Re: [dpdk-dev] [EXT] Re: [PATCH v2 1/3] cryptodev: remove LIST_END enumerators

[Anoob Joseph <anoobj@marvell.com>]

Hi Thomas,

Please see inline.

Thanks,
Anoob

> -----Original Message-----
> From: Thomas Monjalon <thomas@monjalon.net>
> Sent: Tuesday, October 12, 2021 5:22 PM
> To: Kinsella, Ray <mdr@ashroe.eu>; Akhil Goyal <gakhil@marvell.com>;
> dev@dpdk.org; Anoob Joseph <anoobj@marvell.com>
> Cc: david.marchand@redhat.com; hemant.agrawal@nxp.com;
> pablo.de.lara.guarch@intel.com; fiona.trahe@intel.com;
> declan.doherty@intel.com; matan@nvidia.com; g.singh@nxp.com;
> roy.fan.zhang@intel.com; jianjay.zhou@huawei.com; asomalap@amd.com;
> ruifeng.wang@arm.com; konstantin.ananyev@intel.com;
> radu.nicolau@intel.com; ajit.khaparde@broadcom.com; Nagadheeraj Rottela
> <rnagadheeraj@marvell.com>; Ankur Dwivedi <adwivedi@marvell.com>;
> ciara.power@intel.com; Stephen Hemminger <stephen@networkplumber.org>;
> Yigit, Ferruh <ferruh.yigit@intel.com>
> Subject: Re: [EXT] Re: [dpdk-dev] [PATCH v2 1/3] cryptodev: remove LIST_END
> enumerators
> 
> 12/10/2021 13:34, Anoob Joseph:
> > From: Kinsella, Ray <mdr@ashroe.eu>
> > > On 12/10/2021 11:50, Anoob Joseph wrote:
> > > > From: Akhil Goyal <gakhil@marvell.com>
> > > >>> On 08/10/2021 21:45, Akhil Goyal wrote:
> > > >>>> Remove *_LIST_END enumerators from asymmetric crypto lib to
> > > >>>> avoid ABI breakage for every new addition in enums.
> > > >>>>
> > > >>>> Signed-off-by: Akhil Goyal <gakhil@marvell.com>
> > > >>>> ---
> > > >>>> -	} else if (xform->xform_type >=
> > > >>> RTE_CRYPTO_ASYM_XFORM_TYPE_LIST_END
> > > >>>> +	} else if (xform->xform_type >
> RTE_CRYPTO_ASYM_XFORM_ECPM
> [...]
> > > >>>
> > > >>> So I am not sure that this is an improvement.
> 
> Indeed, it is not an improvement.
> 
> > > >>> The cryptodev issue we had, was that _LIST_END was being used to
> > > >>> size arrays.
> > > >>> And that broke when new algorithms got added. Is that an issue,
> > > >>> in this
> > > case?
> > > >>
> > > >> Yes we did this same exercise for symmetric crypto enums earlier.
> > > >> Asym enums were left as it was experimental at that point.
> > > >> They are still experimental, but thought of making this uniform
> > > >> throughout DPDK enums.
> > > >>
> > > >>>
> > > >>> I am not sure that swapping out _LIST_END, and then littering
> > > >>> the code with RTE_CRYPTO_ASYM_XFORM_ECPM and
> > > >>> RTE_CRYPTO_ASYM_OP_SHARED_SECRET_COMPUTE, is an
> improvement
> > > >> here.
> > > >>>
> > > >>> My 2c is that from an ABI PoV RTE_CRYPTO_ASYM_OP_LIST_END is not
> > > >>> better or worse, than
> > > RTE_CRYPTO_ASYM_OP_SHARED_SECRET_COMPUTE?
> > > >>>
> > > >>> Interested to hear other thoughts.
> > > >>
> > > >> I don’t have any better solution for avoiding ABI issues for now.
> > > >> The change is for avoiding ABI breakage. But we can drop this
> > > >> patch For now as asym is still experimental.
> > > >
> > > > [Anoob] Having LIST_END would preclude new additions to asymmetric
> algos?
> > > If yes, then I would suggest we address it now.
> > >
> > > Not at all - but it can be problematic, if two versions of DPDK
> > > disagree with the value of LIST_END.
> > >
> > > > Looking at the "problematic changes", we only have 2-3 application
> > > > & PMD changes. For unit test application, we could may be do
> > > > something like,
> > >
> > > The essental functionality not that different, I am just not sure
> > > that the verbosity below is helping.
> > > What you are really trying to guard against is people using LIST_END
> > > to size arrays.
> >
> > [Anoob] Our problem is application using LIST_END (which comes from library)
> to determine the number of iterations for the loop. My suggestion is to modify
> the UT such that, we could use RTE_DIM(types) (which comes from application)
> to determine iterations of loop. This would solve the problem, right?
> 
> The problem is not the application.
> Are you asking the app to define DPDK types?

[Anoob] I didn't understand how you concluded that. The app is supposed to test "n" asymmetric features supported by DPDK. Currently, it does that by looping from 0 to LIST_END which happens to give you the first n features. Now, if we add any new asymmetric feature, LIST_END value would change. Isn't that the very reason why we removed LIST_END from symmetric library and applications?

Now coming to what I proposed, the app is supposed to test "n" asymmetric features. LIST_END helps in doing the loops. If we remove LIST_END, then application will not be in a position to do a loop. My suggestion is, we list the types that are supposed to be tested by the app, and let that array be used as feature list.

PS: Just to reiterate, my proposal is just a local array which would hold DPDK defined RTE enum values for the features that would be tested by this app/function. 
> > > > +               enum rte_crypto_asym_op_type types[] = { 

> 
> The problem is in DPDK API. We must not suggest a size for enums.

[Anoob] So agreed that LIST_END should be removed?
 
> If we really need a size, then it must be explicit and updated in the lib binary
> (through a function) when the size increases.

[Anoob] Precisely my thoughts. The loop with LIST_END done in application is not correct. 
> 
> 
> 
> > > > -               for (i = 0; i < RTE_CRYPTO_ASYM_OP_LIST_END; i++) {
> > > > +               enum rte_crypto_asym_op_type types[] = {
> > > > +                               RTE_CRYPTO_ASYM_OP_ENCRYPT,
> > > > +                               RTE_CRYPTO_ASYM_OP_DECRYPT,
> > > > +                               RTE_CRYPTO_ASYM_OP_SIGN,
> > > > +                               RTE_CRYPTO_ASYM_OP_VERIFY,
> > > > +                               RTE_CRYPTO_ASYM_OP_PRIVATE_KEY_GENERATE,
> > > > +                               RTE_CRYPTO_ASYM_OP_PUBLIC_KEY_GENERATE,
> > > > +                               RTE_CRYPTO_ASYM_OP_SHARED_SECRET_COMPUTE,
> > > > +               };
> > > > +               for (i = 0; i <= RTE_DIM(types); i++) {
> > > >                         if (tc.modex.xform_type ==
> RTE_CRYPTO_ASYM_XFORM_RSA) {
> > > > -                               if (tc.rsa_data.op_type_flags & (1 << i)) {
> > > > +                               if (tc.rsa_data.op_type_flags & (1
> > > > + <<
> > > > + types[i])) {
> > > >                                         if (tc.rsa_data.key_exp) {
> > > >                                                 status = test_cryptodev_asym_op(
> > > >                                                         &testsuite_params, &tc,
> > > > -                                                       test_msg, sessionless, i,
> > > > +                                                       test_msg,
> > > > + sessionless, types[i],
> > > >                                                         RTE_RSA_KEY_TYPE_EXP);
> > > >                                         }
> > > >                                         if (status)
> > > >                                                 break;
> > > > -                                       if (tc.rsa_data.key_qt && (i ==
> > > > +                                       if (tc.rsa_data.key_qt &&
> > > > + (types[i] ==
> > > >                                                         RTE_CRYPTO_ASYM_OP_DECRYPT ||
> > > > -                                                       i == RTE_CRYPTO_ASYM_OP_SIGN)) {
> > > > +                                                       types[i]
> > > > + ==
> > > > + RTE_CRYPTO_ASYM_OP_SIGN)) {
> > > >                                                 status = test_cryptodev_asym_op(
> > > >                                                         &testsuite_params,
> > > > -                                                       &tc, test_msg, sessionless, i,
> > > > +                                                       &tc,
> > > > + test_msg, sessionless, types[i],
> > > >                                                         RTE_RSA_KET_TYPE_QT);
> > > >                                         }
> > > >                                         if (status)
> > > >
> > > > This way, application would only use the ones which it is designed
> > > > to work
> > > with. For QAT driver changes, we could have an overload if condition
> > > (if alg == x
> > > || alg = y || ...) to get the same effect.
> 
> 
>