powerpc/powernv: Fix CPU hotplug to handle waking on HVI

The IPIs come in as HVI not EE, so we need to test the appropriate
SRR1 bits. The encoding is such that it won't have false positives
on P7 and P8 so we can just test it like that. We also need to handle
the icp-opal variant of the flush.

Fixes: d74361881f ("powerpc/xics: Add ICP OPAL backend")
Cc: stable@vger.kernel.org # v4.8+
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/sysdev/xics/icp-opal.c

@@ -132,6 +132,35 @@ static irqreturn_t icp_opal_ipi_action(int irq, void *dev_id)
 	return smp_ipi_demux();
 }
 
+/*
+ * Called when an interrupt is received on an off-line CPU to
+ * clear the interrupt, so that the CPU can go back to nap mode.
+ */
+void icp_opal_flush_interrupt(void)
+{
+	unsigned int xirr;
+	unsigned int vec;
+
+	do {
+		xirr = icp_opal_get_xirr();
+		vec = xirr & 0x00ffffff;
+		if (vec == XICS_IRQ_SPURIOUS)
+			break;
+		if (vec == XICS_IPI) {
+			/* Clear pending IPI */
+			int cpu = smp_processor_id();
+			kvmppc_set_host_ipi(cpu, 0);
+			opal_int_set_mfrr(get_hard_smp_processor_id(cpu), 0xff);
+		} else {
+			pr_err("XICS: hw interrupt 0x%x to offline cpu, "
+			       "disabling\n", vec);
+			xics_mask_unknown_vec(vec);
+		}
+
+		/* EOI the interrupt */
+	} while (opal_int_eoi(xirr) > 0);
+}
+
 #endif /* CONFIG_SMP */
 
 static const struct icp_ops icp_opal_ops = {