[Qemu-devel] [PATCH 4/6] s390x/kvm: propagate s390 cpu state to kvm

[Jens Freimann <jfrei@linux.vnet.ibm.com>]

From: David Hildenbrand <dahi@linux.vnet.ibm.com>

Let QEMU propagate the cpu state to kvm. If kvm doesn't yet support it, it is
silently ignored as kvm will still handle the cpu state itself in that case.

The state is not synced back, thus kvm won't have a chance to actively modify
the cpu state. To do so, control has to be given back to QEMU (which is already
done so in all relevant cases).

Setting of the cpu state can fail either because kvm doesn't support the
interface yet, or because the state is invalid/not supported. Failed attempts
will be traced

Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
CC: Andreas Faerber <afaerber@suse.de>
---
 target-s390x/cpu.c |  3 +++
 target-s390x/cpu.h |  5 +++++
 target-s390x/kvm.c | 43 +++++++++++++++++++++++++++++++++++++++++--
 trace-events       |  1 +
 4 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/target-s390x/cpu.c b/target-s390x/cpu.c
index dc89eb3..9dbb0df 100644
--- a/target-s390x/cpu.c
+++ b/target-s390x/cpu.c
@@ -288,6 +288,9 @@ unsigned int s390_cpu_set_state(uint8_t cpu_state, S390CPU *cpu)
                      cpu_state);
         exit(1);
     }
+    if (kvm_enabled() && cpu->env.cpu_state != cpu_state) {
+        kvm_s390_set_cpu_state(cpu, cpu_state);
+    }
     cpu->env.cpu_state = cpu_state;
 
     return s390_count_running_cpus();
diff --git a/target-s390x/cpu.h b/target-s390x/cpu.h
index 7b9300e..6b3aaed 100644
--- a/target-s390x/cpu.h
+++ b/target-s390x/cpu.h
@@ -1072,6 +1072,7 @@ int kvm_s390_assign_subch_ioeventfd(EventNotifier *notifier, uint32_t sch,
 int kvm_s390_cpu_restart(S390CPU *cpu);
 int kvm_s390_get_memslot_count(KVMState *s);
 void kvm_s390_clear_cmma_callback(void *opaque);
+int kvm_s390_set_cpu_state(S390CPU *cpu, uint8_t cpu_state);
 #else
 static inline void kvm_s390_io_interrupt(uint16_t subchannel_id,
                                         uint16_t subchannel_nr,
@@ -1102,6 +1103,10 @@ static inline int kvm_s390_get_memslot_count(KVMState *s)
 {
   return MAX_AVAIL_SLOTS;
 }
+static inline int kvm_s390_set_cpu_state(S390CPU *cpu, uint8_t cpu_state)
+{
+    return -ENOSYS;
+}
 #endif
 
 static inline void cmma_reset(S390CPU *cpu)
diff --git a/target-s390x/kvm.c b/target-s390x/kvm.c
index 415baea..7c90b18 100644
--- a/target-s390x/kvm.c
+++ b/target-s390x/kvm.c
@@ -181,9 +181,10 @@ unsigned long kvm_arch_vcpu_id(CPUState *cpu)
     return cpu->cpu_index;
 }
 
-int kvm_arch_init_vcpu(CPUState *cpu)
+int kvm_arch_init_vcpu(CPUState *cs)
 {
-    /* nothing todo yet */
+    S390CPU *cpu = S390_CPU(cs);
+    kvm_s390_set_cpu_state(cpu, cpu->env.cpu_state);
     return 0;
 }
 
@@ -1321,3 +1322,41 @@ int kvm_s390_get_memslot_count(KVMState *s)
 {
     return kvm_check_extension(s, KVM_CAP_NR_MEMSLOTS);
 }
+
+int kvm_s390_set_cpu_state(S390CPU *cpu, uint8_t cpu_state)
+{
+    struct kvm_mp_state mp_state = {};
+    int ret;
+
+    /* the kvm part might not have been initialized yet */
+    if (CPU(cpu)->kvm_state == NULL) {
+        return 0;
+    }
+
+    switch (cpu_state) {
+    case CPU_STATE_STOPPED:
+        mp_state.mp_state = KVM_MP_STATE_STOPPED;
+        break;
+    case CPU_STATE_CHECK_STOP:
+        mp_state.mp_state = KVM_MP_STATE_CHECK_STOP;
+        break;
+    case CPU_STATE_OPERATING:
+        mp_state.mp_state = KVM_MP_STATE_OPERATING;
+        break;
+    case CPU_STATE_LOAD:
+        mp_state.mp_state = KVM_MP_STATE_LOAD;
+        break;
+    default:
+        error_report("Requested CPU state is not a valid S390 CPU state: %u",
+                     cpu_state);
+        exit(1);
+    }
+
+    ret = kvm_vcpu_ioctl(CPU(cpu), KVM_SET_MP_STATE, &mp_state);
+    if (ret) {
+        trace_kvm_failed_cpu_state_set(CPU(cpu)->cpu_index, cpu_state,
+                                       strerror(-ret));
+    }
+
+    return ret;
+}
diff --git a/trace-events b/trace-events
index 5202f20..5290806 100644
--- a/trace-events
+++ b/trace-events
@@ -1369,6 +1369,7 @@ mhp_pc_dimm_assigned_address(uint64_t addr) "0x%"PRIx64
 # target-s390x/kvm.c
 kvm_enable_cmma(int rc) "CMMA: enabling with result code %d"
 kvm_clear_cmma(int rc) "CMMA: clearing with result code %d"
+kvm_failed_cpu_state_set(int cpu_index, uint8_t state, const char *msg) "Warning: Unable to set cpu %d state %" PRIu8 " to KVM: %s"
 
 # hw/dma/i8257.c
 i8257_unregistered_dma(int nchan, int dma_pos, int dma_len) "unregistered DMA channel used nchan=%d dma_pos=%d dma_len=%d"
-- 
1.8.5.5