KVM: PPC: Book3S HV: Don't use existing "prodded" flag for XIVE escalations

The prodded flag is only cleared at the beginning of H_CEDE,
so every time we have an escalation, we will cause the *next*
H_CEDE to return immediately.

Instead use a dedicated "irq_pending" flag to indicate that
a guest interrupt is pending for the VCPU. We don't reuse the
existing exception bitmap so as to avoid expensive atomic ops.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 3aa5b57..bfe5135 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -709,6 +709,7 @@ struct kvm_vcpu_arch {
 	u8 ceded;
 	u8 prodded;
 	u8 doorbell_request;
+	u8 irq_pending; /* Used by XIVE to signal pending guest irqs */
 	u32 last_inst;
 
 	struct swait_queue_head *wqp;