KVM: PPC: Book 3S: XICS: Implement ICS P/Q states

This patch implements P(Presented)/Q(Queued) states for ICS irqs.

When the interrupt is presented, set P. Present if P was not set.
If P is already set, don't present again, set Q.
When the interrupt is EOI'ed, move Q into P (and clear Q). If it is
set, re-present.

The asserted flag used by LSI is also incorporated into the P bit.

When the irq state is saved, P/Q bits are also saved, they need some
qemu modifications to be recognized and passed around to be restored.
KVM_XICS_PENDING bit set and saved should also indicate
KVM_XICS_PRESENTED bit set and saved. But it is possible some old
code doesn't have/recognize the P bit, so when we restore, we set P
for PENDING bit, too.

The idea and much of the code come from Ben.

Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

arch/powerpc/include/uapi/asm/kvm.h

@@ -613,5 +613,7 @@ struct kvm_get_htab_header {
 #define  KVM_XICS_LEVEL_SENSITIVE	(1ULL << 40)
 #define  KVM_XICS_MASKED		(1ULL << 41)
 #define  KVM_XICS_PENDING		(1ULL << 42)
+#define  KVM_XICS_PRESENTED		(1ULL << 43)
+#define  KVM_XICS_QUEUED		(1ULL << 44)
 
 #endif /* __LINUX_KVM_POWERPC_H */