Re: [PATCH v20 06/21] s390x/cpu topology: interception of PTF instruction

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On 5/4/23 13:03, Nina Schoetterl-Glausch wrote:
On Tue, 2023-04-25 at 18:14 +0200, Pierre Morel wrote:
When the host supports the CPU topology facility, the PTF
instruction with function code 2 is interpreted by the SIE,
provided that the userland hypervisor activates the interpretation
by using the KVM_CAP_S390_CPU_TOPOLOGY KVM extension.

The PTF instructions with function code 0 and 1 are intercepted
and must be emulated by the userland hypervisor.

During RESET all CPU of the configuration are placed in
horizontal polarity.

Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
Reviewed-by: Nina Schoetterl-Glausch <nsg@xxxxxxxxxxxxx>

Thanks



See nit below.
---
  include/hw/s390x/s390-virtio-ccw.h |  6 ++++
  hw/s390x/cpu-topology.c            | 51 ++++++++++++++++++++++++++++++
  target/s390x/kvm/kvm.c             | 11 +++++++
  3 files changed, 68 insertions(+)

diff --git a/include/hw/s390x/s390-virtio-ccw.h b/include/hw/s390x/s390-virtio-ccw.h
index 9bba21a916..c1d46e78af 100644
--- a/include/hw/s390x/s390-virtio-ccw.h
+++ b/include/hw/s390x/s390-virtio-ccw.h
@@ -30,6 +30,12 @@ struct S390CcwMachineState {
      uint8_t loadparm[8];
  };
+#define S390_PTF_REASON_NONE (0x00 << 8)
+#define S390_PTF_REASON_DONE (0x01 << 8)
+#define S390_PTF_REASON_BUSY (0x02 << 8)
+#define S390_TOPO_FC_MASK 0xffUL
+void s390_handle_ptf(S390CPU *cpu, uint8_t r1, uintptr_t ra);
+
  struct S390CcwMachineClass {
      /*< private >*/
      MachineClass parent_class;
diff --git a/hw/s390x/cpu-topology.c b/hw/s390x/cpu-topology.c
index c98439ff7a..3c7bbff4bc 100644
--- a/hw/s390x/cpu-topology.c
+++ b/hw/s390x/cpu-topology.c
@@ -96,6 +96,56 @@ static void s390_topology_init(MachineState *ms)
      QTAILQ_INSERT_HEAD(&s390_topology.list, entry, next);
  }
+/*
+ * s390_handle_ptf:
+ *
+ * @register 1: contains the function code
+ *
+ * Function codes 0 (horizontal) and 1 (vertical) define the CPU
+ * polarization requested by the guest.
+ *
+ * Function code 2 is handling topology changes and is interpreted
+ * by the SIE.
+ */
+void s390_handle_ptf(S390CPU *cpu, uint8_t r1, uintptr_t ra)
+{
+    CPUS390XState *env = &cpu->env;
+    uint64_t reg = env->regs[r1];
+    int fc = reg & S390_TOPO_FC_MASK;
+
+    if (!s390_has_feat(S390_FEAT_CONFIGURATION_TOPOLOGY)) {
+        s390_program_interrupt(env, PGM_OPERATION, ra);
+        return;
+    }
+
+    if (env->psw.mask & PSW_MASK_PSTATE) {
+        s390_program_interrupt(env, PGM_PRIVILEGED, ra);
+        return;
+    }
+
+    if (reg & ~S390_TOPO_FC_MASK) {
+        s390_program_interrupt(env, PGM_SPECIFICATION, ra);
+        return;
+    }
+
+    switch (fc) {
+    case S390_CPU_POLARIZATION_VERTICAL:
+    case S390_CPU_POLARIZATION_HORIZONTAL:
I'd give this a name.
bool requested_vertical = !!fc;


OK, looks good, I change this


Thanks.

Regards,

Pierre


+        if (s390_topology.vertical_polarization == !!fc) {
+            env->regs[r1] |= S390_PTF_REASON_DONE;
+            setcc(cpu, 2);
+        } else {
+            s390_topology.vertical_polarization = !!fc;
+            s390_cpu_topology_set_changed(true);
+            setcc(cpu, 0);
+        }
+        break;
+    default:
+        /* Note that fc == 2 is interpreted by the SIE */
+        s390_program_interrupt(env, PGM_SPECIFICATION, ra);
+    }
+}
+
[...]




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