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Message-Id: <9d467999-21db-e362-0b65-f0826c6b485d@linux.ibm.com>
Date: Tue, 7 May 2019 10:22:06 +0200
From: Pierre Morel <pmorel@...ux.ibm.com>
To: Tony Krowiak <akrowiak@...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 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.
Pierre
--
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany
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