Re: [PATCH v4 07/10] hw/mem/cxl_type3: Add DC extent list representative and get DC extent list mailbox support

[Jonathan Cameron]

On Wed, 21 Feb 2024 10:16:00 -0800
nifan.cxl@gmail.com wrote:

> From: Fan Ni <fan.ni@samsung.com>
> 
> Add dynamic capacity extent list representative to the definition of
> CXLType3Dev and add get DC extent list mailbox command per
> CXL.spec.3.1:.8.2.9.9.9.2.
> 
> Signed-off-by: Fan Ni <fan.ni@samsung.com>
Follow on from earlier comment on my preference for anonymous
structure types when we only use them in one place.


> +/*
> + * CXL r3.1 section 8.2.9.9.9.2:
> + * Get Dynamic Capacity Extent List (Opcode 4801h)
> + */
> +static CXLRetCode cmd_dcd_get_dyn_cap_ext_list(const struct cxl_cmd *cmd,
> +                                               uint8_t *payload_in,
> +                                               size_t len_in,
> +                                               uint8_t *payload_out,
> +                                               size_t *len_out,
> +                                               CXLCCI *cci)
> +{
> +    CXLType3Dev *ct3d = CXL_TYPE3(cci->d);
> +    struct get_dyn_cap_ext_list_in_pl {
> +        uint32_t extent_cnt;
> +        uint32_t start_extent_id;
> +    } QEMU_PACKED;
> +
> +    struct get_dyn_cap_ext_list_out_pl {
> +        uint32_t count;
> +        uint32_t total_extents;
> +        uint32_t generation_num;
> +        uint8_t rsvd[4];
> +        CXLDCExtentRaw records[];
> +    } QEMU_PACKED;
> +
> +    struct get_dyn_cap_ext_list_in_pl *in = (void *)payload_in;
> +    struct get_dyn_cap_ext_list_out_pl *out = (void *)payload_out;

As for earlier patches, I think anonymous struct types are fine for
these and lead to shorter code.

> +    uint16_t record_count = 0, i = 0, record_done = 0;
> +    CXLDCExtentList *extent_list = &ct3d->dc.extents;
> +    CXLDCExtent *ent;
> +    uint16_t out_pl_len;
> +    uint32_t start_extent_id = in->start_extent_id;
> +
> +    if (start_extent_id > ct3d->dc.total_extent_count) {
> +        return CXL_MBOX_INVALID_INPUT;
> +    }
> +
> +    record_count = MIN(in->extent_cnt,
> +                       ct3d->dc.total_extent_count - start_extent_id);
> +
> +    out_pl_len = sizeof(*out) + record_count * sizeof(out->records[0]);
> +    assert(out_pl_len <= CXL_MAILBOX_MAX_PAYLOAD_SIZE);
> +
> +    stl_le_p(&out->count, record_count);
> +    stl_le_p(&out->total_extents, ct3d->dc.total_extent_count);
> +    stl_le_p(&out->generation_num, ct3d->dc.ext_list_gen_seq);
> +
> +    if (record_count > 0) {
> +        QTAILQ_FOREACH(ent, extent_list, node) {
> +            if (i++ < start_extent_id) {
> +                continue;
> +            }
> +            stq_le_p(&out->records[record_done].start_dpa, ent->start_dpa);
> +            stq_le_p(&out->records[record_done].len, ent->len);
> +            memcpy(&out->records[record_done].tag, ent->tag, 0x10);
> +            stw_le_p(&out->records[record_done].shared_seq, ent->shared_seq);
> +            record_done++;
> +            if (record_done == record_count) {
> +                break;
> +            }
> +        }
> +    }
> +
> +    *len_out = out_pl_len;
> +    return CXL_MBOX_SUCCESS;
> +}
> +