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

[Pierre Morel <pmorel@linux.ibm.com>]

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@linux.ibm.com>
---
 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);
 #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)
+{
+    S390TopologyEntry *entry;
+
+    QTAILQ_FOREACH(entry, &s390_topology.list, next) {
+        if (polarity == S390_TOPOLOGY_POLARITY_HORIZONTAL) {
+            entry->id.p = polarity;
+        } else {
+            if (entry->id.d) {
+                entry->id.p = S390_TOPOLOGY_POLARITY_VERTICAL_HIGH;
+            } else {
+                entry->id.p = S390_TOPOLOGY_POLARITY_VERTICAL_MEDIUM;
+            }
+        }
+    }
+    s390_cpu_topology_set();
+}
+
+/*
+ * s390_handle_ptf:
+ *
+ * @register 1: contains the function code
+ *
+ * Function codes 0 and 1 handle the CPU polarization.
+ * We assume an horizontal topology, the only one supported currently
+ * by Linux, consequently we answer to function code 0, requesting
+ * horizontal polarization that it is already the current polarization
+ * and reject vertical polarization request without further explanation.
+ *
+ * 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];
+    uint8_t 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 0:    /* Horizontal polarization is already set */
+        if (s390_topology.polarity == S390_TOPOLOGY_POLARITY_HORIZONTAL) {
+            env->regs[r1] |= S390_PTF_REASON_DONE;
+            setcc(cpu, 2);
+        } else {
+            s390_topology_set_polarity(S390_TOPOLOGY_POLARITY_HORIZONTAL);
+            s390_topology.polarity = S390_TOPOLOGY_POLARITY_HORIZONTAL;
+            setcc(cpu, 0);
+        }
+        break;
+    case 1:    /* Vertical polarization is not supported */
+        if (s390_topology.polarity != S390_TOPOLOGY_POLARITY_HORIZONTAL) {
+            env->regs[r1] |= S390_PTF_REASON_DONE;
+            setcc(cpu, 2);
+        } else {
+            s390_topology_set_polarity(S390_TOPOLOGY_POLARITY_VERTICAL_LOW);
+            s390_topology.polarity = S390_TOPOLOGY_POLARITY_VERTICAL_LOW;
+            setcc(cpu, 0);
+        }
+        break;
+    default:
+        /* Note that fc == 2 is interpreted by the SIE */
+        s390_program_interrupt(env, PGM_SPECIFICATION, ra);
+    }
+}
+
+ /**
  * s390_topology_set_entry:
  * @entry: Topology entry to setup
  * @id: topology id to use for the setup
diff --git a/target/s390x/cpu-sysemu.c b/target/s390x/cpu-sysemu.c
index e27864c5f5..8643320947 100644
--- a/target/s390x/cpu-sysemu.c
+++ b/target/s390x/cpu-sysemu.c
@@ -37,6 +37,7 @@
 #include "sysemu/sysemu.h"
 #include "sysemu/tcg.h"
 #include "hw/core/sysemu-cpu-ops.h"
+#include "hw/s390x/cpu-topology.h"
 
 /* S390CPUClass::load_normal() */
 static void s390_cpu_load_normal(CPUState *s)
@@ -311,6 +312,8 @@ void s390_cpu_topology_reset(void)
 {
     int ret;
 
+    s390_topology_set_polarity(S390_TOPOLOGY_POLARITY_HORIZONTAL);
+
     if (kvm_enabled()) {
         ret = kvm_s390_topology_set_mtcr(0);
         if (ret) {
@@ -319,3 +322,16 @@ void s390_cpu_topology_reset(void)
         }
     }
 }
+
+void s390_cpu_topology_set(void)
+{
+    int ret;
+
+    if (kvm_enabled()) {
+        ret = kvm_s390_topology_set_mtcr(1);
+        if (ret) {
+            error_report("Failed to set Modified Topology Change Report: %s",
+                         strerror(-ret));
+        }
+    }
+}
diff --git a/target/s390x/kvm/kvm.c b/target/s390x/kvm/kvm.c
index bc953151ce..fb63be41b7 100644
--- a/target/s390x/kvm/kvm.c
+++ b/target/s390x/kvm/kvm.c
@@ -96,6 +96,7 @@
 
 #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
@@ -1464,6 +1465,13 @@ static int kvm_mpcifc_service_call(S390CPU *cpu, struct kvm_run *run)
     }
 }
 
+static void kvm_handle_ptf(S390CPU *cpu, struct kvm_run *run)
+{
+    uint8_t r1 = (run->s390_sieic.ipb >> 20) & 0x0f;
+
+    s390_handle_ptf(cpu, r1, RA_IGNORED);
+}
+
 static int handle_b9(S390CPU *cpu, struct kvm_run *run, uint8_t ipa1)
 {
     int r = 0;
@@ -1481,6 +1489,9 @@ 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:
+        kvm_handle_ptf(cpu, run);
+        break;
     case PRIV_B9_EQBS:
         /* just inject exception */
         r = -1;
-- 
2.31.1