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Message-Id: <33201b9c-0479-d675-e265-c09b24695f1c@linux.ibm.com>
Date: Mon, 6 May 2019 16:43:44 -0400
From: Tony Krowiak <akrowiak@...ux.ibm.com>
To: pmorel@...ux.ibm.com, linux-s390@...r.kernel.org,
linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc: freude@...ux.ibm.com, borntraeger@...ibm.com, cohuck@...hat.com,
frankja@...ux.ibm.com, david@...hat.com, schwidefsky@...ibm.com,
heiko.carstens@...ibm.com, pasic@...ux.ibm.com,
alex.williamson@...hat.com, kwankhede@...dia.com
Subject: Re: [PATCH v2 6/7] s390: vfio-ap: handle bind and unbind of AP queue
device
On 5/6/19 6:55 AM, Pierre Morel wrote:
> On 03/05/2019 23:14, Tony Krowiak wrote:
>> There is nothing preventing a root user from inadvertently unbinding an
>> AP queue device that is in use by a guest from the vfio_ap device driver
>> and binding it to a zcrypt driver. This can result in a queue being
>> accessible from both the host and a guest.
>>
>> This patch introduces safeguards that prevent sharing of an AP queue
>> between the host when a queue device is unbound from the vfio_ap device
>> driver. In addition, this patch restores guest access to AP queue devices
>> bound to the vfio_ap driver if the queue's APQN is assigned to an mdev
>> device in use by a guest.
>>
>> Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>
>> ---
>> drivers/s390/crypto/vfio_ap_drv.c | 12 +++-
>> drivers/s390/crypto/vfio_ap_ops.c | 100
>> +++++++++++++++++++++++++++++++++-
>> drivers/s390/crypto/vfio_ap_private.h | 2 +
>> 3 files changed, 111 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/s390/crypto/vfio_ap_drv.c
>> b/drivers/s390/crypto/vfio_ap_drv.c
>> index e9824c35c34f..c215978daf39 100644
>> --- a/drivers/s390/crypto/vfio_ap_drv.c
>> +++ b/drivers/s390/crypto/vfio_ap_drv.c
>> @@ -42,12 +42,22 @@ MODULE_DEVICE_TABLE(vfio_ap, ap_queue_ids);
>> static int vfio_ap_queue_dev_probe(struct ap_device *apdev)
>> {
>> + struct ap_queue *queue = to_ap_queue(&apdev->device);
>> +
>> + mutex_lock(&matrix_dev->lock);
>> + vfio_ap_mdev_probe_queue(queue);
>> + mutex_unlock(&matrix_dev->lock);
>> +
>> return 0;
>> }
>> static void vfio_ap_queue_dev_remove(struct ap_device *apdev)
>> {
>> - /* Nothing to do yet */
>> + struct ap_queue *queue = to_ap_queue(&apdev->device);
>> +
>> + mutex_lock(&matrix_dev->lock);
>> + vfio_ap_mdev_remove_queue(queue);
>> + mutex_unlock(&matrix_dev->lock);
>> }
>> static void vfio_ap_matrix_dev_release(struct device *dev)
>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c
>> b/drivers/s390/crypto/vfio_ap_ops.c
>> index ede45184eb67..40324951bd37 100644
>> --- a/drivers/s390/crypto/vfio_ap_ops.c
>> +++ b/drivers/s390/crypto/vfio_ap_ops.c
>> @@ -226,8 +226,6 @@ static struct device
>> *vfio_ap_get_queue_dev(unsigned long apid,
>> &apqn, match_apqn);
>> }
>> -
>> -
>> static int vfio_ap_mdev_validate_masks(unsigned long *apm, unsigned
>> long *aqm)
>> {
>> int ret;
>> @@ -259,6 +257,27 @@ static bool vfio_ap_queues_on_drv(unsigned long
>> *apm, unsigned long *aqm)
>> return true;
>> }
>> +static bool vfio_ap_card_on_drv(struct ap_queue *queue, unsigned long
>> *aqm)
>> +{
>> + unsigned long apid, apqi;
>> + struct device *dev;
>> +
>> + apid = AP_QID_CARD(queue->qid);
>> +
>> + for_each_set_bit_inv(apqi, aqm, AP_DOMAINS) {
>> + if (queue->qid == AP_MKQID(apid, apqi))
>> + continue;
>> +
>> + dev = vfio_ap_get_queue_dev(apid, apqi);
>> + if (!dev)
>> + return false;
>> +
>> + put_device(dev);
>> + }
>> +
>> + return true;
>> +}
>> +
>> /**
>> * assign_adapter_store
>> *
>> @@ -1017,3 +1036,80 @@ void vfio_ap_mdev_unregister(void)
>> {
>> mdev_unregister_device(&matrix_dev->device);
>> }
>> +
>> +static struct ap_matrix_mdev *vfio_ap_mdev_find_matrix_mdev(unsigned
>> long apid,
>> + unsigned long apqi)
>> +{
>> + struct ap_matrix_mdev *matrix_mdev;
>> +
>> + list_for_each_entry(matrix_mdev, &matrix_dev->mdev_list, node) {
>> + if (test_bit_inv(apid, matrix_mdev->matrix.apm) &&
>> + test_bit_inv(apqi, matrix_mdev->matrix.aqm))
>> + return matrix_mdev;
>> + }
>> +
>> + return NULL;
>> +}
>> +
>> +void vfio_ap_mdev_probe_queue(struct ap_queue *queue)
>> +{
>> + struct ap_matrix_mdev *matrix_mdev;
>> + unsigned long *shadow_apm, *shadow_aqm;
>> + unsigned long apid = AP_QID_CARD(queue->qid);
>> + unsigned long apqi = AP_QID_QUEUE(queue->qid);
>> +
>> + /*
>> + * Find the mdev device to which the APQN of the queue device being
>> + * probed is assigned
>> + */
>> + matrix_mdev = vfio_ap_mdev_find_matrix_mdev(apid, apqi);
>> +
>> + /* Check whether we found an mdev device and it is in use by a
>> guest */
>> + if (matrix_mdev && matrix_mdev->kvm) {
>> + shadow_apm = matrix_mdev->shadow_crycb->apm;
>> + shadow_aqm = matrix_mdev->shadow_crycb->aqm;
>> + /*
>> + * If the guest already has access to the adapter card
>> + * referenced by APID or does not have access to the queues
>> + * referenced by APQI, there is nothing to do here.
>> + */
>> + if (test_bit_inv(apid, shadow_apm) ||
>> + !test_bit_inv(apqi, shadow_aqm))
>> + return;
>> +
>> + /*
>> + * If each APQN with the APID of the queue being probed and an
>> + * APQI in the shadow CRYCB references a queue device that is
>> + * bound to the vfio_ap driver, then plug the adapter into the
>> + * guest.
>> + */
>> + if (vfio_ap_card_on_drv(queue, shadow_aqm)) {
>> + set_bit_inv(apid, shadow_apm);
>> + vfio_ap_mdev_update_crycb(matrix_mdev);
>> + }
>> + }
>> +}
>> +
>> +void vfio_ap_mdev_remove_queue(struct ap_queue *queue)
>> +{
>> + struct ap_matrix_mdev *matrix_mdev;
>> + unsigned long apid = AP_QID_CARD(queue->qid);
>> + unsigned long apqi = AP_QID_QUEUE(queue->qid);
>> +
>> + matrix_mdev = vfio_ap_mdev_find_matrix_mdev(apid, apqi);
>> +
>> + /*
>> + * If the queue is assigned to the mdev device and the mdev device
>> + * is in use by a guest, unplug the adapter referred to by the APID
>> + * of the APQN of the queue being removed.
>> + */
>> + if (matrix_mdev && matrix_mdev->kvm) {
>> + if (!test_bit_inv(apid, matrix_mdev->shadow_crycb->apm))
>> + return;
>> +
>> + clear_bit_inv(apid, matrix_mdev->shadow_crycb->apm);
>> + vfio_ap_mdev_update_crycb(matrix_mdev);
>> + }
>> +
>> + vfio_ap_mdev_reset_queue(apid, apqi);
>> +}
>> diff --git a/drivers/s390/crypto/vfio_ap_private.h
>> b/drivers/s390/crypto/vfio_ap_private.h
>> index e8457aa61976..6b1f7df5b979 100644
>> --- a/drivers/s390/crypto/vfio_ap_private.h
>> +++ b/drivers/s390/crypto/vfio_ap_private.h
>> @@ -87,5 +87,7 @@ struct ap_matrix_mdev {
>> extern int vfio_ap_mdev_register(void);
>> extern void vfio_ap_mdev_unregister(void);
>> +void vfio_ap_mdev_remove_queue(struct ap_queue *queue);
>> +void vfio_ap_mdev_probe_queue(struct ap_queue *queue);
>> #endif /* _VFIO_AP_PRIVATE_H_ */
>>
>
>
> AFAIU the apmask/aqmask of the AP_BUS are replacing bind/unbind for the
> admin. Don't they?
Yes, these interfaces are used to bind/unbind.
> Then why not suppress bind/unbind for ap_queues?
I did suppress them in a previous version, but I believe Harald
objected. I don't recall the reason. If any other maintainers
agree with this, I can reinstate that change. I personally would
prefer that. I think leaving the bind/unbind interfaces confuses
the issue.
>
> Otherwise, it seems to me to handle correctly the disappearance of a
> card, which is the only thing that can happen from out of the firmware
> queue change requires configuration change and re-IPL.
You are correct.
>
> Even still need testing, LGTM
I would welcome and appreciate additional testing, thanks in advance.
>
>
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