[PATCH RFC 1/1] vfio-ccw: add some logging

Cornelia Huck
2019-08-16T15:15:19Z

Usually, the common I/O layer logs various things into the s390
cio debug feature, which has been very helpful in the past when
looking at crash dumps. As vfio-ccw devices unbind from the
standard I/O subchannel driver, we lose some information there.

Let's introduce some vfio-ccw debug features and log some things
there. (Unfortunately we cannot reuse the cio debug feature from
a module.)

Signed-off-by: Cornelia Huck <cohuck@redhat.com>
---
drivers/s390/cio/vfio_ccw_drv.c | 50 ++++++++++++++++++++++++++--
drivers/s390/cio/vfio_ccw_fsm.c | 51 ++++++++++++++++++++++++++++-
drivers/s390/cio/vfio_ccw_ops.c | 10 ++++++
drivers/s390/cio/vfio_ccw_private.h | 17 ++++++++++
4 files changed, 124 insertions(+), 4 deletions(-)

diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c
index 9208c0e56c33..45e792f6afd0 100644
--- a/drivers/s390/cio/vfio_ccw_drv.c
+++ b/drivers/s390/cio/vfio_ccw_drv.c
@@ -27,6 +27,9 @@ struct workqueue_struct *vfio_ccw_work_q;
static struct kmem_cache *vfio_ccw_io_region;
static struct kmem_cache *vfio_ccw_cmd_region;

+debug_info_t *vfio_ccw_debug_msg_id;
+debug_info_t *vfio_ccw_debug_trace_id;
+
/*
* Helpers
*/
@@ -164,6 +167,9 @@ static int vfio_ccw_sch_probe(struct subchannel *sch)
if (ret)
goto out_disable;

+ VFIO_CCW_MSG_EVENT(4, "bound to subchannel %x.%x.%04x\n",
+ sch->schid.cssid, sch->schid.ssid,
+ sch->schid.sch_no);
return 0;

out_disable:
@@ -194,6 +200,9 @@ static int vfio_ccw_sch_remove(struct subchannel *sch)
kfree(private->cp.guest_cp);
kfree(private);

+ VFIO_CCW_MSG_EVENT(4, "unbound from subchannel %x.%x.%04x\n",
+ sch->schid.cssid, sch->schid.ssid,
+ sch->schid.sch_no);
return 0;
}

@@ -263,13 +272,46 @@ static struct css_driver vfio_ccw_sch_driver = {
.sch_event = vfio_ccw_sch_event,
};

+static int __init vfio_ccw_debug_init(void)
+{
+ vfio_ccw_debug_msg_id = debug_register("vfio_ccw_msg", 16, 1,
+ 11 * sizeof(long));
+ if (!vfio_ccw_debug_msg_id)
+ goto out_unregister;
+ debug_register_view(vfio_ccw_debug_msg_id, &debug_sprintf_view);
+ debug_set_level(vfio_ccw_debug_msg_id, 2);
+ vfio_ccw_debug_trace_id = debug_register("vfio_ccw_trace", 16, 1, 16);
+ if (!vfio_ccw_debug_trace_id)
+ goto out_unregister;
+ debug_register_view(vfio_ccw_debug_trace_id, &debug_hex_ascii_view);
+ debug_set_level(vfio_ccw_debug_trace_id, 2);
+ return 0;
+
+out_unregister:
+ debug_unregister(vfio_ccw_debug_msg_id);
+ debug_unregister(vfio_ccw_debug_trace_id);
+ return -1;
+}
+
+static void vfio_ccw_debug_exit(void)
+{
+ debug_unregister(vfio_ccw_debug_msg_id);
+ debug_unregister(vfio_ccw_debug_trace_id);
+}
+
static int __init vfio_ccw_sch_init(void)
{
- int ret = -ENOMEM;
+ int ret;
+
+ ret = vfio_ccw_debug_init();
+ if (ret)
+ return ret;

vfio_ccw_work_q = create_singlethread_workqueue("vfio-ccw");
- if (!vfio_ccw_work_q)
- return -ENOMEM;
+ if (!vfio_ccw_work_q) {
+ ret = -ENOMEM;
+ goto out_err;
+ }

vfio_ccw_io_region = kmem_cache_create_usercopy("vfio_ccw_io_region",
sizeof(struct ccw_io_region), 0,
@@ -298,6 +340,7 @@ static int __init vfio_ccw_sch_init(void)
kmem_cache_destroy(vfio_ccw_cmd_region);
kmem_cache_destroy(vfio_ccw_io_region);
destroy_workqueue(vfio_ccw_work_q);
+ vfio_ccw_debug_exit();
return ret;
}

@@ -308,6 +351,7 @@ static void __exit vfio_ccw_sch_exit(void)
kmem_cache_destroy(vfio_ccw_io_region);
kmem_cache_destroy(vfio_ccw_cmd_region);
destroy_workqueue(vfio_ccw_work_q);
+ vfio_ccw_debug_exit();
}
module_init(vfio_ccw_sch_init);
module_exit(vfio_ccw_sch_exit);
diff --git a/drivers/s390/cio/vfio_ccw_fsm.c b/drivers/s390/cio/vfio_ccw_fsm.c
index 49d9d3da0282..4a1e727c62d9 100644
--- a/drivers/s390/cio/vfio_ccw_fsm.c
+++ b/drivers/s390/cio/vfio_ccw_fsm.c
@@ -37,9 +37,14 @@ static int fsm_io_helper(struct vfio_ccw_private *private)
goto out;
}

+ VFIO_CCW_TRACE_EVENT(5, "stIO");
+ VFIO_CCW_TRACE_EVENT(5, dev_name(&sch->dev));
+
/* Issue "Start Subchannel" */
ccode = ssch(sch->schid, orb);

+ VFIO_CCW_HEX_EVENT(5, &ccode, sizeof(ccode));
+
switch (ccode) {
case 0:
/*
@@ -86,9 +91,14 @@ static int fsm_do_halt(struct vfio_ccw_private *private)

spin_lock_irqsave(sch->lock, flags);

+ VFIO_CCW_TRACE_EVENT(2, "haltIO");
+ VFIO_CCW_TRACE_EVENT(2, dev_name(&sch->dev));
+
/* Issue "Halt Subchannel" */
ccode = hsch(sch->schid);

+ VFIO_CCW_HEX_EVENT(2, &ccode, sizeof(ccode));
+
switch (ccode) {
case 0:
/*
@@ -122,9 +132,14 @@ static int fsm_do_clear(struct vfio_ccw_private *private)

spin_lock_irqsave(sch->lock, flags);

+ VFIO_CCW_TRACE_EVENT(2, "clearIO");
+ VFIO_CCW_TRACE_EVENT(2, dev_name(&sch->dev));
+
/* Issue "Clear Subchannel" */
ccode = csch(sch->schid);

+ VFIO_CCW_HEX_EVENT(2, &ccode, sizeof(ccode));
+
switch (ccode) {
case 0:
/*
@@ -149,6 +164,9 @@ static void fsm_notoper(struct vfio_ccw_private *private,
{
struct subchannel *sch = private->sch;

+ VFIO_CCW_TRACE_EVENT(2, "notoper");
+ VFIO_CCW_TRACE_EVENT(2, dev_name(&sch->dev));
+
/*
* TODO:
* Probably we should send the machine check to the guest.
@@ -229,6 +247,7 @@ static void fsm_io_request(struct vfio_ccw_private *private,
struct ccw_io_region *io_region = private->io_region;
struct mdev_device *mdev = private->mdev;
char *errstr = "request";
+ struct subchannel_id schid = get_schid(private);

private->state = VFIO_CCW_STATE_CP_PROCESSING;
memcpy(scsw, io_region->scsw_area, sizeof(*scsw));
@@ -239,18 +258,32 @@ static void fsm_io_request(struct vfio_ccw_private *private,
/* Don't try to build a cp if transport mode is specified. */
if (orb->tm.b) {
io_region->ret_code = -EOPNOTSUPP;
+ VFIO_CCW_MSG_EVENT(2,
+ "%pUl (%x.%x.%04x): transport mode\n",
+ mdev_uuid(mdev), schid.cssid,
+ schid.ssid, schid.sch_no);
errstr = "transport mode";
goto err_out;
}
io_region->ret_code = cp_init(&private->cp, mdev_dev(mdev),
orb);
if (io_region->ret_code) {
+ VFIO_CCW_MSG_EVENT(2,
+ "%pUl (%x.%x.%04x): cp_init=%d\n",
+ mdev_uuid(mdev), schid.cssid,
+ schid.ssid, schid.sch_no,
+ io_region->ret_code);
errstr = "cp init";
goto err_out;
}

io_region->ret_code = cp_prefetch(&private->cp);
if (io_region->ret_code) {
+ VFIO_CCW_MSG_EVENT(2,
+ "%pUl (%x.%x.%04x): cp_prefetch=%d\n",
+ mdev_uuid(mdev), schid.cssid,
+ schid.ssid, schid.sch_no,
+ io_region->ret_code);
errstr = "cp prefetch";
cp_free(&private->cp);
goto err_out;
@@ -259,23 +292,36 @@ static void fsm_io_request(struct vfio_ccw_private *private,
/* Start channel program and wait for I/O interrupt. */
io_region->ret_code = fsm_io_helper(private);
if (io_region->ret_code) {
+ VFIO_CCW_MSG_EVENT(2,
+ "%pUl (%x.%x.%04x): fsm_io_helper=%d\n",
+ mdev_uuid(mdev), schid.cssid,
+ schid.ssid, schid.sch_no,
+ io_region->ret_code);
errstr = "cp fsm_io_helper";
cp_free(&private->cp);
goto err_out;
}
return;
} else if (scsw->cmd.fctl & SCSW_FCTL_HALT_FUNC) {
+ VFIO_CCW_MSG_EVENT(2,
+ "%pUl (%x.%x.%04x): halt on io_region\n",
+ mdev_uuid(mdev), schid.cssid,
+ schid.ssid, schid.sch_no);
/* 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) {
+ VFIO_CCW_MSG_EVENT(2,
+ "%pUl (%x.%x.%04x): clear on io_region\n",
+ mdev_uuid(mdev), schid.cssid,
+ schid.ssid, schid.sch_no);
/* clear is handled via the async cmd region */
io_region->ret_code = -EOPNOTSUPP;
goto err_out;
}

err_out:
- trace_vfio_ccw_io_fctl(scsw->cmd.fctl, get_schid(private),
+ trace_vfio_ccw_io_fctl(scsw->cmd.fctl, schid,
io_region->ret_code, errstr);
}

@@ -308,6 +354,9 @@ static void fsm_irq(struct vfio_ccw_private *private,
{
struct irb *irb = this_cpu_ptr(&cio_irb);

+ VFIO_CCW_TRACE_EVENT(6, "IRQ");
+ VFIO_CCW_TRACE_EVENT(6, dev_name(&private->sch->dev));
+
memcpy(&private->irb, irb, sizeof(*irb));

queue_work(vfio_ccw_work_q, &private->io_work);
diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index 5eb61116ca6f..f0d71ab77c50 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -124,6 +124,11 @@ static int vfio_ccw_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
private->mdev = mdev;
private->state = VFIO_CCW_STATE_IDLE;

+ VFIO_CCW_MSG_EVENT(2, "mdev %pUl, sch %x.%x.%04x: create\n",
+ mdev_uuid(mdev), private->sch->schid.cssid,
+ private->sch->schid.ssid,
+ private->sch->schid.sch_no);
+
return 0;
}

@@ -132,6 +137,11 @@ static int vfio_ccw_mdev_remove(struct mdev_device *mdev)
struct vfio_ccw_private *private =
dev_get_drvdata(mdev_parent_dev(mdev));

+ VFIO_CCW_MSG_EVENT(2, "mdev %pUl, sch %x.%x.%04x: remove\n",
+ mdev_uuid(mdev), private->sch->schid.cssid,
+ private->sch->schid.ssid,
+ private->sch->schid.sch_no);
+
if ((private->state != VFIO_CCW_STATE_NOT_OPER) &&
(private->state != VFIO_CCW_STATE_STANDBY)) {
if (!vfio_ccw_sch_quiesce(private->sch))
diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h
index f1092c3dc1b1..bbe9babf767b 100644
--- a/drivers/s390/cio/vfio_ccw_private.h
+++ b/drivers/s390/cio/vfio_ccw_private.h
@@ -17,6 +17,7 @@
#include <linux/eventfd.h>
#include <linux/workqueue.h>
#include <linux/vfio_ccw.h>
+#include <asm/debug.h>

#include "css.h"
#include "vfio_ccw_cp.h"
@@ -139,4 +140,20 @@ static inline void vfio_ccw_fsm_event(struct vfio_ccw_private *private,

extern struct workqueue_struct *vfio_ccw_work_q;

+
+/* s390 debug feature, similar to base cio */
+extern debug_info_t *vfio_ccw_debug_msg_id;
+extern debug_info_t *vfio_ccw_debug_trace_id;
+
+#define VFIO_CCW_TRACE_EVENT(imp, txt) \
+ debug_text_event(vfio_ccw_debug_trace_id, imp, txt)
+
+#define VFIO_CCW_MSG_EVENT(imp, args...) \
+ debug_sprintf_event(vfio_ccw_debug_msg_id, imp, ##args)
+
+static inline void VFIO_CCW_HEX_EVENT(int level, void *data, int length)
+{
+ debug_event(vfio_ccw_debug_trace_id, level, data, length);
+}
+
#endif
--
2.20.1