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

Harald Freudenberger
2025-03-24T15:52:37Z

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).