Re: [PATCH v13 05/15] s390/vfio-ap: manage link between queue struct and matrix mdev

From: Halil Pasic
Date: Mon Jan 11 2021 - 14:19:02 EST

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On Tue, 22 Dec 2020 20:15:56 -0500
Tony Krowiak <akrowiak@xxxxxxxxxxxxx> wrote:

> Let's create links between each queue device bound to the vfio_ap device
> driver and the matrix mdev to which the queue's APQN is assigned. The idea
> is to facilitate efficient retrieval of the objects representing the queue
> devices and matrix mdevs as well as to verify that a queue assigned to
> a matrix mdev is bound to the driver.
>
> The links will be created as follows:
>
> * When the queue device is probed, if its APQN is assigned to a matrix
> mdev, the structures representing the queue device and the matrix mdev
> will be linked.
>
> * When an adapter or domain is assigned to a matrix mdev, for each new
> APQN assigned that references a queue device bound to the vfio_ap
> device driver, the structures representing the queue device and the
> matrix mdev will be linked.
>
> The links will be removed as follows:
>
> * When the queue device is removed, if its APQN is assigned to a matrix
> mdev, the structures representing the queue device and the matrix mdev
> will be unlinked.
>
> * When an adapter or domain is unassigned from a matrix mdev, for each
> APQN unassigned that references a queue device bound to the vfio_ap
> device driver, the structures representing the queue device and the
> matrix mdev will be unlinked.
>
> Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>

Reviewed-by: Halil Pasic <pasic@xxxxxxxxxxxxx>

> ---
> drivers/s390/crypto/vfio_ap_ops.c | 140 +++++++++++++++++++++-----
> drivers/s390/crypto/vfio_ap_private.h | 3 +
> 2 files changed, 117 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index 835c963ae16d..cdcc6378b4a5 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -27,33 +27,17 @@
> static int vfio_ap_mdev_reset_queues(struct mdev_device *mdev);
> static struct vfio_ap_queue *vfio_ap_find_queue(int apqn);
>
> -/**
> - * vfio_ap_get_queue: Retrieve a queue with a specific APQN from a list
> - * @matrix_mdev: the associated mediated matrix
> - * @apqn: The queue APQN
> - *
> - * Retrieve a queue with a specific APQN from the list of the
> - * devices of the vfio_ap_drv.
> - * Verify that the APID and the APQI are set in the matrix.
> - *
> - * Returns the pointer to the associated vfio_ap_queue
> - */
> -static struct vfio_ap_queue *vfio_ap_get_queue(
> - struct ap_matrix_mdev *matrix_mdev,
> - int apqn)
> +static struct vfio_ap_queue *
> +vfio_ap_mdev_get_queue(struct ap_matrix_mdev *matrix_mdev, unsigned long apqn)
> {
> - struct vfio_ap_queue *q = NULL;
> -
> - if (!test_bit_inv(AP_QID_CARD(apqn), matrix_mdev->matrix.apm))
> - return NULL;
> - if (!test_bit_inv(AP_QID_QUEUE(apqn), matrix_mdev->matrix.aqm))
> - return NULL;
> + struct vfio_ap_queue *q;
>
> - q = vfio_ap_find_queue(apqn);
> - if (q)
> - q->matrix_mdev = matrix_mdev;
> + hash_for_each_possible(matrix_mdev->qtable, q, mdev_qnode, apqn) {
> + if (q && (q->apqn == apqn))
> + return q;
> + }
>
> - return q;
> + return NULL;
> }
>
> /**
> @@ -166,7 +150,6 @@ static struct ap_queue_status vfio_ap_irq_disable(struct vfio_ap_queue *q)
> status.response_code);
> end_free:
> vfio_ap_free_aqic_resources(q);
> - q->matrix_mdev = NULL;
> return status;
> }
>
> @@ -282,7 +265,7 @@ static int handle_pqap(struct kvm_vcpu *vcpu)
> matrix_mdev = container_of(vcpu->kvm->arch.crypto.pqap_hook,
> struct ap_matrix_mdev, pqap_hook);
>
> - q = vfio_ap_get_queue(matrix_mdev, apqn);
> + q = vfio_ap_mdev_get_queue(matrix_mdev, apqn);
> if (!q)
> goto out_unlock;
>
> @@ -325,6 +308,7 @@ static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
>
> matrix_mdev->mdev = mdev;
> vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->matrix);
> + hash_init(matrix_mdev->qtable);
> mdev_set_drvdata(mdev, matrix_mdev);
> matrix_mdev->pqap_hook.hook = handle_pqap;
> matrix_mdev->pqap_hook.owner = THIS_MODULE;
> @@ -553,6 +537,50 @@ static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev)
> return 0;
> }
>
> +static void vfio_ap_mdev_link_queue(struct ap_matrix_mdev *matrix_mdev,
> + struct vfio_ap_queue *q)
> +{
> + if (q) {
> + q->matrix_mdev = matrix_mdev;
> + hash_add(matrix_mdev->qtable,
> + &q->mdev_qnode, q->apqn);
> + }
> +}
> +
> +static void vfio_ap_mdev_link_apqn(struct ap_matrix_mdev *matrix_mdev, int apqn)
> +{
> + struct vfio_ap_queue *q;
> +
> + q = vfio_ap_find_queue(apqn);
> + vfio_ap_mdev_link_queue(matrix_mdev, q);
> +}
> +
> +static void vfio_ap_mdev_unlink_queue(struct vfio_ap_queue *q)
> +{
> + if (q) {
> + q->matrix_mdev = NULL;
> + hash_del(&q->mdev_qnode);
> + }
> +}
> +
> +static void vfio_ap_mdev_unlink_apqn(int apqn)
> +{
> + struct vfio_ap_queue *q;
> +
> + q = vfio_ap_find_queue(apqn);
> + vfio_ap_mdev_unlink_queue(q);
> +}
> +
> +static void vfio_ap_mdev_link_adapter(struct ap_matrix_mdev *matrix_mdev,
> + unsigned long apid)
> +{
> + unsigned long apqi;
> +
> + for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, AP_DOMAINS)
> + vfio_ap_mdev_link_apqn(matrix_mdev,
> + AP_MKQID(apid, apqi));
> +}
> +
> /**
> * assign_adapter_store
> *
> @@ -622,6 +650,7 @@ static ssize_t assign_adapter_store(struct device *dev,
> if (ret)
> goto share_err;
>
> + vfio_ap_mdev_link_adapter(matrix_mdev, apid);
> ret = count;
> goto done;
>
> @@ -634,6 +663,15 @@ static ssize_t assign_adapter_store(struct device *dev,
> }
> static DEVICE_ATTR_WO(assign_adapter);
>
> +static void vfio_ap_mdev_unlink_adapter(struct ap_matrix_mdev *matrix_mdev,
> + unsigned long apid)
> +{
> + unsigned long apqi;
> +
> + for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, AP_DOMAINS)
> + vfio_ap_mdev_unlink_apqn(AP_MKQID(apid, apqi));
> +}
> +
> /**
> * unassign_adapter_store
> *
> @@ -673,6 +711,7 @@ static ssize_t unassign_adapter_store(struct device *dev,
>
> mutex_lock(&matrix_dev->lock);
> clear_bit_inv((unsigned long)apid, matrix_mdev->matrix.apm);
> + vfio_ap_mdev_unlink_adapter(matrix_mdev, apid);
> mutex_unlock(&matrix_dev->lock);
>
> return count;
> @@ -699,6 +738,15 @@ vfio_ap_mdev_verify_queues_reserved_for_apqi(struct ap_matrix_mdev *matrix_mdev,
> return 0;
> }
>
> +static void vfio_ap_mdev_link_domain(struct ap_matrix_mdev *matrix_mdev,
> + unsigned long apqi)
> +{
> + unsigned long apid;
> +
> + for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, AP_DEVICES)
> + vfio_ap_mdev_link_apqn(matrix_mdev, AP_MKQID(apid, apqi));
> +}
> +
> /**
> * assign_domain_store
> *
> @@ -763,6 +811,7 @@ static ssize_t assign_domain_store(struct device *dev,
> if (ret)
> goto share_err;
>
> + vfio_ap_mdev_link_domain(matrix_mdev, apqi);
> ret = count;
> goto done;
>
> @@ -775,6 +824,14 @@ static ssize_t assign_domain_store(struct device *dev,
> }
> static DEVICE_ATTR_WO(assign_domain);
>
> +static void vfio_ap_mdev_unlink_domain(struct ap_matrix_mdev *matrix_mdev,
> + unsigned long apqi)
> +{
> + unsigned long apid;
> +
> + for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, AP_DEVICES)
> + vfio_ap_mdev_unlink_apqn(AP_MKQID(apid, apqi));
> +}
>
> /**
> * unassign_domain_store
> @@ -815,6 +872,7 @@ static ssize_t unassign_domain_store(struct device *dev,
>
> mutex_lock(&matrix_dev->lock);
> clear_bit_inv((unsigned long)apqi, matrix_mdev->matrix.aqm);
> + vfio_ap_mdev_unlink_domain(matrix_mdev, apqi);
> mutex_unlock(&matrix_dev->lock);
>
> return count;
> @@ -1317,6 +1375,28 @@ void vfio_ap_mdev_unregister(void)
> mdev_unregister_device(&matrix_dev->device);
> }
>
> +/*
> + * vfio_ap_queue_link_mdev
> + *
> + * @q: The queue to link with the matrix mdev.
> + *
> + * Links @q with the matrix mdev to which the queue's APQN is assigned.
> + */
> +static void vfio_ap_queue_link_mdev(struct vfio_ap_queue *q)
> +{
> + unsigned long apid = AP_QID_CARD(q->apqn);
> + unsigned long apqi = AP_QID_QUEUE(q->apqn);
> + 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)) {
> + vfio_ap_mdev_link_queue(matrix_mdev, q);
> + break;
> + }
> + }
> +}
> +
> int vfio_ap_mdev_probe_queue(struct ap_device *apdev)
> {
> struct vfio_ap_queue *q;
> @@ -1324,9 +1404,13 @@ int vfio_ap_mdev_probe_queue(struct ap_device *apdev)
> q = kzalloc(sizeof(*q), GFP_KERNEL);
> if (!q)
> return -ENOMEM;
> + mutex_lock(&matrix_dev->lock);
> dev_set_drvdata(&apdev->device, q);
> q->apqn = to_ap_queue(&apdev->device)->qid;
> q->saved_isc = VFIO_AP_ISC_INVALID;
> + vfio_ap_queue_link_mdev(q);
> + mutex_unlock(&matrix_dev->lock);
> +

Does the critical section have to include more than just
vfio_ap_queue_link_mdev()? Did we need the critical section
before this patch?

> return 0;
> }
>
> @@ -1341,6 +1425,10 @@ void vfio_ap_mdev_remove_queue(struct ap_device *apdev)
> apid = AP_QID_CARD(q->apqn);
> apqi = AP_QID_QUEUE(q->apqn);
> vfio_ap_mdev_reset_queue(apid, apqi, 1);
> +
> + if (q->matrix_mdev)
> + vfio_ap_mdev_unlink_queue(q);
> +
> kfree(q);
> mutex_unlock(&matrix_dev->lock);
> }
> diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
> index d9003de4fbad..4e5cc72fc0db 100644
> --- a/drivers/s390/crypto/vfio_ap_private.h
> +++ b/drivers/s390/crypto/vfio_ap_private.h
> @@ -18,6 +18,7 @@
> #include <linux/delay.h>
> #include <linux/mutex.h>
> #include <linux/kvm_host.h>
> +#include <linux/hashtable.h>
>
> #include "ap_bus.h"
>
> @@ -86,6 +87,7 @@ struct ap_matrix_mdev {
> struct kvm *kvm;
> struct kvm_s390_module_hook pqap_hook;
> struct mdev_device *mdev;
> + DECLARE_HASHTABLE(qtable, 8);
> };
>
> extern int vfio_ap_mdev_register(void);
> @@ -97,6 +99,7 @@ struct vfio_ap_queue {
> int apqn;
> #define VFIO_AP_ISC_INVALID 0xff
> unsigned char saved_isc;
> + struct hlist_node mdev_qnode;
> };
>
> int vfio_ap_mdev_probe_queue(struct ap_device *queue);

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