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

Pierre Morel
2019-02-21T12:50:26Z

On 20/02/2019 12:54, Halil Pasic wrote:
> On Thu, 14 Feb 2019 14:51:07 +0100
> Pierre Morel <pmorel@linux.ibm.com> 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@linux.ibm.com>
>> ---
>
> [..]
>
>> +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 Böblingen - Germany