From 33ffc9a93a1d9e72594d5eb3e4fc583a1a2911d1 Mon Sep 17 00:00:00 2001
From: Jianyong Wu <jianyong.wu@arm.com>
Date: Tue, 19 Feb 2019 01:15:32 -0500
Subject: [PATCH 2/5] Enable memory-hotplug using probe for arm64

---
 arch/arm64/Kconfig   |  7 +++++++
 arch/arm64/mm/init.c |  9 ++++++++-
 arch/arm64/mm/mmu.c  | 17 +++++++++++++++++
 arch/arm64/mm/numa.c | 10 ++++++++++
 4 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 1b1a0e95c751..881bea194d53 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -740,6 +740,13 @@ config NUMA
 	  local memory of the CPU and add some more
 	  NUMA awareness to the kernel.
 
+config ARCH_MEMORY_PROBE
+	def_bool y
+	depends on MEMORY_HOTPLUG
+
+config ARCH_ENABLE_MEMORY_HOTPLUG
+	def_bool y
+
 config NODES_SHIFT
 	int "Maximum NUMA Nodes (as a power of 2)"
 	range 1 10
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 787e27964ab9..e66e44b7bafe 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -288,9 +288,16 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max)
 int pfn_valid(unsigned long pfn)
 {
 	phys_addr_t addr = pfn << PAGE_SHIFT;
-
 	if ((addr >> PAGE_SHIFT) != pfn)
 		return 0;
+
+#ifdef CONFIG_SPARSEMEM
+	if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
+		return 0;
+
+	if (!valid_section(__nr_to_section(pfn_to_section_nr(pfn))))
+		return 0;
+#endif
 	return memblock_is_map_memory(addr);
 }
 EXPORT_SYMBOL(pfn_valid);
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 8080c9f489c3..c393b37597af 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1028,3 +1028,20 @@ int pud_free_pmd_page(pud_t *pudp, unsigned long addr)
 	pmd_free(NULL, table);
 	return 1;
 }
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+int arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap,
+		    bool want_memblock)
+{
+	int flags = 0;
+
+	if (debug_pagealloc_enabled())
+		flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
+
+	__create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start),
+			     size, PAGE_KERNEL, pgd_pgtable_alloc, flags);
+
+	return __add_pages(nid, start >> PAGE_SHIFT, size >> PAGE_SHIFT,
+			   altmap, want_memblock);
+}
+#endif
diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
index 146c04ceaa51..d276bd4d38b5 100644
--- a/arch/arm64/mm/numa.c
+++ b/arch/arm64/mm/numa.c
@@ -464,3 +464,13 @@ void __init arm64_numa_init(void)
 
 	numa_init(dummy_numa_init);
 }
+
+/*
+ * We hope that we will be hotplugging memory on nodes we already know about,
+ * such that acpi_get_node() succeeds and we never fall back to this...
+ */
+int memory_add_physaddr_to_nid(u64 addr)
+{
+	pr_warn("Unknown node for memory at 0x%llx, assuming node 0\n", addr);
+	return 0;
+}
-- 
2.20.1