Messages in this thread | | | Date | Mon, 8 Nov 2021 13:50:40 +0100 | Subject | Re: [PATCH] KVM: s390x: add debug statement for diag 318 CPNC data | From | Christian Borntraeger <> |
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Am 08.11.21 um 13:48 schrieb Janosch Frank: > 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.
Yes, ONCE per CPU. And this is exactly what I want to see. (and it did show a bug in qemu that we only set it for one cpu to the correct value).
> > @Collin: Could you check that please?
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