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

[Tony Krowiak <akrowiak@linux.ibm.com>]

On 9/27/20 9:38 PM, Halil Pasic wrote:
> On Fri, 21 Aug 2020 15:56:13 -0400
> Tony Krowiak <akrowiak@linux.ibm.com> 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@linux.ibm.com>
>> Reported-by: kernel test robot <lkp@intel.com>
> 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?

Yes, I'll remove it.

>
>>   	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_ */