linux-kernel - [PATCH 2/3] KVM: s390: preserve deliverable_mask in __airqs_kick_single

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Date:   Tue, 19 Oct 2021 19:54:00 +0200
From:   Halil Pasic <pasic@...ux.ibm.com>
To:     Christian Borntraeger <borntraeger@...ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Michael Mueller <mimu@...ux.ibm.com>,
        linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Halil Pasic <pasic@...ux.ibm.com>,
        David Hildenbrand <david@...hat.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Pierre Morel <pmorel@...ux.ibm.com>,
        Tony Krowiak <akrowiak@...ux.ibm.com>,
        Matthew Rosato <mjrosato@...ux.ibm.com>,
        Niklas Schnelle <schnelle@...ux.ibm.com>, farman@...ux.ibm.com,
        kvm@...r.kernel.org
Subject: [PATCH 2/3] 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.

Signed-off-by: Halil Pasic <pasic@...ux.ibm.com>
Fixes: 9f30f6216378 ("KVM: s390: add gib_alert_irq_handler()")
---
 arch/s390/kvm/interrupt.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

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;
-- 
2.25.1