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Re: [PATCH v2 2/5] s390x: kvm: topology: interception of PTF instruction


From: Pierre Morel
Subject: Re: [PATCH v2 2/5] s390x: kvm: topology: interception of PTF instruction
Date: Tue, 3 Aug 2021 10:10:02 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0



On 7/22/21 7:42 PM, Pierre Morel wrote:
Interception of the PTF instruction depending on the new
KVM_CAP_S390_CPU_TOPOLOGY KVM extension.

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
---
  hw/s390x/s390-virtio-ccw.c         | 45 ++++++++++++++++++++++++++++++
  include/hw/s390x/s390-virtio-ccw.h |  7 +++++
  target/s390x/kvm/kvm.c             | 21 ++++++++++++++
  3 files changed, 73 insertions(+)

diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
index e4b18aef49..500e856974 100644
--- a/hw/s390x/s390-virtio-ccw.c
+++ b/hw/s390x/s390-virtio-ccw.c
@@ -404,6 +404,49 @@ static void s390_pv_prepare_reset(S390CcwMachineState *ms)
      s390_pv_prep_reset();
  }
+int s390_handle_ptf(S390CPU *cpu, uint8_t r1, uintptr_t ra)
+{
+    S390CcwMachineState *ms = S390_CCW_MACHINE(qdev_get_machine());
+    CPUS390XState *env = &cpu->env;
+    uint64_t reg = env->regs[r1];
+    uint8_t fc = reg & S390_TOPO_FC_MASK;
+
+    if (!s390_has_feat(S390_FEAT_CONFIGURATION_TOPOLOGY)) {
+        s390_program_interrupt(env, PGM_OPERAND, ra);
+        return 0;
+    }
+
+    if (env->psw.mask & PSW_MASK_PSTATE) {
+        s390_program_interrupt(env, PGM_PRIVILEGED, ra);
+        return 0;
+    }
+
+    if (reg & ~S390_TOPO_FC_MASK) {
+        s390_program_interrupt(env, PGM_SPECIFICATION, ra);
+        return 0;
+    }
+
+    switch (fc) {
+    case 0:    /* Horizontal polarization is already set */
+        env->regs[r1] = S390_PTF_REASON_DONE;
+        return 2;
+    case 1:    /* Vertical polarization is not supported */
+        env->regs[r1] = S390_PTF_REASON_NONE;
+        return 2;
+    case 2:    /* Report if a topology change report is pending */
+        if (ms->topology_change_report_pending) {
+            ms->topology_change_report_pending = false;
+            return 1;
+        }
+        return 0;
+    default:
+        s390_program_interrupt(env, PGM_SPECIFICATION, ra);
+        break;
+    }
+
+    return 0;
+}
+

Hi all,

it seems the part where the topology change is made pending on CPU creation disappeared from this patch...:

diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
index e02b2a8299..a9eeb11d1f 100644
--- a/hw/s390x/s390-virtio-ccw.c
+++ b/hw/s390x/s390-virtio-ccw.c
@@ -302,12 +302,14 @@ static void s390_cpu_plug(HotplugHandler *hotplug_dev,
                         DeviceState *dev, Error **errp)
 {
     MachineState *ms = MACHINE(hotplug_dev);
+    S390CcwMachineState *s390ms = S390_CCW_MACHINE(ms);
     S390CPU *cpu = S390_CPU(dev);

     g_assert(!ms->possible_cpus->cpus[cpu->env.core_id].cpu);
     ms->possible_cpus->cpus[cpu->env.core_id].cpu = OBJECT(dev);

     s390_topology_new_cpu(cpu->env.core_id);
+    s390ms->topology_change_report_pending = true;

     if (dev->hotplugged) {
         raise_irq_cpu_hotplug();


I will add this on the next round.

Otherwise, the changes in the Linux side to implement interpretation do not affect the QEMU implementation.

so... a gentle ping?

Pierre


  static void s390_machine_reset(MachineState *machine)
  {
      S390CcwMachineState *ms = S390_CCW_MACHINE(machine);
@@ -433,6 +476,8 @@ static void s390_machine_reset(MachineState *machine)
          run_on_cpu(cs, s390_do_cpu_ipl, RUN_ON_CPU_NULL);
          break;
      case S390_RESET_MODIFIED_CLEAR:
+        /* clear topology_change_report pending condition on subsystem reset */
+        ms->topology_change_report_pending = false;
          /*
           * Susbsystem reset needs to be done before we unshare memory
           * and lose access to VIRTIO structures in guest memory.
diff --git a/include/hw/s390x/s390-virtio-ccw.h 
b/include/hw/s390x/s390-virtio-ccw.h
index 3331990e02..fbde357332 100644
--- a/include/hw/s390x/s390-virtio-ccw.h
+++ b/include/hw/s390x/s390-virtio-ccw.h
@@ -27,9 +27,16 @@ struct S390CcwMachineState {
      bool aes_key_wrap;
      bool dea_key_wrap;
      bool pv;
+    bool topology_change_report_pending;
      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
+int s390_handle_ptf(S390CPU *cpu, uint8_t r1, uintptr_t ra);
+
  struct S390CcwMachineClass {
      /*< private >*/
      MachineClass parent_class;
diff --git a/target/s390x/kvm/kvm.c b/target/s390x/kvm/kvm.c
index 5b1fdb55c4..9a0c13d4ac 100644
--- a/target/s390x/kvm/kvm.c
+++ b/target/s390x/kvm/kvm.c
@@ -97,6 +97,7 @@
#define PRIV_B9_EQBS 0x9c
  #define PRIV_B9_CLP                     0xa0
+#define PRIV_B9_PTF                     0xa2
  #define PRIV_B9_PCISTG                  0xd0
  #define PRIV_B9_PCILG                   0xd2
  #define PRIV_B9_RPCIT                   0xd3
@@ -1452,6 +1453,16 @@ static int kvm_mpcifc_service_call(S390CPU *cpu, struct 
kvm_run *run)
      }
  }
+static int kvm_handle_ptf(S390CPU *cpu, struct kvm_run *run)
+{
+    uint8_t r1 = (run->s390_sieic.ipb >> 20) & 0x0f;
+    uint8_t ret;
+
+    ret = s390_handle_ptf(cpu, r1, RA_IGNORED);
+    setcc(cpu, ret);
+    return 0;
+}
+
  static int handle_b9(S390CPU *cpu, struct kvm_run *run, uint8_t ipa1)
  {
      int r = 0;
@@ -1469,6 +1480,9 @@ static int handle_b9(S390CPU *cpu, struct kvm_run *run, 
uint8_t ipa1)
      case PRIV_B9_RPCIT:
          r = kvm_rpcit_service_call(cpu, run);
          break;
+    case PRIV_B9_PTF:
+        r = kvm_handle_ptf(cpu, run);
+        break;
      case PRIV_B9_EQBS:
          /* just inject exception */
          r = -1;
@@ -2470,6 +2484,13 @@ void kvm_s390_get_host_cpu_model(S390CPUModel *model, 
Error **errp)
          set_bit(S390_FEAT_DIAG_318, model->features);
      }
+ /*
+     * Configuration topology is partially handled in KVM
+     */
+    if (kvm_check_extension(kvm_state, KVM_CAP_S390_CPU_TOPOLOGY)) {
+        set_bit(S390_FEAT_CONFIGURATION_TOPOLOGY, model->features);
+    }
+
      /* strip of features that are not part of the maximum model */
      bitmap_and(model->features, model->features, model->def->full_feat,
                 S390_FEAT_MAX);


--
Pierre Morel
IBM Lab Boeblingen



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