On 4/17/20 6:29 AM, Cornelia Huck wrote:
> On Fri, 17 Apr 2020 04:29:55 +0200
> Eric Farman <farman@xxxxxxxxxxxxx> wrote:
>
>> From: Farhan Ali <alifm@xxxxxxxxxxxxx>
>>
>> Register the chp_event callback to receive channel path related
>> events for the subchannels managed by vfio-ccw.
>>
>> Signed-off-by: Farhan Ali <alifm@xxxxxxxxxxxxx>
>> Signed-off-by: Eric Farman <farman@xxxxxxxxxxxxx>
>> ---
>>
>> Notes:
>> v2->v3:
>> - Add a call to cio_cancel_halt_clear() for CHP_VARY_OFF [CH]
>>
>> v1->v2:
>> - Move s390dbf before cio_update_schib() call [CH]
>>
>> v0->v1: [EF]
>> - Add s390dbf trace
>>
>> drivers/s390/cio/vfio_ccw_drv.c | 45 +++++++++++++++++++++++++++++++++
>> 1 file changed, 45 insertions(+)
>>
>> diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c
>> index 8715c1c2f1e1..e48967c475e7 100644
>> --- a/drivers/s390/cio/vfio_ccw_drv.c
>> +++ b/drivers/s390/cio/vfio_ccw_drv.c
>> @@ -19,6 +19,7 @@
>>
>> #include <asm/isc.h>
>>
>> +#include "chp.h"
>> #include "ioasm.h"
>> #include "css.h"
>> #include "vfio_ccw_private.h"
>> @@ -262,6 +263,49 @@ static int vfio_ccw_sch_event(struct subchannel *sch, int process)
>> return rc;
>> }
>>
>> +static int vfio_ccw_chp_event(struct subchannel *sch,
>> + struct chp_link *link, int event)
>> +{
>> + struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
>> + int mask = chp_ssd_get_mask(&sch->ssd_info, link);
>> + int retry = 255;
>> +
>> + if (!private || !mask)
>> + return 0;
>> +
>> + VFIO_CCW_MSG_EVENT(2, "%pUl (%x.%x.%04x): mask=0x%x event=%d\n",
>> + mdev_uuid(private->mdev), sch->schid.cssid,
>> + sch->schid.ssid, sch->schid.sch_no,
>> + mask, event);
>> +
>> + if (cio_update_schib(sch))
>> + return -ENODEV;
>> +
>> + switch (event) {
>> + case CHP_VARY_OFF:
>> + /* Path logically turned off */
>> + sch->opm &= ~mask;
>> + sch->lpm &= ~mask;
>> + cio_cancel_halt_clear(sch, &retry);
>> + break;
>> + case CHP_OFFLINE:
>> + /* Path is gone */
>> + cio_cancel_halt_clear(sch, &retry);
>
> Looking at this again: While calling the same function for both
> CHP_VARY_OFF and CHP_OFFLINE is the right thing to do,
> cio_cancel_halt_clear() is probably not that function. I don't think we
> want to terminate an I/O that does not use the affected path.
>
> Looking at what the normal I/O subchannel driver does, it first checks
> for the lpum and does not do anything if the affected path does not
> show up there. Following down the git history rabbit hole, that basic
> check (surviving several reworks) precedes the first git import, so
> there's unfortunately no patch description explaining that. Looking at
> the PoP, I cannot find a whole lot of details... I think some of the
> path-handling stuff is explained in non-public documentation, and
> whoever wrote the original code (probably me) relied on the information
> there.
>
> tl;dr: We probably should check the lpum here as well.
Makes sense. I'll go through that other doc and fix this up accordingly.
>
>> + break;
>> + case CHP_VARY_ON:
>> + /* Path logically turned on */
>> + sch->opm |= mask;
>> + sch->lpm |= mask;
>> + break;
>> + case CHP_ONLINE:
>> + /* Path became available */
>> + sch->lpm |= mask & sch->opm;
>> + break;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> static struct css_device_id vfio_ccw_sch_ids[] = {
>> { .match_flags = 0x1, .type = SUBCHANNEL_TYPE_IO, },
>> { /* end of list */ },
>> @@ -279,6 +323,7 @@ static struct css_driver vfio_ccw_sch_driver = {
>> .remove = vfio_ccw_sch_remove,
>> .shutdown = vfio_ccw_sch_shutdown,
>> .sch_event = vfio_ccw_sch_event,
>> + .chp_event = vfio_ccw_chp_event,
>> };
>>
>> static int __init vfio_ccw_debug_init(void)
>
