Re: [PATCH v9 08/10] target/s390x: interception of PTF instruction

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On 9/9/22 18:50, Janis Schoetterl-Glausch wrote:
On Fri, 2022-09-02 at 09:55 +0200, 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.

Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>

Reviewed-by: Janis Schoetterl-Glausch <scgl@xxxxxxxxxxxxx>

Thanks


See note below.
---
  hw/s390x/cpu-topology.c            | 52 ++++++++++++++++++++++++++++++
  include/hw/s390x/s390-virtio-ccw.h |  6 ++++
  target/s390x/kvm/kvm.c             | 13 ++++++++
  3 files changed, 71 insertions(+)

diff --git a/hw/s390x/cpu-topology.c b/hw/s390x/cpu-topology.c
index b6bf839e40..7dcaa28ca3 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;

I'm either expecting this function to return -1 here...
+    }
+
+    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);
+    }
+}

[...]
+static int 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);

... and this being returned here...
+
+    return 0;

... or this function being void.
+}


Yes right, thanks

Regards,
Pierre


--
Pierre Morel
IBM Lab Boeblingen



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