[PATCH v10 5/9] target/s390x: interception of PTF instruction

Pierre Morel
2022-10-12T16:21:47Z

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.

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
---
include/hw/s390x/s390-virtio-ccw.h | 6 ++++
hw/s390x/cpu-topology.c | 52 ++++++++++++++++++++++++++++++
target/s390x/kvm/kvm.c | 11 +++++++
3 files changed, 69 insertions(+)

diff --git a/include/hw/s390x/s390-virtio-ccw.h b/include/hw/s390x/s390-virtio-ccw.h
index 8a0090a071..9e7a0d75bc 100644
--- a/include/hw/s390x/s390-virtio-ccw.h
+++ b/include/hw/s390x/s390-virtio-ccw.h
@@ -31,6 +31,12 @@ 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 349f0ad89d..2ad516a97d 100644
--- a/hw/s390x/cpu-topology.c
+++ b/hw/s390x/cpu-topology.c
@@ -20,6 +20,58 @@
#include "hw/s390x/s390-virtio-ccw.h"
#include "hw/s390x/cpu-topology.h"
#include "migration/vmstate.h"
+#include "target/s390x/cpu.h"
+#include "hw/s390x/s390-virtio-ccw.h"
+
+/*
+ * 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 */
+ env->regs[r1] |= S390_PTF_REASON_DONE;
+ setcc(cpu, 2);
+ break;
+ case 1: /* Vertical polarization is not supported */
+ env->regs[r1] |= S390_PTF_REASON_NONE;
+ setcc(cpu, 2);
+ break;
+ default:
+ /* Note that fc == 2 is interpreted by the SIE */
+ s390_program_interrupt(env, PGM_SPECIFICATION, ra);
+ }
+}

S390Topology *s390_get_topology(void)
{
diff --git a/target/s390x/kvm/kvm.c b/target/s390x/kvm/kvm.c
index 9c994d27d5..49a99931a4 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
@@ -1463,6 +1464,13 @@ 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;
@@ -1480,6 +1488,9 @@ 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