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Date: Mon, 27 Dec 2021 09:53:01 +0100
From: Halil Pasic <pasic@...ux.ibm.com>
To: Tony Krowiak <akrowiak@...ux.ibm.com>
Cc: linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
kvm@...r.kernel.org, jjherne@...ux.ibm.com, freude@...ux.ibm.com,
borntraeger@...ibm.com, cohuck@...hat.com, mjrosato@...ux.ibm.com,
alex.williamson@...hat.com, kwankhede@...dia.com,
fiuczy@...ux.ibm.com, Halil Pasic <pasic@...ux.ibm.com>
Subject: Re: [PATCH v17 06/15] s390/vfio-ap: refresh guest's APCB by
filtering APQNs assigned to mdev
On Thu, 21 Oct 2021 11:23:23 -0400
Tony Krowiak <akrowiak@...ux.ibm.com> wrote:
> Refresh the guest's APCB by filtering the APQNs assigned to the matrix mdev
> that do not reference an AP queue device bound to the vfio_ap device
> driver. The mdev's APQNs will be filtered according to the following rules:
>
> * The APID of each adapter and the APQI of each domain that is not in the
> host's AP configuration is filtered out.
>
> * The APID of each adapter comprising an APQN that does not reference a
> queue device bound to the vfio_ap device driver is filtered. The APQNs
> are derived from the Cartesian product of the APID of each adapter and
> APQI of each domain assigned to the mdev.
>
> The control domains that are not assigned to the host's AP configuration
> will also be filtered before assigning them to the guest's APCB.
The v16 version used to filer on queue removal from vfio_ap, which makes
a ton of sense.
This version will "filter back" the queues once these become bound, but
if a queue is removed form vfio_ap, we don't seem to care to filter. Is
this intentional?
Also we could probably do the filtering incrementally. In a sense that
at a time only so much changes, and we know that the invariant was
preserved without that change. But that would probably end up trading
complexity for cycles. I will trust your judgment and your tests on this
matter.
>
> Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>
> ---
> drivers/s390/crypto/vfio_ap_ops.c | 66 ++++++++++++++++++++++++++++++-
> 1 file changed, 64 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index 4305177029bf..46c179363aca 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -314,6 +314,62 @@ static void vfio_ap_matrix_init(struct ap_config_info *info,
> matrix->adm_max = info->apxa ? info->Nd : 15;
> }
>
> +static void vfio_ap_mdev_filter_cdoms(struct ap_matrix_mdev *matrix_mdev)
> +{
> + bitmap_and(matrix_mdev->shadow_apcb.adm, matrix_mdev->matrix.adm,
> + (unsigned long *)matrix_dev->info.adm, AP_DOMAINS);
> +}
> +
> +/*
> + * vfio_ap_mdev_filter_matrix - copy the mdev's AP configuration to the KVM
> + * guest's APCB then filter the APIDs that do not
> + * comprise at least one APQN that references a
> + * queue device bound to the vfio_ap device driver.
> + *
> + * @matrix_mdev: the mdev whose AP configuration is to be filtered.
> + */
> +static void vfio_ap_mdev_filter_matrix(struct ap_matrix_mdev *matrix_mdev)
> +{
> + int ret;
> + unsigned long apid, apqi, apqn;
> +
> + ret = ap_qci(&matrix_dev->info);
> + if (ret)
> + return;
> +
> + vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->shadow_apcb);
> +
> + /*
> + * Copy the adapters, domains and control domains to the shadow_apcb
> + * from the matrix mdev, but only those that are assigned to the host's
> + * AP configuration.
> + */
> + bitmap_and(matrix_mdev->shadow_apcb.apm, matrix_mdev->matrix.apm,
> + (unsigned long *)matrix_dev->info.apm, AP_DEVICES);
> + bitmap_and(matrix_mdev->shadow_apcb.aqm, matrix_mdev->matrix.aqm,
> + (unsigned long *)matrix_dev->info.aqm, AP_DOMAINS);
> +
> + for_each_set_bit_inv(apid, matrix_mdev->shadow_apcb.apm, AP_DEVICES) {
> + for_each_set_bit_inv(apqi, matrix_mdev->shadow_apcb.aqm,
> + AP_DOMAINS) {
> + /*
> + * If the APQN is not bound to the vfio_ap device
> + * driver, then we can't assign it to the guest's
> + * AP configuration. The AP architecture won't
> + * allow filtering of a single APQN, so if we're
> + * filtering APIDs, then filter the APID; otherwise,
> + * filter the APQI.
> + */
> + apqn = AP_MKQID(apid, apqi);
> + if (!vfio_ap_mdev_get_queue(matrix_mdev, apqn)) {
> + clear_bit_inv(apid,
> + matrix_mdev->shadow_apcb.apm);
> + break;
> + }
> + }
> + }
> +}
> +
> static int vfio_ap_mdev_probe(struct mdev_device *mdev)
> {
> struct ap_matrix_mdev *matrix_mdev;
> @@ -703,6 +759,7 @@ static ssize_t assign_adapter_store(struct device *dev,
> goto share_err;
>
> vfio_ap_mdev_link_adapter(matrix_mdev, apid);
> + vfio_ap_mdev_filter_matrix(matrix_mdev);
> ret = count;
> goto done;
>
> @@ -771,6 +828,7 @@ static ssize_t unassign_adapter_store(struct device *dev,
>
> clear_bit_inv((unsigned long)apid, matrix_mdev->matrix.apm);
> vfio_ap_mdev_unlink_adapter(matrix_mdev, apid);
> + vfio_ap_mdev_filter_matrix(matrix_mdev);
> ret = count;
> done:
> mutex_unlock(&matrix_dev->lock);
> @@ -874,6 +932,7 @@ static ssize_t assign_domain_store(struct device *dev,
> goto share_err;
>
> vfio_ap_mdev_link_domain(matrix_mdev, apqi);
> + vfio_ap_mdev_filter_matrix(matrix_mdev);
> ret = count;
> goto done;
>
> @@ -942,6 +1001,7 @@ static ssize_t unassign_domain_store(struct device *dev,
>
> clear_bit_inv((unsigned long)apqi, matrix_mdev->matrix.aqm);
> vfio_ap_mdev_unlink_domain(matrix_mdev, apqi);
> + vfio_ap_mdev_filter_matrix(matrix_mdev);
> ret = count;
>
> done:
> @@ -995,6 +1055,7 @@ static ssize_t assign_control_domain_store(struct device *dev,
> * number of control domains that can be assigned.
> */
> set_bit_inv(id, matrix_mdev->matrix.adm);
> + vfio_ap_mdev_filter_cdoms(matrix_mdev);
> ret = count;
> done:
> mutex_unlock(&matrix_dev->lock);
> @@ -1042,6 +1103,7 @@ static ssize_t unassign_control_domain_store(struct device *dev,
> }
>
> clear_bit_inv(domid, matrix_mdev->matrix.adm);
> + clear_bit_inv(domid, matrix_mdev->shadow_apcb.adm);
> ret = count;
> done:
> mutex_unlock(&matrix_dev->lock);
> @@ -1179,8 +1241,6 @@ static int vfio_ap_mdev_set_kvm(struct ap_matrix_mdev *matrix_mdev,
> kvm_get_kvm(kvm);
> matrix_mdev->kvm = kvm;
> kvm->arch.crypto.data = matrix_mdev;
> - memcpy(&matrix_mdev->shadow_apcb, &matrix_mdev->matrix,
> - sizeof(struct ap_matrix));
> kvm_arch_crypto_set_masks(kvm, matrix_mdev->shadow_apcb.apm,
> matrix_mdev->shadow_apcb.aqm,
> matrix_mdev->shadow_apcb.adm);
> @@ -1536,6 +1596,8 @@ int vfio_ap_mdev_probe_queue(struct ap_device *apdev)
> q->apqn = to_ap_queue(&apdev->device)->qid;
> q->saved_isc = VFIO_AP_ISC_INVALID;
> vfio_ap_queue_link_mdev(q);
> + if (q->matrix_mdev)
> + vfio_ap_mdev_filter_matrix(q->matrix_mdev);
> dev_set_drvdata(&apdev->device, q);
> mutex_unlock(&matrix_dev->lock);
>
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