[PATCH/RFC 10/21] KVM: s390: a VCPU may only stop when no interrupts are left pending

Christian Borntraeger
2015-01-15T13:43:23Z

From: David Hildenbrand <dahi@linux.vnet.ibm.com>

As a SIGP STOP is an interrupt with the least priority, it may only result
in stop of the vcpu when no other interrupts are left pending.

To detect whether a non-stop irq is pending, we need a way to mask out
stop irqs from the general kvm_cpu_has_interrupt() function. For this
reason, the existing function (with an outdated name) is replaced by
kvm_s390_vcpu_has_irq() which allows to mask out pending stop irqs.

Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
arch/s390/kvm/intercept.c | 4 ++++
arch/s390/kvm/interrupt.c | 4 ++--
arch/s390/kvm/kvm-s390.c | 4 ++--
arch/s390/kvm/kvm-s390.h | 2 +-
4 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
index 08e01ac..8976694 100644
--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -74,6 +74,10 @@ static int handle_stop(struct kvm_vcpu *vcpu)

vcpu->stat.exit_stop_request++;

+ /* delay the stop if any non-stop irq is pending */
+ if (kvm_s390_vcpu_has_irq(vcpu, 1))
+ return 0;
+
/* avoid races with the injection/SIGP STOP code */
spin_lock(&li->lock);
flags = li->irq.stop.flags;
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 1872188..f753c0b 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -749,7 +749,7 @@ int kvm_s390_si_ext_call_pending(struct kvm_vcpu *vcpu)
return 0;
}

-int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu)
+int kvm_s390_vcpu_has_irq(struct kvm_vcpu *vcpu, int exclude_stop)
{
struct kvm_s390_float_interrupt *fi = vcpu->arch.local_int.float_int;
struct kvm_s390_interrupt_info *inti;
@@ -773,7 +773,7 @@ int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu)
if (!rc && kvm_s390_si_ext_call_pending(vcpu))
rc = 1;

- if (!rc && kvm_s390_is_stop_irq_pending(vcpu))
+ if (!rc && !exclude_stop && kvm_s390_is_stop_irq_pending(vcpu))
rc = 1;

return rc;
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index b987b56..6a5ed33 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -806,7 +806,7 @@ out:

int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)
{
- return kvm_cpu_has_interrupt(vcpu);
+ return kvm_s390_vcpu_has_irq(vcpu, 0);
}

void s390_vcpu_block(struct kvm_vcpu *vcpu)
@@ -1241,7 +1241,7 @@ static int kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu)
return 0;
if (psw_extint_disabled(vcpu))
return 0;
- if (kvm_cpu_has_interrupt(vcpu))
+ if (kvm_s390_vcpu_has_irq(vcpu, 0))
return 0;
if (!(vcpu->arch.sie_block->gcr[0] & 0x200ul))
return 0;
diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index d72ff62..2becffe 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -228,7 +228,7 @@ int s390int_to_s390irq(struct kvm_s390_interrupt *s390int,
struct kvm_s390_irq *s390irq);

/* implemented in interrupt.c */
-int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu);
+int kvm_s390_vcpu_has_irq(struct kvm_vcpu *vcpu, int exclude_stop);
int psw_extint_disabled(struct kvm_vcpu *vcpu);
void kvm_s390_destroy_adapters(struct kvm *kvm);
int kvm_s390_si_ext_call_pending(struct kvm_vcpu *vcpu);
--
1.9.3