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Re: [Qemu-devel] [PATCH v2] s390: clear registers, psw and prefix at vcp
From: |
Jens Freimann |
Subject: |
Re: [Qemu-devel] [PATCH v2] s390: clear registers, psw and prefix at vcpu reset |
Date: |
Tue, 27 Nov 2012 18:13:46 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Tue, Nov 27, 2012 at 10:37:25AM +0100, Alexander Graf wrote:
>
>
> 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?
The first cpu is set to not-halted by the ipl device reset code.
>
> > + 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 ;).
Ok
> > + /* 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?
Good point. I took a closer look and found that we add an additional
cpu to the counter every time we reboot. Will fix this and send a new
version.
Jens
>
> 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
> >
>
--
Mit freundlichen Grüßen / Kind regards
Jens Freimann
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