[PATCH 4/4] KVM: ioapic: reinject pending interrupts on KVM_SET_IRQCHIP

[Gavin Guo]

From: Paolo Bonzini <pbonzini at redhat.com>

BugLink: https://bugs.launchpad.net/bugs/1791286

After the previous patches, an interrupt whose bit is set in the IRR
register will never be in the LAPIC's IRR and has never been injected
on the migration source.  So inject it on the destination.

This fixes migration of Windows guests without HPET (they use the RTC
to trigger the scheduler tick, and lose it after migration).

Reviewed-by: Alex Williamson <alex.williamson at redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
(cherry picked from commit 673f7b4257a1fe7b181e1a1182ecc2b6b2b795f1)
Signed-off-by: Gavin Guo <gavin.guo at canonical.com>
---
 virt/kvm/ioapic.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
index 6f6460a7c562..05bdad6c6369 100644
--- a/virt/kvm/ioapic.c
+++ b/virt/kvm/ioapic.c
@@ -213,6 +213,18 @@ out:
 	return ret;
 }
 
+static void kvm_ioapic_inject_all(struct kvm_ioapic *ioapic, unsigned long irr)
+{
+	u32 idx;
+
+	rtc_irq_eoi_tracking_reset(ioapic);
+	for_each_set_bit(idx, &irr, IOAPIC_NUM_PINS)
+		ioapic_set_irq(ioapic, idx, 1, true);
+
+	kvm_rtc_eoi_tracking_restore_all(ioapic);
+}
+
+
 static void update_handled_vectors(struct kvm_ioapic *ioapic)
 {
 	DECLARE_BITMAP(handled_vectors, 256);
@@ -612,9 +624,10 @@ int kvm_set_ioapic(struct kvm *kvm, struct kvm_ioapic_state *state)
 
 	spin_lock(&ioapic->lock);
 	memcpy(ioapic, state, sizeof(struct kvm_ioapic_state));
+	ioapic->irr = 0;
 	update_handled_vectors(ioapic);
 	kvm_vcpu_request_scan_ioapic(kvm);
-	kvm_rtc_eoi_tracking_restore_all(ioapic);
+	kvm_ioapic_inject_all(ioapic, state->irr);
 	spin_unlock(&ioapic->lock);
 	return 0;
 }
-- 
2.7.4