[PATCH v4 04/16] vfio: ccw: basic implementation for vfio_ccw driver

Dong Jia Shi
2017-03-17T07:05:29Z

To make vfio support subchannel devices, we need a css driver for
the vfio subchannels. This patch adds a basic vfio-ccw subchannel
driver for this purpose.

To enable VFIO for vfio-ccw, enable S390_CCW_IOMMU config option
and configure VFIO as required.

Acked-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
Signed-off-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
---
arch/s390/Kconfig | 10 ++
arch/s390/include/asm/isc.h | 1 +
drivers/iommu/Kconfig | 8 ++
drivers/s390/cio/Makefile | 3 +
drivers/s390/cio/vfio_ccw_drv.c | 262 ++++++++++++++++++++++++++++++++++++
drivers/s390/cio/vfio_ccw_private.h | 25 ++++
6 files changed, 309 insertions(+)
create mode 100644 drivers/s390/cio/vfio_ccw_drv.c
create mode 100644 drivers/s390/cio/vfio_ccw_private.h

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index a2dcef0..b53f0359 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -672,6 +672,16 @@ config EADM_SCH
To compile this driver as a module, choose M here: the
module will be called eadm_sch.

+config VFIO_CCW
+ def_tristate n
+ prompt "Support for VFIO-CCW subchannels"
+ depends on S390_CCW_IOMMU && VFIO
+ help
+ This driver allows usage of I/O subchannels via VFIO-CCW.
+
+ To compile this driver as a module, choose M here: the
+ module will be called vfio_ccw.
+
endmenu

menu "Dump support"
diff --git a/arch/s390/include/asm/isc.h b/arch/s390/include/asm/isc.h
index 68d7d68..8a0b721 100644
--- a/arch/s390/include/asm/isc.h
+++ b/arch/s390/include/asm/isc.h
@@ -16,6 +16,7 @@
#define CONSOLE_ISC 1 /* console I/O subchannel */
#define EADM_SCH_ISC 4 /* EADM subchannels */
#define CHSC_SCH_ISC 7 /* CHSC subchannels */
+#define VFIO_CCW_ISC IO_SCH_ISC /* VFIO-CCW I/O subchannels */
/* Adapter interrupts. */
#define QDIO_AIRQ_ISC IO_SCH_ISC /* I/O subchannel in qdio mode */
#define PCI_ISC 2 /* PCI I/O subchannels */
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index 37e204f..6ee3a25 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -327,6 +327,14 @@ config S390_IOMMU
help
Support for the IOMMU API for s390 PCI devices.

+config S390_CCW_IOMMU
+ bool "S390 CCW IOMMU Support"
+ depends on S390 && CCW
+ select IOMMU_API
+ help
+ Enables bits of IOMMU API required by VFIO. The iommu_ops
+ is not implemented as it is not necessary for VFIO.
+
config MTK_IOMMU
bool "MTK IOMMU Support"
depends on ARM || ARM64
diff --git a/drivers/s390/cio/Makefile b/drivers/s390/cio/Makefile
index 3ab9aed..3d7390e 100644
--- a/drivers/s390/cio/Makefile
+++ b/drivers/s390/cio/Makefile
@@ -17,3 +17,6 @@ obj-$(CONFIG_CCWGROUP) += ccwgroup.o

qdio-objs := qdio_main.o qdio_thinint.o qdio_debug.o qdio_setup.o
obj-$(CONFIG_QDIO) += qdio.o
+
+vfio_ccw-objs += vfio_ccw_drv.o
+obj-$(CONFIG_VFIO_CCW) += vfio_ccw.o
diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c
new file mode 100644
index 0000000..de4f4f1
--- /dev/null
+++ b/drivers/s390/cio/vfio_ccw_drv.c
@@ -0,0 +1,262 @@
+/*
+ * VFIO based Physical Subchannel device driver
+ *
+ * Copyright IBM Corp. 2017
+ *
+ * Author(s): Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
+ * Xiao Feng Ren <renxiaof@linux.vnet.ibm.com>
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+
+#include <asm/isc.h>
+
+#include "vfio_ccw_private.h"
+
+/*
+ * Helpers
+ */
+static int vfio_ccw_sch_quiesce(struct subchannel *sch)
+{
+ struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
+ DECLARE_COMPLETION_ONSTACK(completion);
+ int iretry, ret = 0;
+
+ spin_lock_irq(sch->lock);
+ if (!sch->schib.pmcw.ena)
+ goto out_unlock;
+ ret = cio_disable_subchannel(sch);
+ if (ret != -EBUSY)
+ goto out_unlock;
+
+ do {
+ iretry = 255;
+
+ ret = cio_cancel_halt_clear(sch, &iretry);
+ while (ret == -EBUSY) {
+ /*
+ * Flush all I/O and wait for
+ * cancel/halt/clear completion.
+ */
+ private->completion = &completion;
+ spin_unlock_irq(sch->lock);
+
+ wait_for_completion_timeout(&completion, 3*HZ);
+
+ spin_lock_irq(sch->lock);
+ private->completion = NULL;
+ ret = cio_cancel_halt_clear(sch, &iretry);
+ };
+
+ ret = cio_disable_subchannel(sch);
+ } while (ret == -EBUSY);
+
+out_unlock:
+ spin_unlock_irq(sch->lock);
+ return ret;
+}
+
+/*
+ * Sysfs interfaces
+ */
+static ssize_t chpids_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct subchannel *sch = to_subchannel(dev);
+ struct chsc_ssd_info *ssd = &sch->ssd_info;
+ ssize_t ret = 0;
+ int chp;
+ int mask;
+
+ for (chp = 0; chp < 8; chp++) {
+ mask = 0x80 >> chp;
+ if (ssd->path_mask & mask)
+ ret += sprintf(buf + ret, "%02x ", ssd->chpid[chp].id);
+ else
+ ret += sprintf(buf + ret, "00 ");
+ }
+ ret += sprintf(buf+ret, "\n");
+ return ret;
+}
+
+static ssize_t pimpampom_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct subchannel *sch = to_subchannel(dev);
+ struct pmcw *pmcw = &sch->schib.pmcw;
+
+ return sprintf(buf, "%02x %02x %02x\n",
+ pmcw->pim, pmcw->pam, pmcw->pom);
+}
+
+static DEVICE_ATTR(chpids, 0444, chpids_show, NULL);
+static DEVICE_ATTR(pimpampom, 0444, pimpampom_show, NULL);
+
+static struct attribute *vfio_subchannel_attrs[] = {
+ &dev_attr_chpids.attr,
+ &dev_attr_pimpampom.attr,
+ NULL,
+};
+
+static struct attribute_group vfio_subchannel_attr_group = {
+ .attrs = vfio_subchannel_attrs,
+};
+
+/*
+ * Css driver callbacks
+ */
+static void vfio_ccw_sch_irq(struct subchannel *sch)
+{
+ struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
+
+ inc_irq_stat(IRQIO_CIO);
+
+ if (!private)
+ return;
+
+ if (private->completion)
+ complete(private->completion);
+}
+
+static int vfio_ccw_sch_probe(struct subchannel *sch)
+{
+ struct pmcw *pmcw = &sch->schib.pmcw;
+ struct vfio_ccw_private *private;
+ int ret;
+
+ if (pmcw->qf) {
+ dev_warn(&sch->dev, "vfio: ccw: does not support QDIO: %s\n",
+ dev_name(&sch->dev));
+ return -ENODEV;
+ }
+
+ private = kzalloc(sizeof(*private), GFP_KERNEL | GFP_DMA);
+ if (!private)
+ return -ENOMEM;
+ private->sch = sch;
+ dev_set_drvdata(&sch->dev, private);
+
+ spin_lock_irq(sch->lock);
+ sch->isc = VFIO_CCW_ISC;
+ ret = cio_enable_subchannel(sch, (u32)(unsigned long)sch);
+ spin_unlock_irq(sch->lock);
+ if (ret)
+ goto out_free;
+
+ ret = sysfs_create_group(&sch->dev.kobj, &vfio_subchannel_attr_group);
+ if (ret)
+ goto out_disable;
+
+ return 0;
+
+out_disable:
+ cio_disable_subchannel(sch);
+out_free:
+ dev_set_drvdata(&sch->dev, NULL);
+ kfree(private);
+ return ret;
+}
+
+static int vfio_ccw_sch_remove(struct subchannel *sch)
+{
+ struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
+
+ vfio_ccw_sch_quiesce(sch);
+
+ sysfs_remove_group(&sch->dev.kobj, &vfio_subchannel_attr_group);
+
+ dev_set_drvdata(&sch->dev, NULL);
+
+ kfree(private);
+
+ return 0;
+}
+
+static void vfio_ccw_sch_shutdown(struct subchannel *sch)
+{
+ vfio_ccw_sch_quiesce(sch);
+}
+
+/**
+ * vfio_ccw_sch_event - process subchannel event
+ * @sch: subchannel
+ * @process: non-zero if function is called in process context
+ *
+ * An unspecified event occurred for this subchannel. Adjust data according
+ * to the current operational state of the subchannel. Return zero when the
+ * event has been handled sufficiently or -EAGAIN when this function should
+ * be called again in process context.
+ */
+static int vfio_ccw_sch_event(struct subchannel *sch, int process)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(sch->lock, flags);
+ if (!device_is_registered(&sch->dev))
+ goto out_unlock;
+
+ if (work_pending(&sch->todo_work))
+ goto out_unlock;
+
+ if (cio_update_schib(sch)) {
+ /* Not operational. */
+ css_sched_sch_todo(sch, SCH_TODO_UNREG);
+
+ /*
+ * TODO:
+ * Probably we should send the machine check to the guest.
+ */
+ goto out_unlock;
+ }
+
+out_unlock:
+ spin_unlock_irqrestore(sch->lock, flags);
+
+ return 0;
+}
+
+static struct css_device_id vfio_ccw_sch_ids[] = {
+ { .match_flags = 0x1, .type = SUBCHANNEL_TYPE_IO, },
+ { /* end of list */ },
+};
+MODULE_DEVICE_TABLE(css, vfio_ccw_sch_ids);
+
+static struct css_driver vfio_ccw_sch_driver = {
+ .drv = {
+ .name = "vfio_ccw",
+ .owner = THIS_MODULE,
+ },
+ .subchannel_type = vfio_ccw_sch_ids,
+ .irq = vfio_ccw_sch_irq,
+ .probe = vfio_ccw_sch_probe,
+ .remove = vfio_ccw_sch_remove,
+ .shutdown = vfio_ccw_sch_shutdown,
+ .sch_event = vfio_ccw_sch_event,
+};
+
+static int __init vfio_ccw_sch_init(void)
+{
+ int ret;
+
+ isc_register(VFIO_CCW_ISC);
+ ret = css_driver_register(&vfio_ccw_sch_driver);
+ if (ret)
+ isc_unregister(VFIO_CCW_ISC);
+
+ return ret;
+}
+
+static void __exit vfio_ccw_sch_exit(void)
+{
+ css_driver_unregister(&vfio_ccw_sch_driver);
+ isc_unregister(VFIO_CCW_ISC);
+}
+module_init(vfio_ccw_sch_init);
+module_exit(vfio_ccw_sch_exit);
+
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h
new file mode 100644
index 0000000..38d69a5
--- /dev/null
+++ b/drivers/s390/cio/vfio_ccw_private.h
@@ -0,0 +1,25 @@
+/*
+ * Private stuff for vfio_ccw driver
+ *
+ * Copyright IBM Corp. 2017
+ *
+ * Author(s): Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
+ * Xiao Feng Ren <renxiaof@linux.vnet.ibm.com>
+ */
+
+#ifndef _VFIO_CCW_PRIVATE_H_
+#define _VFIO_CCW_PRIVATE_H_
+
+#include "css.h"
+
+/**
+ * struct vfio_ccw_private
+ * @sch: pointer to the subchannel
+ * @completion: synchronization helper of the I/O completion
+ */
+struct vfio_ccw_private {
+ struct subchannel *sch;
+ struct completion *completion;
+} __aligned(8);
+
+#endif
--
2.8.4