Re: [PATCH 01/10] vfio: ccw: Moving state change out of IRQ context

From: Pierre Morel
Date: Tue Apr 24 2018 - 04:41:15 EST

On 24/04/2018 08:54, Dong Jia Shi wrote:
* Pierre Morel <pmorel@xxxxxxxxxxxxxxxxxx> [2018-04-19 16:48:04 +0200]:


@@ -94,9 +83,15 @@ static void vfio_ccw_sch_io_todo(struct work_struct *work)
static void vfio_ccw_sch_irq(struct subchannel *sch)
struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev);
+ struct irb *irb = this_cpu_ptr(&cio_irb);

- vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_INTERRUPT);
+ memcpy(&private->irb, irb, sizeof(*irb));
+ WARN_ON(work_pending(&private->io_work));
Hmm, why do we need this?

The current design insure that we have not two concurrent SSCH requests.
How ever I want here to track spurious interrupt.
If we implement cancel, halt or clear requests, we also may trigger (AFAIU)
a second interrupts depending on races between instructions, controller and device.

We do not need it strongly.

+ queue_work(vfio_ccw_work_q, &private->io_work);
+ if (private->completion)
+ complete(private->completion);

static int vfio_ccw_sch_probe(struct subchannel *sch)

Pierre Morel
Linux/KVM/QEMU in BÃblingen - Germany