[PATCH] KVM: PPC: Book3E 64: Fix IRQs warnings and hangs
Scott Wood
scottwood at freescale.com
Sat May 4 04:04:47 EST 2013
On 05/03/2013 11:11:10 AM, 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.
Could you elaborate? If the saved IRQ state was "enabled", why
wouldn't arch_local_irq_restore() hard-enable IRQs? The last thing it
does is __hard_irq_enable().
Where is the arch_local_irq_restore() instance you're talking about?
> 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.
Not sure what you mean by "lets the interrupts hard enabled"... Do you
mean the EE bit in regs->msr, as opposed to the EE bit in the current
MSR?
> Signed-off-by: Mihai Caraman <mihai.caraman at freescale.com>
> ---
> 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(®s);
> - do_IRQ(®s);
> + local_paca->irq_happened |= PACA_IRQ_EE;
> break;
> case BOOKE_INTERRUPT_DECREMENTER:
> kvmppc_fill_pt_regs(®s);
> - timer_interrupt(®s);
> + 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(®s);
> - doorbell_exception(®s);
> + local_paca->irq_happened |= PACA_IRQ_DBELL;
> break;
> #endif
Aren't you breaking 32-bit here?
-Scott
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