From: David Hildenbrand <dahi@xxxxxxxxxxxxxxxxxx>
Commit ea5f49692575 ("KVM: s390: only one external call may be pending
at a time") introduced a bug on machines that don't have SIGP
interpretation facility installed.
The injection of an external call will now always fail with -EBUSY
(if none is already pending).
This leads to the following symptoms:
- An external call will be injected but with the wrong "src cpu id",
as this id will not be remembered.
- The target vcpu will not be woken up, therefore the guest will hang if
it cannot deal with unexpected failures of the SIGP EXTERNAL CALL
instruction.
- If an external call is already pending, -EBUSY will not be reported.
Reviewed-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Reviewed-by: Jens Freimann <jfrei@xxxxxxxxxxxxxxxxxx>
Signed-off-by: David Hildenbrand <dahi@xxxxxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v4.0
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
---
arch/s390/kvm/interrupt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 9de4726..2836b25 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -1061,7 +1061,7 @@ static int __inject_extcall(struct kvm_vcpu *vcpu, struct kvm_s390_irq *irq)
if (sclp_has_sigpif())
return __inject_extcall_sigpif(vcpu, src_id);
- if (!test_and_set_bit(IRQ_PEND_EXT_EXTERNAL, &li->pending_irqs))
+ if (test_and_set_bit(IRQ_PEND_EXT_EXTERNAL, &li->pending_irqs))
return -EBUSY;
*extcall = irq->u.extcall;
atomic_set_mask(CPUSTAT_EXT_INT, li->cpuflags);
--
2.3.0
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