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

"Aneesh Kumar K.V" [off-list ref] writes:

Oliver [off-list ref] writes:

quoted

On Sun, Jun 2, 2019 at 2:44 PM Aneesh Kumar K.V
[off-list ref] wrote:

...

quoted

quoted

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;

...

quoted

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