From 9b57e9d5010bbed7c0d9d445085840f7025e6f9a Mon Sep 17 00:00:00 2001 From: Halil Pasic Date: Tue, 19 Oct 2021 19:53:59 +0200 Subject: KVM: s390: clear kicked_mask before sleeping again The idea behind kicked mask is that we should not re-kick a vcpu that is already in the "kick" process, i.e. that was kicked and is is about to be dispatched if certain conditions are met. The problem with the current implementation is, that it assumes the kicked vcpu is going to enter SIE shortly. But under certain circumstances, the vcpu we just kicked will be deemed non-runnable and will remain in wait state. This can happen, if the interrupt(s) this vcpu got kicked to deal with got already cleared (because the interrupts got delivered to another vcpu). In this case kvm_arch_vcpu_runnable() would return false, and the vcpu would remain in kvm_vcpu_block(), but this time with its kicked_mask bit set. So next time around we wouldn't kick the vcpu form __airqs_kick_single_vcpu(), but would assume that we just kicked it. Let us make sure the kicked_mask is cleared before we give up on re-dispatching the vcpu. Fixes: 9f30f6216378 ("KVM: s390: add gib_alert_irq_handler()") Reported-by: Matthew Rosato Signed-off-by: Halil Pasic Reviewed-by: Christian Borntraeger Reviewed-by: Michael Mueller Reviewed-by: Claudio Imbrenda Link: https://lore.kernel.org/r/20211019175401.3757927-2-pasic@linux.ibm.com Signed-off-by: Christian Borntraeger --- arch/s390/kvm/kvm-s390.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/s390') diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 6a6dd5e1daf6..1c97493d21e1 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -3363,6 +3363,7 @@ out_free_sie_block: int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu) { + clear_bit(vcpu->vcpu_idx, vcpu->kvm->arch.gisa_int.kicked_mask); return kvm_s390_vcpu_has_irq(vcpu, 0); } -- cgit v1.2.3 From 0e9ff65f455dfd0a8aea5e7843678ab6fe097e21 Mon Sep 17 00:00:00 2001 From: Halil Pasic Date: Tue, 19 Oct 2021 19:54:00 +0200 Subject: KVM: s390: preserve deliverable_mask in __airqs_kick_single_vcpu Changing the deliverable mask in __airqs_kick_single_vcpu() is a bug. If one idle vcpu can't take the interrupts we want to deliver, we should look for another vcpu that can, instead of saying that we don't want to deliver these interrupts by clearing the bits from the deliverable_mask. Fixes: 9f30f6216378 ("KVM: s390: add gib_alert_irq_handler()") Signed-off-by: Halil Pasic Reviewed-by: Christian Borntraeger Reviewed-by: Michael Mueller Reviewed-by: Claudio Imbrenda Link: https://lore.kernel.org/r/20211019175401.3757927-3-pasic@linux.ibm.com Signed-off-by: Christian Borntraeger --- arch/s390/kvm/interrupt.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'arch/s390') diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c index 10722455fd02..2245f4b8d362 100644 --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -3053,13 +3053,14 @@ static void __airqs_kick_single_vcpu(struct kvm *kvm, u8 deliverable_mask) int vcpu_idx, online_vcpus = atomic_read(&kvm->online_vcpus); struct kvm_s390_gisa_interrupt *gi = &kvm->arch.gisa_int; struct kvm_vcpu *vcpu; + u8 vcpu_isc_mask; for_each_set_bit(vcpu_idx, kvm->arch.idle_mask, online_vcpus) { vcpu = kvm_get_vcpu(kvm, vcpu_idx); if (psw_ioint_disabled(vcpu)) continue; - deliverable_mask &= (u8)(vcpu->arch.sie_block->gcr[6] >> 24); - if (deliverable_mask) { + vcpu_isc_mask = (u8)(vcpu->arch.sie_block->gcr[6] >> 24); + if (deliverable_mask & vcpu_isc_mask) { /* lately kicked but not yet running */ if (test_and_set_bit(vcpu_idx, gi->kicked_mask)) return; -- cgit v1.2.3