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

Eric Farman
2019-08-21T15:54:36Z

On 8/16/19 11:15 AM, Cornelia Huck wrote:
> 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.)

Boo :(

>
> 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(-)
>

...snip...

> 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

...snip...

> @@ -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);

I suppose these ones could be squashed into err_out, and use errstr as
substitution for the message text. But this is fine.

> 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);

The above idea would need errstr to be set to something other than
"request" here, which maybe isn't a bad thing anyway. :)

> /* 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
>

This all looks pretty standard compared to the existing cio stuff, and
would be a good addition for vfio-ccw.

Reviewed-by: Eric Farman <farman@linux.ibm.com>