[Qemu-devel] [PATCH v2] s390: clear registers, psw and prefix at vcpu reset

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

When resetting vcpus on s390/kvm we have to clear registers, psw
and prefix as described in the z/Architecture PoP, otherwise a
reboot won't work. IPL PSW and prefix are set later on by the
s390-ipl device reset code.

Signed-off-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
---

changes v1->v2:
- moved cpu reset code from kvm.c to cpu.c
- only kvm initial_reset ioctl remains in kvm.c
- registered reset handler for s390 cpu reset, like x86 does it

 target-s390x/cpu.c | 29 +++++++++++++++++++++++++++--
 target-s390x/kvm.c |  9 ++++++++-
 2 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/target-s390x/cpu.c b/target-s390x/cpu.c
index 619b202..f74d6f6 100644
--- a/target-s390x/cpu.c
+++ b/target-s390x/cpu.c
@@ -24,10 +24,21 @@
 #include "qemu-common.h"
 #include "qemu-timer.h"
 
+#ifndef CONFIG_USER_ONLY
+#include "hw/s390x/sclp.h"
+
+/* TODO: remove me, when reset over QOM tree is implemented */
+static void s390_cpu_machine_reset_cb(void *opaque)
+{
+    S390CPU *cpu = opaque;
+    cpu_reset(CPU(cpu));
+}
+#endif
 
 /* CPUClass::reset() */
 static void s390_cpu_reset(CPUState *s)
 {
+    int i;
     S390CPU *cpu = S390_CPU(s);
     S390CPUClass *scc = S390_CPU_GET_CLASS(cpu);
     CPUS390XState *env = &cpu->env;
@@ -40,9 +51,22 @@ static void s390_cpu_reset(CPUState *s)
     scc->parent_reset(s);
 
     memset(env, 0, offsetof(CPUS390XState, breakpoints));
-    /* FIXME: reset vector? */
+
+    env->halted = 1;
+    env->exception_index = EXCP_HLT;
+    for (i = 0; i < 16; i++) {
+        env->regs[i] = 0;
+        env->aregs[i] = 0;
+        env->cregs[i] = 0;
+        env->fregs[i].ll = 0;
+    }
+    /* architectured initial values for CR 0 and 14 */
+    env->cregs[0] = 0xE0UL;
+    env->cregs[14] = 0xC2000000UL;
+    env->psw.mask = 0;
+    env->psw.addr = 0;
+    env->psa = 0;
     tlb_flush(env, 1);
-    s390_add_running_cpu(env);
 }
 
 static void s390_cpu_initfn(Object *obj)
@@ -56,6 +80,7 @@ static void s390_cpu_initfn(Object *obj)
 
     cpu_exec_init(env);
 #if !defined(CONFIG_USER_ONLY)
+    qemu_register_reset(s390_cpu_machine_reset_cb, cpu);
     qemu_get_timedate(&tm, 0);
     env->tod_offset = TOD_UNIX_EPOCH +
                       (time2tod(mktimegm(&tm)) * 1000000000ULL);
diff --git a/target-s390x/kvm.c b/target-s390x/kvm.c
index 94de764..d26555f 100644
--- a/target-s390x/kvm.c
+++ b/target-s390x/kvm.c
@@ -85,7 +85,14 @@ int kvm_arch_init_vcpu(CPUS390XState *env)
 
 void kvm_arch_reset_vcpu(CPUS390XState *env)
 {
-    /* FIXME: add code to reset vcpu. */
+    /* The initial reset call is needed here to reset in-kernel
+     * vcpu data that we can't access directly from QEMU
+     * (i.e. with older kernels which don't support sync_regs/ONE_REG).
+     * Before this ioctl cpu_synchronize_state() is called in common kvm
+     * code (kvm-all) */
+    if (kvm_vcpu_ioctl(env, KVM_S390_INITIAL_RESET, NULL)) {
+        perror("Can't reset vcpu\n");
+    }
 }
 
 int kvm_arch_put_registers(CPUS390XState *env, int level)
-- 
1.7.12.4