Messages in this thread | | | Date | Mon, 8 Nov 2021 13:48:27 +0100 | From | Janosch Frank <> | Subject | Re: [PATCH] KVM: s390x: add debug statement for diag 318 CPNC data |
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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?
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