Re: [PATCH v5 12/15] KVM: s390: do not restore IAM immediately before SIE entry

Pierre Morel
2019-01-03T15:00:36Z

On 19/12/2018 20:17, Michael Mueller wrote:
> The IAM shall no be restored when deliverable interruptions are
> delivered to vcpus by means of the PSW swap mechanism. That would
> trigger the GIB alert millicode although we know that SIE will be
> able to handle the pending interruption on entry.
>
> Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
> ---
> arch/s390/kvm/interrupt.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
> index 8307717e3caf..48a93f5e5333 100644
> --- a/arch/s390/kvm/interrupt.c
> +++ b/arch/s390/kvm/interrupt.c
> @@ -328,11 +328,11 @@ static unsigned long disable_iscs(struct kvm_vcpu *vcpu,
> return active_mask;
> }
>
> -static unsigned long deliverable_irqs(struct kvm_vcpu *vcpu)
> +static unsigned long deliverable_irqs(struct kvm_vcpu *vcpu, u16 irq_flags)
> {
> unsigned long active_mask;
>
> - active_mask = pending_irqs(vcpu, IRQ_MASK_ALL);
> + active_mask = pending_irqs(vcpu, irq_flags);
> if (!active_mask)
> return 0;
>
> @@ -1090,7 +1090,7 @@ int kvm_s390_ext_call_pending(struct kvm_vcpu *vcpu)
>
> int kvm_s390_vcpu_has_irq(struct kvm_vcpu *vcpu, int exclude_stop)
> {
> - if (deliverable_irqs(vcpu))
> + if (deliverable_irqs(vcpu, IRQ_MASK_ALL | IRQ_FLAG_IAM))

Why do we need to restore IAM here?

--
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany