powerpc/xive: Use the "ibm, chip-id" property only under PowerNV

The 'chip_id' field of the XIVE CPU structure is used to choose a
target for a source located on the same chip. For that, the XIVE
driver queries the chip identifier from the "ibm,chip-id" property
and compares it to a 'src_chip' field identifying the chip of a
source. This information is only available on the PowerNV platform,
'src_chip' being assigned to XIVE_INVALID_CHIP_ID under pSeries.

The "ibm,chip-id" property is also not available on all platforms. It
was first introduced on PowerNV and later, under QEMU for pSeries/KVM.
However, the property is not part of PAPR and does not exist under
pSeries/PowerVM.

Assign 'chip_id' to XIVE_INVALID_CHIP_ID by default and let the
PowerNV platform override the value with the "ibm,chip-id" property.
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210413130352.1183267-1-clg@kaod.org

arch/powerpc/sysdev/xive/common.c

@@ -1413,17 +1413,14 @@ static int xive_prepare_cpu(unsigned int cpu)
 
 	xc = per_cpu(xive_cpu, cpu);
 	if (!xc) {
-		struct device_node *np;
-
 		xc = kzalloc_node(sizeof(struct xive_cpu),
 				  GFP_KERNEL, cpu_to_node(cpu));
 		if (!xc)
 			return -ENOMEM;
-		np = of_get_cpu_node(cpu, NULL);
-		if (np)
-			xc->chip_id = of_get_ibm_chip_id(np);
-		of_node_put(np);
 		xc->hw_ipi = XIVE_BAD_IRQ;
+		xc->chip_id = XIVE_INVALID_CHIP_ID;
+		if (xive_ops->prepare_cpu)
+			xive_ops->prepare_cpu(cpu, xc);
 
 		per_cpu(xive_cpu, cpu) = xc;
 	}

arch/powerpc/sysdev/xive/native.c

@@ -380,6 +380,11 @@ static void xive_native_update_pending(struct xive_cpu *xc)
 	}
 }
 
+static void xive_native_prepare_cpu(unsigned int cpu, struct xive_cpu *xc)
+{
+	xc->chip_id = cpu_to_chip_id(cpu);
+}
+
 static void xive_native_setup_cpu(unsigned int cpu, struct xive_cpu *xc)
 {
 	s64 rc;
@@ -462,6 +467,7 @@ static const struct xive_ops xive_native_ops = {
 	.match			= xive_native_match,
 	.shutdown		= xive_native_shutdown,
 	.update_pending		= xive_native_update_pending,
+	.prepare_cpu		= xive_native_prepare_cpu,
 	.setup_cpu		= xive_native_setup_cpu,
 	.teardown_cpu		= xive_native_teardown_cpu,
 	.sync_source		= xive_native_sync_source,

arch/powerpc/sysdev/xive/xive-internal.h

@@ -44,6 +44,7 @@ struct xive_ops {
 				  u32 *sw_irq);
 	int	(*setup_queue)(unsigned int cpu, struct xive_cpu *xc, u8 prio);
 	void	(*cleanup_queue)(unsigned int cpu, struct xive_cpu *xc, u8 prio);
+	void	(*prepare_cpu)(unsigned int cpu, struct xive_cpu *xc);
 	void	(*setup_cpu)(unsigned int cpu, struct xive_cpu *xc);
 	void	(*teardown_cpu)(unsigned int cpu, struct xive_cpu *xc);
 	bool	(*match)(struct device_node *np);