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Date: Tue, 7 May 2019 11:15:27 -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 2/7] s390: vfio-ap: maintain a shadow of the guest's
CRYCB
On 5/7/19 4:22 AM, Pierre Morel wrote:
> On 06/05/2019 21:53, Tony Krowiak wrote:
>> On 5/6/19 2:49 AM, Pierre Morel wrote:
>>> On 03/05/2019 23:14, Tony Krowiak wrote:
>>>> This patch introduces a shadow of the CRYCB being used by a guest. This
>>>> will enable to more effectively manage dynamic changes to the AP
>>>> resources installed on the host that may be assigned to an mdev device
>>>> and being used by a guest. For example:
>>>>
>>>> * AP adapter cards can be dynamically added to and removed from the AP
>>>> configuration via the SE or an SCLP command.
>>>>
>>>> * AP resources that disappear and reappear due to hardware
>>>> malfunctions.
>>>>
>>>> * AP queues bound to and unbound from the vfio_ap device driver by a
>>>> root user.
>>>>
>>>> Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>
>>>> ---
>>>> drivers/s390/crypto/vfio_ap_ops.c | 91
>>>> ++++++++++++++++++++++++++++++++---
>>>> drivers/s390/crypto/vfio_ap_private.h | 2 +
>>>> 2 files changed, 87 insertions(+), 6 deletions(-)
>>>>
>>>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c
>>>> b/drivers/s390/crypto/vfio_ap_ops.c
>>>> index b88a2a2ba075..44a04b4aa9ae 100644
>>>> --- a/drivers/s390/crypto/vfio_ap_ops.c
>>>> +++ b/drivers/s390/crypto/vfio_ap_ops.c
>>>> @@ -297,6 +297,45 @@ static void
>>>> vfio_ap_mdev_wait_for_qempty(unsigned long apid, unsigned long apqi)
>>>> } while (--retry);
>>>> }
>>>> +/*
>>>> + * vfio_ap_mdev_update_crycb
>>>> + *
>>>> + * @matrix_mdev: the mediated matrix device
>>>> + *
>>>> + * Updates the AP matrix in the guest's CRYCB from it's shadow masks.
>>>> + *
>>>> + * Returns zero if the guest's CRYCB is successfully updated;
>>>> otherwise,
>>>> + * returns -ENODEV if a guest is not running or does not have a CRYCB.
>>>> + */
>>>> +static int vfio_ap_mdev_update_crycb(struct ap_matrix_mdev
>>>> *matrix_mdev)
>>>> +{
>>>> + if (!matrix_mdev->kvm || !matrix_mdev->kvm->arch.crypto.crycbd)
>>>> + return -ENODEV;
>>>> +
>>>> + kvm_arch_crypto_set_masks(matrix_mdev->kvm,
>>>> + matrix_mdev->shadow_crycb->apm,
>>>> + matrix_mdev->shadow_crycb->aqm,
>>>> + matrix_mdev->shadow_crycb->adm);
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static int match_apqn(struct device *dev, void *data)
>>>> +{
>>>> + struct ap_queue *apq = to_ap_queue(dev);
>>>> +
>>>> + return (apq->qid == *(unsigned long *)(data)) ? 1 : 0;
>>>> +}
>>>> +
>>>> +static struct device *vfio_ap_get_queue_dev(unsigned long apid,
>>>> + unsigned long apqi)
>>>> +{
>>>> + unsigned long apqn = AP_MKQID(apid, apqi);
>>>> +
>>>> + return driver_find_device(&matrix_dev->vfio_ap_drv->driver, NULL,
>>>> + &apqn, match_apqn);
>>>> +}
>>>> +
>>>> /**
>>>> * assign_adapter_store
>>>> *
>>>> @@ -805,14 +844,9 @@ static int vfio_ap_mdev_group_notifier(struct
>>>> notifier_block *nb,
>>>> if (ret)
>>>> return NOTIFY_DONE;
>>>> - /* If there is no CRYCB pointer, then we can't copy the masks */
>>>> - if (!matrix_mdev->kvm->arch.crypto.crycbd)
>>>> + if (vfio_ap_mdev_update_crycb(matrix_mdev))
>>>> return NOTIFY_DONE;
>>>> - kvm_arch_crypto_set_masks(matrix_mdev->kvm,
>>>> matrix_mdev->matrix.apm,
>>>> - matrix_mdev->matrix.aqm,
>>>> - matrix_mdev->matrix.adm);
>>>> -
>>>> return NOTIFY_OK;
>>>> }
>>>> @@ -867,12 +901,55 @@ static int vfio_ap_mdev_reset_queues(struct
>>>> mdev_device *mdev)
>>>> return rc;
>>>> }
>>>> +static int vfio_ap_mdev_create_shadow_crycb(struct ap_matrix_mdev
>>>> *matrix_mdev)
>>>> +{
>>>> + unsigned long apid, apqi, domid;
>>>> + struct device *dev;
>>>> +
>>>> + matrix_mdev->shadow_crycb =
>>>> kzalloc(sizeof(*matrix_mdev->shadow_crycb),
>>>> + GFP_KERNEL);
>>>> + if (!matrix_mdev->shadow_crycb)
>>>> + return -ENOMEM;
>>>> +
>>>> + vfio_ap_matrix_init(&matrix_dev->info, matrix_mdev->shadow_crycb);
>>>> +
>>>> + /*
>>>> + * Examine each APQN assigned to the mdev device. Set the APID
>>>> and APQI
>>>> + * in the shadow CRYCB if and only if the queue device
>>>> identified by
>>>> + * the APQN is in the configuration.
>>>> + */
>>>> + for_each_set_bit_inv(apid, matrix_mdev->matrix.apm,
>>>> + matrix_mdev->matrix.apm_max + 1) {
>>>> + for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm,
>>>> + matrix_mdev->matrix.aqm_max + 1) {
>>>> + dev = vfio_ap_get_queue_dev(apid, apqi);
>>>> + if (dev) {
>>>> + set_bit_inv(apid,
>>>> + matrix_mdev->shadow_crycb->apm);
>>>> + set_bit_inv(apqi,
>>>> + matrix_mdev->shadow_crycb->aqm);
>>>> + put_device(dev);
>>>> + }
>>>
>>> I think that if we do not find a device here we have a problem.
>>> Don't we?
>>
>> Other than the fact that the guest will not have any AP devices,
>> what would be the problem? What would you suggest?
>>
>
> Suppose we have in matrix_mdev->matrix:
> 1-2
> 1-3
> 2-2
> 2-3
>
> We set the shadow_crycb with:
> we find 1-2 we set 1 2
> we find 1-3 we se 1 3
> we find 2-2 we set 2 2
> we do not find 2-3
>
> we have set apm(1,2) aqm(2,3)
> the guest can access 2-3 but we do not have the device.
Good point. I'll fix this for v4.
>
> Pierre
>
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