Patch "KVM: s390: preserve deliverable_mask in __airqs_kick_single_vcpu" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    KVM: s390: preserve deliverable_mask in __airqs_kick_single_vcpu

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     kvm-s390-preserve-deliverable_mask-in-__airqs_kick_s.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 17dce6cc480826927a83323a9f828cd569717263
Author: Halil Pasic <pasic@xxxxxxxxxxxxx>
Date:   Tue Oct 19 19:54:00 2021 +0200

    KVM: s390: preserve deliverable_mask in __airqs_kick_single_vcpu
    
    [ Upstream commit 0e9ff65f455dfd0a8aea5e7843678ab6fe097e21 ]
    
    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 <pasic@xxxxxxxxxxxxx>
    Reviewed-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
    Reviewed-by: Michael Mueller <mimu@xxxxxxxxxxxxx>
    Reviewed-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20211019175401.3757927-3-pasic@xxxxxxxxxxxxx
    Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index fa9483aa4f57..fd73a8aa89d2 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -2987,13 +2987,14 @@ 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;