[dpdk-dev] [dpdk-stable] [PATCH v3 1/6] mem: add function for checking memsegs IOVAs addresses

Alejandro Lucero alejandro.lucero at netronome.com
Tue Jul 10 13:43:13 CEST 2018


On Tue, Jul 10, 2018 at 12:33 PM, Burakov, Anatoly <
anatoly.burakov at intel.com> wrote:

> On 10-Jul-18 12:14 PM, Eelco Chaudron wrote:
>
>>
>>
>> On 10 Jul 2018, at 12:52, Alejandro Lucero wrote:
>>
>> On Tue, Jul 10, 2018 at 11:06 AM, Eelco Chaudron <echaudro at redhat.com>
>>> wrote:
>>>
>>>
>>>>
>>>> On 10 Jul 2018, at 11:34, Alejandro Lucero wrote:
>>>>
>>>> On Tue, Jul 10, 2018 at 9:56 AM, Eelco Chaudron <echaudro at redhat.com>
>>>>
>>>>> wrote:
>>>>>
>>>>>
>>>>>
>>>>>> On 4 Jul 2018, at 14:53, Alejandro Lucero wrote:
>>>>>>
>>>>>> A device can suffer addressing limitations. This functions checks
>>>>>>
>>>>>> memsegs have iovas within the supported range based on dma mask.
>>>>>>>
>>>>>>> PMD should use this during initialization if supported devices
>>>>>>> suffer addressing limitations, returning an error if this function
>>>>>>> returns memsegs out of range.
>>>>>>>
>>>>>>> Another potential usage is for emulated IOMMU hardware with
>>>>>>> addressing
>>>>>>> limitations.
>>>>>>>
>>>>>>> Signed-off-by: Alejandro Lucero <alejandro.lucero at netronome.com>
>>>>>>> Acked-by: Anatoly Burakov <anatoly.burakov at intel.com>
>>>>>>> ---
>>>>>>>  lib/librte_eal/common/eal_common_memory.c  | 33
>>>>>>> ++++++++++++++++++++++++++++++
>>>>>>>  lib/librte_eal/common/include/rte_memory.h |  3 +++
>>>>>>>  lib/librte_eal/rte_eal_version.map         |  1 +
>>>>>>>  3 files changed, 37 insertions(+)
>>>>>>>
>>>>>>> diff --git a/lib/librte_eal/common/eal_common_memory.c
>>>>>>> b/lib/librte_eal/common/eal_common_memory.c
>>>>>>> index fc6c44d..f5efebe 100644
>>>>>>> --- a/lib/librte_eal/common/eal_common_memory.c
>>>>>>> +++ b/lib/librte_eal/common/eal_common_memory.c
>>>>>>> @@ -109,6 +109,39 @@
>>>>>>>         }
>>>>>>>  }
>>>>>>>
>>>>>>> +/* check memseg iovas are within the required range based on dma
>>>>>>> mask
>>>>>>> */
>>>>>>> +int
>>>>>>> +rte_eal_check_dma_mask(uint8_t maskbits)
>>>>>>> +{
>>>>>>> +
>>>>>>> +       const struct rte_mem_config *mcfg;
>>>>>>> +       uint64_t mask;
>>>>>>> +       int i;
>>>>>>> +
>>>>>>>
>>>>>>>
>>>>>>> I think we should add some sanity check to the input maskbits, i.e.
>>>>>> [64,0)
>>>>>> or [64, 32]? What would be a reasonable lower bound.
>>>>>>
>>>>>>
>>>>>> This is not a user's API, so any invocation will be reviewed, but I
>>>>>> guess
>>>>>>
>>>>> adding a sanity check here does not harm.
>>>>>
>>>>> Not sure about lower bound but upper should 64, although it does not
>>>>> make
>>>>> sense but it is safe. Lower bound is not so problematic.
>>>>>
>>>>>
>>>>>
>>>>> +       /* create dma mask */
>>>>>>
>>>>>> +       mask = ~((1ULL << maskbits) - 1);
>>>>>>> +
>>>>>>> +       /* get pointer to global configuration */
>>>>>>> +       mcfg = rte_eal_get_configuration()->mem_config;
>>>>>>> +
>>>>>>> +       for (i = 0; i < RTE_MAX_MEMSEG; i++) {
>>>>>>> +               if (mcfg->memseg[i].addr == NULL)
>>>>>>> +                       break;
>>>>>>>
>>>>>>>
>>>>>> Looking at some other code, it looks like NULL entries might exists.
>>>> So
>>>> should a continue; rather than a break; be used here?
>>>>
>>>>
>>>> I do not think so. memsegs are allocated sequentially, so first with
>>> addr
>>> as NULL implies no more memsegs.
>>>
>>
>> I was referring to the mem walk functions, rte_memseg_list_walk(). Maybe
>> some having more experience with this area can review/comment.
>>
>
> Pre-18.05, all memsegs are allocated continuously. Memseg lists and memseg
> list walk functions are 18.05+.
>
> Alejandro, perhaps it would be worth it to tag your patchset with
> "pre-18.05" to avoid similar confusion in the future?
>
>
Yes, that will help. I'm sending a new version shortly and I'll make it
clear.



> --
> Thanks,
> Anatoly
>


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