[PATCH v4 6/6] vfio-ccw: add handling for async channel instructions

Cornelia Huck
2019-03-01T09:39:02Z

Add a region to the vfio-ccw device that can be used to submit
asynchronous I/O instructions. ssch continues to be handled by the
existing I/O region; the new region handles hsch and csch.

Interrupt status continues to be reported through the same channels
as for ssch.

Signed-off-by: Cornelia Huck <cohuck@redhat.com>
---
drivers/s390/cio/Makefile | 3 +-
drivers/s390/cio/vfio_ccw_async.c | 88 ++++++++++++++++++++
drivers/s390/cio/vfio_ccw_drv.c | 46 ++++++++---
drivers/s390/cio/vfio_ccw_fsm.c | 119 +++++++++++++++++++++++++++-
drivers/s390/cio/vfio_ccw_ops.c | 13 ++-
drivers/s390/cio/vfio_ccw_private.h | 5 ++
include/uapi/linux/vfio.h | 2 +
include/uapi/linux/vfio_ccw.h | 12 +++
8 files changed, 270 insertions(+), 18 deletions(-)
create mode 100644 drivers/s390/cio/vfio_ccw_async.c

diff --git a/drivers/s390/cio/Makefile b/drivers/s390/cio/Makefile
index f230516abb96..f6a8db04177c 100644
--- a/drivers/s390/cio/Makefile
+++ b/drivers/s390/cio/Makefile
@@ -20,5 +20,6 @@ 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 vfio_ccw_cp.o vfio_ccw_ops.o vfio_ccw_fsm.o
+vfio_ccw-objs += vfio_ccw_drv.o vfio_ccw_cp.o vfio_ccw_ops.o vfio_ccw_fsm.o \
+ vfio_ccw_async.o
obj-$(CONFIG_VFIO_CCW) += vfio_ccw.o
diff --git a/drivers/s390/cio/vfio_ccw_async.c b/drivers/s390/cio/vfio_ccw_async.c
new file mode 100644
index 000000000000..8c1d2357ef5b
--- /dev/null
+++ b/drivers/s390/cio/vfio_ccw_async.c
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Async I/O region for vfio_ccw
+ *
+ * Copyright Red Hat, Inc. 2019
+ *
+ * Author(s): Cornelia Huck <cohuck@redhat.com>
+ */
+
+#include <linux/vfio.h>
+#include <linux/mdev.h>
+
+#include "vfio_ccw_private.h"
+
+static ssize_t vfio_ccw_async_region_read(struct vfio_ccw_private *private,
+ char __user *buf, size_t count,
+ loff_t *ppos)
+{
+ unsigned int i = VFIO_CCW_OFFSET_TO_INDEX(*ppos) - VFIO_CCW_NUM_REGIONS;
+ loff_t pos = *ppos & VFIO_CCW_OFFSET_MASK;
+ struct ccw_cmd_region *region;
+ int ret;
+
+ if (pos + count > sizeof(*region))
+ return -EINVAL;
+
+ mutex_lock(&private->io_mutex);
+ region = private->region[i].data;
+ if (copy_to_user(buf, (void *)region + pos, count))
+ ret = -EFAULT;
+ else
+ ret = count;
+ mutex_unlock(&private->io_mutex);
+ return ret;
+}
+
+static ssize_t vfio_ccw_async_region_write(struct vfio_ccw_private *private,
+ const char __user *buf, size_t count,
+ loff_t *ppos)
+{
+ unsigned int i = VFIO_CCW_OFFSET_TO_INDEX(*ppos) - VFIO_CCW_NUM_REGIONS;
+ loff_t pos = *ppos & VFIO_CCW_OFFSET_MASK;
+ struct ccw_cmd_region *region;
+ int ret;
+
+ if (pos + count > sizeof(*region))
+ return -EINVAL;
+
+ if (!mutex_trylock(&private->io_mutex))
+ return -EAGAIN;
+
+ region = private->region[i].data;
+ if (copy_from_user((void *)region + pos, buf, count)) {
+ ret = -EFAULT;
+ goto out_unlock;
+ }
+
+ vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_ASYNC_REQ);
+
+ ret = region->ret_code ? region->ret_code : count;
+
+out_unlock:
+ mutex_unlock(&private->io_mutex);
+ return ret;
+}
+
+static void vfio_ccw_async_region_release(struct vfio_ccw_private *private,
+ struct vfio_ccw_region *region)
+{
+
+}
+
+const struct vfio_ccw_regops vfio_ccw_async_region_ops = {
+ .read = vfio_ccw_async_region_read,
+ .write = vfio_ccw_async_region_write,
+ .release = vfio_ccw_async_region_release,
+};
+
+int vfio_ccw_register_async_dev_regions(struct vfio_ccw_private *private)
+{
+ return vfio_ccw_register_dev_region(private,
+ VFIO_REGION_SUBTYPE_CCW_ASYNC_CMD,
+ &vfio_ccw_async_region_ops,
+ sizeof(struct ccw_cmd_region),
+ VFIO_REGION_INFO_FLAG_READ |
+ VFIO_REGION_INFO_FLAG_WRITE,
+ private->cmd_region);
+}
diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c
index 5ea0da1dd954..c39d01943a6a 100644
--- a/drivers/s390/cio/vfio_ccw_drv.c
+++ b/drivers/s390/cio/vfio_ccw_drv.c
@@ -3,9 +3,11 @@
* VFIO based Physical Subchannel device driver
*
* Copyright IBM Corp. 2017
+ * Copyright Red Hat, Inc. 2019
*
* Author(s): Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
* Xiao Feng Ren <renxiaof@linux.vnet.ibm.com>
+ * Cornelia Huck <cohuck@redhat.com>
*/

#include <linux/module.h>
@@ -23,6 +25,7 @@

struct workqueue_struct *vfio_ccw_work_q;
static struct kmem_cache *vfio_ccw_io_region;
+static struct kmem_cache *vfio_ccw_cmd_region;

/*
* Helpers
@@ -110,7 +113,7 @@ static int vfio_ccw_sch_probe(struct subchannel *sch)
{
struct pmcw *pmcw = &sch->schib.pmcw;
struct vfio_ccw_private *private;
- int ret;
+ int ret = -ENOMEM;

if (pmcw->qf) {
dev_warn(&sch->dev, "vfio: ccw: does not support QDIO: %s\n",
@@ -124,10 +127,13 @@ static int vfio_ccw_sch_probe(struct subchannel *sch)

private->io_region = kmem_cache_zalloc(vfio_ccw_io_region,
GFP_KERNEL | GFP_DMA);
- if (!private->io_region) {
- kfree(private);
- return -ENOMEM;
- }
+ if (!private->io_region)
+ goto out_free;
+
+ private->cmd_region = kmem_cache_zalloc(vfio_ccw_cmd_region,
+ GFP_KERNEL | GFP_DMA);
+ if (!private->cmd_region)
+ goto out_free;

private->sch = sch;
dev_set_drvdata(&sch->dev, private);
@@ -155,7 +161,10 @@ static int vfio_ccw_sch_probe(struct subchannel *sch)
cio_disable_subchannel(sch);
out_free:
dev_set_drvdata(&sch->dev, NULL);
- kmem_cache_free(vfio_ccw_io_region, private->io_region);
+ if (private->cmd_region)
+ kmem_cache_free(vfio_ccw_cmd_region, private->cmd_region);
+ if (private->io_region)
+ kmem_cache_free(vfio_ccw_io_region, private->io_region);
kfree(private);
return ret;
}
@@ -170,6 +179,7 @@ static int vfio_ccw_sch_remove(struct subchannel *sch)

dev_set_drvdata(&sch->dev, NULL);

+ kmem_cache_free(vfio_ccw_cmd_region, private->cmd_region);
kmem_cache_free(vfio_ccw_io_region, private->io_region);
kfree(private);

@@ -244,7 +254,7 @@ static struct css_driver vfio_ccw_sch_driver = {

static int __init vfio_ccw_sch_init(void)
{
- int ret;
+ int ret = -ENOMEM;

vfio_ccw_work_q = create_singlethread_workqueue("vfio-ccw");
if (!vfio_ccw_work_q)
@@ -254,20 +264,30 @@ static int __init vfio_ccw_sch_init(void)
sizeof(struct ccw_io_region), 0,
SLAB_ACCOUNT, 0,
sizeof(struct ccw_io_region), NULL);
- if (!vfio_ccw_io_region) {
- destroy_workqueue(vfio_ccw_work_q);
- return -ENOMEM;
- }
+ if (!vfio_ccw_io_region)
+ goto out_err;
+
+ vfio_ccw_cmd_region = kmem_cache_create_usercopy("vfio_ccw_cmd_region",
+ sizeof(struct ccw_cmd_region), 0,
+ SLAB_ACCOUNT, 0,
+ sizeof(struct ccw_cmd_region), NULL);
+ if (!vfio_ccw_cmd_region)
+ goto out_err;

isc_register(VFIO_CCW_ISC);
ret = css_driver_register(&vfio_ccw_sch_driver);
if (ret) {
isc_unregister(VFIO_CCW_ISC);
- kmem_cache_destroy(vfio_ccw_io_region);
- destroy_workqueue(vfio_ccw_work_q);
+ goto out_err;
}

return ret;
+
+out_err:
+ kmem_cache_destroy(vfio_ccw_cmd_region);
+ kmem_cache_destroy(vfio_ccw_io_region);
+ destroy_workqueue(vfio_ccw_work_q);
+ return ret;
}

static void __exit vfio_ccw_sch_exit(void)
diff --git a/drivers/s390/cio/vfio_ccw_fsm.c b/drivers/s390/cio/vfio_ccw_fsm.c
index b4a141fbd1a8..49d9d3da0282 100644
--- a/drivers/s390/cio/vfio_ccw_fsm.c
+++ b/drivers/s390/cio/vfio_ccw_fsm.c
@@ -3,8 +3,10 @@
* Finite state machine for vfio-ccw device handling
*
* Copyright IBM Corp. 2017
+ * Copyright Red Hat, Inc. 2019
*
* Author(s): Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
+ * Cornelia Huck <cohuck@redhat.com>
*/

#include <linux/vfio.h>
@@ -73,6 +75,75 @@ static int fsm_io_helper(struct vfio_ccw_private *private)
return ret;
}

+static int fsm_do_halt(struct vfio_ccw_private *private)
+{
+ struct subchannel *sch;
+ unsigned long flags;
+ int ccode;
+ int ret;
+
+ sch = private->sch;
+
+ spin_lock_irqsave(sch->lock, flags);
+
+ /* Issue "Halt Subchannel" */
+ ccode = hsch(sch->schid);
+
+ switch (ccode) {
+ case 0:
+ /*
+ * Initialize device status information
+ */
+ sch->schib.scsw.cmd.actl |= SCSW_ACTL_HALT_PEND;
+ ret = 0;
+ break;
+ case 1: /* Status pending */
+ case 2: /* Busy */
+ ret = -EBUSY;
+ break;
+ case 3: /* Device not operational */
+ ret = -ENODEV;
+ break;
+ default:
+ ret = ccode;
+ }
+ spin_unlock_irqrestore(sch->lock, flags);
+ return ret;
+}
+
+static int fsm_do_clear(struct vfio_ccw_private *private)
+{
+ struct subchannel *sch;
+ unsigned long flags;
+ int ccode;
+ int ret;
+
+ sch = private->sch;
+
+ spin_lock_irqsave(sch->lock, flags);
+
+ /* Issue "Clear Subchannel" */
+ ccode = csch(sch->schid);
+
+ switch (ccode) {
+ case 0:
+ /*
+ * Initialize device status information
+ */
+ sch->schib.scsw.cmd.actl = SCSW_ACTL_CLEAR_PEND;
+ /* TODO: check what else we might need to clear */
+ ret = 0;
+ break;
+ case 3: /* Device not operational */
+ ret = -ENODEV;
+ break;
+ default:
+ ret = ccode;
+ }
+ spin_unlock_irqrestore(sch->lock, flags);
+ return ret;
+}
+
static void fsm_notoper(struct vfio_ccw_private *private,
enum vfio_ccw_event event)
{
@@ -113,6 +184,24 @@ static void fsm_io_retry(struct vfio_ccw_private *private,
private->io_region->ret_code = -EAGAIN;
}

+static void fsm_async_error(struct vfio_ccw_private *private,
+ enum vfio_ccw_event event)
+{
+ struct ccw_cmd_region *cmd_region = private->cmd_region;
+
+ pr_err("vfio-ccw: FSM: %s request from state:%d\n",
+ cmd_region->command == VFIO_CCW_ASYNC_CMD_HSCH ? "halt" :
+ cmd_region->command == VFIO_CCW_ASYNC_CMD_CSCH ? "clear" :
+ "<unknown>", private->state);
+ cmd_region->ret_code = -EIO;
+}
+
+static void fsm_async_retry(struct vfio_ccw_private *private,
+ enum vfio_ccw_event event)
+{
+ private->cmd_region->ret_code = -EAGAIN;
+}
+
static void fsm_disabled_irq(struct vfio_ccw_private *private,
enum vfio_ccw_event event)
{
@@ -176,11 +265,11 @@ static void fsm_io_request(struct vfio_ccw_private *private,
}
return;
} else if (scsw->cmd.fctl & SCSW_FCTL_HALT_FUNC) {
- /* XXX: Handle halt. */
+ /* halt is handled via the async cmd region */
io_region->ret_code = -EOPNOTSUPP;
goto err_out;
} else if (scsw->cmd.fctl & SCSW_FCTL_CLEAR_FUNC) {
- /* XXX: Handle clear. */
+ /* clear is handled via the async cmd region */
io_region->ret_code = -EOPNOTSUPP;
goto err_out;
}
@@ -190,6 +279,27 @@ static void fsm_io_request(struct vfio_ccw_private *private,
io_region->ret_code, errstr);
}

+/*
+ * Deal with an async request from userspace.
+ */
+static void fsm_async_request(struct vfio_ccw_private *private,
+ enum vfio_ccw_event event)
+{
+ struct ccw_cmd_region *cmd_region = private->cmd_region;
+
+ switch (cmd_region->command) {
+ case VFIO_CCW_ASYNC_CMD_HSCH:
+ cmd_region->ret_code = fsm_do_halt(private);
+ break;
+ case VFIO_CCW_ASYNC_CMD_CSCH:
+ cmd_region->ret_code = fsm_do_clear(private);
+ break;
+ default:
+ /* should not happen? */
+ cmd_region->ret_code = -EINVAL;
+ }
+}
+
/*
* Got an interrupt for a normal io (state busy).
*/
@@ -213,26 +323,31 @@ fsm_func_t *vfio_ccw_jumptable[NR_VFIO_CCW_STATES][NR_VFIO_CCW_EVENTS] = {
[VFIO_CCW_STATE_NOT_OPER] = {
[VFIO_CCW_EVENT_NOT_OPER] = fsm_nop,
[VFIO_CCW_EVENT_IO_REQ] = fsm_io_error,
+ [VFIO_CCW_EVENT_ASYNC_REQ] = fsm_async_error,
[VFIO_CCW_EVENT_INTERRUPT] = fsm_disabled_irq,
},
[VFIO_CCW_STATE_STANDBY] = {
[VFIO_CCW_EVENT_NOT_OPER] = fsm_notoper,
[VFIO_CCW_EVENT_IO_REQ] = fsm_io_error,
+ [VFIO_CCW_EVENT_ASYNC_REQ] = fsm_async_error,
[VFIO_CCW_EVENT_INTERRUPT] = fsm_irq,
},
[VFIO_CCW_STATE_IDLE] = {
[VFIO_CCW_EVENT_NOT_OPER] = fsm_notoper,
[VFIO_CCW_EVENT_IO_REQ] = fsm_io_request,
+ [VFIO_CCW_EVENT_ASYNC_REQ] = fsm_async_request,
[VFIO_CCW_EVENT_INTERRUPT] = fsm_irq,
},
[VFIO_CCW_STATE_CP_PROCESSING] = {
[VFIO_CCW_EVENT_NOT_OPER] = fsm_notoper,
[VFIO_CCW_EVENT_IO_REQ] = fsm_io_retry,
+ [VFIO_CCW_EVENT_ASYNC_REQ] = fsm_async_retry,
[VFIO_CCW_EVENT_INTERRUPT] = fsm_irq,
},
[VFIO_CCW_STATE_CP_PENDING] = {
[VFIO_CCW_EVENT_NOT_OPER] = fsm_notoper,
[VFIO_CCW_EVENT_IO_REQ] = fsm_io_busy,
+ [VFIO_CCW_EVENT_ASYNC_REQ] = fsm_async_request,
[VFIO_CCW_EVENT_INTERRUPT] = fsm_irq,
},
};
diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index 3fd663320bbf..ec2f796c70fe 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -149,11 +149,20 @@ 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;
+ int ret;

private->nb.notifier_call = vfio_ccw_mdev_notifier;

- return vfio_register_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY,
- &events, &private->nb);
+ ret = vfio_register_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY,
+ &events, &private->nb);
+ if (ret)
+ return ret;
+
+ ret = vfio_ccw_register_async_dev_regions(private);
+ if (ret)
+ vfio_unregister_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY,
+ &private->nb);
+ return ret;
}

static void vfio_ccw_mdev_release(struct mdev_device *mdev)
diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h
index d888a2573470..f1092c3dc1b1 100644
--- a/drivers/s390/cio/vfio_ccw_private.h
+++ b/drivers/s390/cio/vfio_ccw_private.h
@@ -53,6 +53,8 @@ int vfio_ccw_register_dev_region(struct vfio_ccw_private *private,
const struct vfio_ccw_regops *ops,
size_t size, u32 flags, void *data);

+int vfio_ccw_register_async_dev_regions(struct vfio_ccw_private *private);
+
/**
* struct vfio_ccw_private
* @sch: pointer to the subchannel
@@ -64,6 +66,7 @@ int vfio_ccw_register_dev_region(struct vfio_ccw_private *private,
* @io_region: MMIO region to input/output I/O arguments/results
* @io_mutex: protect against concurrent update of I/O regions
* @region: additional regions for other subchannel operations
+ * @cmd_region: MMIO region for asynchronous I/O commands other than START
* @num_regions: number of additional regions
* @cp: channel program for the current I/O operation
* @irb: irb info received from interrupt
@@ -81,6 +84,7 @@ struct vfio_ccw_private {
struct ccw_io_region *io_region;
struct mutex io_mutex;
struct vfio_ccw_region *region;
+ struct ccw_cmd_region *cmd_region;
int num_regions;

struct channel_program cp;
@@ -116,6 +120,7 @@ enum vfio_ccw_event {
VFIO_CCW_EVENT_NOT_OPER,
VFIO_CCW_EVENT_IO_REQ,
VFIO_CCW_EVENT_INTERRUPT,
+ VFIO_CCW_EVENT_ASYNC_REQ,
/* last element! */
NR_VFIO_CCW_EVENTS
};
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 56e2413d3e00..8f10748dac79 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -354,6 +354,8 @@ struct vfio_region_gfx_edid {
};

#define VFIO_REGION_TYPE_CCW (2)
+/* ccw sub-types */
+#define VFIO_REGION_SUBTYPE_CCW_ASYNC_CMD (1)

/*
* 10de vendor sub-type
diff --git a/include/uapi/linux/vfio_ccw.h b/include/uapi/linux/vfio_ccw.h
index 2ec5f367ff78..cbecbf0cd54f 100644
--- a/include/uapi/linux/vfio_ccw.h
+++ b/include/uapi/linux/vfio_ccw.h
@@ -12,6 +12,7 @@

#include <linux/types.h>

+/* used for START SUBCHANNEL, always present */
struct ccw_io_region {
#define ORB_AREA_SIZE 12
__u8 orb_area[ORB_AREA_SIZE];
@@ -22,4 +23,15 @@ struct ccw_io_region {
__u32 ret_code;
} __packed;

+/*
+ * used for processing commands that trigger asynchronous actions
+ * Note: this is controlled by a capability
+ */
+#define VFIO_CCW_ASYNC_CMD_HSCH (1 << 0)
+#define VFIO_CCW_ASYNC_CMD_CSCH (1 << 1)
+struct ccw_cmd_region {
+ __u32 command;
+ __u32 ret_code;
+} __packed;
+
#endif
--
2.17.2