Re: [PATCH v2 04/20] s390/ap/zcrypt: New xflag parameter and extension of the ap msg flags

[Harald Freudenberger <freude@linux.ibm.com>]

On 2025-03-18 13:16, Holger Dengler wrote:
> On 04/03/2025 18:21, Harald Freudenberger wrote:
>> Introduce a new flag parameter for the both cprb send functions
>> zcrypt_send_cprb() and zcrypt_send_ep11_cprb(). This new
>> xflags parameter ("execution flags") shall be used to provide
>> execution hints and flags for this crypto request.
>> 
>> There are two flags implemented to be used with these functions:
>> * ZCRYPT_XFLAG_USERSPACE - indicates to the lower layers that
>>   all the ptrs address userspace. So when construction the ap msg
>>   copy_from_user() is to be used. If this flag is NOT set, the ptrs
>>   address kernel memory and thus memcpy() is to be used.
>> * ZCRYPT_XFLAG_NOMEMALLOC - indicates that this task must not
>>   allocate memory which may be allocated with io operations.
>>   For the zcrypt layer this limits the number of EP11 targets
>>   to 16 APQNs. But as this flag is passed down the stack, it
>>   may induce further restrictions.
>> 
>> For the AP bus and zcrypt message layer this means:
>> * The ZCRYPT_XFLAG_USERSPACE is mapped to the AP flag
>>   AP_MSG_FLAG_USERSPACE stored into the flags field of each
>>   ap message in the ap_message struct. This replaces the extra
>>   function parameter "userspace" and makes some function
>>   invocations simpler.
>> * The ZCRYPT_XFLAG_NOMEMALLOC causes the AP message buffer to
>>   use buffer space from the AP message mempool instead of
>>   allocating memory via kmalloc. Note that the buffer space
>>   from the AP message mem pool is limited to 12KB per item.
>> 
>> Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
> 
> The boolean parameter `userspace` should only be merged with the
> xflags in functions, which has the need to handle
> ZCRYPT_XFLAG_USERSPACE and ZCRYPT_XFLAG_NOMEMALLOC, e.g
> _zcrypt_send_cprb(). Functions, which either only take one or the
> other flag may stay with the boolean parameter. There is also no need
> for a definition of AP_MSG_FLAG_USERSPACE, as the AP layer does not
> care about userspace pointers at all, only the zcrypt layer is
> affected by this flag. See my comments below.
> 
>> ---
>>  drivers/s390/crypto/ap_bus.c          |  6 +-
>>  drivers/s390/crypto/ap_bus.h          | 11 ++--
>>  drivers/s390/crypto/zcrypt_api.c      | 90 
>> +++++++++++++++------------
>>  drivers/s390/crypto/zcrypt_api.h      | 36 +++++++----
>>  drivers/s390/crypto/zcrypt_ccamisc.c  | 16 ++---
>>  drivers/s390/crypto/zcrypt_ep11misc.c | 10 +--
>>  drivers/s390/crypto/zcrypt_msgtype6.c | 12 ++--
>>  drivers/s390/crypto/zcrypt_msgtype6.h |  4 +-
>>  8 files changed, 107 insertions(+), 78 deletions(-)
>> 
> [...]
>> diff --git a/drivers/s390/crypto/ap_bus.h 
>> b/drivers/s390/crypto/ap_bus.h
>> index a7bd44e5cc76..5581fb13af73 100644
>> --- a/drivers/s390/crypto/ap_bus.h
>> +++ b/drivers/s390/crypto/ap_bus.h
>> @@ -233,12 +233,13 @@ struct ap_message {
>>  			struct ap_message *);
>>  };
>> 
>> -#define AP_MSG_FLAG_SPECIAL  0x0001   /* flag msg as 'special' with 
>> NQAP */
>> -#define AP_MSG_FLAG_USAGE    0x0002   /* CCA, EP11: usage (no admin) 
>> msg */
>> -#define AP_MSG_FLAG_ADMIN    0x0004   /* CCA, EP11: admin (=control) 
>> msg */
>> -#define AP_MSG_FLAG_MEMPOOL  0x0008   /* ap msg buffer allocated from 
>> mempool */
>> +#define AP_MSG_FLAG_SPECIAL    0x0001  /* flag msg as 'special' with 
>> NQAP */
>> +#define AP_MSG_FLAG_USAGE      0x0002  /* CCA, EP11: usage (no admin) 
>> msg */
>> +#define AP_MSG_FLAG_ADMIN      0x0004  /* CCA, EP11: admin (=control) 
>> msg */
>> +#define AP_MSG_FLAG_MEMPOOL    0x0008  /* ap msg buffer allocated 
>> from mempool */
>> +#define AP_MSG_FLAG_USERSPACE  0x0010  /* pointers address userspace 
>> memory */
> 
> Do we really need this flag in the AP layer? IIRC it has only meaning
> in the zcrypt layer. If this is correct, please remove it.
> 
>> 
>> -int ap_init_apmsg(struct ap_message *ap_msg, bool use_mempool);
>> +int ap_init_apmsg(struct ap_message *ap_msg, u32 flags);
>>  void ap_release_apmsg(struct ap_message *ap_msg);
>> 
>>  enum ap_sm_wait ap_sm_event(struct ap_queue *aq, enum ap_sm_event 
>> event);
>> diff --git a/drivers/s390/crypto/zcrypt_api.c 
>> b/drivers/s390/crypto/zcrypt_api.c
>> index ad09c5306e28..659fe7afb67e 100644
>> --- a/drivers/s390/crypto/zcrypt_api.c
>> +++ b/drivers/s390/crypto/zcrypt_api.c
>> @@ -648,7 +648,7 @@ static long zcrypt_rsa_modexpo(struct ap_perms 
>> *perms,
>> 
>>  	trace_s390_zcrypt_req(mex, TP_ICARSAMODEXPO);
>> 
>> -	rc = ap_init_apmsg(&ap_msg, false);
>> +	rc = ap_init_apmsg(&ap_msg, AP_MSG_FLAG_USERSPACE);
> 
> use_mempool == false should be changed to 0, not AP_MSG_FLAG_USERSPACE.
> rc = ap_init_apmsg(&ap_msg, 0);
> 
>>  	if (rc)
>>  		goto out;
>> 
>> @@ -753,7 +753,7 @@ static long zcrypt_rsa_crt(struct ap_perms *perms,
>> 
>>  	trace_s390_zcrypt_req(crt, TP_ICARSACRT);
>> 
>> -	rc = ap_init_apmsg(&ap_msg, false);
>> +	rc = ap_init_apmsg(&ap_msg, AP_MSG_FLAG_USERSPACE);
> 
> Same here.
> rc = ap_init_apmsg(&ap_msg, 0);
> 
>>  	if (rc)
>>  		goto out;
>> 
> [...]
>> @@ -856,16 +856,19 @@ static long _zcrypt_send_cprb(bool userspace, 
>> struct ap_perms *perms,
>>  	unsigned short *domain, tdom;
>>  	int cpen, qpen, qid = 0, rc;
>>  	struct module *mod;
>> +	u32 flags;
>> 
>>  	trace_s390_zcrypt_req(xcrb, TB_ZSECSENDCPRB);
>> 
>>  	xcrb->status = 0;
>> 
>> -	rc = ap_init_apmsg(&ap_msg, false);
>> +	flags = (xflags & ZCRYPT_XFLAG_USERSPACE ? AP_MSG_FLAG_USERSPACE : 
>> 0) |
>> +		(xflags & ZCRYPT_XFLAG_NOMEMALLOC ? AP_MSG_FLAG_MEMPOOL : 0);
>> +	rc = ap_init_apmsg(&ap_msg, flags);
> 
> There is no need to translate ZCRYPT_XFLAG_USERSPACE to ap-msg flags,
> the AP layer should not care about userspace/kernelspace pointer.
> rc = ap_init_apmsg(&ap_msg, xflags & ZCRYPT_XFLAG_NOMEMALLOC ?
> AP_MSG_FLAG_MEMPOOL : 0);
> 
>>  	if (rc)
>>  		goto out;
>> 
>> -	rc = prep_cca_ap_msg(userspace, xcrb, &ap_msg, &func_code, &domain);
>> +	rc = prep_cca_ap_msg(xcrb, &ap_msg, &func_code, &domain);
> 
> The prep_cca_ap_msg() - and all functions below - can stay with the
> bool parameter.
> rc = prep_cca_ap_msg((xflags & ZCRYPT_XFLAG_USERSPACE), xcrb, &ap_msg,
> &func_code, &domain);
> 
>>  	if (rc)
>>  		goto out;
>>  	print_hex_dump_debug("ccareq: ", DUMP_PREFIX_ADDRESS, 16, 1,
>> @@ -956,7 +959,7 @@ static long _zcrypt_send_cprb(bool userspace, 
>> struct ap_perms *perms,
>>  	if (*domain == AUTOSEL_DOM)
>>  		*domain = AP_QID_QUEUE(qid);
>> 
>> -	rc = pref_zq->ops->send_cprb(userspace, pref_zq, xcrb, &ap_msg);
>> +	rc = pref_zq->ops->send_cprb(pref_zq, xcrb, &ap_msg);
> 
> Here as well, stay with the bool parameter userspace in the callback.
> rc = pref_zq->ops->send_cprb((xflags & ZCRYPT_XFLAG_USERSPACE),
> pref_zq, xcrb, &ap_msg);
> 
>>  	if (!rc) {
>>  		print_hex_dump_debug("ccarpl: ", DUMP_PREFIX_ADDRESS, 16, 1,
>>  				     ap_msg.msg, ap_msg.len, false);
> [...]
>> @@ -1029,52 +1032,58 @@ static bool is_desired_ep11_queue(unsigned int 
>> dev_qid,
>>  	return false;
>>  }
>> 
>> -static long _zcrypt_send_ep11_cprb(bool userspace, struct ap_perms 
>> *perms,
>> +static long _zcrypt_send_ep11_cprb(u32 xflags, struct ap_perms 
>> *perms,
>>  				   struct zcrypt_track *tr,
>>  				   struct ep11_urb *xcrb)
>>  {
>>  	struct zcrypt_card *zc, *pref_zc;
>>  	struct zcrypt_queue *zq, *pref_zq;
>> -	struct ep11_target_dev *targets;
>> +	struct ep11_target_dev targetbuf[16], *targets = NULL;
>>  	unsigned short target_num;
>>  	unsigned int wgt = 0, pref_wgt = 0;
>>  	unsigned int func_code = 0, domain;
>>  	struct ap_message ap_msg;
>>  	int cpen, qpen, qid = 0, rc;
>>  	struct module *mod;
>> +	u32 flags;
>> 
>>  	trace_s390_zcrypt_req(xcrb, TP_ZSENDEP11CPRB);
>> 
>> -	rc = ap_init_apmsg(&ap_msg, false);
>> +	flags = (xflags & ZCRYPT_XFLAG_USERSPACE ? AP_MSG_FLAG_USERSPACE : 
>> 0) |
>> +		(xflags & ZCRYPT_XFLAG_NOMEMALLOC ? AP_MSG_FLAG_MEMPOOL : 0);
>> +	rc = ap_init_apmsg(&ap_msg, flags);
> 
> The AP layer does not care about the userspace flag. Please remove it.
> rc = ap_init_apmsg(&ap_msg, xflags & ZCRYPT_XFLAG_NOMEMALLOC ?
> AP_MSG_FLAG_MEMPOOL : 0);
> 
>>  	if (rc)
>>  		goto out;
>> 
>>  	target_num = (unsigned short)xcrb->targets_num;
>> 
>>  	/* empty list indicates autoselect (all available targets) */
>> -	targets = NULL;
>> +	rc = -ENOMEM;
>>  	if (target_num != 0) {
>>  		struct ep11_target_dev __user *uptr;
>> 
>> -		targets = kcalloc(target_num, sizeof(*targets), GFP_KERNEL);
>> -		if (!targets) {
>> -			func_code = 0;
>> -			rc = -ENOMEM;
>> +		if (target_num <= ARRAY_SIZE(targetbuf)) {
>> +			targets = targetbuf;
>> +		} else if (xflags & ZCRYPT_XFLAG_NOMEMALLOC) {
>>  			goto out;
>> +		} else {
>> +			targets = kcalloc(target_num,
>> +					  sizeof(*targets), GFP_KERNEL);
>> +			if (!targets)
>> +				goto out;
>>  		}
>> 
>>  		uptr = (struct ep11_target_dev __force __user *)xcrb->targets;
>> -		if (z_copy_from_user(userspace, targets, uptr,
>> -				     target_num * sizeof(*targets))) {
>> -			func_code = 0;
>> +		if (z_copy_from_user(xflags & ZCRYPT_XFLAG_USERSPACE, targets,
>> +				     uptr, target_num * sizeof(*targets))) {
>>  			rc = -EFAULT;
>> -			goto out_free;
>> +			goto out;
>>  		}
>>  	}
>> 
>> -	rc = prep_ep11_ap_msg(userspace, xcrb, &ap_msg, &func_code, 
>> &domain);
>> +	rc = prep_ep11_ap_msg(xcrb, &ap_msg, &func_code, &domain);
> 
> Stay here with the boolean parameter for userspace.
> 
>>  	if (rc)
>> -		goto out_free;
>> +		goto out;
>>  	print_hex_dump_debug("ep11req: ", DUMP_PREFIX_ADDRESS, 16, 1,
>>  			     ap_msg.msg, ap_msg.len, false);
>> 
> [...]
>> @@ -1154,11 +1163,11 @@ static long _zcrypt_send_ep11_cprb(bool 
>> userspace, struct ap_perms *perms,
>>  			pr_debug("no match for address ff.ffff => ENODEV\n");
>>  		}
>>  		rc = -ENODEV;
>> -		goto out_free;
>> +		goto out;
>>  	}
>> 
>>  	qid = pref_zq->queue->qid;
>> -	rc = pref_zq->ops->send_ep11_cprb(userspace, pref_zq, xcrb, 
>> &ap_msg);
>> +	rc = pref_zq->ops->send_ep11_cprb(pref_zq, xcrb, &ap_msg);
> 
> Keep the boolean parameter for userspace here as well.
> 
>>  	if (!rc) {
>>  		print_hex_dump_debug("ep11rpl: ", DUMP_PREFIX_ADDRESS, 16, 1,
>>  				     ap_msg.msg, ap_msg.len, false);
> [...]

I've picked all your suggestions. See v3 (coming soon).