Re: [PATCH 5/9] hw/cxl: Map lazy memory backend after host acceptance

[Anisa Su <anisa.su887@gmail.com>]

On Wed, Mar 25, 2026 at 06:42:53PM +0000, Alireza Sanaee wrote:
> In the dc-regions-total-size flow, a requested extent is not backed when it
> is queued. It becomes usable only after the host accepts it with Add
> Dynamic Capacity Response.
> 
> Use that response path to look up the first pending group's metadata for
> each accepted extent, enable the selected host backend, and move the
> backend and fixed-window references onto the committed extent list. The
> accepted range is then marked backed just like the non-lazy path.
> 
> This wires host acceptance to the lazy backend lifecycle and leaves the
> fixed-window direct aliasing to the following patch.
> 
> Signed-off-by: Alireza Sanaee <alireza.sanaee@huawei.com>
> ---
>  hw/cxl/cxl-mailbox-utils.c | 76 ++++++++++++++++++++++++++++++++++++--
>  1 file changed, 73 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
> index c5427adb3a..cc7be6e68c 100644
> --- a/hw/cxl/cxl-mailbox-utils.c
> +++ b/hw/cxl/cxl-mailbox-utils.c
[snip]
>  static CXLRetCode cxl_dcd_add_dyn_cap_rsp_dry_run(CXLType3Dev *ct3d,
>          const CXLUpdateDCExtentListInPl *in)
>  {
> @@ -3718,8 +3740,12 @@ static CXLRetCode cmd_dcd_add_dyn_cap_rsp(const struct cxl_cmd *cmd,
>      CXLUpdateDCExtentListInPl *in = (void *)payload_in;
>      CXLType3Dev *ct3d = CXL_TYPE3(cci->d);
>      CXLDCExtentList *extent_list = &ct3d->dc.extents;
> +    struct CXLFixedWindow *fw;
> +    HostMemoryBackend *hmb_dc;
> +    uint8_t tag[0x10];
>      uint32_t i, num;
>      uint64_t dpa, len;
> +    int rid;
>      CXLRetCode ret;
>  
>      if (len_in < sizeof(*in)) {
> @@ -3756,10 +3782,54 @@ static CXLRetCode cmd_dcd_add_dyn_cap_rsp(const struct cxl_cmd *cmd,
>      for (i = 0; i < in->num_entries_updated; i++) {
>          dpa = in->updated_entries[i].start_dpa;
>          len = in->updated_entries[i].len;
> +        if (ct3d->dc.total_capacity_cmd) {
               memcpy(tag, in->updated_entries[i], 0x10);
> +            bool found;
> +            MemoryRegion *mr;
> +
> +            found = cxl_extent_find_extent_detail(&ct3d->dc.extents_pending,
> +                                                  dpa, len, tag,
> +                                                  &hmb_dc, &fw, &rid);
> +
Btw, I'm using this patchset to test my current DCD RFC :) The main thing is I
want to test having multiple extents in the same add request for the new
requirements for tags on the host side. Since we can only add/remove tagged
capacity at once (no incremental add/partial release), would it be possible to
support that? Sorry I didn't have a look sooner

Thanks,
Anisa
 -- 
> 2.50.1 (Apple Git-155)
>