Re: [PATCH v10 13/16] s390/vfio-ap: handle host AP config change notification

From: Halil Pasic
Date: Sun Sep 27 2020 - 21:39:21 EST

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On Fri, 21 Aug 2020 15:56:13 -0400
Tony Krowiak <akrowiak@xxxxxxxxxxxxx> wrote:

> Implements the driver callback invoked by the AP bus when the host
> AP configuration has changed. Since this callback is invoked prior to
> unbinding a device from its device driver, the vfio_ap driver will
> respond by unplugging the AP adapters, domains and control domains
> removed from the host's AP configuration from the guests using them.
>
> Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
> Reported-by: kernel test robot <lkp@xxxxxxxxx>

Looks reasonable, but shouldn't vfio_ap_mdev_remove_queue() already
have code that kicks the queue from the shadow at this stage?

I mean if the removal is for a reason different that host config change,
we wont update the guest_matrix or?

> ---
> drivers/s390/crypto/vfio_ap_drv.c | 5 +-
> drivers/s390/crypto/vfio_ap_ops.c | 147 ++++++++++++++++++++++++--
> drivers/s390/crypto/vfio_ap_private.h | 7 +-
> 3 files changed, 146 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
> index aae5b3d8e3fa..ea0a7603e886 100644
> --- a/drivers/s390/crypto/vfio_ap_drv.c
> +++ b/drivers/s390/crypto/vfio_ap_drv.c
> @@ -115,9 +115,11 @@ static int vfio_ap_matrix_dev_create(void)
>
> /* Fill in config info via PQAP(QCI), if available */
> if (test_facility(12)) {
> - ret = ap_qci(&matrix_dev->info);
> + ret = ap_qci(&matrix_dev->config_info);
> if (ret)
> goto matrix_alloc_err;
> + memcpy(&matrix_dev->config_info_prev, &matrix_dev->config_info,
> + sizeof(struct ap_config_info));
> }
>
> mutex_init(&matrix_dev->lock);
> @@ -177,6 +179,7 @@ static int __init vfio_ap_init(void)
> vfio_ap_drv.remove = vfio_ap_queue_dev_remove;
> vfio_ap_drv.in_use = vfio_ap_mdev_resource_in_use;
> vfio_ap_drv.ids = ap_queue_ids;
> + vfio_ap_drv.on_config_changed = vfio_ap_on_cfg_changed;
>
> ret = ap_driver_register(&vfio_ap_drv, THIS_MODULE, VFIO_AP_DRV_NAME);
> if (ret) {
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index 2b01a8eb6ee7..e002d556abab 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -347,7 +347,9 @@ 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);
> + vfio_ap_matrix_init(&matrix_dev->config_info, &matrix_mdev->matrix);
> + vfio_ap_matrix_init(&matrix_dev->config_info,
> + &matrix_mdev->shadow_apcb);
> hash_init(matrix_mdev->qtable);
> mdev_set_drvdata(mdev, matrix_mdev);
> matrix_mdev->pqap_hook.hook = handle_pqap;
> @@ -526,8 +528,8 @@ static int vfio_ap_mdev_filter_matrix(struct ap_matrix_mdev *matrix_mdev,
> * If the APID is not assigned to the host AP configuration,
> * we can not assign it to the guest's AP configuration
> */
> - if (!test_bit_inv(apid,
> - (unsigned long *)matrix_dev->info.apm)) {
> + if (!test_bit_inv(apid, (unsigned long *)
> + matrix_dev->config_info.apm)) {
> clear_bit_inv(apid, shadow_apcb->apm);
> continue;
> }
> @@ -540,7 +542,7 @@ static int vfio_ap_mdev_filter_matrix(struct ap_matrix_mdev *matrix_mdev,
> * guest's AP configuration
> */
> if (!test_bit_inv(apqi, (unsigned long *)
> - matrix_dev->info.aqm)) {
> + matrix_dev->config_info.aqm)) {
> clear_bit_inv(apqi, shadow_apcb->aqm);
> continue;
> }
> @@ -594,7 +596,7 @@ static bool vfio_ap_mdev_config_shadow_apcb(struct ap_matrix_mdev *matrix_mdev)
> int napm, naqm;
> struct ap_matrix shadow_apcb;
>
> - vfio_ap_matrix_init(&matrix_dev->info, &shadow_apcb);
> + vfio_ap_matrix_init(&matrix_dev->config_info, &shadow_apcb);
> napm = bitmap_weight(matrix_mdev->matrix.apm, AP_DEVICES);
> naqm = bitmap_weight(matrix_mdev->matrix.aqm, AP_DOMAINS);
>
> @@ -741,7 +743,7 @@ static bool vfio_ap_mdev_assign_apqis_4_apid(struct ap_matrix_mdev *matrix_mdev,
>
> for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, AP_DOMAINS) {
> if (!test_bit_inv(apqi,
> - (unsigned long *) matrix_dev->info.aqm))
> + (unsigned long *)matrix_dev->config_info.aqm))
> clear_bit_inv(apqi, aqm);
>
> apqn = AP_MKQID(apid, apqi);
> @@ -764,7 +766,7 @@ static bool vfio_ap_mdev_assign_guest_apid(struct ap_matrix_mdev *matrix_mdev,
> unsigned long apqi, apqn;
>
> if (!vfio_ap_mdev_has_crycb(matrix_mdev) ||
> - !test_bit_inv(apid, (unsigned long *)matrix_dev->info.apm))
> + !test_bit_inv(apid, (unsigned long *)matrix_dev->config_info.apm))
> return false;
>
> if (bitmap_empty(matrix_mdev->shadow_apcb.aqm, AP_DOMAINS))
> @@ -931,8 +933,8 @@ static bool vfio_ap_mdev_assign_apids_4_apqi(struct ap_matrix_mdev *matrix_mdev,
> bitmap_copy(apm, matrix_mdev->matrix.apm, AP_DEVICES);
>
> for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, AP_DEVICES) {
> - if (!test_bit_inv(apid,
> - (unsigned long *) matrix_dev->info.apm))
> + if (!test_bit_inv(apid, (unsigned long *)
> + matrix_dev->config_info.apm))
> clear_bit_inv(apqi, apm);
>
> apqn = AP_MKQID(apid, apqi);
> @@ -955,7 +957,7 @@ static bool vfio_ap_mdev_assign_guest_apqi(struct ap_matrix_mdev *matrix_mdev,
> unsigned long apid, apqn;
>
> if (!vfio_ap_mdev_has_crycb(matrix_mdev) ||
> - !test_bit_inv(apqi, (unsigned long *)matrix_dev->info.aqm))
> + !test_bit_inv(apqi, (unsigned long *)matrix_dev->config_info.aqm))
> return false;
>
> if (bitmap_empty(matrix_mdev->shadow_apcb.apm, AP_DEVICES))
> @@ -1702,7 +1704,7 @@ int vfio_ap_mdev_probe_queue(struct ap_queue *queue)
> void vfio_ap_mdev_remove_queue(struct ap_queue *queue)
> {
> struct vfio_ap_queue *q;
> - int apid, apqi;
> + unsigned long apid, apqi;
>

Unrelated?

> mutex_lock(&matrix_dev->lock);
> q = dev_get_drvdata(&queue->ap_dev.device);
> @@ -1727,3 +1729,126 @@ bool vfio_ap_mdev_resource_in_use(unsigned long *apm, unsigned long *aqm)
>
> return in_use;
> }
> +
> +/**
> + * vfio_ap_mdev_unassign_apids
> + *
> + * @matrix_mdev: The matrix mediated device
> + *
> + * @aqm: A bitmap with 256 bits. Each bit in the map represents an APID from 0
> + * to 255 (with the leftmost bit corresponding to APID 0).
> + *
> + * Unassigns each APID specified in @aqm that is assigned to the shadow CRYCB
> + * of @matrix_mdev. Returns true if at least one APID is unassigned; otherwise,
> + * returns false.
> + */
> +static bool vfio_ap_mdev_unassign_apids(struct ap_matrix_mdev *matrix_mdev,
> + unsigned long *apm_unassign)
> +{
> + unsigned long apid;
> + bool unassigned = false;
> +
> + /*
> + * If the matrix mdev is not in use by a KVM guest, return indicating
> + * that no APIDs have been unassigned.
> + */
> + if (!vfio_ap_mdev_has_crycb(matrix_mdev))
> + return false;
> +
> + for_each_set_bit_inv(apid, apm_unassign, AP_DEVICES) {
> + unassigned |= vfio_ap_mdev_unassign_guest_apid(matrix_mdev,
> + apid);
> + }

I guess, we could accomplish the unassign with operations operating on
full bitmaps (without looping over bits), but I have no strong opinion
here.

> +
> + return unassigned;
> +}
> +
> +/**
> + * vfio_ap_mdev_unassign_apqis
> + *
> + * @matrix_mdev: The matrix mediated device
> + *
> + * @aqm: A bitmap with 256 bits. Each bit in the map represents an APQI from 0
> + * to 255 (with the leftmost bit corresponding to APQI 0).
> + *
> + * Unassigns each APQI specified in @aqm that is assigned to the shadow CRYCB
> + * of @matrix_mdev. Returns true if at least one APQI is unassigned; otherwise,
> + * returns false.
> + */
> +static bool vfio_ap_mdev_unassign_apqis(struct ap_matrix_mdev *matrix_mdev,
> + unsigned long *aqm_unassign)
> +{
> + unsigned long apqi;
> + bool unassigned = false;
> +
> + /*
> + * If the matrix mdev is not in use by a KVM guest, return indicating
> + * that no APQIs have been unassigned.
> + */
> + if (!vfio_ap_mdev_has_crycb(matrix_mdev))
> + return false;
> +
> + for_each_set_bit_inv(apqi, aqm_unassign, AP_DOMAINS) {
> + unassigned |= vfio_ap_mdev_unassign_guest_apqi(matrix_mdev,
> + apqi);
> + }
> +
> + return unassigned;
> +}
> +
> +void vfio_ap_on_cfg_changed(struct ap_config_info *new_config_info,
> + struct ap_config_info *old_config_info)
> +{
> + bool unassigned;
> + int ap_remove, aq_remove;
> + struct ap_matrix_mdev *matrix_mdev;
> + DECLARE_BITMAP(apm_unassign, AP_DEVICES);
> + DECLARE_BITMAP(aqm_unassign, AP_DOMAINS);
> +
> + unsigned long *cur_apm, *cur_aqm, *prev_apm, *prev_aqm;
> +
> + if (matrix_dev->flags & AP_MATRIX_CFG_CHG) {
> + WARN_ONCE(1, "AP host configuration change already reported");
> + return;
> + }
> +
> + memcpy(&matrix_dev->config_info, new_config_info,
> + sizeof(struct ap_config_info));
> + memcpy(&matrix_dev->config_info_prev, old_config_info,
> + sizeof(struct ap_config_info));
> +
> + cur_apm = (unsigned long *)matrix_dev->config_info.apm;
> + cur_aqm = (unsigned long *)matrix_dev->config_info.aqm;
> + prev_apm = (unsigned long *)matrix_dev->config_info_prev.apm;
> + prev_aqm = (unsigned long *)matrix_dev->config_info_prev.aqm;
> +
> + ap_remove = bitmap_andnot(apm_unassign, prev_apm, cur_apm, AP_DEVICES);
> + aq_remove = bitmap_andnot(aqm_unassign, prev_aqm, cur_aqm, AP_DOMAINS);
> +
> + mutex_lock(&matrix_dev->lock);
> + matrix_dev->flags |= AP_MATRIX_CFG_CHG;
> +
> + list_for_each_entry(matrix_mdev, &matrix_dev->mdev_list, node) {
> + if (!vfio_ap_mdev_has_crycb(matrix_mdev))
> + continue;
> +
> + unassigned = false;
> +
> + if (ap_remove)
> + if (bitmap_intersects(matrix_mdev->shadow_apcb.apm,
> + apm_unassign, AP_DEVICES))
> + if (vfio_ap_mdev_unassign_apids(matrix_mdev,
> + apm_unassign))

This can be done with a single "if".

if (A)
if (B)
if (C)
D;

should be equivalent with
if (A && B && C)
D;
and your wouldn't end up that deep indentation. It is a style thing,
so unless regulated by the official coding style, it is up to you :)

> + unassigned = true;
> + if (aq_remove)
> + if (bitmap_intersects(matrix_mdev->shadow_apcb.aqm,
> + aqm_unassign, AP_DOMAINS))
> + if (vfio_ap_mdev_unassign_apqis(matrix_mdev,
> + aqm_unassign))
> + unassigned = true;
> +
> + if (unassigned)
> + vfio_ap_mdev_commit_shadow_apcb(matrix_mdev);
> + }
> + mutex_unlock(&matrix_dev->lock);
> +}
> diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
> index 055bce6d45db..fc8629e28ad3 100644
> --- a/drivers/s390/crypto/vfio_ap_private.h
> +++ b/drivers/s390/crypto/vfio_ap_private.h
> @@ -40,10 +40,13 @@
> struct ap_matrix_dev {
> struct device device;
> atomic_t available_instances;
> - struct ap_config_info info;
> + struct ap_config_info config_info;
> + struct ap_config_info config_info_prev;
> struct list_head mdev_list;
> struct mutex lock;
> struct ap_driver *vfio_ap_drv;
> + #define AP_MATRIX_CFG_CHG (1UL << 0)
> + unsigned long flags;
> };
>
> extern struct ap_matrix_dev *matrix_dev;
> @@ -108,5 +111,7 @@ int vfio_ap_mdev_probe_queue(struct ap_queue *queue);
> void vfio_ap_mdev_remove_queue(struct ap_queue *queue);
>
> bool vfio_ap_mdev_resource_in_use(unsigned long *apm, unsigned long *aqm);
> +void vfio_ap_on_cfg_changed(struct ap_config_info *new_config_info,
> + struct ap_config_info *old_config_info);
>
> #endif /* _VFIO_AP_PRIVATE_H_ */

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