[PATCH] powerpc/nvdimm: Add support for multibyte read/write for metadata

[Michael Ellerman]

"Aneesh Kumar K.V" <aneesh.kumar at linux.ibm.com> writes:
> Oliver <oohall at gmail.com> writes:
>> On Sun, Jun 2, 2019 at 2:44 PM Aneesh Kumar K.V
>> <aneesh.kumar at linux.ibm.com> wrote:
...
>>> diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
>>> index 0176ce66673f..e33cebb8ee6c 100644
>>> --- a/arch/powerpc/platforms/pseries/papr_scm.c
>>> +++ b/arch/powerpc/platforms/pseries/papr_scm.c
>>> @@ -97,42 +97,102 @@ static int drc_pmem_unbind(struct papr_scm_priv *p)
>>>  }
>>>
>>>  static int papr_scm_meta_get(struct papr_scm_priv *p,
>>> -                       struct nd_cmd_get_config_data_hdr *hdr)
>>> +                            struct nd_cmd_get_config_data_hdr *hdr)
>>>  {
>>>         unsigned long data[PLPAR_HCALL_BUFSIZE];
>>> +       unsigned long offset, data_offset;
>>> +       int len, read;
>>>         int64_t ret;
>>>
>>> -       if (hdr->in_offset >= p->metadata_size || hdr->in_length != 1)
>>> +       if ((hdr->in_offset + hdr->in_length) >= p->metadata_size)
>>>                 return -EINVAL;
>>>
>>> -       ret = plpar_hcall(H_SCM_READ_METADATA, data, p->drc_index,
>>> -                       hdr->in_offset, 1);
>>> -
>>> -       if (ret == H_PARAMETER) /* bad DRC index */
>>> -               return -ENODEV;
>>> -       if (ret)
>>> -               return -EINVAL; /* other invalid parameter */
>>> -
>>> -       hdr->out_buf[0] = data[0] & 0xff;
>>> -
>>> +       for (len = hdr->in_length; len; len -= read) {
>>> +
>>> +               data_offset = hdr->in_length - len;
>>> +               offset = hdr->in_offset + data_offset;
>>> +
>>> +               if (len >= 8)
>>> +                       read = 8;
>>> +               else if (len >= 4)
>>> +                       read = 4;
>>> +               else if ( len >= 2)
>>> +                       read = 2;
>>> +               else
>>> +                       read = 1;
>>> +
>>> +               ret = plpar_hcall(H_SCM_READ_METADATA, data, p->drc_index,
>>> +                                 offset, read);
>>> +
>>> +               if (ret == H_PARAMETER) /* bad DRC index */
>>> +                       return -ENODEV;
>>> +               if (ret)
>>> +                       return -EINVAL; /* other invalid parameter */
>>> +
>>> +               switch (read) {
>>> +               case 8:
>>> +                       *(uint64_t *)(hdr->out_buf + data_offset) = be64_to_cpu(data[0]);
>>> +                       break;
>>> +               case 4:
>>> +                       *(uint32_t *)(hdr->out_buf + data_offset) = be32_to_cpu(data[0] & 0xffffffff);
>>> +                       break;
...
>>
>> I assume you got the qemu bits sorted out with Shiva? Looks good otherwise.
>
> That is correct. I also tested with different xfer values (1, 2, 4, 8)
> on both Qemu and PowerVM.

With a big endian kernel?

cheers