Re: [Qemu-devel] [PATCH 2/3] s390: Add CPU reset handler

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

On Wed, Dec 12, 2012 at 02:38:40PM +0100, Alexander Graf wrote:
> 
> On 12.12.2012, at 14:08, Jens Freimann wrote:
> 
> > Add a CPU reset handler to have all CPUs in a PoP compliant
> > state.
> > 
> > Signed-off-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
> > 
> > ---
> > v1 -> v2:
> > * move setting of control registers and psa to s390_cpu_reset
> >  and call it from the new s390_machine_cpu_reset_cb()
> >  This makes it more similar to how it is done on x86
> > * in s390_cpu_reset() set env->halted state of cpu after
> >  the memset. This is needed to keep our s390_cpu_running
> >  counter in sync when s390_cpu_reset is called via the
> >  qemu_devices_reset path
> > * set env->halted state in s390_cpu_initfn to 1 to avoid
> >  decrementing the cpu counter during first reset
> > ---
> > target-s390x/cpu.c | 31 +++++++++++++++++++++++++++++--
> > target-s390x/kvm.c |  9 ++++++++-
> > 2 files changed, 37 insertions(+), 3 deletions(-)
> > 
> > diff --git a/target-s390x/cpu.c b/target-s390x/cpu.c
> > index 619b202..75f60b3 100644
> > --- a/target-s390x/cpu.c
> > +++ b/target-s390x/cpu.c
> > @@ -4,6 +4,7 @@
> >  * Copyright (c) 2009 Ulrich Hecht
> >  * Copyright (c) 2011 Alexander Graf
> >  * Copyright (c) 2012 SUSE LINUX Products GmbH
> > + * Copyright (c) 2012 IBM Corp.
> >  *
> >  * This library is free software; you can redistribute it and/or
> >  * modify it under the terms of the GNU Lesser General Public
> > @@ -18,9 +19,13 @@
> >  * You should have received a copy of the GNU Lesser General Public
> >  * License along with this library; if not, see
> >  * <http://www.gnu.org/licenses/lgpl-2.1.html>
> > + * Contributions after 2012-12-11 are licensed under the terms of the
> > + * GNU GPL, version 2 or (at your option) any later version.
> > + *
> >  */
> > 
> > #include "cpu.h"
> > +#include "hw/hw.h"
> > #include "qemu-common.h"
> > #include "qemu-timer.h"
> > 
> > @@ -37,12 +42,29 @@ static void s390_cpu_reset(CPUState *s)
> >         log_cpu_state(env, 0);
> >     }
> > 
> > -    scc->parent_reset(s);
> > +    s390_del_running_cpu(env);
> > 
> > +    scc->parent_reset(s);
> >     memset(env, 0, offsetof(CPUS390XState, breakpoints));
> > +
> > +    /* architectured initial values for CR 0 and 14 */
> > +    env->cregs[0] = 0xE0UL;
> > +    env->cregs[14] = 0xC2000000UL;
> > +    /* set to z/Architecture mode */
> > +    env->psw.mask = 0x0000000180000000ULL;
> > +    env->psa = 0;
> > +    /* set halted to 1 to make sure we can add the cpu in
> > +     * s390_ipl_cpu code */
> > +    env->halted = 1;
> 
> So who sets cpu0 to halted=0 again? Please add that as a comment here.

It is set to halted=0 by s390_add_running_cpu() in s390_ipl_cpu() for
cpu 0 and via the sigp restart path for all other cpus.
I will add a comment and send a new version. 
 
 Jens

> Alex
> 
> >     /* FIXME: reset vector? */
> >     tlb_flush(env, 1);
> > -    s390_add_running_cpu(env);
> > +}
> > +
> > +static void s390_cpu_machine_reset_cb(void *opaque)
> > +{
> > +    S390CPU *cpu = opaque;
> > +
> > +    cpu_reset(CPU(cpu));
> > }
> > 
> > static void s390_cpu_initfn(Object *obj)
> > @@ -66,7 +88,12 @@ static void s390_cpu_initfn(Object *obj)
> >     env->cpu_num = cpu_num++;
> >     env->ext_index = -1;
> > 
> > +    /* set env->halted state to 1 to avoid decrementing the running
> > +     * cpu counter in s390_cpu_reset to a negative number at 
> > +     * initial ipl */
> > +    env->halted = 1;
> >     cpu_reset(CPU(cpu));
> > +    qemu_register_reset(s390_cpu_machine_reset_cb, cpu);
> > }
> > 
> > static void s390_cpu_class_init(ObjectClass *oc, void *data)
> > diff --git a/target-s390x/kvm.c b/target-s390x/kvm.c
> > index 94de764..fda9f1f 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
> > 
> 

-- 
Mit freundlichen Grüßen / Kind regards 

Jens Freimann 

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