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KVM: s390: Add tracepoint for DIAG 9c directed yield operations

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Add a new tracepoint, kvm_s390_diag_9c, to provide visibility into
directed yield operations. The tracepoint records:

  - Source vCPU context via the standard vCPU tracepoint fields
  - Target vCPU ID
  - Target physical CPU number
  - Operation result (done, ignored, or yield forwarded)

This improves observability of vCPU scheduling behaviour and helps
diagnose performance issues related to directed yields in virtualised
s390 environments.

Signed-off-by: Ciunas Bennett <ciunas@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
This commit is contained in:
Ciunas Bennett 2026-07-24 12:39:58 +02:00 committed by Christian Borntraeger
parent a3928021b9
commit 5ff53ce9a4
2 changed files with 27 additions and 0 deletions
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1
arch/s390/kvm/diag.c
View File

@ -228,6 +228,7 @@ static int __diag_time_slice_end_directed(struct kvm_vcpu *vcpu)
out:
VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d: %s", tid,
result);
trace_kvm_s390_diag_9c(vcpu, tid, tcpu_cpu, result);
return 0;
}

26
arch/s390/kvm/trace.h
View File

@ -283,6 +283,32 @@ TRACE_EVENT(kvm_s390_handle_diag,
__print_symbolic(__entry->code, diagnose_codes))
);
TRACE_EVENT(kvm_s390_diag_9c,
TP_PROTO(VCPU_PROTO_COMMON, int target_vcpu, int target_cpu,
const char *result),
TP_ARGS(VCPU_ARGS_COMMON, target_vcpu, target_cpu, result),
TP_STRUCT__entry(
VCPU_FIELD_COMMON
__field(int, target_vcpu)
__field(int, target_cpu)
__string(result, result)
),
TP_fast_assign(
VCPU_ASSIGN_COMMON
__entry->target_vcpu = target_vcpu;
__entry->target_cpu = target_cpu;
__assign_str(result);
),
VCPU_TP_PRINTK(
"diag=9c target_vcpu=%d target_pcpu=%d result=%s",
__entry->target_vcpu,
__entry->target_cpu,
__get_str(result))
);
TRACE_EVENT(kvm_s390_handle_lctl,
TP_PROTO(VCPU_PROTO_COMMON, int g, int reg1, int reg3, u64 addr),
TP_ARGS(VCPU_ARGS_COMMON, g, reg1, reg3, addr),