2 files changed, 55 insertions, 4 deletions

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 74c22741f3ce..f860733d3e4e 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -47,6 +47,8 @@
 #define RDIST_FLAGS_RD_TABLES_PREALLOCATED	(1 << 1)
 
 #define RD_LOCAL_LPI_ENABLED                    BIT(0)
+#define RD_LOCAL_PENDTABLE_PREALLOCATED         BIT(1)
+#define RD_LOCAL_MEMRESERVE_DONE                BIT(2)
 
 static u32 lpi_id_bits;
 
@@ -3065,15 +3067,13 @@ static void its_cpu_init_lpis(void)
 		paddr &= GENMASK_ULL(51, 16);
 
 		WARN_ON(!gic_check_reserved_range(paddr, LPI_PENDBASE_SZ));
-		its_free_pending_table(gic_data_rdist()->pend_page);
-		gic_data_rdist()->pend_page = NULL;
+		gic_data_rdist()->flags |= RD_LOCAL_PENDTABLE_PREALLOCATED;
 
 		goto out;
 	}
 
 	pend_page = gic_data_rdist()->pend_page;
 	paddr = page_to_phys(pend_page);
-	WARN_ON(gic_reserve_range(paddr, LPI_PENDBASE_SZ));
 
 	/* set PROPBASE */
 	val = (gic_rdists->prop_table_pa |
@@ -3163,7 +3163,8 @@ out:
 	gic_data_rdist()->flags |= RD_LOCAL_LPI_ENABLED;
 	pr_info("GICv3: CPU%d: using %s LPI pending table @%pa\n",
 		smp_processor_id(),
-		gic_data_rdist()->pend_page ? "allocated" : "reserved",
+		gic_data_rdist()->flags & RD_LOCAL_PENDTABLE_PREALLOCATED ?
+		"reserved" : "allocated",
 		&paddr);
 }
 
@@ -5202,6 +5203,38 @@ int its_cpu_init(void)
 	return 0;
 }
 
+static int its_cpu_memreserve_lpi(unsigned int cpu)
+{
+	struct page *pend_page;
+	int ret = 0;
+
+	/* This gets to run exactly once per CPU */
+	if (gic_data_rdist()->flags & RD_LOCAL_MEMRESERVE_DONE)
+		return 0;
+
+	pend_page = gic_data_rdist()->pend_page;
+	if (WARN_ON(!pend_page)) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	/*
+	 * If the pending table was pre-programmed, free the memory we
+	 * preemptively allocated. Otherwise, reserve that memory for
+	 * later kexecs.
+	 */
+	if (gic_data_rdist()->flags & RD_LOCAL_PENDTABLE_PREALLOCATED) {
+		its_free_pending_table(pend_page);
+		gic_data_rdist()->pend_page = NULL;
+	} else {
+		phys_addr_t paddr = page_to_phys(pend_page);
+		WARN_ON(gic_reserve_range(paddr, LPI_PENDBASE_SZ));
+	}
+
+out:
+	gic_data_rdist()->flags |= RD_LOCAL_MEMRESERVE_DONE;
+	return ret;
+}
+
 static const struct of_device_id its_device_id[] = {
 	{	.compatible	= "arm,gic-v3-its",	},
 	{},
@@ -5385,6 +5418,23 @@ static void __init its_acpi_probe(void)
 static void __init its_acpi_probe(void) { }
 #endif
 
+int __init its_lpi_memreserve_init(void)
+{
+	int state;
+
+	if (!efi_enabled(EFI_CONFIG_TABLES))
+		return 0;
+
+	state = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
+				  "irqchip/arm/gicv3/memreserve:online",
+				  its_cpu_memreserve_lpi,
+				  NULL);
+	if (state < 0)
+		return state;
+
+	return 0;
+}
+
 int __init its_init(struct fwnode_handle *handle, struct rdists *rdists,
 		    struct irq_domain *parent_domain)
 {
diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index daec3309b014..9fa3e1d16721 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -1802,6 +1802,7 @@ static int __init gic_init_bases(void __iomem *dist_base,
 	if (gic_dist_supports_lpis()) {
 		its_init(handle, &gic_data.rdists, gic_data.domain);
 		its_cpu_init();
+		its_lpi_memreserve_init();
 	} else {
 		if (IS_ENABLED(CONFIG_ARM_GIC_V2M))
 			gicv2m_init(handle, gic_data.domain);