[PATCH v2 2/3] powerpc/papr_scm: Update drc_pmem_unbind() to use H_SCM_UNBIND_ALL

[Oliver O'Halloran]

On Tue, Jun 25, 2019 at 10:27 PM Vaibhav Jain <vaibhav at linux.ibm.com> wrote:
>
> The new hcall named H_SCM_UNBIND_ALL has been introduce that can
> unbind all the memory drc memory-blocks assigned to an lpar.

This is a little muddy. For normal memory each block has a DRC so you
can add/remove individual blocks by configuring or deconfiguring the
DRC for that block. For storage class memory the DRC refers to the SCM
volume as a whole rather than an individual block so a "memory DRC"
isn't really what you're taking about here.

This is probably being a little pedantic, but I find the whole DRC
system confusing enough as-is so it's good to be clear about these
things.

> more efficient than using H_SCM_UNBIND_MEM as currently we don't
> support partial unbind of drc memory-blocks.
>
> Hence this patch proposes following changes to drc_pmem_unbind():
>
>     * Update drc_pmem_unbind() to replace hcall H_SCM_UNBIND_MEM to
>       H_SCM_UNBIND_ALL.
>
>     * Update drc_pmem_unbind() to handles cases when PHYP asks the guest
>       kernel to wait for specific amount of time before retrying the
>       hcall via the 'LONG_BUSY' return value.
>
> * Ensure appropriate error code is returned back from the function
>       in case of an error.
>
> Signed-off-by: Vaibhav Jain <vaibhav at linux.ibm.com>
> ---
> Change-log:
>
> v2:
> * Added a dev_dbg when unbind operation succeeds [Oliver]
> * Changed type of variable 'rc' to int64_t [Oliver]
> * Removed the code that was logging a warning in case bind operation
>   takes >1-seconds [Oliver]
> * Spinned off changes to hvcall.h as a separate patch. [Oliver]

Looks good otherwise, when you respin feel free to add:

Reviewed-by: Oliver O'Halloran <oohall at gmail.com>