RE: [PATCH] cxl/region: reset the cxl endpoint decoder HPA range on teardown

[Dan Williams <dan.j.williams@intel.com>]

Vishal Verma wrote:
> The endpoint decoder HPA range gets set up during cxl_region_attach, but
> cxl_region_detach() neglects to reset it back to a 'free' state. As a
> result, a create-destroy-create cycle with the same region parameters
> results in the second create-region failing with an EBUSY when trying to
> reserver DPA.
> 
>   # cxl create-region -d decoder3.2 -m mem4 -g 1024
>   cxl region: create_region: decoder11.1: set_dpa_size failed: Device or resource busy
>   cxl region: cmd_create_region: created 0 regions
> 
> Set the endpoint decoder's hpa_range to [0, -1] to mark it as free in
> cxl_region_detach().
> 
> Fixes: 292bdc6af8f2 ("cxl/region: Move HPA setup to cxl_region_attach()")
> Cc: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
> ---
>  drivers/cxl/core/region.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> Hi Dan,
> 
> This is a fixup-to-a-fixup, and the commit in Fixes: is only in
> 'preview'. Feel free to squash this into the original fix if you so
> prefer.

Will do, I think this also needs to kill the cxld_clear_hpa() helper and
call in cxl_decoder_reset().

> Another question - should we be resetting the endpoint decoder's mode to
> CXL_DECODER_DEAD while in here? I notice that a freed decoder still
> lists mode:pmem in cxl-list.

The DEAD state is a internal-only hack while the decoder is being torn
down, it's not visible to userspace. Perhaps just hide the none state
and default the mode to 'ram' when no DPA is allocated?