KVM: powerpc: Improve DEC handling

We treated the DEC interrupt like an edge based one. This is not true for
Book3s. The DEC keeps firing until mtdec is issued again and thus clears
the interrupt line.

So let's implement this logic in KVM too. This patch moves the line clearing
from the firing of the interrupt to the mtdec emulation.

This makes PPC64 guests work without AGGRESSIVE_DEC defined.

Signed-off-by: Alexander Graf <agraf@suse.de>
Acked-by: Acked-by: Hollis Blanchard <hollis@penguinppc.org>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c
index 4a9ac6640fad..303457b2f52a 100644
--- a/arch/powerpc/kvm/emulate.c
+++ b/arch/powerpc/kvm/emulate.c
@@ -83,6 +83,9 @@ void kvmppc_emulate_dec(struct kvm_vcpu *vcpu)
 
         pr_debug("mtDEC: %x\n", vcpu->arch.dec);
 #ifdef CONFIG_PPC64
+        /* mtdec lowers the interrupt line when positive. */
+        kvmppc_core_dequeue_dec(vcpu);
+
         /* POWER4+ triggers a dec interrupt if the value is < 0 */
         if (vcpu->arch.dec & 0x80000000) {
                 hrtimer_try_to_cancel(&vcpu->arch.dec_timer);