Re: [PATCH v3 2/3] s390/vfio-ap: set status response code to 06 on gisc registration failure

Harald Freudenberger
2023-10-27T08:26:06Z

On 2023-10-26 20:32, Tony Krowiak wrote:
> From: Anthony Krowiak <akrowiak@linux.ibm.com>
>
> The interception handler for the PQAP(AQIC) command calls the
> kvm_s390_gisc_register function to register the guest ISC with the
> channel
> subsystem. If that call fails, the status response code 08 - indicating
> Invalid ZONE/GISA designation - is returned to the guest. This response
> code does not make sense because the non-zero return code from the
> kvm_s390_gisc_register function can be due one of two things: Either
> the
> ISC passed as a parameter by the guest to the PQAP(AQIC) command is
> greater
> than the maximum ISC value allowed, or the guest is not using a GISA.
>
> Since this scenario is very unlikely to happen and there is no status
> response code to indicate an invalid ISC value, let's set the
> response code to 06 indicating 'Invalid address of AP-queue
> notification
> byte'. While this is not entirely accurate, it is better than
> indicating
> that the ZONE/GISA designation is invalid which is something the guest
> can do nothing about since those values are set by the hypervisor.
>
> Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
> Suggested-by: Halil Pasic <pasic@linux.ibm.com>
> ---
> drivers/s390/crypto/vfio_ap_ops.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c
> b/drivers/s390/crypto/vfio_ap_ops.c
> index 9cb28978c186..25d7ce2094f8 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -393,8 +393,8 @@ static int ensure_nib_shared(unsigned long addr,
> struct gmap *gmap)
> * Register the guest ISC to GIB interface and retrieve the
> * host ISC to issue the host side PQAP/AQIC
> *
> - * Response.status may be set to AP_RESPONSE_INVALID_ADDRESS in case
> the
> - * vfio_pin_pages failed.
> + * status.response_code may be set to AP_RESPONSE_INVALID_ADDRESS in
> case the
> + * vfio_pin_pages or kvm_s390_gisc_register failed.
> *
> * Otherwise return the ap_queue_status returned by the ap_aqic(),
> * all retry handling will be done by the guest.
> @@ -458,7 +458,7 @@ static struct ap_queue_status
> vfio_ap_irq_enable(struct vfio_ap_queue *q,
> __func__, nisc, isc, q->apqn);
>
> vfio_unpin_pages(&q->matrix_mdev->vdev, nib, 1);
> - status.response_code = AP_RESPONSE_INVALID_GISA;
> + status.response_code = AP_RESPONSE_INVALID_ADDRESS;
> return status;
> }

Interesting ... The INVALID_GISA is handled in the default arm of the
switch
in ap_queue.c but the INVALID_ADDRESS is handled as irq enablement
failed.
So this change fits more to the current AP bus code. Thanks

Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>