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

[Eelco Chaudron]

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.

>
>
>>
>> +
>>>>> +               if (mcfg->memseg[i].iova & mask) {
>>>>> +                       RTE_LOG(INFO, EAL,
>>>>> +                               "memseg[%d] iova %"PRIx64" out of
>>>>> range:\n",
>>>>> +                               i, mcfg->memseg[i].iova);
>>>>> +
>>>>> +                       RTE_LOG(INFO, EAL, "\tusing dma mask
>>>>> %"PRIx64"\n",
>>>>> +                               mask);
>>>>> +                       return -1;
>>>>> +               }
>>>>> +       }
>>>>> +
>>>>> +       return 0;
>>>>> +}
>>>>> +
>>>>>  /* return the number of memory channels */
>>>>>  unsigned rte_memory_get_nchannel(void)
>>>>>  {
>>>>> diff --git a/lib/librte_eal/common/include/rte_memory.h
>>>>> b/lib/librte_eal/common/include/rte_memory.h
>>>>> index 80a8fc0..b2a0168 100644
>>>>> --- a/lib/librte_eal/common/include/rte_memory.h
>>>>> +++ b/lib/librte_eal/common/include/rte_memory.h
>>>>> @@ -209,6 +209,9 @@ struct rte_memseg {
>>>>>   */
>>>>>  unsigned rte_memory_get_nrank(void);
>>>>>
>>>>> +/* check memsegs iovas are within a range based on dma mask */
>>>>> +int rte_eal_check_dma_mask(uint8_t maskbits);
>>>>> +
>>>>>  /**
>>>>>   * Drivers based on uio will not load unless physical
>>>>>   * addresses are obtainable. It is only possible to get
>>>>> diff --git a/lib/librte_eal/rte_eal_version.map
>>>>> b/lib/librte_eal/rte_eal_version.map
>>>>> index f4f46c1..aa6cf87 100644
>>>>> --- a/lib/librte_eal/rte_eal_version.map
>>>>> +++ b/lib/librte_eal/rte_eal_version.map
>>>>> @@ -184,6 +184,7 @@ DPDK_17.11 {
>>>>>
>>>>>         rte_eal_create_uio_dev;
>>>>>         rte_bus_get_iommu_class;
>>>>> +       rte_eal_check_dma_mask;
>>>>>         rte_eal_has_pci;
>>>>>         rte_eal_iova_mode;
>>>>>         rte_eal_mbuf_default_mempool_ops;
>>>>> --
>>>>> 1.9.1
>>>>>
>>>>>
>>>>
>>
>>