Re: [PATCH 15/21] qemu-kvm: Clean up mpstate synchronization

[Jan Kiszka <jan.kiszka@siemens.com>]

Gleb Natapov wrote:
> On Tue, Feb 02, 2010 at 01:31:50PM +0100, Jan Kiszka wrote:
>> Gleb Natapov wrote:
>>> On Tue, Feb 02, 2010 at 09:19:01AM +0100, Jan Kiszka wrote:
>>>> Push mpstate reading/writing into kvm_arch_load/save_regs and, on x86,
>>>> properly synchronize with halted in the accessor functions.
>>>>
>>>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>>>> ---
>>>>  hw/apic.c             |    7 ----
>>>>  qemu-kvm-ia64.c       |    4 ++-
>>>>  qemu-kvm-x86.c        |   88 +++++++++++++++++++++++++++---------------------
>>>>  qemu-kvm.c            |   30 -----------------
>>>>  qemu-kvm.h            |   15 --------
>>>>  target-i386/machine.c |    6 ---
>>>>  target-ia64/machine.c |    3 ++
>>>>  7 files changed, 55 insertions(+), 98 deletions(-)
>>>>
>>>> diff --git a/hw/apic.c b/hw/apic.c
>>>> index 3e03e10..092c61e 100644
>>>> --- a/hw/apic.c
>>>> +++ b/hw/apic.c
>>>> @@ -507,13 +507,6 @@ void apic_init_reset(CPUState *env)
>>>>      s->wait_for_sipi = 1;
>>>>  
>>>>      env->halted = !(s->apicbase & MSR_IA32_APICBASE_BSP);
>>>> -#ifdef KVM_CAP_MP_STATE
>>>> -    if (kvm_enabled() && kvm_irqchip_in_kernel()) {
>>>> -        env->mp_state
>>>> -            = env->halted ? KVM_MP_STATE_UNINITIALIZED : KVM_MP_STATE_RUNNABLE;
>>>> -        kvm_load_mpstate(env);
>>>> -    }
>>>> -#endif
>>>>  }
>>>>  
>>>>  static void apic_startup(APICState *s, int vector_num)
>>>> diff --git a/qemu-kvm-ia64.c b/qemu-kvm-ia64.c
>>>> index fc8110e..39bcbeb 100644
>>>> --- a/qemu-kvm-ia64.c
>>>> +++ b/qemu-kvm-ia64.c
>>>> @@ -124,7 +124,9 @@ void kvm_arch_cpu_reset(CPUState *env)
>>>>  {
>>>>      if (kvm_irqchip_in_kernel(kvm_context)) {
>>>>  #ifdef KVM_CAP_MP_STATE
>>>> -	kvm_reset_mpstate(env->kvm_cpu_state.vcpu_ctx);
>>>> +        struct kvm_mp_state mp_state = {.mp_state = KVM_MP_STATE_UNINITIALIZED
>>>> +        };
>>>> +        kvm_set_mpstate(env, &mp_state);
>>>>  #endif
>>>>      } else {
>>>>  	env->interrupt_request &= ~CPU_INTERRUPT_HARD;
>>>> diff --git a/qemu-kvm-x86.c b/qemu-kvm-x86.c
>>>> index 63cd095..6b5895f 100644
>>>> --- a/qemu-kvm-x86.c
>>>> +++ b/qemu-kvm-x86.c
>>>> @@ -754,6 +754,48 @@ static int get_msr_entry(struct kvm_msr_entry *entry, CPUState *env)
>>>>          return 0;
>>>>  }
>>>>  
>>>> +static void kvm_arch_save_mpstate(CPUState *env)
>>>> +{
>>>> +#ifdef KVM_CAP_MP_STATE
>>>> +    int r;
>>>> +    struct kvm_mp_state mp_state;
>>>> +
>>>> +    r = kvm_get_mpstate(env, &mp_state);
>>>> +    if (r < 0) {
>>>> +        env->mp_state = -1;
>>>> +    } else {
>>>> +        env->mp_state = mp_state.mp_state;
>>>> +        if (kvm_irqchip_in_kernel()) {
>>>> +            env->halted = (env->mp_state == KVM_MP_STATE_HALTED);
>>>> +        }
>>>> +    }
>>>> +#else
>>>> +    env->mp_state = -1;
>>>> +#endif
>>>> +}
>>>> +
>>>> +static void kvm_arch_load_mpstate(CPUState *env)
>>>> +{
>>>> +#ifdef KVM_CAP_MP_STATE
>>>> +    struct kvm_mp_state mp_state;
>>>> +
>>>> +    /*
>>>> +     * -1 indicates that the host did not support GET_MP_STATE ioctl,
>>>> +     *  so don't touch it.
>>>> +     */
>>>> +    if (env->mp_state != -1) {
>>>> +        if (kvm_irqchip_in_kernel()) {
>>>> +            env->mp_state = env->halted ? KVM_MP_STATE_UNINITIALIZED :
>>>> +                                          KVM_MP_STATE_RUNNABLE;
>>> When irqchip is in kernel env->halted doesn't contain any relevant
>>> information, so this is incorrect. Actually env->halted is updated only
>>> to show correct cpu state during "info cpus".
>> OK, copied from apic_init_reset, see above. So that hunk was probably at
>> least useless, and now it's harmfull. Will drop this and only sync from
>> mp_state -> halted.
>>
> It was not useless in apic_init_reset it was a shortcut for:
> env->mp_state = !(s->apicbase & MSR_IA32_APICBASE_BSP) ? KVM_MP_STATE_UNINITIALIZED : KVM_MP_STATE_RUNNABLE;
> 
> On reset BSP VCPU should set env->mp_state to KVM_MP_STATE_RUNNABLE and
> all others to KVM_MP_STATE_UNINITIALIZED.

OK, belongs to kvm vpcu init code then - less encrypted.

Jan

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