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

Halil Pasic
2019-02-20T11:54:33Z

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.

> + qstatus = vfio_ap_setirq(q);
> + if (qstatus.response_code) {
> + q->nib = 0;
> + q->isc = 0;
> + }
> + } else
> + qstatus = vfio_ap_clrirq(q);
> +
> +out:
> + memcpy(&vcpu->run->s.regs.gprs[1], &qstatus, sizeof(qstatus));
> + vfio_ap_put_queue(q);
> + return 0;
> +}

[..]

>
> @@ -877,11 +1052,15 @@ static int vfio_ap_mdev_reset_queue(unsigned int apid, unsigned int apqi,
> unsigned int retry)
> {
> struct ap_queue_status status;
> + struct vfio_ap_queue *q;
> +
> + q = vfio_ap_get_queue(AP_MKQID(apid, apqi));
>
> do {
> status = ap_zapq(AP_MKQID(apid, apqi));
> switch (status.response_code) {
> case AP_RESPONSE_NORMAL:

You could do the get queue here

> + vfio_ap_free_irq(q);

And the put here.

Regards,
Halil

> return 0;
> case AP_RESPONSE_RESET_IN_PROGRESS:
> case AP_RESPONSE_BUSY:
> @@ -999,6 +1178,11 @@ static int vfio_ap_mdev_open(struct mdev_device *mdev)
> if (ret)
> goto err_group;
>
> + if (!matrix_mdev->kvm) {
> + ret = -ENODEV;
> + goto err_iommu;
> + }
> +
> matrix_mdev->iommu_notifier.notifier_call = vfio_ap_mdev_iommu_notifier;
> events = VFIO_IOMMU_NOTIFY_DMA_UNMAP;
>

[..]