Re: [PATCH] s390: vfio-ap: trace the update of APCB masks

Cornelia Huck
2018-10-05T07:50:58Z

On Fri, 5 Oct 2018 09:33:01 +0200
Pierre Morel <pmorel@linux.ibm.com> wrote:

> Define a tracing function to trace in the KVM trace buffer
> and trace the changes of the APCB masks.

In general, trace events are good :)

>
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> ---
> drivers/s390/crypto/vfio_ap_ops.c | 22 ++++++++++++++++++++++
> drivers/s390/crypto/vfio_ap_private.h | 4 ++++
> 2 files changed, 26 insertions(+)
>
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index a8a9984..00e632a 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -753,6 +753,28 @@ static void vfio_ap_mdev_copy_masks(struct ap_matrix_mdev *matrix_mdev)
> memcpy(aqm, matrix_mdev->matrix.aqm, nbytes);
> nbytes = DIV_ROUND_UP(matrix_mdev->matrix.adm_max + 1, BITS_PER_BYTE);
> memcpy(adm, matrix_mdev->matrix.adm, nbytes);
> +
> + switch (matrix_mdev->kvm->arch.crypto.crycbd & CRYCB_FORMAT_MASK) {
> + case CRYCB_FORMAT2:
> + VM_AP_EVENT(matrix_mdev->kvm, 3,
> + "SET CRYCB: apm %016lx %016lx %016lx %016lx",
> + apm[0], apm[1], apm[2], apm[3]);
> + VM_AP_EVENT(matrix_mdev->kvm, 3,
> + "SET CRYCB: aqm %016lx %016lx %016lx %016lx",
> + aqm[0], aqm[1], aqm[2], aqm[3]);
> + VM_AP_EVENT(matrix_mdev->kvm, 3,
> + "SET CRYCB: adm %016lx %016lx %016lx %016lx",
> + adm[0], adm[1], adm[2], adm[3]);
> + break;
> + case CRYCB_FORMAT1:
> + case CRYCB_FORMAT0: /* Both CRYCB format uses APCB format 0 */
> + default: /* Can not happen */

If it can't happen, trace "SET CRYCB: invalid format '%x'" instead?

> + VM_AP_EVENT(matrix_mdev->kvm, 3,
> + "SET CRYCB: apm %016lx aqm %04x adm %04x", apm[0],
> + *((unsigned short *)aqm), *((unsigned short *)adm));
> + break;
> + }
> +
> }
>
> /**
> diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
> index 5675492..4cd779d 100644
> --- a/drivers/s390/crypto/vfio_ap_private.h
> +++ b/drivers/s390/crypto/vfio_ap_private.h
> @@ -19,6 +19,10 @@
>
> #include "ap_bus.h"
>
> +#define VM_AP_EVENT(d_kvm, d_loglevel, d_string, d_args...)\
> + debug_sprintf_event(d_kvm->arch.dbf, d_loglevel, d_string "\n", \
> + d_args)
> +
> #define VFIO_AP_MODULE_NAME "vfio_ap"
> #define VFIO_AP_DRV_NAME "vfio_ap"
>

One thing I don't like about this is that you're using the kvm dbf from
driver code, which looks odd. OTOH, these are kvm-specific masks...

Is there anything else that you may want to trace in the vfio-ap
driver, so that you could add a dbf for it?