powerpc/xive: introduce a common routine xive_queue_page_alloc()

This routine will be used in the spapr backend. Also introduce a short
xive_alloc_order() helper.
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/sysdev/xive/common.c

@@ -1428,6 +1428,22 @@ bool __init xive_core_init(const struct xive_ops *ops, void __iomem *area, u32 o
 	return true;
 }
 
+__be32 *xive_queue_page_alloc(unsigned int cpu, u32 queue_shift)
+{
+	unsigned int alloc_order;
+	struct page *pages;
+	__be32 *qpage;
+
+	alloc_order = xive_alloc_order(queue_shift);
+	pages = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL, alloc_order);
+	if (!pages)
+		return ERR_PTR(-ENOMEM);
+	qpage = (__be32 *)page_address(pages);
+	memset(qpage, 0, 1 << queue_shift);
+
+	return qpage;
+}
+
 static int __init xive_off(char *arg)
 {
 	xive_cmdline_disabled = true;

arch/powerpc/sysdev/xive/native.c

@@ -202,17 +202,12 @@ EXPORT_SYMBOL_GPL(xive_native_disable_queue);
 static int xive_native_setup_queue(unsigned int cpu, struct xive_cpu *xc, u8 prio)
 {
 	struct xive_q *q = &xc->queue[prio];
-	unsigned int alloc_order;
-	struct page *pages;
 	__be32 *qpage;
 
-	alloc_order = (xive_queue_shift > PAGE_SHIFT) ?
-		(xive_queue_shift - PAGE_SHIFT) : 0;
-	pages = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL, alloc_order);
-	if (!pages)
-		return -ENOMEM;
-	qpage = (__be32 *)page_address(pages);
-	memset(qpage, 0, 1 << xive_queue_shift);
+	qpage = xive_queue_page_alloc(cpu, xive_queue_shift);
+	if (IS_ERR(qpage))
+		return PTR_ERR(qpage);
+
 	return xive_native_configure_queue(get_hard_smp_processor_id(cpu),
 					   q, prio, qpage, xive_queue_shift, false);
 }
@@ -227,8 +222,7 @@ static void xive_native_cleanup_queue(unsigned int cpu, struct xive_cpu *xc, u8
 	 * from an IPI and iounmap isn't safe
 	 */
 	__xive_native_disable_queue(get_hard_smp_processor_id(cpu), q, prio);
-	alloc_order = (xive_queue_shift > PAGE_SHIFT) ?
-		(xive_queue_shift - PAGE_SHIFT) : 0;
+	alloc_order = xive_alloc_order(xive_queue_shift);
 	free_pages((unsigned long)q->qpage, alloc_order);
 	q->qpage = NULL;
 }

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

@@ -56,6 +56,12 @@ struct xive_ops {
 
 bool xive_core_init(const struct xive_ops *ops, void __iomem *area, u32 offset,
 		    u8 max_prio);
+__be32 *xive_queue_page_alloc(unsigned int cpu, u32 queue_shift);
+
+static inline u32 xive_alloc_order(u32 queue_shift)
+{
+	return (queue_shift > PAGE_SHIFT) ? (queue_shift - PAGE_SHIFT) : 0;
+}
 
 extern bool xive_cmdline_disabled;