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

Dong Jia Shi
2017-03-17T03:17:33Z

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 <pmorel@linux.vnet.ibm.com>
Signed-off-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
---
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 <bjsdjshi@linux.vnet.ibm.com>
+ * Xiao Feng Ren <renxiaof@linux.vnet.ibm.com>
+ */
+
+#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