Re: [PATCH v3 7/9] s390: ap: implement PAPQ AQIC interception in kernel

[Pierre Morel]

On 20/02/2019 12:54, Halil Pasic wrote:
> On Thu, 14 Feb 2019 14:51:07 +0100
> Pierre Morel <pmorel@xxxxxxxxxxxxx> wrote:
>
> > We register the AP PQAP instruction hook during the open
> > of the mediated device. And unregister it on release.
> >
> > In the AP PQAP instruction hook, if we receive a demand to
> > enable IRQs,
> > - we retrieve the vfio_ap_queue based on the APQN we receive
> >    in REG1,
> > - we retrieve the page of the guest address, (NIB), from
> >    register REG2
> > - we the mediated device to use the VFIO pinning infratrsucture
> >    to pin the page of the guest address,
> > - we retrieve the pointer to KVM to register the guest ISC
> >    and retrieve the host ISC
> > - finaly we activate GISA
> >
> > If we receive a demand to disable IRQs,
> > - we deactivate GISA
> > - unregister from the GIB
> > - unping the NIB
> >
> > Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
> > ---
>
> [..]
>
> > +static int handle_pqap(struct kvm_vcpu *vcpu)
> > +{
> > +	uint64_t status;
> > +	uint16_t apqn;
> > +	struct vfio_ap_queue *q;
> > +	struct ap_queue_status qstatus = {};
> > +	struct ap_matrix_mdev *matrix_mdev;
> > +
> > +	/* If we do not use the AIV facility just go to userland */
> > +	if (!(vcpu->arch.sie_block->eca & ECA_AIV))
> > +		return -EOPNOTSUPP;
> > +
> > +	apqn = vcpu->run->s.regs.gprs[0] & 0xffff;
> > +	q = vfio_ap_get_queue(apqn);
> > +	if (!q) {
> > +		qstatus.response_code = AP_RESPONSE_Q_NOT_AVAIL;
> > +		goto out;
> > +	}
> > +
> > +	/* Check if the queue is associated with a guest matrix */
> > +	matrix_mdev = q->matrix;
> > +	if (!matrix_mdev || !matrix_mdev->kvm) {
> > +		qstatus.response_code = AP_RESPONSE_DECONFIGURED;
> > +		goto out;
> > +	}
> > +
> > +	status = vcpu->run->s.regs.gprs[1];
> > +
> > +	/* If IR bit(16) is set we enable the interrupt */
> > +	if ((status >> (63 - 16)) & 0x01) {
> > +		q->isc = status & 0x07;
> > +		q->nib = vcpu->run->s.regs.gprs[2];
>
> Careful! You may already have q->nib set (may or may not be a 0x07
> scenario). You should unpin the old nib if set interruption controls
> works out, if we get 0x07 response then you unpin the new one.

You are right. We already had this discussion and the corrected patch.
It seems I misunderstood what we wanted to do by sending this patch 
series out.

I will make this right.

regards,
Pierre


--
Pierre Morel
Linux/KVM/QEMU in BÃblingen - Germany