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

[Alexander Graf]

On 27.11.2012, at 09:33, Jens Freimann <address@hidden> wrote:

> 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 <address@hidden>
> ---
> 
> 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;

Every cpu would start in halted state? So how does the primary one get rolling?

> +    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;
> +    }

Please make this more self-adjusting. For example using memset(sizeof));. You 
could also make the clear implicit by ensuring the registers are in the cpu 
struct before breakpoints. But explicit tends to be more readable ;).

> +    /* 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);

Why can we remove this one?

Alex

> }
> 
> 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
>