Re: [PATCH] Drivers: hv: Use meaningful errnos for hypercall status codes

[Naman Jain]

On 7/28/2026 2:53 AM, Easwar Hariharan wrote:
> Hi Hardik,
>
> On 7/27/2026 14:11, Hardik Garg wrote:
> > Commit 3817854ba892 ("hyperv: Log hypercall status codes as strings")
> > converted hv_result_to_errno() from a switch to a table and added status
> > codes used for string logging. Statuses without an existing specific
> > mapping were assigned the generic -EIO fallback even when a more specific
> > errno was available.
> >
> > Map HV_STATUS_ACCESS_DENIED and HV_STATUS_OPERATION_DENIED to -EACCES,
> > HV_STATUS_UNKNOWN_PROPERTY and HV_STATUS_PROPERTY_VALUE_OUT_OF_RANGE to
> > -EINVAL, and HV_STATUS_PROCESSOR_FEATURE_NOT_SUPPORTED to -EOPNOTSUPP.
> > This lets callers distinguish permission, argument, and capability
> > failures from generic I/O errors.
> >
> > The table conversion also added duplicate HV_STATUS_INVALID_LP_INDEX and
> > HV_STATUS_INVALID_REGISTER_VALUE entries. Remove the later -EIO entries,
> > which are unreachable because find_hv_status_info() returns the first
> > match.
> >
> > Signed-off-by: Hardik Garg <hargar@xxxxxxxxxxxxxxxxxxx>
> > ---
> >   drivers/hv/hv_common.c | 12 +++++-------
> >   1 file changed, 5 insertions(+), 7 deletions(-)
> Glad to see that this was something that bothered you as well. If you like, you
> can pick up feedback from Nuno on my attempt to solve this [1] and do a de-facto v3.
>
> [1] https://lore.kernel.org/all/479242d4-ae08-442c-b61b-c9408ba2e9b0@xxxxxxxxxxxxxxxxxxx/
>
> Thanks,
> Easwar (he/him)

I see no harm but only benefits in returning meaningful error code 
corresponding to HV_STATUS_*, where we can, specially when such an error 
code exists. So I agree with the motivation of this exercise.

On this patch or a new v3 of previous patch, feel free to pick my review:

Reviewed-by: Naman Jain <namjain@xxxxxxxxxxxxxxxxxxx>

Regards,
Naman