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

[David Hildenbrand <david@redhat.com>]

On 05/10/2018 09:50, Cornelia Huck wrote:
> 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...

Maybe factor out the setting of the actual masks to KVM code and do
tracing there?

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


-- 

Thanks,

David / dhildenb