Re: [PATCH] KVM: PPC: Book3E 64: Fix IRQs warnings and hangs

[Alexander Graf]

On 03.05.2013, at 18:11, Mihai Caraman wrote:

> A change in the generic code highlighted that we were running with IRQs
> (soft) enabled on Book3E 64-bit when trying to restart interrupts from
> handle_exit(). This is a lesson to configure lockdep often :)
> 
> There is no reason to exit guest with soft_enabled == 1, a local_irq_enable()
> call will do this for us so get rid of kvmppc_layz_ee() calls. With this fix
> we eliminate irqs_disabled() warnings and some guest and host hangs revealed
> under stress tests, but guests still exhibit some unresponsiveness.
> 
> The unresponsiveness has to do with the fact that arch_local_irq_restore()
> does not guarantees to hard enable interrupts. To do so replace exception
> function calls like timer_interrupt() with irq_happened flags. The
> local_irq_enable() call takes care of replaying them and lets the interrupts
> hard enabled.
> 
> Signed-off-by: Mihai Caraman <mihai.cara...@freescale.com>

Ben, could you please review?


Alex

> ---
> arch/powerpc/kvm/booke.c |    9 +++------
> 1 files changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
> index 1020119..82f155e 100644
> --- a/arch/powerpc/kvm/booke.c
> +++ b/arch/powerpc/kvm/booke.c
> @@ -673,7 +673,6 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct 
> kvm_vcpu *vcpu)
>               ret = s;
>               goto out;
>       }
> -     kvmppc_lazy_ee_enable();
> 
>       kvm_guest_enter();
> 
> @@ -789,16 +788,16 @@ static void kvmppc_restart_interrupt(struct kvm_vcpu 
> *vcpu,
>       switch (exit_nr) {
>       case BOOKE_INTERRUPT_EXTERNAL:
>               kvmppc_fill_pt_regs(&regs);
> -             do_IRQ(&regs);
> +             local_paca->irq_happened |= PACA_IRQ_EE;
>               break;
>       case BOOKE_INTERRUPT_DECREMENTER:
>               kvmppc_fill_pt_regs(&regs);
> -             timer_interrupt(&regs);
> +             local_paca->irq_happened |= PACA_IRQ_DEC;
>               break;
> #if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_BOOK3E_64)
>       case BOOKE_INTERRUPT_DOORBELL:
>               kvmppc_fill_pt_regs(&regs);
> -             doorbell_exception(&regs);
> +             local_paca->irq_happened |= PACA_IRQ_DBELL;
>               break;
> #endif
>       case BOOKE_INTERRUPT_MACHINE_CHECK:
> @@ -1148,8 +1147,6 @@ int kvmppc_handle_exit(struct kvm_run *run, struct 
> kvm_vcpu *vcpu,
>               if (s <= 0) {
>                       local_irq_enable();
>                       r = (s << 2) | RESUME_HOST | (r & RESUME_FLAG_NV);
> -             } else {
> -                     kvmppc_lazy_ee_enable();
>               }
>       }
> 
> -- 
> 1.7.4.1
> 
> 
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