Messages in this thread | | | Subject | Re: [PATCH 04/10] vfio: ccw: replace IO_REQ event with SSCH_REQ event | From | Pierre Morel <> | Date | Thu, 3 May 2018 14:06:51 +0200 |
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On 30/04/2018 17:30, Cornelia Huck wrote: > On Wed, 25 Apr 2018 15:52:19 +0200 > Pierre Morel <pmorel@linux.vnet.ibm.com> wrote: > >> On 25/04/2018 10:41, Cornelia Huck wrote: >>> On Thu, 19 Apr 2018 16:48:07 +0200 >>> Pierre Morel<pmorel@linux.vnet.ibm.com> wrote: >>>> diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h >>>> index 3284e64..93aab87 100644 >>>> --- a/drivers/s390/cio/vfio_ccw_private.h >>>> +++ b/drivers/s390/cio/vfio_ccw_private.h >>>> @@ -76,7 +76,7 @@ enum vfio_ccw_state { >>>> */ >>>> enum vfio_ccw_event { >>>> VFIO_CCW_EVENT_NOT_OPER, >>>> - VFIO_CCW_EVENT_IO_REQ, >>>> + VFIO_CCW_EVENT_SSCH_REQ, >>>> VFIO_CCW_EVENT_INTERRUPT, >>>> VFIO_CCW_EVENT_SCH_EVENT, >>>> /* last element! */ >>> I don't think we should separate the ssch handling. The major >>> difference to halt/clear is that it needs channel program translation. >>> Everything else (issuing the instruction and processing the interrupt) >>> are basically the same. If we just throw everything at the hardware >>> and let the host's channel subsystem figure it out, we already should >>> be fine with regard to most of the races. >> We must test at a moment or another the kind of request we do, >> cancel, halt and clear only need the subchannel id in register 1 and as >> you said are much more direct to implement. >> >> If we do not separate them here, we need a switch in the "do_io_request" >> function. >> Is it what you mean? > Yes. Most of the handling should be the same for any function.
I really don't know, the 4 functions are quite different.
- SSCH uses an ORB, and has a quite long kernel execution time for VFIO - there is a race between SSCH and the others instructions - XSCH makes subchannel no longer start pending, also reset the busy indications - CSCH cancels both SSCH and HSCH instruction, and perform path management - HSCH has different busy (entry) conditions
But since they are not implemented today, I can keep the old name.
-- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany
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