[PATCH v16 06/11] s390x/cpu topology: interception of PTF instruction

Pierre Morel
2023-02-22T14:21:37Z

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@linux.ibm.com>
---
include/hw/s390x/s390-virtio-ccw.h | 6 +++
hw/s390x/cpu-topology.c | 85 ++++++++++++++++++++++++++++++
target/s390x/kvm/kvm.c | 11 ++++
3 files changed, 102 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 08642e0e04..40253a2444 100644
--- a/hw/s390x/cpu-topology.c
+++ b/hw/s390x/cpu-topology.c
@@ -87,6 +87,89 @@ static void s390_topology_init(MachineState *ms)
QTAILQ_INSERT_HEAD(&s390_topology.list, entry, next);
}

+/**
+ * s390_topology_set_cpus_entitlement:
+ * @polarization: polarization requested by the caller
+ *
+ * Set all CPU entitlement according to polarization and
+ * dedication.
+ * Default vertical entitlement is S390_CPU_ENTITLEMENT_MEDIUM as
+ * it does not require host modification of the CPU provisioning
+ * until the host decide to modify individual CPU provisioning
+ * using QAPI interface.
+ * However a dedicated vCPU will have a S390_CPU_ENTITLEMENT_HIGH
+ * entitlement.
+ */
+static void s390_topology_set_cpus_entitlement(int polarization)
+{
+ CPUState *cs;
+
+ CPU_FOREACH(cs) {
+ if (polarization == S390_CPU_POLARIZATION_HORIZONTAL) {
+ S390_CPU(cs)->env.entitlement = 0;
+ } else if (S390_CPU(cs)->env.dedicated) {
+ S390_CPU(cs)->env.entitlement = S390_CPU_ENTITLEMENT_HIGH;
+ } else {
+ S390_CPU(cs)->env.entitlement = S390_CPU_ENTITLEMENT_MEDIUM;
+ }
+ }
+}
+
+/*
+ * s390_handle_ptf:
+ *
+ * @register 1: contains the function code
+ *
+ * Function codes 0 (horizontal) and 1 (vertical) define the CPU
+ * polarization requested by the guest.
+ *
+ * Verify that the polarization really need to change and call
+ * s390_topology_set_cpus_entitlement() specifying the requested polarization
+ * to set for all CPUs.
+ *
+ * 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:
+ if (s390_topology.polarization == fc) {
+ env->regs[r1] |= S390_PTF_REASON_DONE;
+ setcc(cpu, 2);
+ } else {
+ s390_topology.polarization = fc;
+ s390_cpu_topology_set_changed(true);
+ s390_topology_set_cpus_entitlement(fc);
+ setcc(cpu, 0);
+ }
+ break;
+ default:
+ /* Note that fc == 2 is interpreted by the SIE */
+ s390_program_interrupt(env, PGM_SPECIFICATION, ra);
+ }
+}
+
/**
* s390_topology_reset:
*
@@ -96,6 +179,8 @@ static void s390_topology_init(MachineState *ms)
void s390_topology_reset(void)
{
s390_cpu_topology_set_changed(false);
+ s390_topology.polarization = S390_CPU_POLARIZATION_HORIZONTAL;
+ s390_topology_set_cpus_entitlement(S390_CPU_POLARIZATION_HORIZONTAL);
}

/**
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