor drivers MUST unpin pages in response to an
+        * invalidation.
+        */
+       if (action == VFIO_IOMMU_NOTIFY_DMA_UNMAP)
+               return NOTIFY_BAD;
+
+       return NOTIFY_DONE;
+}
+
+static ssize_t name_show(struct kobject *kobj, struct device *dev, char *buf)
+{
+       return sprintf(buf, "I/O subchannel (Non-QDIO)\n");
+}
+MDEV_TYPE_ATTR_RO(name);
+
+static ssize_t device_api_show(struct kobject *kobj, struct device *dev,
+                              char *buf)
+{
+       return sprintf(buf, "%s\n", VFIO_DEVICE_API_CCW_STRING);
+}
+MDEV_TYPE_ATTR_RO(device_api);
+
+static ssize_t available_instances_show(struct kobject *kobj,
+                                       struct device *dev, char *buf)
+{
+       struct vfio_ccw_private *private = dev_get_drvdata(dev);
+
+       return sprintf(buf, "%d\n", atomic_read(&private->avail));
+}
+MDEV_TYPE_ATTR_RO(available_instances);
+
+static struct attribute *mdev_types_attrs[] = {
+       &mdev_type_attr_name.attr,
+       &mdev_type_attr_device_api.attr,
+       &mdev_type_attr_available_instances.attr,
+       NULL,
+};
+
+static struct attribute_group mdev_type_group = {
+       .name  = "io",
+       .attrs = mdev_types_attrs,
+};
+
+struct attribute_group *mdev_type_groups[] = {
+       &mdev_type_group,
+       NULL,
+};
+
+static int vfio_ccw_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
+{
+       struct vfio_ccw_private *private =
+               dev_get_drvdata(mdev_parent_dev(mdev));
+
+       if (atomic_dec_if_positive(&private->avail) < 0)
+               return -EPERM;
+
+       private->mdev = mdev;
+
+       return 0;
+}
+
+static int vfio_ccw_mdev_remove(struct mdev_device *mdev)
+{
+       struct vfio_ccw_private *private;
+       struct subchannel *sch;
+       int ret;
+
+       private = dev_get_drvdata(mdev_parent_dev(mdev));
+       sch = private->sch;
+       ret = vfio_ccw_sch_quiesce(sch);
+       if (ret)
+               return ret;
+       ret = cio_enable_subchannel(sch, (u32)(unsigned long)sch);
+       if (ret)
+               return ret;
+
+       private->mdev = NULL;
+       atomic_inc(&private->avail);
+
+       return 0;
+}
+
+static int vfio_ccw_mdev_open(struct mdev_device *mdev)
+{
+       struct vfio_ccw_private *private =
+               dev_get_drvdata(mdev_parent_dev(mdev));
+       unsigned long events = VFIO_IOMMU_NOTIFY_DMA_UNMAP;
+
+       private->nb.notifier_call = vfio_ccw_mdev_notifier;
+
+       return vfio_register_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY,
+                                     &events, &private->nb);
+}
+
+void vfio_ccw_mdev_release(struct mdev_device *mdev)
+{
+       struct vfio_ccw_private *private =
+               dev_get_drvdata(mdev_parent_dev(mdev));
+
+       vfio_unregister_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY,
+                                &private->nb);
+}
+
+static const struct mdev_parent_ops vfio_ccw_mdev_ops = {
+       .owner                  = THIS_MODULE,
+       .supported_type_groups  = mdev_type_groups,
+       .create                 = vfio_ccw_mdev_create,
+       .remove                 = vfio_ccw_mdev_remove,
+       .open                   = vfio_ccw_mdev_open,
+       .release                = vfio_ccw_mdev_release,
+};
+
+int vfio_ccw_mdev_reg(struct subchannel *sch)
+{
+       return mdev_register_device(&sch->dev, &vfio_ccw_mdev_ops);
+}
+
+void vfio_ccw_mdev_unreg(struct subchannel *sch)
+{
+       mdev_unregister_device(&sch->dev);
+}
diff --git a/drivers/s390/cio/vfio_ccw_private.h 
b/drivers/s390/cio/vfio_ccw_private.h
index 38d69a5..5afb3ba 100644
--- a/drivers/s390/cio/vfio_ccw_private.h
+++ b/drivers/s390/cio/vfio_ccw_private.h
@@ -16,10 +16,21 @@
  * struct vfio_ccw_private
  * @sch: pointer to the subchannel
  * @completion: synchronization helper of the I/O completion
+ * @avail: available for creating a mediated device
+ * @mdev: pointer to the mediated device
+ * @nb: notifier for vfio events
  */
 struct vfio_ccw_private {
        struct subchannel       *sch;
        struct completion       *completion;
+       atomic_t                avail;
+       struct mdev_device      *mdev;
+       struct notifier_block   nb;
 } __aligned(8);
 
+extern int vfio_ccw_mdev_reg(struct subchannel *sch);
+extern void vfio_ccw_mdev_unreg(struct subchannel *sch);
+
+extern int vfio_ccw_sch_quiesce(struct subchannel *sch);
+
 #endif
-- 
2.8.4