Re: [PATCH v14 06/11] s390x/cpu topology: interception of PTF instruction

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On 1/16/23 19:24, Nina Schoetterl-Glausch wrote:
On Thu, 2023-01-05 at 15:53 +0100, 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 hypervizor 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 hypervizor.

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

Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
---
  include/hw/s390x/cpu-topology.h    |  3 +
  include/hw/s390x/s390-virtio-ccw.h |  6 ++
  target/s390x/cpu.h                 |  1 +
  hw/s390x/cpu-topology.c            | 92 ++++++++++++++++++++++++++++++
  target/s390x/cpu-sysemu.c          | 16 ++++++
  target/s390x/kvm/kvm.c             | 11 ++++
  6 files changed, 129 insertions(+)

diff --git a/include/hw/s390x/cpu-topology.h b/include/hw/s390x/cpu-topology.h
index 9571aa70e5..33e23d78b9 100644
--- a/include/hw/s390x/cpu-topology.h
+++ b/include/hw/s390x/cpu-topology.h
@@ -55,11 +55,13 @@ typedef struct S390Topology {
      QTAILQ_HEAD(, S390TopologyEntry) list;
      uint8_t *sockets;
      CpuTopology *smp;
+    int polarity;
  } S390Topology;
#ifdef CONFIG_KVM
  bool s390_has_topology(void);
  void s390_topology_set_cpu(MachineState *ms, S390CPU *cpu, Error **errp);
+void s390_topology_set_polarity(int polarity);
  #else
  static inline bool s390_has_topology(void)
  {
@@ -68,6 +70,7 @@ static inline bool s390_has_topology(void)
  static inline void s390_topology_set_cpu(MachineState *ms,
                                           S390CPU *cpu,
                                           Error **errp) {}
+static inline void s390_topology_set_polarity(int polarity) {}
  #endif
  extern S390Topology s390_topology;
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/target/s390x/cpu.h b/target/s390x/cpu.h
index 01ade07009..5da4041576 100644
--- a/target/s390x/cpu.h
+++ b/target/s390x/cpu.h
@@ -864,6 +864,7 @@ void s390_do_cpu_set_diag318(CPUState *cs, run_on_cpu_data arg);
  int s390_assign_subch_ioeventfd(EventNotifier *notifier, uint32_t sch_id,
                                  int vq, bool assign);
  void s390_cpu_topology_reset(void);
+void s390_cpu_topology_set(void);

I don't like this name much, it's nondescript.
s390_cpu_topology_set_modified ?

  #ifndef CONFIG_USER_ONLY
  unsigned int s390_cpu_set_state(uint8_t cpu_state, S390CPU *cpu);
  #else
diff --git a/hw/s390x/cpu-topology.c b/hw/s390x/cpu-topology.c
index 438055c612..e6b4692581 100644
--- a/hw/s390x/cpu-topology.c
+++ b/hw/s390x/cpu-topology.c
@@ -97,6 +97,98 @@ static s390_topology_id s390_topology_from_cpu(S390CPU *cpu)
  }
/**
+ * s390_topology_set_polarity
+ * @polarity: horizontal or vertical
+ *
+ * Changes the polarity of all the CPU in the configuration.
+ *
+ * If the dedicated CPU modifier attribute is set a vertical
+ * polarization is always high (Architecture).
+ * Otherwise we decide to set it as medium.
+ *
+ * Once done, advertise a topology change.
+ */
+void s390_topology_set_polarity(int polarity)

I don't like that this function ignores what kind of vertical polarization is passed,
it's confusing.
That seems like a further reason to split horizontal/vertical from the entitlement.


Yes.
I will also make the ordering of the TLE at the last moment instead of doing it during hotplug or QAPI command. This is something Cedric proposed some time ago and I think it is right, it will be easier to do it once in STSI than on every change of topology,
hotplug, QAPI and polarization change with PTF.

Regards,
Pierre

--
Pierre Morel
IBM Lab Boeblingen



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