From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Fri, 13 Jul 2018 15:45:36 +0200
Subject: irqchip/gic-v3-its: Move ITS' ->pend_page allocation into an early
 CPU up hook
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
Git-commit: e1301e80afde312f1a2d9c4b9dbcc26ee51cb400
Patch-mainline: Queued in subsystem maintainer repository
References: SLE Realtime Extension

[ Upstream commit e083f14dc2e98ced872bf077b4d1cccf95b7e4f8 ]

The AP-GIC-starting hook allocates memory for the ->pend_page while the
CPU is started during boot-up. This callback is invoked on the target
CPU with disabled interrupts.
This does not work on -RT beacuse memory allocations are not possible
with disabled interrupts.
Move the memory allocation to an earlier hotplug step which invoked with
enabled interrupts on the boot CPU.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Mike Galbraith <mgalbraith@suse.de>
---
 drivers/irqchip/irq-gic-v3-its.c |   42 +++++++++++++++++++++++++++++++++++----
 1 file changed, 38 insertions(+), 4 deletions(-)

--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -1989,12 +1989,14 @@ static int its_alloc_collections(struct
 	return 0;
 }
 
-static struct page *its_allocate_pending_table(gfp_t gfp_flags)
+static struct page *its_allocate_pending_table(unsigned int cpu)
 {
 	struct page *pend_page;
+	unsigned int order;
 
-	pend_page = alloc_pages(gfp_flags | __GFP_ZERO,
-				get_order(LPI_PENDBASE_SZ));
+	order = get_order(LPI_PENDBASE_SZ);
+	pend_page = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL | __GFP_ZERO,
+				     order);
 	if (!pend_page)
 		return NULL;
 
@@ -2065,6 +2067,28 @@ static int __init allocate_lpi_tables(vo
 	return 0;
 }
 
+static int its_alloc_pend_page(unsigned int cpu)
+{
+	struct page *pend_page;
+	phys_addr_t paddr;
+
+	pend_page = gic_data_rdist_cpu(cpu)->pend_page;
+	if (pend_page)
+		return 0;
+
+	pend_page = its_allocate_pending_table(cpu);
+	if (!pend_page) {
+		pr_err("Failed to allocate PENDBASE for CPU%d\n",
+		       smp_processor_id());
+		return -ENOMEM;
+	}
+
+	paddr = page_to_phys(pend_page);
+	pr_info("CPU%d: using LPI pending table @%pa\n", cpu, &paddr);
+	gic_data_rdist_cpu(cpu)->pend_page = pend_page;
+	return 0;
+}
+
 static void its_cpu_init_lpis(void)
 {
 	void __iomem *rbase = gic_data_rdist_rd_base();
@@ -2957,7 +2981,7 @@ static int its_vpe_init(struct its_vpe *
 		return vpe_id;
 
 	/* Allocate VPT */
-	vpt_page = its_allocate_pending_table(GFP_KERNEL);
+	vpt_page = its_allocate_pending_table(raw_smp_processor_id());
 	if (!vpt_page) {
 		its_vpe_id_free(vpe_id);
 		return -ENOMEM;
@@ -3823,6 +3847,16 @@ int __init its_init(struct fwnode_handle
 	if (err)
 		return err;
 
+	err = cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "irqchip/arm/gicv3:prepare",
+				its_alloc_pend_page, NULL);
+	if (err < 0) {
+		pr_warn("ITS: Can't register CPU-hoplug callback.\n");
+		return err;
+	}
+	err = its_alloc_pend_page(smp_processor_id());
+	if (err < 0)
+		return err;
+
 	list_for_each_entry(its, &its_nodes, entry)
 		has_v4 |= its->is_v4;