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KVM: x86: ioapic: Fix level-triggered EOI and userspace I/OAPIC reconfigure race

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When scanning userspace I/OAPIC entries, intercept EOI for level-triggered
IRQs if the current vCPU has a pending and/or in-service IRQ for the
vector in its local API, even if the vCPU doesn't match the new entry's
destination.  This fixes a race between userspace I/OAPIC reconfiguration
and IRQ delivery that results in the vector's bit being left set in the
remote IRR due to the eventual EOI not being forwarded to the userspace
I/OAPIC.

Commit 0fc5a36dd6 ("KVM: x86: ioapic: Fix level-triggered EOI and IOAPIC
reconfigure race") fixed the in-kernel IOAPIC, but not the userspace
IOAPIC configuration, which has a similar race.

Fixes: 0fc5a36dd6 ("KVM: x86: ioapic: Fix level-triggered EOI and IOAPIC reconfigure race")

Signed-off-by: Adamos Ttofari <attofari@amazon.de>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221208094415.12723-1-attofari@amazon.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Adamos Ttofari 2022-12-08 09:44:14 +00:00 committed by Paolo Bonzini
parent 55c590adfe
commit fceb3a36c2
1 changed files with 3 additions and 2 deletions
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5
arch/x86/kvm/irq_comm.c
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@ -426,8 +426,9 @@ void kvm_scan_ioapic_routes(struct kvm_vcpu *vcpu,
kvm_set_msi_irq(vcpu->kvm, entry, &irq);
if (irq.trig_mode &&
kvm_apic_match_dest(vcpu, NULL, APIC_DEST_NOSHORT,
irq.dest_id, irq.dest_mode))
(kvm_apic_match_dest(vcpu, NULL, APIC_DEST_NOSHORT,
irq.dest_id, irq.dest_mode) ||
kvm_apic_pending_eoi(vcpu, irq.vector)))
__set_bit(irq.vector, ioapic_handled_vectors);
}
}