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Date: Fri, 13 Nov 2020 15:58:18 -0500
From: Tony Krowiak <akrowiak@...ux.ibm.com>
To: Harald Freudenberger <freude@...ux.ibm.com>,
linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
kvm@...r.kernel.org
Cc: borntraeger@...ibm.com, cohuck@...hat.com, mjrosato@...ux.ibm.com,
pasic@...ux.ibm.com, alex.williamson@...hat.com,
kwankhede@...dia.com, fiuczy@...ux.ibm.com, frankja@...ux.ibm.com,
david@...hat.com, hca@...ux.ibm.com, gor@...ux.ibm.com
Subject: Re: [PATCH v11 11/14] s390/zcrypt: Notify driver on config changed
and scan complete callbacks
On 10/27/20 1:28 PM, Harald Freudenberger wrote:
> On 22.10.20 19:12, Tony Krowiak wrote:
>> This patch intruduces an extension to the ap bus to notify device drivers
>> when the host AP configuration changes - i.e., adapters, domains or
>> control domains are added or removed. To that end, two new callbacks are
>> introduced for AP device drivers:
>>
>> void (*on_config_changed)(struct ap_config_info *new_config_info,
>> struct ap_config_info *old_config_info);
>>
>> This callback is invoked at the start of the AP bus scan
>> function when it determines that the host AP configuration information
>> has changed since the previous scan. This is done by storing
>> an old and current QCI info struct and comparing them. If there is any
>> difference, the callback is invoked.
>>
>> Note that when the AP bus scan detects that AP adapters, domains or
>> control domains have been removed from the host's AP configuration, it
>> will remove the associated devices from the AP bus subsystem's device
>> model. This callback gives the device driver a chance to respond to
>> the removal of the AP devices from the host configuration prior to
>> calling the device driver's remove callback. The primary purpose of
>> this callback is to allow the vfio_ap driver to do a bulk unplug of
>> all affected adapters, domains and control domains from affected
>> guests rather than unplugging them one at a time when the remove
>> callback is invoked.
>>
>> void (*on_scan_complete)(struct ap_config_info *new_config_info,
>> struct ap_config_info *old_config_info);
>>
>> The on_scan_complete callback is invoked after the ap bus scan is
>> complete if the host AP configuration data has changed.
>>
>> Note that when the AP bus scan detects that adapters, domains or
>> control domains have been added to the host's configuration, it will
>> create new devices in the AP bus subsystem's device model. The primary
>> purpose of this callback is to allow the vfio_ap driver to do a bulk
>> plug of all affected adapters, domains and control domains into
>> affected guests rather than plugging them one at a time when the
>> probe callback is invoked.
>>
>> Please note that changes to the apmask and aqmask do not trigger
>> these two callbacks since the bus scan function is not invoked by changes
>> to those masks.
>>
>> Signed-off-by: Harald Freudenberger <freude@...ux.ibm.com>
> Did I really sign-off this ? I know, I saw this code but ...
Good question, but I would not have introduced this myself. It's been
so long since this patch was created that I don't recall all of the details,
but I vaguely remember maybe getting an early version of this code
from you, although I could be wrong. I recognize the last comment in
the description as being yours. I will remove the Signed-off-by if you
prefer.
> First of all, please separate the ap bus changes from the vfio_ap driver changes.
> This makes backports and code change history much easier.
The problem is if I remove the vfio_ap driver changes, then this patch
will not build. I've been told in the past that this is a no-no.
>> Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>
>> ---
>> drivers/s390/crypto/ap_bus.c | 88 ++++++++++++++++++++++++++-
>> drivers/s390/crypto/ap_bus.h | 12 ++++
>> drivers/s390/crypto/vfio_ap_drv.c | 2 +-
>> drivers/s390/crypto/vfio_ap_ops.c | 11 ++--
>> drivers/s390/crypto/vfio_ap_private.h | 2 +-
>> 5 files changed, 106 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c
>> index 998e61cd86d9..5b94956ef6bc 100644
>> --- a/drivers/s390/crypto/ap_bus.c
>> +++ b/drivers/s390/crypto/ap_bus.c
>> @@ -73,8 +73,10 @@ struct ap_perms ap_perms;
>> EXPORT_SYMBOL(ap_perms);
>> DEFINE_MUTEX(ap_perms_mutex);
>> EXPORT_SYMBOL(ap_perms_mutex);
>> +DEFINE_MUTEX(ap_config_lock);
> This mutes is unnecessary, but see details below.
>>
>> static struct ap_config_info *ap_qci_info;
>> +static struct ap_config_info *ap_qci_info_old;
>>
>> /*
>> * AP bus related debug feature things.
>> @@ -1420,6 +1422,52 @@ static int __match_queue_device_with_queue_id(struct device *dev, const void *da
>> && AP_QID_QUEUE(to_ap_queue(dev)->qid) == (int)(long) data;
>> }
>>
>> +/* Helper function for notify_config_changed */
>> +static int __drv_notify_config_changed(struct device_driver *drv, void *data)
>> +{
>> + struct ap_driver *ap_drv = to_ap_drv(drv);
>> +
>> + if (try_module_get(drv->owner)) {
>> + if (ap_drv->on_config_changed)
>> + ap_drv->on_config_changed(ap_qci_info,
>> + ap_qci_info_old);
>> + module_put(drv->owner);
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +/* Notify all drivers about an qci config change */
>> +static inline void notify_config_changed(void)
>> +{
>> + bus_for_each_drv(&ap_bus_type, NULL, NULL,
>> + __drv_notify_config_changed);
>> +}
>> +
>> +/* Helper function for notify_scan_complete */
>> +static int __drv_notify_scan_complete(struct device_driver *drv, void *data)
>> +{
>> + struct ap_driver *ap_drv = to_ap_drv(drv);
>> +
>> + if (try_module_get(drv->owner)) {
>> + if (ap_drv->on_scan_complete)
>> + ap_drv->on_scan_complete(ap_qci_info,
>> + ap_qci_info_old);
>> + module_put(drv->owner);
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +/* Notify all drivers about bus scan complete */
>> +static inline void notify_scan_complete(void)
>> +{
>> + bus_for_each_drv(&ap_bus_type, NULL, NULL,
>> + __drv_notify_scan_complete);
>> +}
>> +
>> +
>> +
>> /*
>> * Helper function for ap_scan_bus().
>> * Remove card device and associated queue devices.
>> @@ -1696,15 +1744,45 @@ static inline void ap_scan_adapter(int ap)
>> put_device(&ac->ap_dev.device);
>> }
>>
>> +static int ap_config_changed(void)
> I don't like the name here. This function is effectively fetching the qci info
> and then comparing the new with the prev. qci info. So it is the new
> ap_get_configuration() which returns bool true (config changed) or
> false (old and current config are the very same).
Okay, so I think what you are saying there is you prefer the name
ap_get_configuration()?
>> +{
>> + int cfg_chg = 0;
>> +
>> + if (ap_qci_info) {
>> + if (!ap_qci_info_old) {
>> + ap_qci_info_old = kzalloc(sizeof(*ap_qci_info_old),
>> + GFP_KERNEL);
>> + if (!ap_qci_info_old)
>> + return 0;
>> + } else {
>> + memcpy(ap_qci_info_old, ap_qci_info,
>> + sizeof(struct ap_config_info));
>> + }
>> + ap_fetch_qci_info(ap_qci_info);
>> + cfg_chg = memcmp(ap_qci_info,
>> + ap_qci_info_old,
>> + sizeof(struct ap_config_info)) != 0;
>> + }
>> +
>> + return cfg_chg;
>> +}
>> +
>> /**
>> * ap_scan_bus(): Scan the AP bus for new devices
>> * Runs periodically, workqueue timer (ap_config_time)
>> */
>> static void ap_scan_bus(struct work_struct *unused)
>> {
>> - int ap;
>> + int ap, config_changed = 0;
>> +
>> + mutex_lock(&ap_config_lock);
> This mutex is more or less surrrounding the ap_scan_bus function.
> The ap_scan_bus function is only called via a workqueue which is
> making sure there is only one invocation at a point in time. So it
> is not needed.
Makes sense, I'll remove it.
>>
>> - ap_fetch_qci_info(ap_qci_info);
>> + /* config change notify */
>> + config_changed = ap_config_changed();
>> + if (config_changed)
>> + notify_config_changed();
>> + memcpy(ap_qci_info_old, ap_qci_info,
>> + sizeof(struct ap_config_info));
>> ap_select_domain();
>>
>> AP_DBF_DBG("%s running\n", __func__);
>> @@ -1713,6 +1791,12 @@ static void ap_scan_bus(struct work_struct *unused)
>> for (ap = 0; ap <= ap_max_adapter_id; ap++)
>> ap_scan_adapter(ap);
>>
>> + /* scan complete notify */
>> + if (config_changed)
>> + notify_scan_complete();
>> +
>> + mutex_unlock(&ap_config_lock);
>> +
>> /* check if there is at least one queue available with default domain */
>> if (ap_domain_index >= 0) {
>> struct device *dev =
>> diff --git a/drivers/s390/crypto/ap_bus.h b/drivers/s390/crypto/ap_bus.h
>> index 6ce154d924d3..c021ea5121a9 100644
>> --- a/drivers/s390/crypto/ap_bus.h
>> +++ b/drivers/s390/crypto/ap_bus.h
>> @@ -146,6 +146,18 @@ struct ap_driver {
>> int (*probe)(struct ap_device *);
>> void (*remove)(struct ap_device *);
>> bool (*in_use)(unsigned long *apm, unsigned long *aqm);
>> + /*
>> + * Called at the start of the ap bus scan function when
>> + * the crypto config information (qci) has changed.
>> + */
>> + void (*on_config_changed)(struct ap_config_info *new_config_info,
>> + struct ap_config_info *old_config_info);
>> + /*
>> + * Called at the end of the ap bus scan function when
>> + * the crypto config information (qci) has changed.
>> + */
>> + void (*on_scan_complete)(struct ap_config_info *new_config_info,
>> + struct ap_config_info *old_config_info);
>> };
>>
>> #define to_ap_drv(x) container_of((x), struct ap_driver, driver)
> Rest of this patch is vfio related and should be in a separate patch.
As stated above, if I remove the vfio-related changes then this patch will
not build which I've been told in the past is a no-no.
>
> Please note: The ap bus scan function does actively destroy card and associated queue
> devices when the TAPQ invocation tells that the function bits have changed (e.g. from
> EP11 mode to CCA mode) or the type has changed (e.g. from CEX6 to CEX7).
> This does not come with an change in the qci apm or adm bitfields !
Yes, I am aware of that and have coded the vfio_ap driver's probe and
remove functions accordingly.
>
>> diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
>> index 8934471b7944..f06e19754de3 100644
>> --- a/drivers/s390/crypto/vfio_ap_drv.c
>> +++ b/drivers/s390/crypto/vfio_ap_drv.c
>> @@ -87,7 +87,7 @@ 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;
>> }
>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
>> index dae1fba41941..c4ea80ec8599 100644
>> --- a/drivers/s390/crypto/vfio_ap_ops.c
>> +++ b/drivers/s390/crypto/vfio_ap_ops.c
>> @@ -354,8 +354,9 @@ 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->info, &matrix_mdev->shadow_apcb);
>> + 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;
>> @@ -540,8 +541,8 @@ static int vfio_ap_mdev_filter_guest_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;
>> }
>> @@ -554,7 +555,7 @@ static int vfio_ap_mdev_filter_guest_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;
>> }
>> diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
>> index fc8634cee485..5065f0367ea2 100644
>> --- a/drivers/s390/crypto/vfio_ap_private.h
>> +++ b/drivers/s390/crypto/vfio_ap_private.h
>> @@ -40,7 +40,7 @@
>> struct ap_matrix_dev {
>> struct device device;
>> atomic_t available_instances;
>> - struct ap_config_info info;
>> + struct ap_config_info config_info;
>> struct list_head mdev_list;
>> struct mutex lock;
>> struct ap_driver *vfio_ap_drv;
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