lkml.org 
[lkml]   [2021]   [Nov]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] KVM: s390x: add debug statement for diag 318 CPNC data
On 11/8/21 13:04, Christian Borntraeger wrote:
>
>
> Am 08.11.21 um 12:12 schrieb Janosch Frank:
>> On 10/27/21 04:54, Collin Walling wrote:
>>> The diag 318 data contains values that denote information regarding the
>>> guest's environment. Currently, it is unecessarily difficult to observe
>>> this value (either manually-inserted debug statements, gdb stepping, mem
>>> dumping etc). It's useful to observe this information to obtain an
>>> at-a-glance view of the guest's environment, so lets add a simple VCPU
>>> event that prints the CPNC to the s390dbf logs.
>>>
>>> Signed-off-by: Collin Walling <walling@linux.ibm.com>
>>> ---
>>>   arch/s390/kvm/kvm-s390.c | 1 +
>>>   1 file changed, 1 insertion(+)
>>>
>>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
>>> index 6a6dd5e1daf6..da3ff24eabd0 100644
>>> --- a/arch/s390/kvm/kvm-s390.c
>>> +++ b/arch/s390/kvm/kvm-s390.c
>>> @@ -4254,6 +4254,7 @@ static void sync_regs_fmt2(struct kvm_vcpu *vcpu)
>>>       if (kvm_run->kvm_dirty_regs & KVM_SYNC_DIAG318) {
>>>           vcpu->arch.diag318_info.val = kvm_run->s.regs.diag318;
>>>           vcpu->arch.sie_block->cpnc = vcpu->arch.diag318_info.cpnc;
>>> +        VCPU_EVENT(vcpu, 2, "setting cpnc to %d", vcpu->arch.diag318_info.cpnc);
>>>       }
>>>       /*
>>>        * If userspace sets the riccb (e.g. after migration) to a valid state,
>>>
>>
>> Won't that turn up for every vcpu and spam the log?
>
> only if the userspace always sets the dirty bit (which it should not).
>

But that's exactly what it does, no?
We do a loop over all vcpus and call kvm_s390_set_diag318() which sets
the info in kvm_run and sets the diag318 bit in the kvm_dirty_regs.

@Collin: Could you check that please?
\
 
 \ /
  Last update: 2021-11-08 13:49    [W:0.063 / U:0.396 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site