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Thu, 16 Jun 2022 16:33:55 +0000 (GMT) Received: from [9.211.56.136] (unknown [9.211.56.136]) by b03ledav002.gho.boulder.ibm.com (Postfix) with ESMTP; Thu, 16 Jun 2022 16:33:55 +0000 (GMT) Message-ID: <0816ab3a-8601-0462-6c2b-4ba7fa8a1e2b@linux.ibm.com> Date: Thu, 16 Jun 2022 12:33:50 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH v2 07/10] vfio/ccw: Create an OPEN FSM Event Content-Language: en-US To: Eric Farman Cc: Jason Gunthorpe , Alex Williamson , Cornelia Huck , Halil Pasic , kvm@vger.kernel.org, linux-s390@vger.kernel.org References: <20220615203318.3830778-1-farman@linux.ibm.com> <20220615203318.3830778-8-farman@linux.ibm.com> From: Matthew Rosato In-Reply-To: <20220615203318.3830778-8-farman@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: GSDu_1LVU3yCzKwkroV2dBdSOXD4Ug7w X-Proofpoint-GUID: 5qb3tBapchWviQP6DXBGDX-wRC93J5Zr X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.883,Hydra:6.0.517,FMLib:17.11.64.514 definitions=2022-06-16_12,2022-06-16_01,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 bulkscore=0 lowpriorityscore=0 phishscore=0 adultscore=0 mlxscore=0 malwarescore=0 mlxlogscore=999 spamscore=0 impostorscore=0 suspectscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2204290000 definitions=main-2206160068 Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On 6/15/22 4:33 PM, Eric Farman wrote: > Move the process of enabling a subchannel for use by vfio-ccw > into the FSM, such that it can manage the sequence of lifecycle > events for the device. > > That is, if the FSM state is NOT_OPER(erational), then do the work > that would enable the subchannel and move the FSM to STANDBY state. > An attempt to perform this event again from any of the other operating > states (IDLE, CP_PROCESSING, CP_PENDING) will convert the device back > to NOT_OPER so the configuration process can be started again. Except STANDBY, which ignores the event via fsm_nop. I wonder though, whether that's the right thing to do. For each of the other states you're saying 'if it's already open, go back to NOT_OPER so we can start over' -- In this case a STANDBY->STANDBY is also a case of 'it's already open' so shouldn't we also go back to NOT_OPER so we can start over? Seems to me really we just don't expect to ever get an OPEN event unless we are in NOT_OPER. If there's a reason to keep STANDBY->STANDBY as a nop, but we don't expect to see it and don't' want to WARN because of it, then maybe a log entry at least would make sense. As for the IDLE/CP_PROCESSING/CP_PENDING cases, going fsm_notoper because this is unexpected probably makes sense, but the logging is going to be really confusing (before this change, you know that you called fsm_notoper because you got VFIO_CCW_EVENT_NOT_OPER -- now you'll see a log entry cut for NOT_OPER but won't be sure if it was for EVENT_NOT_OPER or EVENT_OPEN). Maybe you can look at 'event' inside fsm_notoper and cut a slightly different trace entry when arriving here for EVENT_OPEN? ... > +static void fsm_open(struct vfio_ccw_private *private, > + enum vfio_ccw_event event) > +{ > + struct subchannel *sch = private->sch; > + int ret; > + > + spin_lock_irq(sch->lock); > + sch->isc = VFIO_CCW_ISC; > + ret = cio_enable_subchannel(sch, (u32)(unsigned long)sch); > + if (!ret) > + private->state = VFIO_CCW_STATE_STANDBY; nit: could get rid of 'ret' and just do if (!cio_enable...) private->state = VFIO_CCW_STATE_STANDBY; > + spin_unlock_irq(sch->lock); > +} > + > /* > * Device statemachine > */ > @@ -373,29 +389,34 @@ fsm_func_t *vfio_ccw_jumptable[NR_VFIO_CCW_STATES][NR_VFIO_CCW_EVENTS] = { > [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_EVENT_OPEN] = fsm_open, > }, > [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_EVENT_OPEN] = fsm_nop, > }, > [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_EVENT_OPEN] = fsm_notoper, > }, > [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_EVENT_OPEN] = fsm_notoper, > }, > [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, > + [VFIO_CCW_EVENT_OPEN] = fsm_notoper, > }, > }; > diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h > index 4cfdd5fc0961..8dff1699a7d9 100644 > --- a/drivers/s390/cio/vfio_ccw_private.h > +++ b/drivers/s390/cio/vfio_ccw_private.h > @@ -142,6 +142,7 @@ enum vfio_ccw_event { > VFIO_CCW_EVENT_IO_REQ, > VFIO_CCW_EVENT_INTERRUPT, > VFIO_CCW_EVENT_ASYNC_REQ, > + VFIO_CCW_EVENT_OPEN, > /* last element! */ > NR_VFIO_CCW_EVENTS > };