From: Sebastian Andrzej Siewior <bige...@linutronix.de>

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 <bige...@linutronix.de>
---
 drivers/irqchip/irq-gic-v3-its.c | 60 +++++++++++++++++++++++++++-------------
 1 file changed, 41 insertions(+), 19 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 0b691d1..23c5818 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -171,6 +171,7 @@ static DEFINE_RAW_SPINLOCK(vmovp_lock);
 static DEFINE_IDA(its_vpeid_ida);
 
 #define gic_data_rdist()               (raw_cpu_ptr(gic_rdists->rdist))
+#define gic_data_rdist_cpu(cpu)                (per_cpu_ptr(gic_rdists->rdist, 
cpu))
 #define gic_data_rdist_rd_base()       (gic_data_rdist()->rd_base)
 #define gic_data_rdist_vlpi_base()     (gic_data_rdist_rd_base() + SZ_128K)
 
@@ -1738,15 +1739,17 @@ static int its_alloc_collections(struct its_node *its)
        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;
        /*
         * The pending pages have to be at least 64kB aligned,
         * hence the 'max(LPI_PENDBASE_SZ, SZ_64K)' below.
         */
-       pend_page = alloc_pages(gfp_flags | __GFP_ZERO,
-                               get_order(max_t(u32, LPI_PENDBASE_SZ, SZ_64K)));
+       order = get_order(max_t(u32, LPI_PENDBASE_SZ, SZ_64K));
+       pend_page = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL | __GFP_ZERO,
+                                    order);
        if (!pend_page)
                return NULL;
 
@@ -1762,6 +1765,28 @@ static void its_free_pending_table(struct page *pt)
                   get_order(max_t(u32, LPI_PENDBASE_SZ, SZ_64K)));
 }
 
+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();
@@ -1770,21 +1795,8 @@ static void its_cpu_init_lpis(void)
 
        /* If we didn't allocate the pending table yet, do it now */
        pend_page = gic_data_rdist()->pend_page;
-       if (!pend_page) {
-               phys_addr_t paddr;
-
-               pend_page = its_allocate_pending_table(GFP_NOWAIT);
-               if (!pend_page) {
-                       pr_err("Failed to allocate PENDBASE for CPU%d\n",
-                              smp_processor_id());
-                       return;
-               }
-
-               paddr = page_to_phys(pend_page);
-               pr_info("CPU%d: using LPI pending table @%pa\n",
-                       smp_processor_id(), &paddr);
-               gic_data_rdist()->pend_page = pend_page;
-       }
+       if (!pend_page)
+               return;
 
        /* Disable LPIs */
        val = readl_relaxed(rbase + GICR_CTLR);
@@ -2603,7 +2615,7 @@ static int its_vpe_init(struct its_vpe *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;
@@ -3350,6 +3362,16 @@ int __init its_init(struct fwnode_handle *handle, struct 
rdists *rdists,
        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;
 
-- 
2.10.5

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